CN116683491A - Inertia control method for new energy micro-grid - Google Patents
Inertia control method for new energy micro-grid Download PDFInfo
- Publication number
- CN116683491A CN116683491A CN202310666239.1A CN202310666239A CN116683491A CN 116683491 A CN116683491 A CN 116683491A CN 202310666239 A CN202310666239 A CN 202310666239A CN 116683491 A CN116683491 A CN 116683491A
- Authority
- CN
- China
- Prior art keywords
- inertia
- virtual synchronous
- micro
- virtual
- synchronous generator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 38
- 230000001360 synchronised effect Effects 0.000 claims abstract description 167
- 238000011217 control strategy Methods 0.000 claims abstract description 46
- 238000004146 energy storage Methods 0.000 claims abstract description 24
- 230000002457 bidirectional effect Effects 0.000 claims abstract description 9
- 230000033228 biological regulation Effects 0.000 claims description 18
- 230000005284 excitation Effects 0.000 claims description 16
- 230000001105 regulatory effect Effects 0.000 claims description 16
- 230000003044 adaptive effect Effects 0.000 claims description 6
- 230000001276 controlling effect Effects 0.000 claims description 3
- 238000010276 construction Methods 0.000 claims description 2
- 230000008859 change Effects 0.000 abstract description 12
- 238000004088 simulation Methods 0.000 description 17
- 238000004804 winding Methods 0.000 description 16
- 238000010586 diagram Methods 0.000 description 9
- 238000013016 damping Methods 0.000 description 8
- 239000011159 matrix material Substances 0.000 description 7
- 230000009466 transformation Effects 0.000 description 7
- 230000004044 response Effects 0.000 description 5
- 230000003068 static effect Effects 0.000 description 5
- 230000004907 flux Effects 0.000 description 4
- 238000013461 design Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000001052 transient effect Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 238000004422 calculation algorithm Methods 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- 240000008168 Ficus benjamina Species 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000036039 immunity Effects 0.000 description 1
- 230000006855 networking Effects 0.000 description 1
- 238000010606 normalization Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Classifications
-
- 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
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
-
- 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
-
- 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
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
- H02J3/241—The oscillation concerning frequency
-
- 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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
-
- 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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/50—Controlling the sharing of the out-of-phase component
-
- 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]
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Eletrric Generators (AREA)
Abstract
The application discloses an inertia control method of a new energy micro-grid, which comprises the following steps: adding a virtual synchronous generator control strategy into the micro-source side inverter, and providing a non-difference grid-connected mode and micro-source side inertia support by combining with a presynchronization control strategy; adding a load virtual synchronous machine control strategy into a load side rectifier to provide load side inertia support; and inertia self-adaptive control is added on the energy storage side, so that the bidirectional energy storage converter provides inertia support on the micro-source side and/or the load side. The application replaces the problem of reduced inertia level of the power system caused by the traditional generator based on massive grid connection of high-proportion new energy, improves the inertia level of the power system, reduces the instantaneous change rate of system frequency, inhibits the frequency fluctuation range of the power system, optimizes the dynamic performance of the power system, enhances the anti-interference capability of the power system under the environment of high-frequency fluctuation and large disturbance, and maintains the stable operation of the power system by applying the virtual synchronous generator, the virtual inertia of the load virtual synchronous machine and the self-adaptive control.
Description
Technical Field
The application belongs to the technical field of micro-grids, and particularly relates to an inertia control method of a new energy micro-grid.
Background
Along with the proposal and realization of a novel power system strategic target taking new energy as a main body, the traditional synchronous generator is gradually replaced by new energy units such as photovoltaics, fans and the like, but a micro-grid system formed by new energy is mainly composed of a power electronic converter, has low inertia, so that the inertia level of a modern power system is continuously reduced, the disturbance rejection capability is weakened, and the frequency stability of the power system cannot be guaranteed when the power disturbance is suffered. The traditional power system has enough inertia support, and when power step or fault occurs, the adjusting time can be prolonged, the power angle oscillation is assisted to be balanced, and the power system has the capability of actively balancing fluctuation. Therefore, in order to improve stability and immunity of the system, inertia compensation and control of the micro grid in the new power system is very necessary.
At present, a great deal of literature is available for researching inertia compensation and control aspects of a micro-grid system, and the most common inertia compensation method is to apply a virtual synchronous machine control strategy and a self-adaptive inertia control method to a power electronic converter. The virtual synchronous machine control strategy comprises a virtual synchronous generator strategy and a load virtual synchronous machine strategy. The virtual synchronous generator strategy is an inversion control strategy of the micro-grid, and is essentially that the inverter is controlled to simulate the external characteristics of the synchronous generator, so that the inverter has fixed inertia, however, when the new energy duty ratio of the micro-grid changes, the inertia cannot respond to the change, and the frequency response of the micro-grid system is deteriorated. The load virtual synchronous machine control strategy aims at a rectifying converter, an active loop simulates inertia and primary frequency modulation characteristics of a synchronous motor, a reactive loop simulates voltage characteristics of a stator, and a post-stage DC/DC converter based on proportional-integral control weakens frequency modulation performance of the load virtual synchronous machine strategy. The self-adaptive inertia control method can adjust the control parameters of the system and optimize the dynamic performance, so that the self-adaptive inertia control method can be combined to carry out inertia compensation or control on the new energy micro-grid system on the basis of a virtual synchronous control strategy.
Disclosure of Invention
The application aims to solve the defects of the prior art, and provides an inertia control method of a new energy micro-grid, wherein a virtual synchronous generator control strategy is added to a micro-source side inverter to simulate a synchronous generator, and a presynchronization control strategy is combined to provide a non-difference grid connection and an inertia support; then adding a load virtual synchronous machine control strategy into the load side rectifier, wherein an active loop simulates inertia and primary frequency modulation characteristics of a synchronous motor, and a reactive loop simulates voltage characteristics of a stator, so that the rectifier has inertia supporting capacity; and finally, self-adaptive control virtual inertia is designed on the energy storage side, so that the bidirectional energy storage converter can provide inertia.
In order to achieve the above object, the present application provides the following solutions:
an inertia control method of a new energy micro-grid comprises the following steps:
adding a virtual synchronous generator control strategy into the micro-source side inverter, and providing a non-difference grid-connected mode and micro-source side inertia support by combining with a presynchronization control strategy;
adding a load virtual synchronous machine control strategy into a load side rectifier to provide load side inertia support;
and inertia self-adaptive control is added on the energy storage side, so that the bidirectional energy storage converter provides inertia support on the micro-source side and/or the load side.
Preferably, the adding method of the virtual synchronous generator control strategy comprises the following steps:
constructing a virtual synchronous generator model in the micro-source side inverter;
and generating the virtual synchronous generator control strategy based on the virtual synchronous generator model.
Preferably, the method for constructing the virtual synchronous generator model comprises the following steps:
constructing a virtual synchronous generator mechanical model;
calculating the electric quantity of each part in the traditional synchronous generator mechanical model, and obtaining a virtual synchronous generator electrical model through the stator excitation characteristics and the rotor mechanical characteristics;
and constructing the virtual synchronous generator model based on the virtual synchronous generator mechanical model and the virtual synchronous generator electrical model.
Preferably, the virtual synchronous generator control strategy includes: active frequency modulation and reactive voltage regulation;
the active frequency modulation comprises: the virtual speed regulator simulates the virtual synchronous generator model, and the rotor rotating speed of the virtual synchronous generator model is regulated through the virtual speed regulator to finish active frequency modulation;
the reactive voltage regulation includes: and simulating an excitation controller of the virtual synchronous generator model, and regulating the stator excitation voltage of the virtual synchronous generator model through the excitation controller to complete reactive voltage regulation.
Preferably, the pre-synchronization control strategy includes: and performing PI control on the phase angle difference of the virtual synchronous generator model, and if the phase angle difference is kept to be 0, completing the presynchronization control.
Preferably, the adding method of the virtual synchronous machine control strategy comprises the following steps:
introducing a three-phase PWM rectifier on the load side;
constructing a virtual synchronous machine model in the three-phase PWM rectifier;
and generating the virtual synchronous machine control strategy based on the virtual synchronous machine model.
Preferably, the virtual synchronous machine control strategy includes:
simulating inertia and primary frequency modulation characteristics of the virtual synchronous machine model by using an active ring to perform active adjustment;
and simulating the stator voltage characteristic of the virtual synchronous machine model by using a reactive ring, and performing reactive power regulation.
Preferably, the adding method of the inertia adaptive control includes:
giving virtual inertia and rated frequency values of a micro-grid system, and collecting system voltage values and system current values of the micro-grid system;
and calculating self-adaptive control virtual inertia based on the virtual inertia, the rated frequency value, the system voltage value and the system current value.
Preferably, the control method for inertia adaptive control includes:
according to the actual running condition of the new energy micro-grid, controlling the energy storage side to carry out bidirectional inertia support on the micro-source side and the load side:
when the micro source side needs to be regulated and controlled, the energy storage side is controlled to discharge;
and when the load side needs to be regulated and controlled, the energy storage side is controlled to charge.
Compared with the prior art, the application has the beneficial effects that:
the application replaces the problem of reduced inertia level of the power system caused by the traditional generator based on massive grid connection of high-proportion new energy, improves the inertia level of the power system, reduces the instantaneous change rate of system frequency, inhibits the frequency fluctuation range of the power system, optimizes the dynamic performance of the power system, enhances the anti-interference capability of the power system under the environment of high-frequency fluctuation and large disturbance, and maintains the stable operation of the power system by applying the virtual synchronous generator, the virtual inertia of the load virtual synchronous machine and the self-adaptive control.
Drawings
In order to more clearly illustrate the technical solutions of the present application, the drawings that are needed in the embodiments are briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a method according to an embodiment of the application;
FIG. 2 is a schematic diagram of a virtual synchronous generator model according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of a new energy micro-grid system according to an embodiment of the present application;
FIG. 4 is a control block diagram of a virtual synchronous generator according to an embodiment of the present application;
FIG. 5 is a typical topology and control block diagram of a virtual synchronous machine model according to an embodiment of the present application;
FIG. 6 is a reactive ring control diagram of an embodiment of the present application;
FIG. 7 is a schematic diagram of the adjustment time and overshoot corresponding to the virtual inertia J according to the embodiment of the present application;
FIG. 8 is a three-dimensional state diagram of inertia time constants according to an embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In order that the above-recited objects, features and advantages of the present application will become more readily apparent, a more particular description of the application will be rendered by reference to the appended drawings and appended detailed description.
Example 1
In this embodiment, virtual synchronous generator control of the micro-grid inverter is essentially implemented by the inverter to simulate a conventional synchronous generator. The new energy source is equivalent to the direct current side of the inverter, can be regarded as a prime mover in the traditional power grid, and the inversion control system can be equivalent to a synchronous generator; the equivalent resistance of the inverter and the filter inductor may be equivalent to the synchronous resistance of the synchronous generator.
As shown in fig. 1, the inertia control method of the new energy micro-grid comprises the following steps:
s1, adding a virtual synchronous generator control strategy into a micro-source side inverter, and providing a non-difference grid-connected mode and micro-source side inertia support by combining with a presynchronization control strategy.
The adding method of the virtual synchronous generator control strategy comprises the following steps: constructing a virtual synchronous generator model in the micro-source side inverter; based on the virtual synchronous generator model, a virtual synchronous generator control strategy is generated.
The construction method of the virtual synchronous generator model comprises the following steps: constructing a virtual synchronous generator mechanical model; calculating the electric quantity of each part in the traditional synchronous generator mechanical model, and obtaining a virtual synchronous generator electrical model through the stator excitation characteristics and the rotor mechanical characteristics; and constructing a virtual synchronous generator model based on the virtual synchronous generator mechanical model and the virtual synchronous generator electrical model.
In this embodiment, taking the hidden pole synchronous generator as an example, assuming that the air gap is uniform, the winding is not damped, and the pole pair number is 1, a mechanical model is built, as shown in fig. 2. When the synchronous generator is operating stably, the exciting current i f Almost no change can be regarded as a constant value, so the potential e in the three-phase winding a 、e b And e c Can be expressed as:
wherein M is f Is the maximum mutual inductance between the exciting winding and a, b and c three-phase stator windings.
According to the synchronous generator model shown in fig. 2, the electric quantity of each part is calculated, and the flux linkage on the three-phase windings of a, b and c is respectively psi a 、Ψ b 、Ψ c Flux linkage on exciting winding is psi f The current of the three-phase windings a, b and c are respectively i a 、i b 、i c Exciting winding current is i f Three-phase winding current i a 、i b And i c The magnitudes of (2) are equal and the phases differ by 120 °, so that:
m is the mutual inductance value between every two windings; m is M af 、M bf 、M cf The mutual inductance values among a, b and c three-phase stator windings are respectively; psi a 、Ψ v 、Ψ c A, b and c are respectively three-phase stator winding flux linkages; i.e f Is the field winding current.
Assuming that the resistance of each phase stator winding is R S The three-phase output voltage of the synchronous generator can be obtained as follows:
wherein v is a 、v b 、v c The output voltages of the a, b and c phases are respectively.
Bringing a three-phase stator flux linkage equation into a voltage equation, and obtaining after simplification:
the output voltage of the synchronous generator represented by formula (4) is composed of two parts, one part is that the current on the three-phase winding is L s And R is R s The voltage drop generated on the three-phase winding is the other part of the voltage drop generated by the exciting current, and the part is called the internal potential of the synchronous generator.
The three-phase voltage and the three-phase current are both time-varying alternating current, and the time-varying alternating current is adopted for analysis, so that errors are prone to occur, and coordinate transformation work is needed to be carried out, so that the time-varying alternating current is converted into direct current of a rotating coordinate system.
First through C 3/2 The transformation matrix converts various electric quantities under the abc three-phase static coordinate system into two-phase static;
then pass through C 2s/2r The transformation matrix converts the electrical quantities in the stationary coordinate system into the rotational coordinate system dq:
c is C 3/2 Transformation matrix and C 2s/2r The transformation matrix is combined to obtain a transformation matrix capable of directly converting electric quantity from a three-phase static abc coordinate system to a two-phase dq rotation coordinate system, namely C 2s/2r A matrix;
based on the conversion matrix, the alternating current quantity of the static coordinate system can be converted into the direct current quantity of the rotary coordinate system, and the modeling of the electric model is completed.
The virtual synchronous generator control strategy comprises the following steps: active frequency modulation and reactive voltage regulation; active frequency modulation includes: the virtual speed regulator simulates a virtual synchronous generator model, and the rotor rotating speed of the virtual synchronous generator model is regulated through the virtual speed regulator to finish active frequency modulation; reactive voltage regulation includes: and simulating an excitation controller of the virtual synchronous generator model, and regulating the stator excitation voltage of the virtual synchronous generator model through the excitation controller to complete reactive voltage regulation.
In this embodiment, the virtual synchronous generator control strategy mainly consists of two parts:
(1) An active frequency modulation part which simulates a virtual speed regulator of the synchronous generator and is analogous to a rotor part in the synchronous generator, and the rotor rotating speed is connected with the output active power:
wherein P is m To synchronize the mechanical power of the generator, P e For synchronizing the electromagnetic power of the generator, P D For damping power, D is a virtual damping coefficient, ω 0 For synchronous angular velocity, ω is mechanical angular velocity, J is virtual moment of inertia, T m Is mechanical torque, T e Is electromagnetic torque, T d Damping torque for synchronous machine, J s Is the rotational inertia of the synchronous machine.
(2) The reactive voltage regulating part simulates a virtual excitation controller and is analogous to a stator part in the synchronous machine, and the stator excitation voltage is connected with the output reactive power:
wherein u is ref For voltage reference value u N Is rated voltage effective value, Q e For the actual absorbed active power, Q ref Is the absorbed active power reference value.
By means of active frequency modulation and reactive voltage regulation combined control, inertia and damping characteristics are introduced, simulation of the power converter on the operation characteristics of the synchronous generator is achieved, and adverse effects caused by randomness, uncontrollability and the like of new energy sources can be eliminated. The new energy micro-grid system structure is shown in figure 3.
If the pole pair number ρ=1, the electrical angular velocity and the mechanical angular velocity are equal. On the other hand, by outputting current I abc And terminal voltage U abc The output instantaneous electromagnetic power P can be obtained e ：
From the control block diagram 4 of the virtual synchronous generator, it is possible to obtain:
E＝E 0 +E Q ＝E 0 +n(Q ref -Q) (12)
wherein E is the amplitude of the potential in the reference, P ref Representing the active reference value, P e For instantaneous electromagnetic power, Q ref Is the absorbed active power reference value.
The synchronous generator set converts power by means of a rotor motion equation and transmits active power by means of a power angle difference of a transmission line, and as the rotor motion equation and the power angle difference represent a vector relation between two power generation units, energy exchange exists as long as the balance of the vector relation is broken, and the new vector balance is maintained again, and the functional quantity exchange can reach a steady state, so that the frequency/rotation speed of the synchronous generator set is a global variable of the system, and the synchronous generator set is consistent in the power system under the steady state condition.
The presynchronization control strategy comprises the following steps: and performing PI control on the phase angle difference of the virtual synchronous generator model, and if the phase angle difference is kept to be 0, completing presynchronization control. When the synchronous generator is networked or put into a large power grid, in order to reduce electromagnetic impact and mechanical impact, the waveform, frequency, phase and amplitude of the instantaneous value of the voltage at the generator end are required to be consistent with the instantaneous value of the power grid voltage. Similarly, when the virtual synchronous generator is switched from an independent operation mode to a grid-connected or networking mode operation, in order to avoid power impact and damage to sensitive load, frequency and phase angle are required to be adjusted simultaneously, and adjustment of the phase angle, frequency and amplitude is realized through pre-synchronization control.
S2, adding a load virtual synchronous machine control strategy into the load side rectifier to provide load side inertia support.
The adding method of the virtual synchronous machine control strategy comprises the following steps: introducing a three-phase PWM rectifier at the load side; constructing a virtual synchronous machine model in a three-phase PWM rectifier; and generating a virtual synchronous machine control strategy based on the virtual synchronous machine model.
In this embodiment, a three-phase PWM rectifier is introduced at the load side, and a synchronous machine control strategy is introduced into the three-phase PWM rectifier, so that the rectifier can have inertia and damping, which has the advantage of tracking the grid frequency without a phase-locked loop. Constructing a virtual synchronous machine model in a three-phase PWM rectifier, wherein typical topology and control of the model are shown in fig. 5, L and C are filter inductance and filter capacitance of the input side of the load virtual synchronous machine, and C d Voltage stabilizing capacitor at direct current side of load virtual synchronous machine, i oabc For the input current of the load virtual synchronous machine, V sabc For loading the internal potential of virtual synchronous machines, v dc Is a direct current side voltage.
The virtual synchronous machine control strategy comprises the following steps: utilizing an active loop to simulate the inertia and primary frequency modulation characteristics of a virtual synchronous machine model to perform active adjustment; and (5) simulating the stator voltage characteristic of the virtual synchronous machine model by using the reactive ring, and performing reactive power regulation.
In this embodiment, the active loop of the load virtual synchronous machine simulates the inertia and primary frequency modulation characteristics of the synchronous motor, and can be expressed as:
wherein ω and ω n Outputting a rotor angular frequency and a rated rotor angular frequency for the LVSM; θ represents the phase of the potential within the LVSM; j is virtual synchronous moment of inertia; d (D) p And setting a reference value for the droop damping coefficient of the power frequency controller, wherein P is the active power of the LVSM.
The reactive ring of the load virtual synchronous machine simulates the voltage characteristic of the stator, and the reactive ring control diagram of the load virtual synchronous machine is shown in fig. 6, and can be expressed as follows:
wherein E is m For LVSM stator voltage amplitude, U n For the rated value of the voltage U, K is the reactive ring inertia coefficient, Q is the rated value of the output reactive power Q of the magnetic regulator resistor, D q For exciting regulator damping coefficient E 0 Is the initial value of the ideal voltage amplitude.
According to the instantaneous power theory, the power measurement link is realized, and the output active power P of the virtual synchronous machine can be calculated under the two-phase rotation coordinate system dq e And reactive power Q e The calculation formula is as follows:
wherein U is od 、U oq D and q axis components of instantaneous three-phase voltage, I od 、I oq The d and q axis components of the instantaneous three-phase current, respectively.
The virtual internal potential instantaneous value is calculated as:
where delta is the phase angle of the active loop output, E is the amplitude of the reference internal potential,and->Respectively virtual internal potential instantaneous d, q axis components.
The three formulas according to the circuit equation are as follows:
wherein i is d 、i q For current loop output, u dc Is output as a voltage loop.
As shown in fig. 5, after the active regulation and reactive regulation are completed, the components of the potential of the load virtual synchronous machine under the natural coordinate system are obtained through a circuit equation series three-term formula, then the reference value of the three-phase alternating current is obtained through an electromagnetic equation, finally the reference value is compared with the actual three-phase current i, tracking regulation is performed through a PI controller, and the corresponding duty ratio is obtained through a PWM module.
The virtual impedance and the current loop control are realized under the grid voltage synchronous rotation reference system, the delta and E are utilized to directly obtain the instantaneous value of the virtual internal potential under the grid voltage synchronous rotation reference system, the virtual impedance control simulates the electrical characteristics of the stator of the synchronous machine, and meanwhile, the output impedance of the load virtual synchronous machine is increased, so that the possible circulation problem of multi-machine parallel connection can be restrained. The dq coordinate system decoupling control current loop based on the proportional-integral (PI) controller is introduced, so that the response speed of the load virtual synchronous machine and the power quality of an alternating current side can be improved. Through the topological structure and the control strategy, the load virtual synchronous machine is enabled to be equivalent to the synchronous motor in the external operation characteristic, and meanwhile, the load virtual synchronous machine has the capability of actively participating in frequency modulation and voltage regulation of the power grid.
S3, inertia self-adaptive control is added to the energy storage side, so that the bidirectional energy storage converter provides inertia support on the micro-source side and/or the load side.
The adding method of the inertia self-adaptive control comprises the following steps: giving a virtual inertia and a rated frequency value of a micro-grid system, and collecting a system voltage value and a system current value of the micro-grid system; and calculating the self-adaptive control virtual inertia based on the virtual inertia, the rated frequency value, the system voltage value and the system current value.
The inertia self-adaptive control method comprises the following steps: according to the actual running condition of the new energy micro-grid, controlling the energy storage side to carry out bidirectional inertia support on the micro-source side and the load side: when the micro source side needs to be regulated and controlled, the energy storage side is controlled to discharge; when the load side needs to be regulated and controlled, the energy storage side is controlled to charge.
In the present embodiment, currently, inertia may be obtained by taking the moment of inertia J s Generator inertia time constant T J And the inertia time constant H is defined in three forms. The virtual inertia J of a typical virtual synchronous generator transfer function obtained according to the topological relation is constant. With time constant H based on power dynamics and topology of each device s By means of a transfer function from disturbance to frequency output, the suppression effect of the virtual inertia on the system frequency disturbance can be quantified.
Wherein T is m To synchronize the mechanical torque of the generator, T e To synchronize the electromagnetic torque of the generator, T d For damping torque, ω is mechanical angular velocity, J s Is the moment of inertia.
Fig. 7 shows the adjustment time and overshoot corresponding to the virtual inertia J. FIG. 7 (a) verifies the relationship of the adjustment time to the virtual inertia, with the adjustment time increasing as the virtual inertia increases; fig. 7 (b) verifies the relationship between the maximum angular frequency change rate and the virtual inertia, and the angular frequency overshoot gradually decreases as the virtual inertia increases.
The frequency dynamic model is shown in a formula (21), in order to improve transient performance of a control strategy, an adaptive control virtual inertia J can be designed, so that the hybrid energy storage system accords with design expectations, and frequency variation delta omega and frequency variation rate domega/dt are introduced as adaptive control standards.
Wherein P is e For synchronizing the electromagnetic power of the generator omega N For nominal mechanical angular velocity, K p Is the voltage ring parameter, J is the virtual inertia, P ref Is the reference power value.
Wherein J is 0 The virtual inertia reference value refers to the Siemens secondary optimal system, and the virtual inertia reference value is taken as a system target value, so that the damping rate is guaranteed to be 0.707.k (k) 1 And k 2 The adjustment factors are all larger than 0, and the dynamic characteristics of the system can be changed by setting different adjustment factors, and the embodiment uses an arctangent function which is rapid in response to symbol transformation, so that the normalization effect is realized, and the adjustment amount is convenient to set.
Next, let k be explained in detail 1 And k 2 Is a value principle of the (a). In the grid, the output power of a virtual synchronous generator can be expressed as:
wherein Z is the equivalent impedance between the virtual synchronous generator and the infinite network; alpha is the impedance angle value; by E s Representing a steady-state operating point voltage of the inverter power supply; by E g Representing the terminal voltage of the inverter power supply; by delta S E representing an inverter power supply s And U g Phase angle difference between them. Delta S 、E s The specific calculation is as follows:
when the equivalent impedance of the circuit is inductance and the power angle is small, the relation between the output active power and the power angle of the virtual synchronous generator is as follows:
the response under power schedule according to equation (25) is obtained by:
meanwhile, in order to avoid system oscillation instability, the virtual inertia parameter must meet that all characteristic roots are on the left half axis of the complex plane, and as can be seen from the formula (26), the virtual inertia J cannot be taken to be too large.
Substitution formula (26) can be obtained:
changing arctan (dω/dt) to k (dω/dt) is substituted into equation (22), and the rate of change of angular frequency is signed during vibration, so that the characteristic root can be obtained by removing the constant negative root:
in the case of dω/dt with a real solution, it is required to satisfy:
the three-dimensional state of the inertia time constant under the frequency offset and the frequency change is plotted according to equation (29), as shown in fig. 8.
From the above formula analysis, it can be seen that k 1 、k 2 There is an upper threshold and this will vary with power shortage, angular frequency deviation, angular frequency rate of change, etc., while also ensuring that the feature root cannot be negative. As can be seen from equation (28), when D is relatively large, the virtual inertia J can be rapidly reduced, which is advantageous for accelerating the dynamic response of the system. However, if D is too large, it can cause severe overshoot of the system and even create negative virtual inertia J; the virtual inertia J can reduce overshoot of the control system, but the stronger inertia J can affect the adjustment rate of the system instead and can exceed the maximum limit under the restriction of the instruction. In summary, the adjustment time and the overshoot need to be comprehensively considered, and in practical application, the energy storage dynamic characteristics of the converter side need to be considered.
The self-adaptive control flow comprises the following steps: firstly, setting initial values of a model and giving virtual inertia J 0 The initial value is A, and the initial values of different systems are not identical; given the system nominal frequency omega n The value of (2) is 50Hz. Then adopting voltage and current values in the system, calculating values of |delta omega|, ddelta omega/dt and delta omega (ddelta omega/dt), and judging the working state of the system; if the vehicle is in an acceleration state, an inertia increasing method is adopted, so that excessive overshoot is avoided; if the speed is reduced, the inertia reduction method is adopted to accelerate the adjustment time. And finally judging whether the output J is still in a stable range, if so, outputting normally, and if not, outputting according to the maximum or minimum inertia J, thereby avoiding the excessive overshoot and the adjustment time of the system. When the micro source side needs to be regulated and controlled, the energy storage side is controlled to discharge; when the load side needs to be regulated and controlled, the energy storage side is controlled to charge.
Example two
In the embodiment, the feasibility of the provided virtual inertia control method is verified through the Simulink module simulation of Matlab, a typical new energy micro-grid system model is established, the simulation and the physical verification of the inversion control of the virtual synchronous generator are performed first, and then the simulation and the physical verification of the rectification control of the load virtual synchronous machine are performed; the simulation model consists of a battery unit, a bidirectional DC-AC converter and a control loop.
1. Simulation and analysis of a virtual synchronous generator model:
basic parameters of the new energy micro-grid system are listed in table 1, and other key parameters are: j=0.5. The mechanical power Pe value of the system is set to be 2KW, and the exciting voltage is set to be 600V. Firstly, under the normal working condition of the virtual synchronous generator converter, the output three-phase exciting voltage and the three-phase output current condition are analyzed.
TABLE 1
After analyzing the steady states of the three-phase exciting voltage and the three-phase output current, analyzing the dynamic working condition of the local load change. The waveform of the designed virtual synchronous generator converter is observed and analyzed through the sudden increase of the load. A load of 2kW was suddenly applied at 0.2s, and the PCC closing system became a grid-connected state at 0.5 s.
The simulation experiment is divided into three stages:
and I, stage: the first 0.2s, the system is in constant load condition. As can be seen from simulation results, the algorithm can keep the system running stably, and can enable the frequency and inertia time constant of the system to meet preset requirements under certain load conditions; and secondly, the stability of the internal excitation reference can be kept, and a constant reference value is provided for the output voltage.
And II, stage: the system is in a variable load working condition, and the local load changes in 0.2s moment. As can be seen from simulation results, the voltage output by the system can also track the load change, and the inertia coefficient and three-phase output current are changed while the output voltage is stabilized, and according to the finally output U q As can be seen at 0, the system achieves phase error free tracking. The voltage frequency reference of the system is stabilized at the power frequency, the voltage frequency of the actual output is basically stabilized at the reference value, although the voltage frequency has small amplitude fluctuation, and the fluctuation is within the allowable range. But due to the internal virtual inertia J, the three-phase output current is regulated for a longer time than the output three-phase voltage.
And III, stage: when the system is in a grid-connected state, the PCC is closed when the system is in a 0.5s state, and the micro-grid system is converted from an island state to a grid-connected state. From simulation results, the system is subjected to transient adjustment before and after grid-connected change, the voltage amplitude does not have large fluctuation, the current is quickly adjusted, the power angle is kept stable, and the system enters new stable operation. The presynchronization control module is described to realize grid connection without dead zone, and the purpose of design is achieved. And because the selected large power grid state is an infinite power grid, the inertia is considered to be large enough, and inertia measurement is not carried out on the system after grid connection.
2. Simulation and analysis of virtual synchronous machine model
According to the coordination control strategy of the virtual load synchronous machine of the load virtual synchronous machine shown in fig. 5, a simulation model of the hybrid energy micro-grid system is built, and the simulation model consists of two parts: the simulation main circuit part consists of a load virtual synchronous machine rectifier and Buck/Boost cascading, wherein the voltage peak value of an alternating current bus is 311V, and the voltage of the direct current bus is 700V; the load synchronous machine system control loop part consists of a load virtual synchronous machine control module and a DC/DC control module, wherein the load virtual synchronous machine module controls the three-phase rectifier bridge to stably output direct-current voltage of 700V, and the DC/DC control module controls the Buck/Boost loop to charge an energy storage module with the opposite terminal voltage of 200V at a constant voltage.
The active power-frequency control loop of the load virtual synchronous machine is controlled by utilizing inertia parameters, so that the control of a driving motor of the load virtual synchronous machine is realized. The simulation parameters are shown in table 2, which satisfy the static stability of the system and can ensure the dynamic performance.
TABLE 2
The simulation experiment is divided into three stages:
and I, stage: the three-phase voltage and current at the alternating current side start to stabilize for the first 0.2s, and an obvious adjustment process exists. Simulation results show that the algorithm can keep the system running stably and can enable the frequency and inertia time constant of the system to meet preset requirements under certain load conditions; and secondly, the stability of the internal excitation reference can be kept, and a constant reference value is provided for the output voltage.
And II, stage: the system ac voltage measurement is in a stable phase. Due to the internal virtual inertia J, the regulation time on the dc side is longer compared to the output three-phase voltage and current. And when the temperature is 1s, the direct current side of the system is nearly stable, so that the design purpose is achieved.
And III, stage: the system changes load conditions. It can be seen from the graph that the system is subjected to transient adjustment before and after the load change, the voltage amplitude is not greatly fluctuated, the current is quickly adjusted, the power angle is kept stable, and the system enters new stable operation. The load virtual synchronous machine control module is described to realize quick adjustment.
The above embodiments are merely illustrative of the preferred embodiments of the present application, and the scope of the present application is not limited thereto, but various modifications and improvements made by those skilled in the art to which the present application pertains are made without departing from the spirit of the present application, and all modifications and improvements fall within the scope of the present application as defined in the appended claims.
Claims (9)
1. The inertia control method of the new energy micro-grid is characterized by comprising the following steps of:
adding a virtual synchronous generator control strategy into the micro-source side inverter, and providing a non-difference grid-connected mode and micro-source side inertia support by combining with a presynchronization control strategy;
adding a load virtual synchronous machine control strategy into a load side rectifier to provide load side inertia support;
and inertia self-adaptive control is added on the energy storage side, so that the bidirectional energy storage converter provides inertia support on the micro-source side and/or the load side.
2. The inertia control method of the new energy micro-grid according to claim 1, wherein the adding method of the virtual synchronous generator control strategy comprises the following steps:
constructing a virtual synchronous generator model in the micro-source side inverter;
and generating the virtual synchronous generator control strategy based on the virtual synchronous generator model.
3. The inertia control method of the new energy micro-grid according to claim 2, wherein the construction method of the virtual synchronous generator model comprises the following steps:
constructing a virtual synchronous generator mechanical model;
calculating the electric quantity of each part in the traditional synchronous generator mechanical model, and obtaining a virtual synchronous generator electrical model through the stator excitation characteristics and the rotor mechanical characteristics;
and constructing the virtual synchronous generator model based on the virtual synchronous generator mechanical model and the virtual synchronous generator electrical model.
4. The inertia control method of the new energy micro grid according to claim 2, wherein the virtual synchronous generator control strategy comprises: active frequency modulation and reactive voltage regulation;
the active frequency modulation comprises: the virtual speed regulator simulates the virtual synchronous generator model, and the rotor rotating speed of the virtual synchronous generator model is regulated through the virtual speed regulator to finish active frequency modulation;
the reactive voltage regulation includes: and simulating an excitation controller of the virtual synchronous generator model, and regulating the stator excitation voltage of the virtual synchronous generator model through the excitation controller to complete reactive voltage regulation.
5. The inertia control method of the new energy micro grid according to claim 2, wherein the pre-synchronization control strategy comprises: and performing PI control on the phase angle difference of the virtual synchronous generator model, and if the phase angle difference is kept to be 0, completing the presynchronization control.
6. The inertia control method of the new energy micro-grid according to claim 1, wherein the adding method of the virtual synchronous machine control strategy comprises the following steps:
introducing a three-phase PWM rectifier on the load side;
constructing a virtual synchronous machine model in the three-phase PWM rectifier;
and generating the virtual synchronous machine control strategy based on the virtual synchronous machine model.
7. The inertia control method of the new energy micro grid according to claim 6, wherein the virtual synchronous machine control strategy comprises:
simulating inertia and primary frequency modulation characteristics of the virtual synchronous machine model by using an active ring to perform active adjustment;
and simulating the stator voltage characteristic of the virtual synchronous machine model by using a reactive ring, and performing reactive power regulation.
8. The inertia control method of the new energy micro grid according to claim 1, wherein the adding method of the inertia adaptive control comprises the following steps:
giving virtual inertia and rated frequency values of a micro-grid system, and collecting system voltage values and system current values of the micro-grid system;
and calculating self-adaptive control virtual inertia based on the virtual inertia, the rated frequency value, the system voltage value and the system current value.
9. The inertia control method of the new energy micro grid according to claim 1, wherein the inertia adaptive control method comprises the following steps:
according to the actual running condition of the new energy micro-grid, controlling the energy storage side to carry out bidirectional inertia support on the micro-source side and the load side:
when the micro source side needs to be regulated and controlled, the energy storage side is controlled to discharge;
and when the load side needs to be regulated and controlled, the energy storage side is controlled to charge.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310666239.1A CN116683491A (en) | 2023-06-07 | 2023-06-07 | Inertia control method for new energy micro-grid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310666239.1A CN116683491A (en) | 2023-06-07 | 2023-06-07 | Inertia control method for new energy micro-grid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116683491A true CN116683491A (en) | 2023-09-01 |
Family
ID=87785000
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310666239.1A Pending CN116683491A (en) | 2023-06-07 | 2023-06-07 | Inertia control method for new energy micro-grid |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116683491A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116995693A (en) * | 2023-09-26 | 2023-11-03 | 西安热工研究院有限公司 | Method for controlling energy storage virtual inertia of network super capacitor |
-
2023
- 2023-06-07 CN CN202310666239.1A patent/CN116683491A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116995693A (en) * | 2023-09-26 | 2023-11-03 | 西安热工研究院有限公司 | Method for controlling energy storage virtual inertia of network super capacitor |
| CN116995693B (en) * | 2023-09-26 | 2024-01-30 | 西安热工研究院有限公司 | Method for controlling energy storage virtual inertia of network super capacitor |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| WO2022077847A1 (en) | Virtual synchronous machine control method for hybrid microgrid mmc interconnected converter | |
| Adzic et al. | Maximum power search in wind turbine based on fuzzy logic control | |
| CN108429289B (en) | Control method and system based on virtual synchronous generator | |
| CN110611331B (en) | Method for supporting grid frequency by grid-connected power electronic equipment | |
| CN106998074B (en) | Control method and system for modular multi-level flexible direct current converter station | |
| CN110518600A (en) | A kind of grid-connected active support and control structure of PMSG of the modified multi-machine parallel connection based on VSG | |
| Abokhalil | Grid connection control of DFIG for variable speed wind turbines under turbulent conditions | |
| Martínez et al. | Dynamic performance of compressed air energy storage (CAES) plant for applications in power systems | |
| Xie et al. | An improved virtual inertia control strategy of DFIG-based wind turbines for grid frequency support | |
| CN113131522A (en) | Virtual inertia control and stability analysis method for doubly-fed wind generator | |
| CN115764989A (en) | Virtual synchronous generator system based on network-building type current converter | |
| CN116683491A (en) | Inertia control method for new energy micro-grid | |
| CN115882762A (en) | Frequency optimization control method of grid-connected wind power system | |
| Loucif et al. | Nonlinear sliding mode power control of DFIG under wind speed variation and grid connexion | |
| Yan et al. | Backstepping-based direct power control for dual-cage rotor brushless doubly fed induction generator | |
| Zhao et al. | Maximal power point tracking under speed-mode control for wind energy generation system with doubly fed introduction generator | |
| CN116388264A (en) | Control system and method for direct-current self-synchronizing enhanced permanent magnet direct-drive fan | |
| Frasetyo et al. | Islanded wind farm microgrid stability control using synchronverter algorithm | |
| Kenne et al. | Adaptive PI control strategy for a self-excited induction generator driven by a variable speed wind turbine | |
| Shao et al. | Adaptive damping coefficient control of virtual synchronous generator of microgrid inverter | |
| Dinesh et al. | Independent operation of DFIG-based WECS using resonant feedback compensators under unbalanced grid voltage conditions | |
| Li et al. | Harmonic compensation for variable speed DFIG wind turbines using multiple reference frame theory | |
| Zhang et al. | Research on the Unbalanced Load for Brushless Doubly Fed Induction Generation System on Predictive Current Control | |
| Chang et al. | Overall control strategy for voltage-controlled PMSG-based wind turbines with frequency support | |
| Abdoune et al. | Improved control strategy for a stand-alone DFIG under unbalanced load conditions |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication |