CN107196316B - Multi-stage reactive voltage coordination control method in active power distribution network - Google Patents

Multi-stage reactive voltage coordination control method in active power distribution network Download PDF

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CN107196316B
CN107196316B CN201710475103.7A CN201710475103A CN107196316B CN 107196316 B CN107196316 B CN 107196316B CN 201710475103 A CN201710475103 A CN 201710475103A CN 107196316 B CN107196316 B CN 107196316B
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voltage
photovoltaic
stage
power
voltage regulation
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CN107196316A (en
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李振坤
路群
符杨
王永全
苏向敬
米阳
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Shanghai University of Electric Power
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Shanghai University of Electric Power
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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
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • H02J3/1828—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepwise control, the possibility of switching in or out the entire compensating arrangement not being considered as stepwise control
    • 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
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • 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
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers
    • 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)
  • Supply And Distribution Of Alternating Current (AREA)
  • Control Of Electrical Variables (AREA)

Abstract

The invention relates to a multi-stage reactive voltage coordination control method in an active power distribution network, which is used for grading voltage regulation resources in the active power distribution network, sequentially executing four-stage voltage regulation from low to high, judging whether the voltage level of the whole network is qualified or not after each stage of voltage regulation, and not executing the next stage of voltage regulation when the voltage level of the whole network is qualified. Compared with the prior art, the method and the device make full use of the dispersed voltage regulation resources in the active power distribution network, and have the advantages of effectively reducing the action times of the VQC device, improving the voltage level of the power distribution network and the like.

Description

Multi-stage reactive voltage coordination control method in active power distribution network
Technical Field
The invention relates to the field of reactive voltage control of a power distribution network, mainly relates to a distributed power supply reactive voltage local control strategy in the power distribution network and active power distribution network layered reactive voltage control research, and particularly relates to a multi-stage reactive voltage coordination control method in the active power distribution network.
Background
With the increasing load demand of power systems and the increasing environmental protection problem, the distributed power generation realized by using clean renewable energy becomes the mainstream trend of power grid development. On one hand, the access of a Distributed Generation (DG) realizes the local balance of energy and reduces the loss caused by long-distance power transmission, on the other hand, the access of a large amount of DGs changes the operation mode of the original power Distribution network, the problem of voltage out-of-limit becomes a key factor influencing the safe and stable operation of the power grid, and the traditional voltage regulation mode is difficult to meet the voltage operation requirement of the power grid. In order to adapt to the access of a DG with high permeability and ensure the voltage quality of a system, an Active Distribution Network (ADN) reactive voltage control technology becomes an important means.
The overvoltage phenomenon caused by the massive connection of the distributed power supply is intensively researched by a plurality of scholars. The document 'calculation of maximum allowable access peak capacity of a distributed photovoltaic power supply under overvoltage limitation' (model Yuan Liang, Zhao waves, Jiangyuan, and the like. power system automation, 2012, 36 (17): 40-44) improves the permeability of the distributed power supply by reasonably planning the position and the capacity of a grid-connected DG; the document "Advanced voltage regulation method of Power distributed storage and generation systems" (Choi JH, Kim J C. IEEE Transactions on Power Delivery,2001,16(2): 329) adjusts the transformer taps to cope with the voltage fluctuations caused by DG access, but DG fluctuations are frequent and rapid, and are limited by the ability to regulate the voltage solely by means of the transformer taps. For this reason, many researches propose to perform centralized coordination and optimization on network voltage regulation resources so as to solve the problem of the shortage of the traditional voltage regulation device. Research on dynamic reactive power optimization scheduling of grid connection of distributed power supplies (Yang Su Qin, Lumoniwa, Hanjiuzhou. power system protection and control, 2013,41(17): 122-. The document "Aspect of voltage stability and reactive power support in reactive Distribution" (major R.IET Generation, Transmission & Distribution,2014,8(3):442-450) guarantees the line voltage level by centralized coordinated control of DG, DSTATCOM, OLTC and capacitor banks within the grid. The document 'comprehensive reactive power optimization of a power distribution network based on multiple active management strategies' (chen navy, Cheng Hao loyal, Zhang Yi. power grid technology, 2015, 39 (6): 1504-.
However, if there are more DG in the network, these measures will have higher requirements on the system coordination capability. In the document, "review of reactive voltage control method in active power distribution network background" (cheng xu, zhanggyongarmy, huang yi min. power system automation, 2016 (1): 143-. The document "generated connected to the low-voltage distribution network-Technical requirements for the connection to and parallel operation with low-voltage distribution networks" divides the power distribution network into an autonomous control area and a coordinated control area, implements a top-down active power distribution network voltage hierarchical coordination control strategy, and avoids the problem of large operation dimension of centralized control. These strategies do not give a DG specific control strategy. The literature, "analysis and countermeasure of voltage out-of-limit problem under high-density distributed photovoltaic access" (wanying, fuxu, zhao, etc., report of chinese motor engineering 2016, 36 (5): 1200-.
The german institute of electrical engineers proposes four inverter reactive power control strategies for the problem of grid-connected Photovoltaic (PV) reactive voltage control: constant reactive power Q control, constant power factorControl based on photovoltaic active power outputAnd a Q (U) control strategy based on the grid-connected point voltage amplitude. The constant reactive power Q control means that the photovoltaic system maintains constant and invariable reactive power operation, and the control strategy is poor in universality. Constant power factor control means that photovoltaic is switched in and operated according to a set power factor, generally, the set power factor is 0.95 or 0.98, and the reactive power input effect is difficult to ensure by the control strategy. The Q (U) control strategy based on the grid-connected point voltage amplitude refers to that the photovoltaic reactive output value is only changed according to the grid-connected point voltage of the photovoltaic, and although the reactive input effect is guaranteed, the photovoltaic capacity is out of limit or the grid-connected power factor is unqualified. Photovoltaic active power output-basedControl, which means that the value of the power factor is related to the active power of the photovoltaic power supply, the control curve is shown in fig. 1, and when the photovoltaic output is small, the photovoltaic power supply operates at a large power factor value; with the increase of the photovoltaic active output, the influence on the voltage is enhanced, the power factor value is adjusted downwards, and a certain amount of reactive power is absorbed, so that the lifting amplitude of the photovoltaic active output to the voltage is reduced; when the photovoltaic output is increased to a certain value, the photovoltaic is operated according to a preset minimum power factor value, namely, the voltage is regulated to the maximum capacity. The applicability of the control strategy is improved to a certain extent, but the control strategy does not consider the voltage information of a grid-connected point, and when the photovoltaic output and the load are both large and the voltage is not out of limit, the voltage level of a power grid can be damaged by adopting the control strategy.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a multi-stage reactive voltage coordination control method in an active power distribution network, which fully utilizes the dispersed voltage regulation resources in the active power distribution network, effectively reduces the action times of VQC devices and improves the voltage level of the power distribution network.
The purpose of the invention can be realized by the following technical scheme:
the control method is used for grading voltage regulation resources in the active power distribution network, sequentially executing four-stage voltage regulation from low to high, judging whether the voltage level of the whole network is qualified or not after each stage of voltage regulation, and not executing next-stage voltage regulation when the voltage level of the whole network is qualified.
In the four-level voltage regulation, the first-level voltage regulation adopts the combined control based on the voltage of a photovoltaic grid-connected point and the photovoltaic active power outputAnd (5) controlling the strategy.
The above-mentionedThe control strategy specifically comprises the following steps:
1) according to the voltage of the photovoltaic grid-connected point, calculating the lower limit value of the power factor under the voltage level of the photovoltaic grid-connected point
Wherein, C2Minimum power factor value, U, allowed for photovoltaic inverter1Is a lower limit value of voltage, U2For lower upper limit of voltage, U3Is a voltage higher than the lower limit value, U4Is the voltage upper limit.
2) Determining an operation mode of the photovoltaic inverter according to the photovoltaic grid-connected point voltage, wherein,
a) the voltage U of the grid-connected point satisfies U1≤U≤U2When the photovoltaic inverter operates in a power factor hysteresis mode, the lower limit value of the power factor is increased along with the rise of the voltage;
b) the voltage U of the grid-connected point satisfies U3≤U≤U4When the photovoltaic inverter operates in a power factor leading mode, the lower limit value of the power factor is reduced along with the rise of the voltage;
c) the voltage U of the grid-connected point satisfies U2≤U≤U3When the photovoltaic inverter operates in a unit power factor mode, the lower limit value of the power factor is 1;
3) determining the operation power factor of the photovoltaic according to the photovoltaic active power output P and the operation mode of the photovoltaic inverter obtained in the step 2)Wherein the content of the first and second substances,
when the photovoltaic inverter is operating in the power factor hysteretic mode,
when the photovoltaic inverter is operating in the power factor hysteretic mode,
wherein, P1And P2All represent the threshold value of the active power output of the photovoltaic system, and when the active power is lower than P1At a minimum power factorRun late, when successfully higher than P2At a minimum power factorAnd (4) performing advanced operation.
In the four-stage voltage regulation, the two-stage voltage regulation and the three-stage voltage regulation both adopt an optimization algorithm to realize voltage regulation control, and the adopted objective function is the optimal system node voltage:
wherein, Ui、Ui,refNode voltage and node voltage expected value of the node i are respectively, and N is the total number of nodes of the system.
The three-stage voltage regulation specifically coordinates and controls the tap position of the transformer and the switching group number of the capacitors.
In the four-stage voltage regulation, the four-stage voltage regulation adopts an optimization algorithm to realize voltage regulation control, and the adopted objective function is that the photovoltaic active reduction is minimum:
wherein, Pi,pvlossAnd the amount of the active output of the photovoltaic power station i is reduced, and n is the number of photovoltaic power station accesses.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, classification and classification processing is carried out on the active power distribution network voltage regulation resources according to different characteristics of the voltage regulation resources, a four-stage voltage regulation strategy of the system is realized, the existing resources in the network can be fully utilized, the voltage regulation effect and the action rationality of various resources are effectively improved, the action times of a VQC device are reduced, the management and control capability of the system on the voltage of the power grid is enhanced, and the voltage level of the whole power grid is ensured.
2. The primary voltage regulation of the invention aims at a small-capacity distributed photovoltaic power supply and adopts the combined control based on the voltage of a photovoltaic grid-connected point and the photovoltaic active power outputAccording to the control strategy, the lower limit value of the power factor can be adaptively changed according to the voltage amplitude of the grid-connected point, the reactive compensation amplitude of the photovoltaic at different grid-connected point voltages and different active output levels is effectively distinguished, the photovoltaic voltage regulation effect is effectively improved, and the real-time quick response of the photovoltaic reactive output is realized.
3. The photovoltaic power station reactive power output in the secondary voltage regulation coordination control network can well improve the voltage level of the whole system and greatly reduce the reactive power flow of the system. If the voltage level of the whole network is qualified after the secondary voltage regulation, the following steps are performed: the method has the advantages that firstly, the action times of a transformer tap and a capacitor bank are reduced, and the service life of equipment is prevented from being lost due to frequent action; and secondly, active scheduling of photovoltaic is reduced, and the power generation proportion of clean energy is improved.
4. The secondary, tertiary and quaternary voltage regulation of the invention is centralized coordination control, on the basis of ensuring the voltage quality of the whole network, the accepting capability of the power grid to the distributed photovoltaic and the voltage regulation capability of the system are improved, the voltage regulation means and the purpose of each level are defined, and the problem of uncertain physical meaning of action results when all variables are uniformly coordinated and controlled is avoided.
Drawings
FIG. 1 is a conventional distributed power supplyA control strategy curve;
FIG. 2 is a diagram of distributed photovoltaic of the present inventionIn the control strategyA variation curve with voltage U;
FIG. 3 shows the present inventionControlling a strategy curve cluster;
FIG. 4 is a flow chart of a first-stage voltage regulation load flow calculation;
fig. 5 is a flow chart of active power distribution network multi-level reactive voltage control;
FIG. 6 is a diagram of a modified IEEE33 node distribution network in one embodiment;
FIG. 7 is a graph of total solar output of load and photovoltaic;
FIG. 8 is a photovoltaic power plant reactive power output change curve at node 7;
FIG. 9 is a photovoltaic power plant reactive power output change curve at node 27;
FIG. 10 is a graph of transformer tap behavior;
fig. 11 is a capacitor bank switching action curve;
FIG. 12 is a graph showing the change of the voltage at the node 3 per day under different control modes;
fig. 13 is a daily voltage variation curve of the node 19 under different control modes.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
The invention provides a multi-stage reactive voltage coordination control method in an active power distribution network, which is used for grading voltage regulation resources such as distributed photovoltaic power supplies, active and reactive power outputs of photovoltaic power stations, transformer taps, capacitor banks and the like in the active power distribution network, sequentially executing four-stage voltage regulation from low to high, judging whether the voltage level of the whole network is qualified or not after each stage of voltage regulation, and not executing the next stage of voltage regulation when the voltage level of the whole network is qualified, wherein the four-stage voltage regulation specifically comprises the following steps: the method comprises the steps of firstly utilizing a small-capacity distributed photovoltaic power supply to realize primary voltage regulation management of a system, and then respectively realizing secondary, tertiary and quaternary voltage regulation of the system by scheduling reactive power output of a photovoltaic power station, regulating a VQC device and reducing active power output of the photovoltaic power station. Through adopting the level four voltage regulation strategy of this patent, but make full use of current resource in the network, effectively improve the effect of all kinds of resource voltage regulation and the rationality of action, reduce VQC device action number of times, the management and control ability of reinforcing system to the grid voltage guarantees whole network voltage level.
Primary voltage regulation: the small distributed photovoltaic system accessed by the user is dispersed and is not easy to be controlled in a centralized way, and the primary voltage regulation mode of the invention is dispersed local control and adoptsThe distributed voltage regulation task of photovoltaic is accomplished to the local control strategy, has effectively guaranteed every photovoltaic reactive voltage control effect. The voltage regulation range is distributed photovoltaic local or adjacent nodes.
Secondary voltage regulation: because the small photovoltaic capacity is small, the capacity of participating in voltage regulation is limited, the voltage level of the whole network at each time interval cannot be guaranteed, and the reactive power output of photovoltaic power stations in the network needs to be coordinated and controlled at the moment. The general capacity of a photovoltaic power station is larger according to the technical regulation of photovoltaic power generation system access to a power distribution network[15]The grid-connected power factor value of the photovoltaic power station is lower than that of the small-sized photovoltaic grid-connected power factor, so that the photovoltaic power station has stronger reactive power regulation capacity. The voltage level of the whole system can be well improved through two-stage voltage regulation, and reactive power flow of the system is greatly reduced. The photovoltaic power station is selected as a secondary voltage regulation means for the following reasons: frequency of transformer taps and capacitor banksThe action will consume the service life of the equipment, and the action times need to be reduced as much as possible; and secondly, the active scheduling of photovoltaic is reduced, and the improvement of the power generation proportion of clean energy is one of the targets of the active distribution network.
Three-stage pressure regulation: at certain times of large photovoltaic output or overload, the voltage quality requirement cannot be met only by regulating the voltage of the whole network through the photovoltaic in the network. Therefore, when the primary and secondary voltage regulation effects are not ideal, the third voltage regulation is carried out on the system by coordinately controlling the tap position of the transformer and the switching group number of the capacitors.
Four-stage pressure regulation: in order to guarantee the requirements of users on voltage quality and the safe and stable operation of the system, a central dispatching control system manages and controls the active output of a photovoltaic power station in the system and even allows the photovoltaic power station to exit the operation.
1. Distributed photovoltaicIn-situ reactive voltage control model
After the distributed photovoltaic is connected to the power distribution network, the photovoltaics located at different positions at the same time and the photovoltaics located at the same position at different times all adopt the same control curve, obviously lack universality, andthe control strategy only considers the photovoltaic absorption reactive voltage reduction capability and does not consider the voltage raising effect of photovoltaic power factor lagging operation. Therefore, the present invention proposes toThe lower limit value of the power factor in the control curve can be adaptively changed according to the voltage amplitude of the grid-connected point, so that the photovoltaic grid-connected point voltage and photovoltaic active power output combined control is realizedAnd (5) controlling the strategy. The control strategy includes three types of scenarios: the photovoltaic power factor operates in a lagging mode, the photovoltaic power factor operates in a leading mode, and the photovoltaic power factor operates according to the unit power factor. As shown in fig. 2: 1) when the voltage of the grid-connected point is low (i.e. U)1≤U≤U2) The photovoltaic inverter operates in a power factor hysteresis mode, and at the moment, the lower limit value of the power factor is increased along with the rise of voltage, namely, the maximum photovoltaic reactive output is reduced, and the lifting capacity of the system voltage is reduced; the power factor is operated at a given minimum value at the lower limit of the voltage. 2) When the voltage of the grid-connected point is higher (i.e. U)3≤U≤U4) The photovoltaic inverter operates in a power factor advance mode, and at the moment, the lower limit value of the power factor is reduced along with the rise of voltage, namely, the maximum photovoltaic reactive absorption capacity is increased, and the system voltage inhibition capacity of the photovoltaic inverter is improved; the power factor is operated at a given minimum value as the voltage is higher. 3) When the grid-connected point is in a better state (i.e. U)2≤U≤U3) The photovoltaic inverter operates in a unity power factor mode, i.e., the lower power factor limit is 1.
In FIG. 2, the calculation is based on the voltage UWherein C is2The minimum allowed power factor value for the photovoltaic inverter.The mathematical expression of (A) is shown in formula (1):
as can be seen from fig. 2, after the operation mode of the photovoltaic inverter is determined according to the grid-connected point voltage, the lower limit value of the power factor under the grid-connected point voltage level can be determined, and further, as shown in fig. 3, can be determinedSpecific curves in the curve cluster. At lower voltage levels, i.e. the upper half of the horizontal axis in fig. 3, the photovoltaic power factor increases with the photovoltaic active power outputThe reactive output value is increased and reduced, and overcompensation is avoided; when the voltage level is higher, namely the lower half of the horizontal axis in fig. 3, the photovoltaic power factor is reduced along with the increase of the photovoltaic active output, the reactive absorption value is improved, and the active-to-voltage rise is reduced; when the voltage is out of limit, the power factors of the photovoltaic inverter operate at the minimum value, and the voltage is regulated to the maximum capacity; when the voltage is better, the photovoltaic inverter operates according to the unit power factor without voltage regulation.
From the graph of FIG. 3, the photovoltaic specific operating power factor is determined from the change in the photovoltaic active power output PThe mathematical expressions are as (2) and (3).
The combination of the formulas (1), (2) and (3) forms the wholeAnd (5) controlling the strategy. The control strategy effectively distinguishes the reactive compensation amplitude of the photovoltaic under different grid-connected point voltages and different active output levels, effectively improves the photovoltaic voltage regulation effect, and realizes real-time quick response of the photovoltaic reactive output.
In FIG. 3, P1And P2All represent the threshold value of the active power output of the photovoltaic system, and when the active power is lower than P1At a minimum power factorRun late, when successfully higher than P2At a minimum power factorAnd (4) performing advanced operation.
2. Multi-stage voltage regulation controlled mathematical model
(1) Objective function
In the multi-level voltage control, different optimization targets are adopted according to different voltage regulation resource characteristics and different costs. The primary voltage regulating equipment is a small-capacity photovoltaic power supply and is controlled by a photovoltaic inverter on site without being controlled by a central control system. And secondly, voltage regulation control is realized in the third stage by adopting an optimization algorithm, and a voltage regulation objective function is set to be optimal in system node voltage:
wherein, Ui、Ui,refNode voltage and node voltage expected value of the node i are respectively, and N is the total number of nodes of the system.
The four-stage voltage regulation adopts an optimization algorithm to realize voltage regulation control, the voltage qualification is taken as a constraint condition, and a target function is set as the minimum of photovoltaic active reduction:
wherein, Pi,pvlossAnd the amount of the active output of the photovoltaic power station i is reduced, and n is the number of photovoltaic power station accesses.
(2) Constraint conditions
The constraint conditions are constraints of the whole voltage control system, and comprise equality constraint conditions and inequality constraint conditions.
The equality constraint, i.e. the power balance equation:
in the formula, Pi、QiThe active power and the reactive power injected at the node i are represented; gij、Bij、θijRepresenting the angle of phase difference between the conductance, susceptance and voltage between nodes i, j.
The inequality constraint conditions are respectively voltage, tap gear of the transformer, switching group number of the capacitor bank and active and reactive power output constraints of the photovoltaic power station:
in the formula, Ppvimax、Ppvimin、Qpvimax、QpviminRespectively representing the upper limit and the lower limit of active power output and the lower limit of reactive power output of the photovoltaic power station i; t ismax、TminThe upper and lower limits of the tap gear of the transformer are set; cmax、CminThe upper and lower limits of the number of groups of capacitors are switched.
The first voltage constraint in the formula (6) and the formula (7) needs to be satisfied in the whole process, namely, the power balance constraint and the voltage upper and lower limit constraint of each level of voltage regulation need to be satisfied. The four inequality constraints from 2 to 5 in the formula (7) are operation constraints for each voltage regulating measure, and specifically, the constraints of the 2 nd and the 3 rd in the formula (7) on T and C are on-load tap changer and capacitor bank constraints and are on three-level voltage regulating constraints; the constraints on P and Q of 4 th and 5 th in equation 7) are the operating constraints of the photovoltaic power plant during the whole voltage regulation process.
As shown in fig. 4-5, in the simulation process of reactive voltage control of the active power distribution network, first, the small-capacity distributed photovoltaic is adoptedAnd the distributed local control strategy determines the reactive power output of the distributed local control strategy according to the voltage of the grid-connected point and the current active power output, then detects whether the current voltage of the whole network is qualified, if so, indicates that the voltage regulation of the level can meet the requirement, and if not, applies for the next level of voltage regulation until the voltage of the whole network is qualified.
3. Examples of the applications
The simulation is carried out on the basis of the improved IEEE33 node power distribution network system, the transformer taps, the capacitors and the small-capacity photovoltaic and photovoltaic power stations are calculated, and the structure of a power distribution network is shown in figure 6. The model of the 110/10kV on-load tap changer is SFZ9-6300/110, and the voltage regulation range is 110 +/-8 multiplied by 1.25%; the parallel compensation capacitor banks are 8 in number, and the capacity of each bank is 100 kVar; 3 small-capacity photovoltaics are respectively accessed to the nodes 18, 23 and 33; capacity of 2 photovoltaic power stations is 1424.88kW, respectively connected to nodes 10, 27. The total maximum active power output of the photovoltaic in the system is 4749.6 kW; the maximum active load of the system is 3302.97kW, and the total sunrise force curve of the load and the photovoltaic is shown in FIG. 7; assuming that the voltage of the high-voltage bus is constant at 110kV, the tap position at the initial simulation moment is +2 gears (10.25kV), and the switching initial state of the parallel compensation capacitor bank is 0 bank.Respectively taking U in control strategy1＝0.95、U2＝0.98、U3＝1.02、U41.05. The genetic algorithm is adopted for solving in the two, three and four-stage pressure regulating optimization algorithm, the coding mode adopts a binary system, the cross probability is set to be 0.8, the variation probability is set to be 0.1, the population size is 50, and the maximum iteration number is 100.
And (3) simulation result analysis: as can be seen from fig. 8 and 9, the voltage of the whole network can be maintained in a reasonable interval by distributed local control in most of time, and the system performs secondary voltage regulation control only in the noon and evening time period, while the reactive power output of the photovoltaic power station is not considered in the conventional voltage regulation mode, so that the voltage of the whole network does not act all the time.
As shown by the dotted lines in fig. 10 and 11, if the reactive voltage regulation capability of the low-capacity photovoltaic and photovoltaic power station at the user side is not considered, the transformer tap and the capacitor bank are affected by the output fluctuation of the grid-connected photovoltaic, and will frequently act, so that the service life of the equipment is affected, even the maximum capability of the VQC apparatus cannot meet the existing voltage regulation requirement, the voltage quality of the whole grid needs to be maintained by the measure of reducing the active output of the photovoltaic, and the photovoltaic absorption capability of the system is reduced. After small-capacity photovoltaic local reactive voltage control and photovoltaic power station reactive scheduling are considered, the quality of the whole network voltage in most time can be guaranteed, the VQC device needs to be scheduled and regulated only in the time period with large load fluctuation changes at noon and at night, and the action times of the VQC device are obviously reduced. As shown by the solid lines in fig. 10 and 11, when the multi-stage voltage regulation control means is adopted, the number of times of operation of the transformer is reduced from 9 times to 2 times, and the number of times of operation of the capacitor bank is reduced from 7 times to 1 time. The simulation program considers the active power reduction link of the photovoltaic power station, and the situation of reducing the active power output of the photovoltaic power station does not appear in the simulation result due to the fact that the voltage regulation and control capacity of the first three-level voltage regulation means is high.
As shown in fig. 12 and 13, different voltage control modes are compared. When the photovoltaic grid is connected by adopting the unit power factor, the phenomenon that the voltage of nodes at the head end and the tail end is out of limit is obvious; when the system only depends on the VQC device for voltage regulation, the tail end node has voltage out-of-limit behavior at night; the multistage voltage control technology provided by the patent has a remarkable effect in the aspect of voltage control, the voltage of a power grid is greatly improved, the voltage in the whole grid range and each time period is in a better level, and the voltage fluctuation range is obviously reduced.
Therefore, based on the multi-stage voltage regulation control strategy provided by the invention, the first-stage voltage regulation object is a small-capacity distributed photovoltaic, the control mode is distributed local control, the second, third and fourth-stage voltage regulation objects are respectively a photovoltaic power station reactive power and a VQC device and a photovoltaic power station active power, the control mode is centralized coordination control, on the basis of ensuring the voltage quality of the whole network, the accepting capability of a power grid to the distributed photovoltaic and the voltage regulation capability of a system are improved, the voltage regulation means and purposes of all stages are determined, the problem that the physical meaning of an action result is ambiguous when all variables are uniformly coordinated and controlled is avoided, and the action times of the traditional VQC device are obviously reduced.
The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.

Claims (4)

1. A multi-stage reactive voltage coordination control method in an active power distribution network is characterized in that the control method grades voltage regulation resources in the active power distribution network, four-stage voltage regulation is sequentially carried out from low to high, whether the voltage level of the whole network is qualified or not is judged after each stage of voltage regulation, when the voltage level of the whole network is qualified, the next stage of voltage regulation is not carried out, and the four-stage voltage regulation specifically realizes one-stage, two-stage, three-stage and four-stage voltage regulation of a power system by utilizing a distributed photovoltaic power supply, the reactive power of a photovoltaic power station, a traditional VQC device and the active power of the photovoltaic power station;
in the four-level voltage regulation, the first-level voltage regulation adopts the combined control based on the voltage of a photovoltaic grid-connected point and the photovoltaic active power outputA control strategy ofThe control strategy specifically comprises the following steps:
1) according to the voltage of the photovoltaic grid-connected point, calculating the lower limit value of the power factor under the voltage level of the photovoltaic grid-connected point
Wherein, C2Minimum power factor value, U, allowed for photovoltaic inverter1For voltage allowable lower limit value, U2For lower upper limit of voltage, U3Is a voltage higher than the lower limit value, U4An allowable upper limit value of voltage;
2) determining an operation mode of the photovoltaic inverter according to the photovoltaic grid-connected point voltage, wherein,
a) the voltage U of the grid-connected point satisfies U1≤U≤U2When the photovoltaic inverter operates in a power factor hysteresis mode, the lower limit value of the power factor is increased along with the rise of the voltage;
b) the voltage U of the grid-connected point satisfies U3≤U≤U4When the photovoltaic inverter operates in a power factor leading mode, the lower limit value of the power factor is reduced along with the rise of the voltage;
c) the voltage U of the grid-connected point satisfies U2≤U≤U3When the photovoltaic inverter operates in a unit power factor mode, the lower limit value of the power factor is 1;
3) determining the operation power factor of the photovoltaic according to the photovoltaic active power output P and the operation mode of the photovoltaic inverter obtained in the step 2)Wherein the content of the first and second substances,
when the photovoltaic inverter is operating in the power factor hysteretic mode,
when the photovoltaic inverter is operating in power factor lead mode,
wherein, P1And P2All represent the threshold value of the active power output of the photovoltaic system, and when the active power is lower than P1At a minimum power factorRun late, when successfully higher than P2At a minimum power factorAnd (4) performing advanced operation.
2. The multi-stage reactive voltage coordination control method in the active power distribution network according to claim 1, wherein in the four-stage voltage regulation, the two-stage voltage regulation and the three-stage voltage regulation both adopt an optimization algorithm to realize voltage regulation control, and the adopted objective function is the optimal system node voltage:
wherein, Ui、Ui,refNode voltage and node voltage expected value of the node i are respectively, and N is the total number of nodes of the system.
3. The method for coordinated control of the multi-stage reactive voltage in the active power distribution network according to claim 1, wherein the three-stage voltage regulation is specifically coordinated control of tap positions of the transformer and the number of switching groups of the capacitor.
4. The multi-stage reactive voltage coordination control method in the active power distribution network according to claim 1, wherein in the four-stage voltage regulation, the four-stage voltage regulation adopts an optimization algorithm to realize voltage regulation control, and an adopted objective function is that the photovoltaic active reduction is minimum:
wherein, Pi,pvlossAnd the amount of the active output of the photovoltaic power station i is reduced, and n is the number of photovoltaic power station accesses.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3855592A1 (en) * 2020-01-23 2021-07-28 Electricité de France Adjustment of the voltage in a low-voltage branch of a distribution network

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108879700B (en) * 2018-08-22 2021-09-17 广东电网有限责任公司 Method, device and equipment for adjusting power grid voltage
CN109149662A (en) * 2018-08-28 2019-01-04 南京理工大学 A kind of more reactive sources of photovoltaic parallel in system coordinate the control method of power output
CN110086186B (en) * 2019-04-24 2023-01-31 国网山东省电力公司枣庄供电公司 Urban distribution network voltage control method considering street lamp charging pile
CN113572174B (en) * 2021-09-13 2022-04-22 国网浙江省电力有限公司湖州供电公司 Distribution network power supply quality regulation and control device and automatic voltage regulation method thereof
FR3131121A1 (en) 2021-12-21 2023-06-23 Electricite De France Process for joint regulation of the voltage in an MV medium voltage branch and LV low voltage branches including a three-phase LV low voltage branch
CN116365526A (en) * 2023-02-28 2023-06-30 国网江苏省电力有限公司电力科学研究院 Multistage voltage interactive control method

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103166226A (en) * 2013-03-29 2013-06-19 华北电力大学（保定） Network voltage reactive-power compound coordination control system and method for new energy power generation
CN105140964A (en) * 2015-09-24 2015-12-09 中国南方电网有限责任公司 10kV power distribution network power coordination control method with photovoltaic power supply
CN106410850A (en) * 2016-11-11 2017-02-15 国网江苏省电力公司常州供电公司 Controlling method for grid-connected photovoltaic system including two-stage voltage inverter
CN106451477A (en) * 2016-10-31 2017-02-22 国网甘肃省电力公司经济技术研究院 Reactive power voltage coordination control method adaptable to clustered wind-solar-electricity access system
CN106849111A (en) * 2016-11-24 2017-06-13 东南大学 A kind of statements based on collusion circuit pressure regulation method based on photovoltaic DC-to-AC converter phase modulation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103166226A (en) * 2013-03-29 2013-06-19 华北电力大学（保定） Network voltage reactive-power compound coordination control system and method for new energy power generation
CN105140964A (en) * 2015-09-24 2015-12-09 中国南方电网有限责任公司 10kV power distribution network power coordination control method with photovoltaic power supply
CN106451477A (en) * 2016-10-31 2017-02-22 国网甘肃省电力公司经济技术研究院 Reactive power voltage coordination control method adaptable to clustered wind-solar-electricity access system
CN106410850A (en) * 2016-11-11 2017-02-15 国网江苏省电力公司常州供电公司 Controlling method for grid-connected photovoltaic system including two-stage voltage inverter
CN106849111A (en) * 2016-11-24 2017-06-13 东南大学 A kind of statements based on collusion circuit pressure regulation method based on photovoltaic DC-to-AC converter phase modulation

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3855592A1 (en) * 2020-01-23 2021-07-28 Electricité de France Adjustment of the voltage in a low-voltage branch of a distribution network
FR3106705A1 (en) * 2020-01-23 2021-07-30 Electricite De France Voltage regulation in a low voltage branch of a distribution network

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