CN115051398A - Dynamic voltage compensation device and multi-mode fast switching control method thereof - Google Patents

Dynamic voltage compensation device and multi-mode fast switching control method thereof Download PDF

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CN115051398A
CN115051398A CN202210710583.1A CN202210710583A CN115051398A CN 115051398 A CN115051398 A CN 115051398A CN 202210710583 A CN202210710583 A CN 202210710583A CN 115051398 A CN115051398 A CN 115051398A
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voltage
current
load
phase
side converter
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CN115051398B (en
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陈伟
渠学景
张建绮
丁小刚
李建
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Pushon Beijing Electric Co ltd
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Pushon Beijing Electric Co ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
    • H02H7/262—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations involving transmissions of switching or blocking orders
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00002—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by monitoring
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/14—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by switching loads on to, or off from, network, e.g. progressively balanced loading
    • H02J3/144—Demand-response operation of the power transmission or distribution network
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2310/00—The network for supplying or distributing electric power characterised by its spatial reach or by the load
    • H02J2310/50—The network for supplying or distributing electric power characterised by its spatial reach or by the load for selectively controlling the operation of the loads
    • H02J2310/56—The network for supplying or distributing electric power characterised by its spatial reach or by the load for selectively controlling the operation of the loads characterised by the condition upon which the selective controlling is based
    • H02J2310/58—The condition being electrical
    • H02J2310/60—Limiting power consumption in the network or in one section of the network, e.g. load shedding or peak shaving
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Electrical Variables (AREA)

Abstract

The invention relates to the technical field of electric energy quality, and provides a dynamic voltage compensation device and a multi-mode fast switching control method thereof, which can effectively solve the transient electric energy quality problems of voltage sag, voltage rise, short-time interruption and the like, provide dynamic voltage compensation, and can realize steady-state electric energy quality index treatment of voltage deviation, voltage fluctuation, harmonic distortion and the like, compensate reactive power and improve power factors, thereby realizing multi-target electric energy quality index comprehensive treatment in a real sense and solving the defects and the defects of single function, low equipment utilization rate and the like of the conventional current or voltage treatment device.

Description

Dynamic voltage compensation device and multi-mode fast switching control method thereof
Technical Field
The invention belongs to the technical field of electric energy quality, and particularly relates to a dynamic voltage compensation device and a multi-mode fast switching control method thereof.
Background
The power quality problem is wide in range and can be generally divided into two types, namely steady state and transient state. The steady-state power quality index comprises voltage deviation (high voltage and low voltage) caused by system reactive power unbalance, harmonic distortion caused by nonlinear load, voltage fluctuation and flicker problem caused by impact load and the like; the transient power quality comprises voltage sag, voltage rise, short-time interruption and the like, the interference generating the transient power quality problem mainly comes from nature, system faults, operation and the like, if short-circuit faults are the main reasons causing most of voltage to suddenly drop or power supply interruption, the duration is about 10-50 cycles, and the coverage is very wide.
The steady state power quality problem will cause a series of harms such as equipment insulation aging, life-span decline, circuit overload, loss increase, protection automation secondary equipment maloperation, along with the improvement of the standard of living, the use of a large amount of life production electrical equipment, especially the appearance of a large amount of non-linear, impulsive load, make steady state power quality index continuously worsen, exceed standard, must comply with the principle of "who pollutes, who administers", take scientific, effective compensation and administration measures, guarantee that steady state power quality indexes such as harmonic wave, voltage fluctuation, deviation are qualified.
In addition, the transient power quality problem cannot be ignored, and the problems of voltage sag, voltage rise, short-time interruption and the like become main factors threatening the power supply reliability of sensitive loads. Through statistics, a power customer with high automation degree suffers from the interference of transient power quality problems for dozens of times every year, wherein the number of accidents caused by voltage sag and interruption accounts for about 83% of the total number of accidents, and is far more than the number of accidents caused by normal complete power supply interruption. Many sensitive loads have high requirements on the quality of electric energy, can endure power supply interruption for a short time, ensure high-quality power supply even if the system is in a transient process, otherwise cause serious adverse effects, such as a plurality of sensitive industrial users in automobile factories, chip factories, textile factories and the like, and bear huge economic losses due to transient electric energy quality interference every year.
In order to solve the above technical problems, consumer Power technology (Customer Power) based on Power electronics technology is a tool for improving Power quality, and represents technologies such as Active Power Filter (APF) and Dynamic Voltage Regulator (DVR). However, the above devices have single function and low utilization rate, and are easy to cause resource waste, for example, the APF can only filter low-order harmonics, and cannot improve steady-state power quality indexes such as voltage deviation and fluctuation, and is not helpful to transient power quality indexes; the DVR can only improve voltage sag and works for a short time, and is in a standby state under most working conditions.
Therefore, there is a need to provide an electric energy device that can effectively solve the transient electric energy quality problems such as voltage sag, voltage rise, and short-time interruption, provide dynamic voltage compensation, and achieve the management of steady-state electric energy quality indexes such as voltage deviation, voltage fluctuation, and harmonic distortion.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a dynamic voltage compensation device and a multi-mode fast switching control method thereof.
In order to achieve the technical purpose, the invention provides a dynamic voltage compensation device which comprises a power grid side current sampling mutual inductor (1), a power grid side circuit breaker (2), an input side current sampling mutual inductor (3), a thyristor bypass valve (4), a power grid side converter connecting reactor (5), a power grid side converter (6), a direct current supporting capacitor (7), a load side converter (8), a load side converter connecting reactor (9), an output side current sampling mutual inductor (10), a load side circuit breaker (11), a load direct supply circuit breaker (12) and a whole machine control protection system (13); the power grid side current sampling mutual inductor (1) is connected between the alternating current power supply inlet side and the first alternating current bus; the power grid side circuit breaker (2), the input side current sampling mutual inductor (3), the power grid side converter connecting reactor (5) and the power grid side converter (6) are sequentially connected in series between the first alternating current bus and the direct current bus; the load direct supply breaker (12), the load side breaker (11), the output side current sampling mutual inductor (10), the load side converter connecting reactor (9) and the load side converter (8) are sequentially connected in series between the first alternating current bus and the direct current bus; the thyristor bypass valve (4) is connected in series between the outlet end of the input side current sampling transformer (3) and the input end of the output side current sampling transformer (10); the power grid side converter (6) and the load side converter (8) are respectively connected to two sides of the direct current support capacitor (7); and the whole machine control protection system (13) receives sampling signals of the power grid side current sampling mutual inductor (1) and the output side current sampling mutual inductor (10) and outputs control signals to the thyristor bypass valve (4), the power grid side current converter (6) and the load side current converter (8).
Preferably, the grid side current sampling mutual inductor (1) is three single-phase current mutual inductors which respectively sample phase-A, phase-B and phase-C current signals I of the inlet side of the alternating current power supply a 、I b 、I c The three-phase current sampling signal I a 、I b 、I c Input to the whole machine control protection system (13).
Preferably, the grid-side circuit breaker (2) is a three-phase circuit breaker.
Preferably, the input side current sampling mutual inductor (3) is three single-phase current mutual inductors, and three-phase current signals I between the power grid side circuit breaker (2) and the power grid side converter connecting reactor (5) are respectively sampled a1 、I b1 、I c1 The three-phase current sampling signal I a1 、I b1 、I c1 Input to the whole machine control protection system (13).
Preferably, the thyristor bypass valve (4) comprises 6 thyristors, T1, T2, T3, T4, T5 and T6, which are connected in a reverse parallel mode and are divided into three groups, wherein T1 and T2 are connected in a reverse parallel mode and are connected to phase A, T3 and T4 are connected to phase B in a reverse parallel mode, and T5 and T6 are connected to phase C in a reverse parallel mode.
Preferably, the grid-side converter connecting reactor (5) is composed of three reactors L a1 、L b1 、L c1 Composition of the reactor L a1 、L b1 、L c1 The three-phase reactor is respectively connected in series between the input side current sampling mutual inductor (3) and the power grid side converter (6), and the inductance values of the three-phase reactor are all first inductance values L1.
Preferably, the grid-side converter (6) comprises six turn-off only devices V11, V12, V13, V14, V15, V16 and diodes connected in anti-parallel therewith, in a three-phase bridge voltage source connection.
Preferably, the load side converter (8) comprises six turn-off only devices V21, V22, V23, V24, V25, V26 and diodes connected in anti-parallel therewith, in a three-phase bridge voltage source connection.
Preferably, the load-side converter connecting reactor (9) is composed of three reactors L a2 、L b2 、L c2 Composition of the reactor L a2 、L b2 、L c2 The three-phase current sampling mutual inductors (10) are respectively connected in series between the load-side converter (8) and the output-side current sampling mutual inductor (10), and the inductance values of the three-phase reactors are all second inductance values L2.
Preferably, the output side current sampling mutual inductor (10) adopts three single-phase current mutual inductors, and three-phase current signals I between the load side circuit breaker (11) and the load side converter connecting reactor (9) are respectively sampled a2 、I b2 、I c2 The three-phase current sampling signal I a2 、I b2 、I c2 Input to the whole machine control protection system (13).
Preferably, the load side circuit breaker (11) and the load direct acting circuit breaker (12) are not closed at the same time.
Preferably, the whole machine control protection system (13) adopts a digital programmable processor to realize the functions of signal conversion, index calculation, logic control, PWM pulse signal output and the like, and outputs four groups of control signals which are respectively a thyristor bypass valve (4) on-off signal, a power grid side converter (6) three-phase PWM pulse signal, a load side converter (8) three-phase PWM pulse signal and a direct current conventional load 1-n power supply loop circuit breaker on-off control signal.
The invention also provides a multi-mode fast switching control method applied to the dynamic voltage compensation device, which comprises the following steps:
the first step is to open the load direct-current breaker (12), manually throw in the grid-side breaker (2) and the load-side breaker (11), and set the operating state constant value of the dynamic voltage compensation device: high voltage action constant value U set1 Low voltage action constant value U set2 DC voltage operation value U dcset Maximum inductive reactive current I in dynamic reactive support mode Lmax Maximum capacitive reactive current I in dynamic reactive support mode Cmax Transient output voltage U dset ；
Secondly, when the voltage of the alternating current power supply is normal, namely the three-phase voltage signals of the first alternating current bus simultaneously meet the requirement of U set1 >U a1 >U set2 、U set1 >U b1 >U set2 、U set1 >U c1 >U set2 When the direct current voltage is in a zero voltage state, the complete machine control protection system (13) outputs a continuous conduction signal of the thyristor bypass valve (4), the power grid side converter (6) works according to a first control method of the power grid side converter, and the direct current voltage operation value U is obtained through the operation method dcset And DC bus voltage U dc The difference value of (A) is input into a PI regulator, and the three-phase current sampling signal I a 、I b 、I c With said three-phase voltage signal U a1 、U b1 、U c1 After reactive power calculation, the three-phase current is reversely input into a PI regulator, and the three-phase current is sampled a1 、I b1 、I c1 With said three-phase voltage signal U a1 、U b1 、U c1 Dq conversion is respectively carried out, output signals of the two PI regulators and the dq conversion and an inductance value L1 of the power grid side converter connecting reactor (5) are subjected to inner loop decoupling control, then subjected to dq inverse conversion and PWM modulation, and then PWM control signals of the power grid side converter (6) are output, so that the direct current voltage is gradually increased to a target value, and power utilization conditions of a direct current power supply, a direct current conventional load and a direct current sensitive load are met; the load side converter (8) operates according to a first control method of the load side converter (8) and samples the three-phase current I a 、I b 、I c After difference values are respectively obtained with current values obtained after dq conversion, low-pass filtering and dq inverse conversion, PWM control signals of the load side converter (8) are output through a hysteresis comparator and a D trigger so as to output harmonic currents which are opposite in phase and equal in amplitude to the sampling point harmonic currents and reduce the harmonic currents of the nonlinear load injected into a power grid;
thirdly, when the voltage of the alternating current power supply is abnormal, namely the three-phase voltage signal of the first alternating current bus appears as U a1 >U set1 、U b1 >U set1 、U c1 >U set1 、U a1 <U set1 、U b1 <U set2 、U c1 <U set2 In either case; under the two second control methods, the complete machine control protection system (13) stops sending the trigger signal of the thyristor bypass valve (4) and simultaneously sends control signals to the grid side converter (6) and the load side converter (8) so as to rapidly turn off the thyristor bypass valve (4);
fourthly, when the alternating voltage returns to normal, namely the three-phase voltage signals of the first alternating current bus simultaneously meet the requirement of U set1 >U a1 >U set2 、U set1 >U b1 >U set2 、U set1 >U c1 >U set2 And then, the complete machine control protection system (13) sends out a continuous conduction signal of the thyristor bypass valve (4), the power grid side converter (6) is switched to the first control method of the power grid side converter to continue working, and the load side converter (8) is switched to the first control method of the load side converter to continue working.
Preferably, the control method further comprises that after all three phases of the thyristor bypass valve (4) are turned off, the grid side converter (6) and the load side converter (8) are switched to a third control method to work; wherein the third control method of the grid-side converter (6) comprises the step of setting the DC voltage operation value U dcset And DC bus voltage U dc The difference value of (A) is input into a PI regulator, and the three-phase current sampling signal I a1 、I b1 、I c1 With said three-phase voltage signal U a1 、U b1 、U c1 Reactive power calculation is carried out to obtain reactive current I q Three-phase voltage signal U a1 、U b1 、U c1 Respectively with the high-voltage action fixed value U set1 And the low voltage action fixed value U set2 Comparing the result to determine the maximum inductive reactive current I in the dynamic reactive support mode Lmax And maximum capacitive reactive current I in dynamic reactive support mode Cmax With the above-mentioned reactive current I q The difference value of (A) is input into a PI regulator, and the three-phase current sampling signal I a1 、I b1 、I c1 With said three-phase voltage signal U a1 、U b1 、U c1 Dq conversion is respectively carried out, and output signals of the two PI regulators and the dq conversion and an inductance value L1 of the power grid side converter connecting reactor (5) are subjected to dq inverse conversion and PWM modulation after inner loop decoupling control and output PWM control signals of the power grid side converter (6); the third control method of the load side converter (8) comprises the step of operating the DC voltage value U dcset D-axis component U of second AC bus voltage d2 Is inputted to the PI regulator, q-axis component U of the second AC bus voltage q2 Reverse input PI regulator, said three-phase current sampling signal I a2 、I b2 、I c2 With said three-phase voltage signal U a2 、U b2 、U c2 And d, respectively carrying out dq conversion, carrying out dq conversion on output signals of the two PI regulators and the dq conversion together with an inductance value L2 of the load side converter connecting reactor (9), carrying out dq inverse conversion and PWM modulation on the output signals after inner loop decoupling control, and outputting a PWM control signal of the load side converter (8) so as to output three-phase alternating-current voltage with stable amplitude and frequency.
Preferably, the control method further includes: when the voltage of the alternating current power supply is abnormal, the whole machine control protection system (13) sends a switching-off control signal to the circuit breakers of the power supply loops of the direct current conventional loads 1-n to enable the direct current conventional loads to quit the system when detecting voltage sag and interruption events.
Preferably, the control method further includes: when the alternating current voltage returns to normal, the complete machine control protection system (13) further comprises a switch-on control signal which is sent to the circuit breakers of the direct current conventional load 1-n power supply circuit, so that the direct current conventional load returns to power utilization.
Preferably, the control method further includes: when equipment needs to be overhauled, the power grid side circuit breaker (2) and the load side circuit breaker (11) are disconnected, the sensitive load direct supply circuit breaker (12) is closed, the device is enabled to exit from the running state, and normal electricity utilization of the sensitive load is not influenced during overhaul of the device.
Preferably, the control method further includes: the load side circuit breaker (11) and the load direct supply circuit breaker (12) are not closed at the same time.
Compared with the prior art, the invention has the advantages that:
the dynamic voltage compensation device provided by the invention not only can effectively solve the transient power quality problems of voltage sag, voltage rise, short-time interruption and the like, provide dynamic voltage compensation, but also can realize steady-state power quality index management of voltage deviation, voltage fluctuation, harmonic distortion and the like, compensate reactive power and improve power factors, thereby realizing multi-target power quality index comprehensive management in a real sense and solving the defects and shortcomings of single function, low equipment utilization rate and the like of the conventional APF or DVR device.
The dynamic voltage compensation device provided by the invention is provided with a plurality of alternating current and direct current ports, the alternating current ports are divided into alternating current conventional loads and alternating current sensitive loads, the direct current ports can be connected with a direct current power supply, and the direct current conventional loads and the direct current sensitive loads can be connected, so that the requirements of different power utilization characteristics and power supply reliability of various electrical equipment are met.
The multi-mode fast switching control method of the dynamic voltage compensation device provided by the invention decomposes the steady-state and transient-state control and compensation indexes, and the power grid side converter and the load side converter are matched with each other under various working conditions.
The dynamic voltage compensation device provided by the invention can charge the direct current bus through the residual voltage on the side of the power grid and the direct current power supply when the transient power quality problem occurs, and the voltage stability of a direct current system is ensured, so that the device does not need a large-capacity energy storage device, a direct current link can work only by a small-capacity capacitor, and the size and the weight of the device are reduced.
Electronic equipment used in the dynamic voltage compensation device provided by the invention, such as a thyristor bypass valve (4), a power grid side converter (6) and a load side converter (8), can operate in a scheduled period, and faults of any components such as devices, drives, optical fibers and the like can be timely discovered through a monitoring loop, so that the equipment can be prevented from operating with faults, and the hidden danger that the equipment cannot normally operate during transient compensation is eliminated.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts:
FIG. 1 is a preferred electrical main wiring diagram of the disclosed dynamic voltage compensation arrangement;
fig. 2 is a schematic diagram of a 1 st control strategy of a power grid side converter, namely a synchronous rectification/inversion strategy;
fig. 3 is a schematic diagram of a 2 nd control strategy of the grid-side converter disclosed by the invention, namely a thyristor fast turn-off strategy;
fig. 4 is a schematic diagram of a 3 rd control strategy of a power grid side converter, namely a dynamic reactive power support strategy;
FIG. 5 is a schematic diagram of the 1 st control strategy "steady-state harmonic cancellation strategy" of the disclosed load side converter;
FIG. 6 is a schematic diagram of the control strategy "thyristor fast turn-off strategy" of the 2 nd type of load-side converter disclosed in the present invention;
fig. 7 is a schematic diagram of a 3 rd control strategy of the load-side converter disclosed in the present invention, namely, a "constant voltage and constant frequency inversion strategy";
fig. 8 is a schematic diagram of a preferred control method of the dynamic voltage compensation device disclosed in the present invention.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, a detailed description of the present invention will be given below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.
In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention, and the described embodiments are merely a subset of the embodiments of the present invention, rather than a complete embodiment. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without any creative efforts shall fall within the protection scope of the present invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
The dynamic voltage compensation device disclosed by the invention is low-voltage equipment, adopts an alternating current 400/230V three-phase power supply for power supply, and is provided with an alternating current output bus and a direct current output bus, wherein the alternating current output bus can be connected with a plurality of groups of alternating current sensitive loads, and the direct current output bus can be connected with a direct current power supply (such as distributed photovoltaic), a direct current conventional load and a direct current sensitive load.
Under the condition of steady-state operation, the dynamic voltage compensation device compensates reactive power and harmonic current at the line inlet side of the alternating current power supply, ensures that various steady-state electric energy quality indexes such as power supply voltage deviation, voltage fluctuation, harmonic distortion rate and the like are qualified, and simultaneously improves the power factor, reduces the network loss and ensures the high-efficiency operation of a power grid; when the power supply generates transient power quality events such as voltage sag, voltage rise, short-time interruption and the like, the dynamic voltage compensation device continuously supplies power for alternating current and direct current sensitive loads by quickly switching the power supply loop, so that the power supply reliability is improved, and the economic loss caused by power failure of the sensitive loads is avoided.
The present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1, in order to achieve the above technical object, the present invention provides a dynamic voltage compensation device, which includes a grid-side current sampling transformer 1, a grid-side circuit breaker 2, an input-side current sampling transformer 3, a thyristor bypass valve 4, a grid-side converter connecting reactor 5, a grid-side converter 6, a dc support capacitor 7, a load-side converter 8, a load-side converter connecting reactor 9, an output-side current sampling transformer 10, a load-side circuit breaker 11, a load direct-supply circuit breaker 12, and a complete machine control protection system (control protection system) 13.
The power grid side current sampling mutual inductor 1 is connected between the alternating current power supply incoming line side and the first alternating current bus; the power grid side circuit breaker 2, the input side current sampling mutual inductor 3, the power grid side converter connecting reactor 5 and the power grid side converter 6 are sequentially connected in series between the first alternating current bus and the direct current bus; the load direct supply circuit breaker 12, the load side circuit breaker 11, the output side current sampling mutual inductor 10, the load side converter connecting reactor 9, and the load side converter 8 are sequentially connected in series between the first alternating current bus and the direct current bus; the thyristor bypass valve 4 is connected in series between the outlet end of the input side current sampling transformer 3 and the input end of the output side current sampling transformer 10; the grid side converter 6 and the load side converter 8 are respectively connected to two sides of the direct current support capacitor 7; the whole machine control protection system 13 receives sampling signals of the power grid side current sampling mutual inductor 1 and the output side current sampling mutual inductor 10, and outputs control signals to the thyristor bypass valve 4, the power grid side current converter 6 and the load side current converter 8.
Preferably, the grid-side current sampling transformer 1 is three single-phase current transformers, and respectively samples power of a phase a, a phase B and a phase C at the incoming line side of the alternating current power supplyStream signal I a 、I b 、I c The three-phase current sampling signal I a 、I b 、I c And inputting the data into a complete machine control and protection system 13.
Preferably, the grid-side circuit breaker 2 is a three-phase circuit breaker.
Preferably, the input-side current sampling mutual inductor 3 is three single-phase current mutual inductors, and respectively samples three-phase current signals I between the grid-side circuit breaker 2 and the grid-side converter connecting reactor 5 a1 、I b1 、I c1 The three-phase current sampling signal I a1 、I b1 、I c1 And inputting the data into a complete machine control and protection system 13.
Preferably, the thyristor bypass valve 4 comprises 6 thyristors, T1, T2, T3, T4, T5 and T6, which are connected in a reverse parallel connection mode and are divided into three groups, wherein T1 is connected in reverse parallel with T2 and is connected to phase a, T3 is connected in reverse parallel with T4 and is connected to phase B, and T5 is connected in reverse parallel with T6 and is connected to phase C.
Preferably, the grid-side converter connecting reactor 5 is composed of three reactors L a1 、L b1 、L c1 Composition of the reactor L a1 、L b1 、L c1 The three-phase reactors are respectively connected in series between the input side current sampling mutual inductor 3 and the power grid side current converter 6, and the inductance values of the three-phase reactors are all first inductance values L1.
Preferably, the grid-side converter 6 comprises six turn-off only devices V11, V12, V13, V14, V15, V16 and diodes connected in anti-parallel therewith, and is connected in a three-phase bridge voltage source connection and operated in a three-phase PWM modulation mode.
Preferably, the load-side inverter 8 includes six turn-off only devices V21, V22, V23, V24, V25, V26 and diodes connected in anti-parallel therewith, and is operated in a three-phase PWM modulation mode using a three-phase bridge voltage source connection.
Preferably, the load-side converter connecting reactor 9 is composed of three reactors L a2 、L b2 、L c2 Composition of the reactor L a2 、L b2 、L c2 Are respectively connected in series toBetween the load-side inverter 8 and the output-side current sampling transformer 10, the inductance values of the three-phase reactors are all the second inductance values L2.
Preferably, the output side current sampling mutual inductor 10 adopts three single-phase current mutual inductors, and three-phase current signals I between the load side circuit breaker 11 and the load side converter connecting reactor 9 are respectively sampled a2 、I b2 、I c2 The three-phase current sampling signal I a2 、I b2 、I c2 And inputting the data into a complete machine control and protection system 13.
Preferably, the load side circuit breaker 11 and the load direct current circuit breaker 12 are provided with a mechanical or electrical interlock, and the two circuit breakers are not closed at the same time.
Preferably, the whole machine control protection system 13 adopts a digital programmable processor to realize the functions of signal conversion, index calculation, logic control, PWM pulse signal output and the like, and outputs four groups of control signals, namely, a thyristor bypass valve 4 on/off signal, a grid side converter 6 three-phase PWM pulse signal, a load side converter 8 three-phase PWM pulse signal, and a dc conventional load 1-n power supply circuit breaker on/off control signal.
The electrical interface of the dynamic voltage compensation device is connected with three buses, namely a first alternating current bus, a second alternating current bus and a direct current bus.
For convenience of describing the electrical connection mode, the main electrical nodes inside the dynamic voltage compensation device are numbered as follows: the three-phase electrical nodes of the first AC bus are respectively marked as U a1 、U b1 、U c1 And the three-phase electrical nodes of the second alternating current bus are respectively marked as U a2 、U b2 、U c2 And the three-phase electrical nodes at the lower port side of the power grid side circuit breaker 2 are respectively marked as U a3 、U b3 、U c3 The three-phase electrical nodes at the lower port side of the load side breaker 11 are respectively marked as U a4 、U b4 、U c4 The three-phase electrical nodes on the AC side of the grid-side converter 6 are respectively marked as U a5 、U b5 、U c5 Identification of three-phase electrical nodes on the AC side of the load-side converter 8Is U a6 、U b6 、U c6 The positive and negative electrical nodes of the direct current bus are respectively marked as U dc+ 、U dc- 。
The power grid side current sampling mutual inductor 1 is marked with a terminal which is respectively connected to A, B, C phases on the incoming line side of an alternating current power supply, and a non-marked terminal which is respectively connected to A, B, C phases of a first alternating current bus and is used for measuring phase current signals of A phase, B phase and C phase on the incoming line side of the alternating current power supply and three-phase current sampling signals I a 、I b 、I c And inputting the data into a complete machine control and protection system 13.
The upper port of the power grid side circuit breaker 2 is connected to a first alternating current bus, and the lower port of the power grid side circuit breaker is connected to the marked star end of the input side current sampling mutual inductor 3.
The current sampling mutual inductor 3 with the input side is marked with a 'terminal' and is respectively connected to the lower port of the circuit breaker 2 on the power grid side, and the non-marked 'terminal' is respectively connected to an electrical node U a3 、U b3 、U c3 。
Left side of thyristor bypass valve 4 is connected to electrical node U a3 、U b3 、U c3 Right side connected to electrical node U a4 、U b4 、U c4 . Thyristors T1 and T2 are connected in parallel in a positive and negative way and then connected with an electric node U a3 And U a4 The thyristors T3 and T4 are connected in parallel in a positive and negative way and then connected with an electrical node U b3 And U b4 The thyristors T5 and T6 are connected in parallel in a positive and negative way and then connected with an electrical node U c3 And U c4 In the meantime.
Grid side converter connecting reactor 5 is marked with a side and connected to an electrical node U a3 、U b3 、U c3 The non-marked "" side of which is connected to an electrical node U on the AC side of the grid-side converter 6 a5 、U b5 、U c5 。
AC side electric node U of power grid side converter 6 a5 、U b5 、U c5 The connection reactor 5 connected to the grid side converter is connected to the non-marked star side, and the middle point of the series connection of the internal V11 and the V14 is connected to an electric terminal U a5 V13 and V16 are connected in series and then are connected to an electrical terminal U in a middle-point mode b5 V15 and V12 are connected in series and then are connected to an electrical terminal U in a middle-point mode c5 Set of three devices V11, V13 and V15Electrodes are shorted together to a DC positive bus U dc+ The emitters of the three devices V14, V16 and V12 are connected together in short to a DC negative bus U dc- 。
The positive terminal of the DC support capacitor 7 is connected to the DC positive bus U dc+ The negative terminal is connected to a DC negative bus U dc- 。
AC side electrical node U of load side converter 8 a6 、U b6 、U c6 Connected to the load side converter connecting reactor 9 at the non-marked star side, and connected to the electric terminal U at the midpoint after the internal V21 and V24 are connected in series a6 V23 and V26 are connected in series and then are connected to an electrical terminal U in a middle-point mode b6 V25 and V22 are connected in series and then are connected to an electrical terminal U in a middle-point mode c6 The collectors of the three devices V21, V23 and V25 are connected together in short to a direct current positive bus U dc+ The emitters of the three devices V24, V26 and V22 are connected together in short to a DC negative bus U dc- 。
The load side converter connecting reactor 9 is marked with a side which is connected to the non-marked side of the output side current sampling mutual inductor 10, and the non-marked side is connected to the alternating current side electric node U of the load side converter 8 a6 、U b6 、U c6 。
The output side current sampling transformer 10 is marked with a "+" side and connected to an electrical node U a4 、U b4 、U c4 The non-labeled "-side is connected to the load-side converter connection reactor 9 labeled" ".
The upper port of the load side breaker 11 is connected to a three-phase electrical node U of a second alternating current bus a2 、U b2 、U c2 Lower port connected to electrical node U a4 、U b4 、U c4 。
The upper port of the load direct supply breaker 12 is connected to a first alternating current bus three-phase electrical node U a1 、U b1 、U c1 The lower port is connected to a second AC bus three-phase electrical node U a2 、U b2 、U c2 。
Six groups of electric quantity signals are input into the whole machine control protection system 13 and are respectively a first alternating current bus three-phase voltage signal U a1 、U b1 、U c1 Second AC bus three-phase voltage signal U a2 、U b2 、U c2 Positive and negative voltage signals U of DC bus dc Sampling signal I of three-phase current at inlet side of AC power supply a 、I b 、I c Input side three-phase current sampling signal I a1 、I b1 、I c1 Output side three-phase current sampling signal I a2 、I b2 、I c2 . The whole machine control protection system 13 outputs four groups of control signals, namely a thyristor bypass valve 4 on-off signal, a grid side converter 6PWM pulse signal, a load side converter 8PWM pulse signal and a direct current conventional load 1-n power supply loop circuit breaker on-off control signal.
The operation principle of the dynamic voltage compensation device disclosed in the present invention is explained below.
Ac and dc electric equipment (including power supply and load) is divided into five categories: the system comprises an alternating current conventional load, an alternating current sensitive load, a direct current conventional load, a direct current sensitive load and a direct current power supply. Wherein the AC conventional load is completely connected to the three-phase electrical node U of the first AC bus a1 、U b1 、U c1 The AC sensitive load is connected to the three-phase electrical node U of the second AC bus a2 、U b2 、U c2 The direct current conventional load, the direct current sensitive load and the direct current power supply are all connected to the positive electrode electrical node U of the direct current bus dc+ And negative electrical node U dc- 。
When the power grid side circuit breaker 2 and the load side circuit breaker 11 are disconnected and the load direct supply circuit breaker 12 is closed, the dynamic voltage compensation device enters an overhaul isolation state, an alternating current power supply supplies power to an alternating current conventional load through a first alternating current bus, an alternating current sensitive load through a second alternating current bus, the first alternating current bus and the second alternating current bus are equal to the same bus, and the direct current conventional load, the direct current sensitive load and the direct current power supply which are connected to the direct current bus exit the operation; when the power grid side circuit breaker 2 and the load side circuit breaker 11 are closed and the load direct supply circuit breaker 12 is disconnected, the device exits from maintenance and isolation and enters a working state, the first alternating current bus supplies power for the alternating current conventional load, the second alternating current bus supplies power for the alternating current sensitive load, and the direct current conventional load, the direct current sensitive load and the direct current power supply connected to the direct current bus are put into operation.
Preferably, the control method of the dynamic voltage compensation device disclosed by the invention is based on a synchronous rotation coordinate system (dq coordinate system) and a corresponding proportional-integral (PI) control algorithm. The control method establishes mathematical models of the converters at the power grid side and the load side under a synchronous rotating coordinate system, converts three-phase intersection flow under an abc coordinate system into two-axis direct-current flow under a dq coordinate system, simplifies the mathematical models of the converters and simplifies the design of a controller. The power grid side converter and the load side converter both adopt an inner ring-outer ring control mode, the inner ring control is classical dq axis decoupling control, the algorithms are consistent in various modes, only the outer ring control is in different working stages, and different converters have different control targets. Both the grid side converter 6 and the load side converter 8 have 3 control strategies.
According to the invention, steady-state and transient-state control and compensation indexes are decomposed, a power grid side converter and a load side converter are matched with each other under various working conditions, the division of labor is clear, fundamental wave reactive current compensation is completed by the power grid side converter under the steady-state condition, and harmonic current compensation is completed by the load side converter; in the process of shutting down the thyristor, the grid side converter and the load side converter work in a matching way to accelerate the shutting down speed of the thyristor; in the transient state compensation process, the power grid side converter provides energy support for the load side converter, and capacitive (inductive) reactive current support is provided for a fault power grid, so that the voltage recovery speed is accelerated. The method simplifies the control strategy of the current converter, so that different current converters respectively have different control targets, thereby improving the compensation effect, reducing the electrical stress of the current converter and avoiding the overload of the current converter.
The control strategy of the grid-side converter and the load-side converter is described in detail below with reference to the accompanying drawings.
The operation state constant value of the dynamic voltage compensation device disclosed by the invention comprises the following steps: high voltage action constant value U set1 Low voltage action constant value U set2 DC voltage operation value U dcset Maximum inductive reactive current I in dynamic reactive support mode Lmax Maximum capacitive reactive current I in dynamic reactive support mode Cmax Transient output voltage U dset 。
The first control method of the grid-side converter 6 is a "synchronous rectification/inversion strategy", and the specific flow is shown in fig. 2. The first control method of the grid-side converter comprises the following steps: operating the DC voltage to a value U dcset And DC bus voltage U dc The difference value of (A) is input into a PI regulator, and the three-phase current sampling signal I a 、I b 、I c With said three-phase voltage signal U a1 、U b1 、U c1 After reactive power calculation, the three-phase current is reversely input into a PI regulator, and the three-phase current is sampled a1 、I b1 、I c1 With said three-phase voltage signal U a1 、U b1 、U c1 And d, respectively carrying out dq conversion, and outputting the output signals of the two PI regulators and the dq conversion together with the inductance L1 of the grid side converter connecting reactor 5 through dq inverse conversion and PWM modulation after inner loop decoupling control and then outputting the PWM control signal of the grid side converter 6.
Through the first control method of the power grid side converter, the control target of the outer ring d axis is the direct-current bus voltage U dc Approaches the set value U dcset When the power generation power of the direct current power supply is higher than the power consumption requirements of the direct current conventional load and the direct current sensitive load, the power grid side converter 6 inverts the surplus direct current power and transmits the surplus direct current power to the alternating current power grid, and when the power generation power of the direct current power supply is lower than the power consumption requirements of the direct current conventional load and the direct current sensitive load, the power grid side converter 6 rectifies the alternating current power into direct current power to supply power for the direct current load; the outer ring q-axis control target is that the reactive power approaches to 0, so that the power factor of the inlet side of the alternating current power supply approaches to 1, and the reactive power requirement is reduced to the maximum extent. And an output signal of the outer ring control is sequentially input into the inner ring decoupling control, dq inverse transformation and PWM (pulse-width modulation) links and then output to a PWM control signal of the power grid side converter 6.
The second control method of the grid-side converter 6 is a "thyristor fast turn-off strategy", and a specific flow chart thereof is shown in fig. 3. The second control method of the grid-side converter comprises the following steps: the whole machine control protection system 13 stops sending the trigger signal of the thyristor bypass valve 4 after detecting transient power quality events such as voltage sag, voltage rise, interruption and the like, and simultaneously sends control signals to the grid side converter 6 and the load side converter 8 to accelerate the current turn-off of the thyristor, for the grid side converter 6, when the current of the thyristor bypass valve 4 is in a positive direction, a lower tube corresponding to the grid side converter 6 is conducted, when the current of the thyristor bypass valve 4 is in a negative direction, a tube corresponding to the grid side converter 6 is conducted, and the grid side converter 6 and the load side converter 8 work in a matched mode, so that the thyristor bypass valve 4 is accelerated and rapidly turned off.
The 3 rd control strategy of the grid-side converter 6 is a "dynamic reactive support strategy", and the specific flow of the control strategy is shown in fig. 4. The third control method of the grid-side converter comprises the following steps: operating the DC voltage to a value U dcset And DC bus voltage U dc The difference value of (A) is input into a PI regulator, and the three-phase current sampling signal I a1 、I b1 、I c1 With said three-phase voltage signal U a1 、U b1 、U c1 Reactive power calculation is carried out to obtain reactive current I q Three-phase voltage signal U a1 、U b1 、U c1 Respectively with the high-voltage action fixed value U set1 And the low voltage action fixed value U set2 Maximum inductive reactive current I in dynamic reactive support mode determined by comparison result Lmax And maximum capacitive reactive current I in dynamic reactive support mode Cmax With the above-mentioned reactive current I q The difference value of (A) is input into a PI regulator, and the three-phase current sampling signal I a1 、I b1 、I c1 With said three-phase voltage signal U a1 、U b1 、U c1 And d, respectively carrying out dq conversion, and outputting the output signals of the two PI regulators and the dq conversion together with the inductance L1 of the grid side converter connecting reactor 5 through dq inverse conversion and PWM modulation after inner loop decoupling control and then outputting the PWM control signal of the grid side converter 6.
Through the third control method of the power grid side converter, the control target of the outer ring d axis is the direct-current bus voltage U dc When the power generated by the DC power supply is higher than the power demand of the DC load, the grid-side converter 6 willThe surplus direct current power is inverted and transmitted to an alternating current power grid, and when the power generation power of a direct current power supply is lower than the power consumption requirement of a direct current load, a power grid side converter 6 rectifies the alternating current side power into direct current power to supply power for the direct current load; the outer ring q-axis control target is that the self reactive current output of the device reaches the capacitive (inductive) maximum value, and when the three-phase voltage signal U of the first alternating current bus a1 、U b1 、U c1 Is simultaneously higher than U set1 The device outputs the maximum inductive reactive current I Lmax When the first AC bus three-phase voltage signal U a1 、U b1 、U c1 While being lower than U set2 The device outputs the maximum capacitive reactive current I Cmax . And an output signal of the outer ring control is sequentially input into the inner ring decoupling control, dq inverse transformation and PWM modulation links and then output to a PWM control signal of the power grid side converter 6.
The first control method of the load-side converter 8 is a "steady-state harmonic elimination strategy", and the specific flow chart is shown in fig. 5. The first control method of the load-side converter 8 includes: sampling the three-phase current a 、I b 、I c And respectively obtaining difference values with current values obtained after dq conversion, low-pass filtering and dq inverse conversion, and outputting PWM control signals of the power grid side converter 6 through a hysteresis comparator and a D trigger.
The first control method of the load side converter 8 adopts a timing comparison current tracking type PWM control method, outputs harmonic current with the same amplitude and opposite phase with a sampling point and injects the harmonic current into a power grid, so that the harmonic current at the incoming line side of the alternating current power supply is reduced. Side current I of power grid a 、I b 、I c After dq conversion, the n-order positive sequence component is changed into the n-1-order component under the dq coordinate system, the n-order negative sequence component is changed into the n + 1-order component under the dq coordinate system, only the fundamental wave positive sequence component is converted into the direct current component under the dq coordinate system, the high-frequency component is filtered by a low-pass filter (LPF), and the current I representing the side current of the power grid is obtained a 、I b 、I c The direct current component of the fundamental component, then using I d 、I q Subtracting the direct current component to obtain the side current I of the power grid a 、I b 、I c In which harmonic components need to be compensatedQuantity I d* And I q* Is shown by d* And I q* And after dq inverse transformation is carried out, the data is sent to a hysteresis comparator and a timing D trigger, and then a PWM control signal of the load side converter 8 is output.
The second control method of the load-side converter 8 is a "thyristor fast turn-off strategy", and a specific flow thereof is shown in fig. 6. The second control method of the load-side converter 8 includes: the whole machine control protection system 13 stops sending the trigger signal of the thyristor bypass valve 4 after detecting transient electric energy quality events such as voltage sag, voltage rise, interruption and the like, and simultaneously sends out a thyristor forced turn-off signal to the power grid side converter 6 and the load side converter 8, for the load side converter 8, when the current passing through the thyristor bypass valve 4 is in a positive direction, the corresponding upper pipe of the load side converter 8 is conducted, when the current passing through the thyristor bypass valve 4 is in a negative direction, the corresponding lower pipe of the load side converter 8 is conducted, and the power grid side converter 6 and the load side converter 8 work cooperatively, so that the thyristor bypass valve 4 is turned off in an accelerated manner.
The third control method of the load-side converter 8 is a "constant-voltage constant-frequency inversion strategy", and a specific flow thereof is shown in fig. 7. The third control method of the load-side converter includes the step of comparing the dc voltage operation value Udcset with the d-axis component U of the second ac bus voltage d2 Is inputted to the PI regulator, q-axis component U of the second AC bus voltage q2 Reverse input PI regulator, said three-phase current sampling signal I a2 、I b2 、I c2 With said three-phase voltage signal U a2 、U b2 、U c2 And d, respectively carrying out dq conversion, and outputting the output signals of the two PI regulators and the dq conversion together with the inductance L2 of the load side converter connecting reactor 9 through inner loop decoupling control, then carrying out dq inverse conversion and PWM modulation, and outputting a PWM control signal of the power grid side converter 6 so as to output three-phase alternating-current voltage with stable amplitude and frequency.
Through the third control method of the load side converter, the d-axis of the outer ring controls the d-axis component U of the voltage of the second alternating current bus d2 Transient output voltage U reaching the target value dset Q-axis component U q2 The output signal of the outer ring control is sequentially input into the inner ring decoupling control, dq inverse transformation,And outputting a PWM control signal of the load side converter 8 after the PWM modulation link. Under the mode, the load side converter 8 outputs a three-phase alternating current voltage source with constant amplitude and frequency, and continuous and stable power supply of the alternating current sensitive load is guaranteed.
In a preferred embodiment, after the whole machine control protection system 13 detects a voltage sag or interruption event, a switching-off control signal is sent to the breakers of the power supply loops of the direct current conventional loads 1-n, so that the direct current conventional loads exit the system, the dynamic voltage compensation loading capacity and the power supply time of the device are improved by automatically switching off the loads, and the power supply reliability of the alternating current sensitive loads and the direct current sensitive loads is further ensured.
In a preferred embodiment, after the voltage is recovered, the complete machine control protection system 13 sends a closing control signal to the circuit breakers of the power supply loops 1 to n of the direct current normal load, so that the direct current normal load is recovered to operate.
As shown in fig. 8, a preferred control method of the dynamic voltage compensation apparatus disclosed in the present invention is as follows:
a multi-mode fast switching control method of a dynamic voltage compensation device, the control method comprising:
in the first step, the load direct-current circuit breaker 12 is opened, the grid-side circuit breaker 2 and the load-side circuit breaker 11 are manually put in, and the operating state constant value of the dynamic voltage compensation device is set as follows: high voltage action constant value U set1 Low voltage action constant value U set2 DC voltage operation value U dcset Maximum inductive reactive current I in dynamic reactive support mode Lmax Maximum capacitive reactive current I in dynamic reactive support mode Cmax Transient output voltage U dset 。
Secondly, when the voltage of the alternating current power supply is normal, namely the three-phase voltage signals of the first alternating current bus simultaneously meet the requirement of U set1 >U a1 >U set2 、U set1 >U b1 >U set2 、U set1 >U c1 >U set2 When the control and protection system 13 outputs the continuous conduction signal of the thyristor bypass valve 4, the thyristor bypass valve 4 is continuously conducted, and the bidirectional through-flow is conductedEnabling the second alternating current bus to have alternating current sensitive load power supply conditions when being electrified; the grid-side converter 6 operates according to a first control method of the grid-side converter, which operates on said DC voltage operating value U dcset And DC bus voltage U dc The difference value of (A) is input into a PI regulator, and the three-phase current sampling signal I a 、I b 、I c With said three-phase voltage signal U a1 、U b1 、U c1 After reactive power calculation, the three-phase current is reversely input into a PI regulator, and the three-phase current is sampled a1 、I b1 、I c1 With said three-phase voltage signal U a1 、U b1 、U c1 Dq conversion is respectively carried out, and output signals of the two PI regulators and the dq conversion and an inductance value L1 of the power grid side converter connecting reactor 5 are subjected to inner loop decoupling control and then subjected to dq inverse conversion and PWM modulation to output a PWM control signal of the power grid side converter 6 so as to gradually increase the direct current voltage to a target value and enable the direct current voltage to meet power consumption conditions of a direct current power supply, a direct current conventional load and a direct current sensitive load; the load side converter 8 operates according to a first control method of the load side converter 8, which samples the three-phase current I a 、I b 、I c After difference values are respectively obtained with current values obtained after dq conversion, low-pass filtering and dq inverse conversion, the difference values are output through a hysteresis comparator and a D trigger, PWM control signals of the load side converter 8 are output, harmonic currents with opposite phases and equal amplitudes with the sampling point harmonic currents are output, the harmonic currents of nonlinear loads injected into a power grid are reduced, and voltage quality is improved. Meanwhile, the AC conventional load, the AC sensitive load, the DC conventional load, the DC sensitive load and the DC power supply are respectively connected to the corresponding buses to work normally.
Thirdly, when the voltage of the alternating current power supply is abnormal, namely the three-phase voltage signal of the first alternating current bus appears as U a1 >U set1 、U b1 >U set1 、U c1 >U set1 、U a1 <U set1 、U b1 <U set2 、U c1 <U set2 In either case; complete machine control protection system 13 shutdown thyristor bypass valve 4 conduction signalAnd under the two second control methods, the whole machine control protection system 13 stops sending the trigger signal of the thyristor bypass valve 4 and simultaneously sends control signals to the grid side converter 6 and the load side converter 8 so as to quickly turn off the thyristor bypass valve 4.
Fourthly, when the alternating voltage returns to normal, namely the three-phase voltage signals of the first alternating current bus simultaneously meet the requirement of U set1 >U a1 >U set2 、U set1 >U b1 >U set2 、U set1 >U c1 >U set2 And then, the whole machine control protection system 13 sends out a continuous conducting signal of the thyristor bypass valve 4, the grid side converter 6 is switched to the first control method of the grid side converter to continue working, and the load side converter 8 is switched to the first control method of the load side converter to continue working.
Preferably, the control method further includes switching the grid side converter 6 and the load side converter 8 to the third control method when all three phases of the thyristor bypass valves 4 are turned off.
Wherein the third control method of the grid-side converter 6 comprises the step of operating the DC voltage by a value U dcset And DC bus voltage U dc The difference value of (A) is input into a PI regulator, and the three-phase current sampling signal I a1 、I b1 、I c1 With said three-phase voltage signal U a1 、U b1 、U c1 Reactive power calculation is carried out to obtain reactive current I q Three-phase voltage signal U a1 、U b1 、U c1 Respectively with the high-voltage action fixed value U set1 And the low voltage action fixed value U set2 Maximum inductive reactive current I in dynamic reactive support mode determined by comparison result Lmax And maximum capacitive reactive current I in dynamic reactive support mode Cmax The difference value of the three-phase current and the reactive current Iq is input into a PI regulator, and the three-phase current is sampled according to a signal I a1 、I b1 、I c1 With said three-phase voltage signal U a1 、U b1 、U c1 Dq conversion is respectively carried out, output signals of the two PI regulators and the dq conversion and an inductance value L1 of the power grid side converter connecting reactor 5 are subjected to inner loop decoupling control and then subjected to dq inverse conversion and PWM modulation to output PWM control signals of the power grid side converter 6, so that residual voltage of an alternating current power grid supports direct current side voltage through the power grid side converter 6, a direct current bus only remains a direct current power supply and a direct current sensitive load, the direct current power supply can also provide support for the voltage of the direct current bus, and when the three-phase voltage of the first alternating current bus is higher than the U voltage, the three-phase voltage of the first alternating current bus is higher than the U voltage set1 The device outputs the maximum inductive reactive current I Lmax When the three-phase voltage of the first alternating current bus is lower than U set2 The device outputs the maximum capacitive reactive current I Cmax 。
The third control method of the load-side converter 8 comprises the step of comparing the dc voltage operating value Udcset with the d-axis component U of the second ac busbar voltage d2 Is inputted to the PI regulator, q-axis component U of the second AC bus voltage q2 Reverse input PI regulator, said three-phase current sampling signal I a2 、I b2 、I c2 With said three-phase voltage signal U a2 、U b2 、U c2 And d, dq conversion is respectively carried out, output signals of the two PI regulators and the dq conversion and an inductance value L2 of the load side converter connecting reactor 9 are subjected to inner loop decoupling control and then subjected to dq inverse conversion and PWM modulation, PWM control signals of the power grid side converter 6 are output, three-phase alternating-current voltage with stable amplitude and frequency is output, and direct-current side electric energy is inverted to provide three-phase alternating-current voltage with stable amplitude and frequency for the sensitive load, so that the sensitive load is ensured to be continuously and reliably powered, and economic loss caused by the transient electric energy quality problem is reduced.
Preferably, the control method further includes, when the voltage of the ac power supply is abnormal, further including, when the complete machine control protection system 13 detects a voltage sag or an interruption event, sending a tripping control signal to the circuit breaker of the power supply loop 1-n of the dc normal load, so as to make the dc normal load quit the system.
Preferably, the control method further includes that, when the ac voltage returns to normal, the complete machine control protection system 13 sends a closing control signal to the dc normal load 1-n power supply loop circuit breaker to return the dc normal load to power.
Preferably, the control method further comprises the step of disconnecting the power grid side circuit breaker 2 and the load side circuit breaker 11 when the equipment needs to be overhauled, closing the sensitive load direct supply circuit breaker 12 to enable the device to exit the running state, and normal electricity utilization of the sensitive load is not influenced by overhaul of the device.
Preferably, the control method further includes that the load side circuit breaker 11 and the load direct supply circuit breaker 12 are not closed at the same time.
As described above, the dynamic voltage compensation device disclosed in the present invention has three states of steady state power quality index comprehensive management, transient voltage compensation, and steady state to transient state fast switching, and accordingly, the power source side converter and the load side converter both adopt 3 control methods, the 3 control methods of the power source side converter are respectively a "synchronous rectification/inversion strategy", a "thyristor fast turn-off strategy", and a "dynamic reactive power support strategy", and the 3 control methods of the load side converter are respectively a "steady state harmonic elimination strategy", a "thyristor fast turn-off strategy", and a "constant voltage constant frequency inversion strategy". Under the condition of steady-state compensation, the power side converter and the load side converter adopt a first control method, the power side converter and the load side converter work in a matching mode to respectively compensate reactive current and harmonic current, various steady-state electric energy quality indexes such as voltage deviation, voltage fluctuation, waveform distortion and the like are improved, the power factor is improved, and the network loss is reduced; in the process of switching from the steady state to the transient state, the power side converter and the load side converter both adopt the second control method, when the current of the thyristor bypass valve is positive, the lower tube corresponding to the phase of the power side converter is conducted, the upper tube corresponding to the phase of the load side converter is conducted, when the current of the thyristor bypass valve is negative, the upper tube corresponding to the phase of the power side converter is conducted, the lower tube corresponding to the phase of the load side converter is conducted, and the power side converter and the load side converter work cooperatively to accelerate and rapidly turn off the thyristor bypass valve. Under the condition of transient compensation, the power supply side converter and the load side converter both adopt a third control method, the power grid side converter provides energy support for the load side converter, capacitive (inductive) reactive support is provided for a fault power grid at the same time, the voltage recovery speed is accelerated, the load side converter is equivalent to a three-phase alternating current voltage source with constant amplitude and frequency, and the continuous and stable power supply of the alternating current sensitive load is ensured.
It should be emphasized that the embodiments described herein are exemplary rather than limiting, and thus the present invention is not limited to the embodiments described in the detailed description, as other embodiments derived from the technical solutions of the present invention by those skilled in the art also belong to the protection scope of the present invention.

Claims (18)

1. A dynamic voltage compensation device is characterized by comprising an alternating current power supply, a first alternating current bus, a second alternating current bus, a direct current bus, a power grid side current sampling mutual inductor (1), a power grid side circuit breaker (2), an input side current sampling mutual inductor (3), a thyristor bypass valve (4), a power grid side current converter connecting reactor (5), a power grid side current converter (6), a direct current supporting capacitor (7), a load side current converter (8), a load side current converter connecting reactor (9), an output side current sampling mutual inductor (10), a load side circuit breaker (11), a load direct supply circuit breaker (12) and a whole machine control protection system (13); the power grid side current sampling mutual inductor (1) is connected between the alternating current power supply inlet side and the first alternating current bus; the power grid side circuit breaker (2), the input side current sampling mutual inductor (3), the power grid side converter connecting reactor (5) and the power grid side converter (6) are sequentially connected in series between the first alternating current bus and the direct current bus; the load direct supply circuit breaker (12), the load side circuit breaker (11), the output side current sampling mutual inductor (10), the load side converter connecting reactor (9) and the load side converter (8) are sequentially connected in series between the first alternating current bus and the direct current bus; the thyristor bypass valve (4) is connected in series between the outlet end of the input side current sampling transformer (3) and the input end of the output side current sampling transformer (10); the power grid side converter (6) and the load side converter (8) are respectively connected to two sides of the direct current support capacitor (7); and the whole machine control protection system (13) receives sampling signals of the power grid side current sampling mutual inductor (1) and the output side current sampling mutual inductor (10) and outputs control signals to the thyristor bypass valve (4), the power grid side current converter (6) and the load side current converter (8).
2. The dynamic voltage compensation device according to claim 1, wherein the grid-side current sampling transformers (1) are three single-phase current transformers, and respectively sample current signals I of a phase, a phase and a phase at the inlet side of the ac power supply a 、I b 、I c The three-phase current sampling signal I a 、I b 、I c Input to the whole machine control protection system (13).
3. The dynamic voltage compensation device according to claim 2, characterized in that the grid-side circuit breaker (2) is a three-phase circuit breaker.
4. A dynamic voltage compensation device according to claim 3, characterized in that the input side current sampling transformers (3) are three single phase current transformers, sampling the three phase current signals I between the grid side circuit breaker (2) and the grid side converter connecting reactor (5) respectively a1 、I b1 、I c1 The three-phase current sampling signal I a1 、I b1 、I c1 Input to the whole machine control protection system (13).
5. Dynamic voltage compensation device according to claim 4, characterized in that the thyristor bypass valve (4) comprises 6 thyristors, T1, T2, T3, T4, T5, T6, in a reverse parallel connection, divided into three groups, where T1 is connected in reverse parallel with T2 and then connected to phase a, T3 is connected in reverse parallel with T4 and then connected to phase B, and T5 is connected in reverse parallel with T6 and then connected to phase C.
6. The dynamic voltage compensation device of claim 5, wherein the voltage compensation device comprises a voltage compensation circuitThe grid side converter connecting reactor (5) is composed of three reactors L a1 、L b1 、L c1 Composition of the reactor L a1 、L b1 、L c1 The three-phase reactor is respectively connected in series between the input side current sampling mutual inductor (3) and the power grid side converter (6), and the inductance values of the three-phase reactor are all first inductance values L1.
7. Dynamic voltage compensation device according to claim 6, characterized in that the grid-side converter (6) comprises six turn-off only devices V11, V12, V13, V14, V15, V16 and diodes connected in anti-parallel with the six turn-off only devices, respectively, in a three-phase bridge voltage source connection.
8. Dynamic voltage compensation device according to claim 7, characterized in that the load side converter (8) comprises six turn-off only devices V21, V22, V23, V24, V25, V26 and diodes connected in anti-parallel with the six turn-off only devices, respectively, in a three-phase bridge voltage source connection.
9. Dynamic voltage compensation device according to claim 8, characterized in that the load side converter connection reactor (9) consists of three reactors L a2 、L b2 、L c2 Composition of the reactor L a2 、L b2 、L c2 The three-phase current sampling mutual inductors (10) are respectively connected in series between the load-side converter (8) and the output-side current sampling mutual inductor (10), and the inductance values of the three-phase reactors are all second inductance values L2.
10. The dynamic voltage compensation device according to claim 9, wherein the output side current sampling transformer (10) employs three single-phase current transformers for sampling three-phase current signals I between the load side circuit breaker (11) and the load side converter connecting reactor (9), respectively a2 、I b2 、I c2 The three-phase current sampling signal I a2 、I b2 、I c2 Input to the whole machine control protection system (13).
11. Dynamic voltage compensation device according to claim 10, characterized in that the load-side circuit breaker (11) and the load-side direct-feed circuit breaker (12) are not closed at the same time.
12. The dynamic voltage compensation device according to claim 11, wherein the complete machine control protection system (13) adopts a digital programmable processor, and outputs four groups of control signals, namely a thyristor bypass valve (4) on-off signal, a grid side converter (6) three-phase PWM pulse signal, a load side converter (8) three-phase PWM pulse signal, and a direct current normal load 1-n power supply loop circuit breaker on-off control signal.
13. A multi-mode fast switching control method applied to the dynamic voltage compensation device of any one of claims 2-12, wherein the control method comprises:
the first step is to open the load direct-current breaker (12), manually throw in the grid-side breaker (2) and the load-side breaker (11), and set the operating state constant value of the dynamic voltage compensation device: high voltage action constant value U set1 Low voltage action constant value U set2 DC voltage operation value U dcset Maximum inductive reactive current I in dynamic reactive support mode Lmax Maximum capacitive reactive current I in dynamic reactive support mode Cmax Transient output voltage U dset ；
Secondly, when the voltage of the alternating current power supply is normal, namely the three-phase voltage signals of the first alternating current bus simultaneously meet the requirement of U set1 >U a1 >U set2 、U set1 >U b1 >U set2 、U set1 >U c1 >U set2 When the direct current voltage is in a zero voltage state, the complete machine control protection system (13) outputs a continuous conduction signal of the thyristor bypass valve (4), the power grid side converter (6) works according to a first control method of the power grid side converter, and the direct current voltage operation value U is obtained through the operation method dcset And DC bus voltage U dc Is inputted to the PI regulator, threePhase current sampling signal I a 、I b 、I c With said three-phase voltage signal U a1 、U b1 、U c1 After reactive power calculation, the three-phase current is reversely input into a PI regulator, and the three-phase current is sampled a1 、I b1 、I c1 With said three-phase voltage signal U a1 、U b1 、U c1 Dq conversion is respectively carried out, output signals of the two PI regulators and the dq conversion and an inductance value L1 of the power grid side converter connecting reactor (5) are subjected to inner loop decoupling control, then subjected to dq inverse conversion and PWM modulation, and then PWM control signals of the power grid side converter (6) are output, so that the direct current voltage is gradually increased to a target value, and the direct current voltage meets power utilization conditions of a direct current power supply, a direct current conventional load and a direct current sensitive load; the load side converter (8) operates according to a first control method of the load side converter (8) and samples the three-phase current I a 、I b 、I c After difference values are respectively obtained with current values obtained after dq conversion, low-pass filtering and dq inverse conversion, PWM control signals of the load side converter (8) are output through a hysteresis comparator and a D trigger so as to output harmonic currents with opposite phases and equal amplitudes with the harmonic currents of sampling points;
thirdly, when the voltage of the alternating current power supply is abnormal, namely the three-phase voltage signal of the first alternating current bus appears as U a1 >U set1 、U b1 >U set1 、U c1 >U set1 、U a1 <U set1 、U b1 <U set2 、U c1 <U set2 In either case; the complete machine control protection system (13) stops sending a thyristor bypass valve (4) conduction signal, the power grid side converter (6) is switched to a power grid side converter second control method to work, the load side converter (8) is also switched to a load side converter second control method to work, and under the power grid side converter second control method and the load side converter second control method, the complete machine control protection system (13) stops sending a thyristor bypass valve (4) trigger signal and simultaneously sends control signals to the power grid side converter (6) and the load side converter (8) so as to quickly turn off the thyristor bypass valve (4);
fourthly, when the alternating voltage returns to normal, namely the three-phase voltage signals of the first alternating current bus simultaneously meet the requirement of U set1 >U a1 >U set2 、U set1 >U b1 >U set2 、U set1 >U c1 >U set2 And then, the whole machine control protection system (13) sends out a continuous conduction signal of the thyristor bypass valve (4), the power grid side converter (6) is switched to the first control method of the power grid side converter to continue working, and the load side converter (8) is switched to the first control method of the load side converter to continue working.
14. The control method according to claim 13, characterized by further comprising, when all three phases of the thyristor bypass valve (4) are turned off, switching the grid side converter (6) and the load side converter (8) to a third control method for operation; wherein the third control method of the grid-side converter (6) comprises the step of setting the DC voltage operation value U dcset And DC bus voltage U dc The difference value of (A) is input into a PI regulator, and the three-phase current sampling signal I a1 、I b1 、I c1 With said three-phase voltage signal U a1 、U b1 、U c1 Reactive power calculation is carried out to obtain reactive current I q Three-phase voltage signal U a1 、U b1 、U c1 Respectively with the high-voltage action fixed value U set1 And the low voltage action fixed value U set2 Maximum inductive reactive current I in dynamic reactive support mode determined by comparison result Lmax And maximum capacitive reactive current I in dynamic reactive support mode Cmax With the above-mentioned reactive current I q The difference value of (A) is input into a PI regulator, and the three-phase current sampling signal I a1 、I b1 、I c1 With said three-phase voltage signal U a1 、U b1 、U c1 Dq conversion is respectively carried out, and output signals of the two PI regulators and the dq conversion and an inductance value L1 of the power grid side converter connecting reactor (5) are subjected to dq inverse conversion and PWM modulation after inner loop decoupling control and output PWM control signals of the power grid side converter (6); said loadThe third control method of the side converter (8) comprises the step of operating the DC voltage value U dcset D-axis component U of second AC bus voltage d2 Is inputted to the PI regulator, q-axis component U of the second AC bus voltage q2 Reverse input PI regulator, said three-phase current sampling signal I a2 、I b2 、I c2 With said three-phase voltage signal U a2 、U b2 、U c2 And d, respectively carrying out dq conversion, and outputting a PWM control signal of the load side converter (8) after carrying out dq inverse conversion and PWM modulation on output signals of the two PI regulators and the dq conversion together with an inductance value L2 of the load side converter connecting reactor (9) after inner loop decoupling control so as to output three-phase alternating-current voltage with stable amplitude and frequency.
15. The control method according to claim 14, wherein when the ac power voltage is abnormal, the overall control and protection system (13) further comprises a step of sending an opening control signal to the circuit breaker of the dc normal load 1-n power supply loop to make the dc normal load exit the system when detecting a voltage sag or interruption event.
16. The control method according to claim 15, wherein when the ac voltage returns to normal, the complete machine control and protection system (13) further comprises a step of returning the dc normal load to power by sending a closing control signal to the dc normal load 1-n power supply loop circuit breaker.
17. A control method according to claim 16, characterized by further comprising, when equipment needs to be serviced, opening the grid-side circuit breaker (2) and the load-side circuit breaker (11), and closing the sensitive load-direct-supply circuit breaker (12) to bring the device out of operation.
18. A control method according to claim 17, characterized in that the load-side circuit breaker (11) and the load-side direct-feed circuit breaker (12) are not closed at the same time.
CN202210710583.1A 2022-06-22 2022-06-22 Dynamic voltage compensation device and multi-mode fast switching control method thereof Active CN115051398B (en)

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CN113872201A (en) * 2021-10-25 2021-12-31 华瑞清能(北京)电力电子技术有限公司 Join in marriage net side electric energy quality and synthesize and administer and energy-conserving increase device

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