A control method and system of a virtual synchronous generator system

Abstract

This invention discloses a control method and system for a virtual synchronous generator system. The control method includes: performing power outer loop control to obtain the virtual rotor angle and virtual electromotive force of the virtual synchronous generator; performing current inner loop control by substituting the obtained virtual rotor angle and virtual electromotive force into the stator equations to calculate current reference values ​​and current reference phasors, and generating three-phase current reference values ​​by combining the virtual rotor angle; comparing the three-phase current reference values ​​with the actual three-phase currents through hysteresis to obtain a PWM wave drive signal; optimizing the particle swarm optimization algorithm based on the rated capacity to obtain PID controller parameters, which are then used for control and adjustment of the power outer loop and the current inner loop to control the virtual synchronous generator system. This control method can improve the dynamic response capability of the power grid to reactive power during load changes.

Description

Technical Field

[0001] This invention belongs to the field of power electronics and power system control technology, specifically relating to a control method and system for a virtual synchronous generator system. Background Technology

[0002] my country's new energy development strategy has shifted from relying on base-based development to distributed development, leveraging the advantages of distributed production, centralized utilization, and local consumption. With the continuous increase in investment in new energy construction, the proportion of new energy power generation in my country has been steadily rising, with some regions exceeding 80% of their power grid connected to the grid. Although my country's new energy industry is showing a booming development trend, it still faces many difficulties in its advancement. Supported by my country's ultra-high-voltage direct current transmission and inter-regional AC / DC hybrid power grid technologies, green electricity from wind and solar saturated areas in the west can be transmitted to developed areas in the east, but this places high demands on the power grid structure and operating characteristics. Long-distance transmission means an increase in transmission lines, which will significantly increase the reactive power demand of the system. Limited by load levels, power system transmission capacity, and voltage stability, the weak inertia and weak voltage support capacity of high-proportion new energy power systems remain significant factors restricting this deficiency. At the same time, the volatility and intermittency of new energy sources, as well as uneven load distribution, will lead to insufficient reactive power supply from the power grid system, causing a certain degree of voltage drop at the bus, affecting user electricity consumption, and hindering the construction of new energy power grids. Engineering practice shows that when a power system experiences a fault, the bus voltage at the grid connection point is prone to momentary drops, leading to risks such as disconnection or disconnection of closely electrically connected equipment within a certain distance. Voltage drops further affect the transmission system, causing faults such as DC blocking, thus deteriorating the stability of the AC system. Furthermore, the system's reactive power demand increases to some extent, and insufficient reactive power can lead to serious accidents such as voltage instability or system regulation failure. Connecting reactive power compensation devices to the power source side of the power system to supplement reactive power capacity is currently a popular implementation method.

[0003] Commonly used reactive power compensation schemes include shunt capacitors, synchronous reactors, synchronous condensers, static var compensators (SVCs), and static synchronous compensators (STATCOMs). Traditional shunt capacitors and shunt reactors offer advantages such as ease of operation and simple structure, but they cannot achieve continuous reactive power regulation and are unsuitable for high-voltage switching; therefore, they have been largely replaced. With the development of power electronics technology, devices such as SVCs and STATCOMs have shown more significant advantages, better improving power quality, enhancing grid voltage stability and support strength, and offering greater safety compared to shunt capacitors and shunt reactors. However, because their reactive power capacity is limited by operating voltage and overcurrent, they cannot guarantee the system's reactive power needs when the grid voltage is low, leading to the risk of grid disconnection. Furthermore, SVCs and similar technologies have certain limitations in dynamic reactive power regulation and dynamic response speed, but overall, they remain the mainstream reactive power compensation schemes. Synchronous condensers, as a new type of reactive power compensation scheme, have the ability to dynamically adjust reactive power output and quickly respond to changes in bus voltage. By sending or absorbing reactive power to the grid, they can quickly respond to the reactive power demand of the power system, thereby regulating voltage, suppressing voltage fluctuations, and meeting the dynamic response requirements of the power system.

[0004] Virtual Synchronous Generator (VSG) is a new technology in reactive power compensation schemes, but currently there is a lack of a stable and effective control method for its application. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a control method and system for a virtual synchronous generator system, which can improve the dynamic response capability of the power grid to reactive power during load changes.

[0006] This invention provides a control method for a virtual synchronous generator system, the control method comprising:

[0007] Perform power outer loop control to obtain the virtual rotor angle of the virtual synchronous generator. and virtual potential ; Perform current inner loop control and obtain the virtual rotor angle and the virtual potential Substitute into the stator equation: , in, , For the grid connection point voltage phasor, Equivalent resistance / reactance; The current reference value was calculated. Current reference phasor And combined with virtual rotor angle Generate three-phase current reference values The PWM wave drive signal is obtained by comparing the three-phase current reference value with the actual three-phase current through hysteresis. The particle swarm optimization algorithm is optimized based on the rated capacity to obtain PID controller parameters, which are then used to adjust the power outer loop and current inner loop to control the virtual synchronous generator system.

[0008] Furthermore, according to the control method for the virtual synchronous generator system provided by the present invention, the power outer loop control includes active frequency control and reactive voltage control.

[0009] Furthermore, according to the control method for the virtual synchronous generator system provided by the present invention, the active frequency control includes: measuring the frequency of the power grid, obtaining the deviation between the actual frequency and the rated frequency, applying it as input to the motor rotor equation after droop control, and using an integrator to obtain the virtual rotor angle. and electric angular velocity .

[0010] Furthermore, according to the control method of the virtual synchronous generator system provided by the present invention, the speed of the virtual synchronous generator and the grid frequency have the following relationship: ; in, The synchronous speed is expressed in r / min. This refers to the power grid frequency, measured in Hz. The number of magnetic pole pairs; This refers to the mechanical angular velocity, measured in rad / s. ω represents electric angular velocity, measured in rad / s.

[0011] Furthermore, according to the control method of the virtual synchronous generator system provided by the present invention, the reactive power voltage control includes: controlling the reactive power... Reactive power reference value The difference is calculated, and after passing through a PID controller, it is compared with the rated voltage. Adding them together, we obtain the transient potential. The transient potential The output virtual potential amplitude after filtering and amplification And combined with virtual rotor angle Generate three-phase voltage reference values: .

[0012] Furthermore, according to the control method for the virtual synchronous generator system provided by the present invention, the inner current loop control includes: a current reference value. and the current in the actual circuit The difference is obtained by subtraction. The inputs are respectively fed into the hysteresis comparator, and the hysteresis band half-width is set to... The hysteresis bandwidth is The current error threshold is and The two are compared to obtain the PWM wave drive signal.

[0013] Furthermore, according to the control method for the virtual synchronous generator system provided by the present invention, the comparison process of the hysteresis comparator includes: defining the current difference value. ,in This is the current reference value. For the actual line current, the hysteresis band half-width is set to... ; when When, it means The hysteresis comparator outputs a second PWM trigger signal, causing the inverter to switch to a switching state that reduces the output current, thereby reducing current error; when When, it means The hysteresis comparator outputs a first PWM trigger signal, causing the inverter to switch to a switching state that increases the output current, thereby reducing current error; when At this time, keep the previous switching state unchanged to stabilize the current at the reference value. Inside the belt.

[0014] Furthermore, according to the control method for the virtual synchronous generator system provided by the present invention, the optimization of the particle swarm optimization algorithm based on the rated capacity includes: Initialize particle swarm parameters, including those based on rated capacity. Determine the rated value of the controlled variable and set the search boundary for the PID parameters; Calculate and update PID parameters; Initialize local and global optimal values; Perform particle fitness evaluation to determine whether the iteration meets the termination condition; If the termination condition is met, the process ends; if the termination condition is not met, the inertia weights are updated. After updating the inertia weights, the particle velocity and position are updated, and then the particle fitness evaluation step is returned.

[0015] Furthermore, according to the control method for the virtual synchronous generator system provided by the present invention, the method for updating the inertia weight is as follows: ; in, Indicates inertia weight; Indicates inertia weight The maximum value; Indicates inertia weight The minimum value; Indicates the number of algorithm iterations; This indicates the maximum number of iterations the algorithm can perform.

[0016] The present invention also provides a control system for a virtual synchronous generator, the control system using the control method for the virtual synchronous generator system of the present invention, the control system comprising: Measurement unit, the measurement unit being used to measure the mains voltage Grid current and power grid frequency ; The comparison feedback unit is used to obtain an active power reference value. Reactive power reference value and respectively compared with the actual active power With reactive power By comparison, the deviations were obtained respectively. , And based on this, a virtual potential is generated. and related control quantities; The rotor equation calculation and integration unit is used to calculate the virtual electric angular velocity based on the frequency deviation. The virtual rotor angle is obtained by integration. The rotor equation calculation and integration unit outputs the calculation results to the current hysteresis control unit. A proportional-integral-derivative (PI-DE) control unit is used to adjust the error signal; Current hysteresis control unit, used to determine the current hysteresis control unit based on the current hysteresis control unit. and The comparison result generates the PWM trigger signal for the inverter IGBT; The filtering unit is used to filter the transient potential and voltage reference to suppress high-frequency components.

[0017] The beneficial effects of this invention are as follows: This invention provides a control method and system for a virtual synchronous generator system. This control method establishes an outer power loop control consisting of active power frequency control and a reactive power voltage loop, as well as an inner current loop control. It proposes an improved PSO algorithm based on rated capacity, optimizing the initial particle population to improve the quality of the search particles. Simultaneously, it introduces an inertia weight adjustment strategy to address the accuracy issue of the algorithm's search. The improved PSO algorithm can find the optimal population within a shorter iteration cycle and, in step response tests, can quickly follow the target with almost no overshoot. Attached Figure Description

[0018] The technical solution and other beneficial effects of the present invention will become apparent from the following detailed description of specific embodiments of the invention, in conjunction with the accompanying drawings.

[0019] Figure 1 This is a flowchart illustrating the control method for the virtual synchronous generator system provided in this embodiment.

[0020] Figure 2 This is a schematic diagram of the primary frequency regulation principle of the control method for the virtual synchronous generator system provided in this embodiment.

[0021] Figure 3 This is a block diagram of the active frequency control structure of the control method for the virtual synchronous generator system provided in this embodiment.

[0022] Figure 4 This is a block diagram of the reactive voltage control loop structure of the control method for the virtual synchronous generator system provided in this embodiment.

[0023] Figure 5 This is a current hysteresis control structure diagram of the control method for the virtual synchronous generator system provided in this embodiment.

[0024] Figure 6 The current waveform diagram is shown during current hysteresis tracking in the control method of the virtual synchronous generator system provided in this embodiment.

[0025] Figure 7 The flowchart shows the improved PSO algorithm for the control method of the virtual synchronous generator system provided in this embodiment.

[0026] Figure 8 The graph shows the fitness function value of the control method for the virtual synchronous generator system provided in this embodiment.

[0027] Figure 9 The step response time-domain curve of the control method for the virtual synchronous generator system provided in this embodiment is shown.

[0028] Figure 10This is a schematic diagram of the control structure of the virtual synchronous generator control system provided in this embodiment. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0032] The embodiments of the present invention will now be further described in conjunction with the accompanying drawings and specific implementation details.

[0033] Figure 1 This is a flowchart illustrating the control method for the virtual synchronous generator system provided in this embodiment.

[0034] like Figure 1 As shown, the control method includes: Perform power outer loop control to obtain the virtual rotor angle of the virtual synchronous generator. and virtual potential ; Perform current inner loop control and obtain the virtual rotor angle and the virtual potential Substitute into the stator equation: , in, , For the grid connection point voltage phasor, Equivalent resistance / reactance; The current reference value was calculated. Current reference phasor And combined with virtual rotor angle Generate three-phase current reference values The PWM wave drive signal is obtained by comparing the three-phase current reference value with the actual three-phase current through hysteresis. The particle swarm optimization algorithm is optimized based on the rated capacity to obtain PID controller parameters, which are then used to adjust the power outer loop and current inner loop to control the virtual synchronous generator system.

[0035] In this embodiment, the power outer loop control includes active frequency control and reactive voltage control.

[0036] Specifically, in the active power frequency control, the synchronous generator speed and the grid frequency have the following relationship: ; In the formula, This indicates the rotor speed of the synchronous generator, in r / min. This indicates the power grid frequency, measured in Hz. This indicates the number of magnetic pole pairs (pole pairs) of the generator. This represents the mechanical angular velocity, with the unit being rad / s; This represents electric angular velocity, measured in rad / s.

[0037] The rotor motion equation of a synchronous generator is: ; Power form (per unit / electric angular velocity): , ; in, Represents the equivalent moment of inertia; Let represent the electric angular velocity and rated electric angular velocity of the virtual synchronous generator, respectively. ; This represents the electromagnetic torque and mechanical torque of the synchronous motor; D is the damping coefficient. The phase angle (electric angle) of the output voltage of the virtual synchronous generator satisfies... .

[0038] By performing a Laplace transform on the rotor motion equation of the synchronous generator, the relationship between motor power and frequency can be obtained as follows:

[0039]

[0040] As shown in the above equation, when there is a deviation between the mechanical power and electromagnetic power of a synchronous generator, it will cause changes in the motor speed, resulting in fluctuations in the motor's output frequency and a discrepancy between the motor frequency and the grid frequency. This power-frequency relationship can be explained using... Figure 2 The schematic diagram shown is as follows.

[0041] Depend on Figure 2 It can be seen that in a power system, when the comprehensive active load is generated by a point... Rise to point At that time, the system frequency was changed from Descending to Typically, the power frequency of 50Hz is taken as the reference value, and the frequency deviation is used as the input of the speed controller. Increasing or decreasing the motor speed adjusts its output active power, thereby regulating the frequency. This is the principle of primary frequency regulation.

[0042] Based on the primary frequency regulation and inertia support characteristics of the motor, using Indicates the rated frequency. Indicates the power grid frequency. This indicates the active power loss of the motor. This indicates the active power output of the motor. This represents the droop control coefficient. Represents the inertial constant. Representing the rotor angle, we can obtain, as follows: Figure 3 The diagram shows the active-frequency control structure block diagram. Figure 3 As shown, by measuring the grid frequency, the deviation between the actual frequency and the rated frequency is obtained. After droop control, this deviation is used as input to the motor rotor equation (i.e., the rotor motion equation of the synchronous generator). An integrator is then used to obtain the virtual rotor angle. and electric angular velocity This control method introduces a process where the frequency follows changes in the grid voltage, making the virtual synchronous generator system more sensitive to frequency fluctuations and enhancing the VSG's role in frequency stabilization.

[0043] Figure 4 This is a block diagram of the reactive voltage control loop structure provided in this embodiment.

[0044] like Figure 4 As shown, the control principle of the reactive voltage loop is similar to that of the active frequency control. The reactive power... Reactive power reference value The difference is calculated, and after passing through a PID controller, it is compared with the rated voltage. Adding them together, we obtain the transient potential. The virtual potential is then output after filtering and amplification. And combined with virtual rotor angle Generate three-phase voltage reference values: That is, the theoretical three-phase voltage reference value.

[0045] In this embodiment, the current inner loop control includes: power outer loop control to obtain the virtual rotor angle of the VSG. and virtual potential The current output after passing through the stator is used as a reference value, and then current hysteresis control is used to obtain the PWM wave drive signal. A system based on the Simulink platform is established as follows: Figure 5 The current hysteresis control structure is shown.

[0046] like Figure 5 As shown, the three current reference values ​​obtained from the stator equations are... and the current in the actual circuit The difference is obtained by subtraction. ,in This is the current reference value. The actual line current is input to the hysteresis comparator, and the hysteresis band half-width is set to... (hysteresis bandwidth is) The current error threshold is and The two are compared to obtain the switching signals of each IGBT circuit in the inverter, i.e., the PWM wave, to achieve current inner-loop control. The current hysteresis control method provided in this embodiment is simple, requires no carrier wave, and compares with the reference current in real time, enabling it to quickly respond to changes in current in the circuit and reduce the impact of fluctuations.

[0047] The comparison process of a hysteresis comparator is as follows: Figure 6 As shown. Current in the actual circuit. Stabilize at current reference value of Within the range, when the current difference ,express The hysteresis comparator outputs a second PWM trigger signal, causing the inverter to switch to a switching state that reduces the output current, thereby reducing current error; when When, it means The hysteresis comparator outputs a first PWM trigger signal, causing the inverter to switch to a switching state that increases the output current, thereby reducing current error; when At this time, keep the previous switching state unchanged to stabilize the current at the reference value. Within the band. Therefore, the current is always limited to the ring width. Within this range, the performance of current tracking can be adjusted by changing the size of the ring width.

[0048] like Figure 7 As shown, in this embodiment, the optimization of the particle swarm algorithm based on the rated capacity includes: Initialize particle swarm parameters, including those based on rated capacity. Determine the rated value of the controlled variable and set the search boundary for the PID parameters; Calculate and update PID parameters; Initialize local and global optimal values; Perform particle fitness evaluation to determine whether the iteration meets the termination condition; If the termination condition is met, the process ends; if the termination condition is not met, the inertia weights are updated. After updating the inertia weights, the particle velocity and position are updated, and then the particle fitness evaluation step is returned.

[0049] Specifically, in initializing the PID parameters for rated capacity, the initial parameters are determined based on the characteristics of the controlled system, using the maximum control quantity of the control system (PWM duty cycle) and the rated value of the controlled variable, respectively: ; In the formula, Indicates the proportionality coefficient; Indicates the integration time constant; Represents the differential time constant; Represents the system's inertial time constant. To control the maximum amplitude, The rated value of the controlled quantity.

[0050] By control law The coefficients of the PID controller can be obtained as follows: ; In the formula, These represent the proportional, integral, and differential coefficients, respectively.

[0051] Based on the above formula, an initial set of PID coefficients is calculated. After randomly generating a particle swarm, these coefficients are used to replace a certain set of particles, thereby improving the initial PID coefficients.

[0052] Inertia weight The inertial weight has a significant impact on the convergence direction and speed of PSO particle swarm optimization. If the inertial weight is too large, the particle swarm will always search within the global range, which not only increases the computational load but also makes it easy for the particles to fail to converge, resulting in divergent results. If the inertial weight is too small, the particle swarm is likely to get trapped in some intervals too early, resulting in local optima and failing to obtain the global optimum.

[0053] Therefore, in this embodiment, the inertia weight adjustment strategy includes: in the early stage of algorithm convergence, a larger value is given to the inertia weight so that it has global observation capability and can obtain the optimal solution with a greater probability in the global context; in the later stage of algorithm convergence, the value of the inertia weight is reduced to avoid the divergence of the current optimal solution, improve the search accuracy of the algorithm, and further reduce the fitness error.

[0054] The inertia weight adjustment scheme is shown in the following formula: ; in, Indicates inertia weight; Indicates inertia weight The maximum value; Indicates inertia weight The minimum value; Indicates the number of algorithm iterations; This indicates the maximum number of iterations the algorithm can perform.

[0055] In this embodiment, the inertia weight modification strategy is linearization, which ensures that the algorithm has different levels of search capabilities in the early, middle and late stages.

[0056] In this embodiment, simulation verification and analysis were conducted to verify the effectiveness of the improved PSO algorithm.

[0057] Establish a standard second-order system for step testing: ； In the formula, This represents the system's inertial time constant, which can be taken as 0.1; This represents the damping ratio, which can be taken as 0.2.

[0058] Furthermore, it can be expressed as: ; Substituting the calculated PID parameters into the test results, we can obtain the following: Figure 8 , Figure 9 The fitness function values ​​and step response time-domain curves are shown. Figure 8 It can be seen that the improved PSO algorithm can quickly find the optimal proportional, integral, and differential coefficients with fewer iterations;

[0059] in, The evaluation time (simulation termination time or control evaluation window length) is used for evaluation. To adjust the time, For overshoot, For error, As weight. As a particle fitness value, a smaller fitness indicates a better control effect. Depend on Figure 9 As can be seen from the step response time-domain curve, the PID parameters calculated by the improved PSO algorithm have good control effect, almost no overshoot, and the settling time is about 0.1s, which meets the control requirements.

[0060] This invention provides a control method for a virtual synchronous generator system. This method establishes an outer power control loop consisting of power frequency control and a reactive power voltage loop, as well as an inner current control loop. It proposes an improved PSO algorithm based on rated capacity, optimizing the initial particle population to improve the quality of the search particles. Simultaneously, it introduces an inertia weight adjustment strategy to address the accuracy issue of the algorithm's search. The improved PSO algorithm can find the optimal population in fewer iteration cycles and, in step response tests, can quickly follow the target with almost no overshoot.

[0061] Figure 10 This is a schematic diagram of the control structure of the virtual synchronous generator control system provided in this embodiment.

[0062] like Figure 10 As shown, the control system includes: Measurement unit, the measurement unit being used to measure the mains voltage Grid current and power grid frequency ; The comparison feedback unit is used to obtain an active power reference value. Reactive power reference value and respectively compared with the actual active power With reactive power By comparison, the deviations were obtained respectively. , And based on this, a virtual potential is generated. and related control quantities; The rotor equation calculation and integration unit is used to calculate the virtual electric angular velocity based on the frequency deviation. The virtual rotor angle is obtained by integration. The integral satisfies The rotor equation calculation and integration unit outputs the calculation results to the current hysteresis control unit. A proportional-integral-derivative (PID) control unit is used to adjust the error signal; The current hysteresis control unit is used to, according to and The comparison result generates the PWM trigger signal for the inverter IGBT; The filtering unit is used to filter the transient potential and voltage reference to suppress high-frequency components.

[0063] The control system proposed in this embodiment obtains the grid voltage through the measurement unit. Grid current and power grid frequency Key electrical quantities, after being proportionally amplified and integrally processed by the PID control unit, yield reference values ​​for the active and reactive power of the virtual synchronous generator. These reference values ​​are then compared with the actual values ​​via feedback to obtain the transient electromotive force. Hysteresis control generates a reference current, thereby stabilizing the active and reactive power of the virtual synchronous generator near the ideal values, achieving dynamic regulation.

[0064] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the present invention. Finally, it should be noted that in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0065] The control method and system of a virtual synchronous generator system provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of the present invention. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method for a virtual synchronous generator system, characterized in that, The control method includes: Perform power outer loop control to obtain the virtual rotor angle of the virtual synchronous generator. and virtual potential ; Perform current inner loop control and obtain the virtual rotor angle and the virtual potential Substitute into the stator equation: ， in, , For the grid connection point voltage phasor, Equivalent resistance / reactance; The current reference value was calculated. Current reference phasor And combined with virtual rotor angle Generate three-phase current reference values The PWM wave drive signal is obtained by comparing the three-phase current reference value with the actual three-phase current through hysteresis. The particle swarm optimization algorithm is optimized based on the rated capacity to obtain PID controller parameters, which are then used for control and regulation of the power outer loop and the current inner loop to control the virtual synchronous generator system.

2. The control method for the virtual synchronous generator system according to claim 1, characterized in that, The power outer loop control includes active frequency control and reactive voltage control.

3. The control method for the virtual synchronous generator system according to claim 2, characterized in that, The active power frequency control includes: measuring the grid frequency, obtaining the deviation between the actual frequency and the rated frequency, applying the deviation to the motor rotor equation after droop control, and using an integrator to obtain the virtual rotor angle. and electric angular velocity .

4. The control method for the virtual synchronous generator system according to claim 3, characterized in that, The virtual synchronous generator speed and the grid frequency have the following relationship: ； in, The synchronous speed is expressed in r / min. This refers to the power grid frequency, measured in Hz. The number of magnetic pole pairs; This refers to the mechanical angular velocity, measured in rad / s. ω represents electric angular velocity, measured in rad / s.

5. The control method for the virtual synchronous generator system according to claim 2, characterized in that, The reactive power control includes: controlling reactive power... Reactive power reference value The difference is calculated, and after passing through a PID controller, it is compared with the rated voltage. Adding them together, we obtain the transient potential. The transient potential The output virtual potential is obtained after filtering and amplification. And combined with virtual rotor angle Generate three-phase voltage reference values: 。 6. The control method for the virtual synchronous generator system according to claim 1, characterized in that, The current inner loop control includes: current reference value. and the current in the actual circuit The difference is obtained by subtraction. The inputs are respectively fed into the hysteresis comparator, and the hysteresis band half-width is set to... The hysteresis bandwidth is The current error threshold is and The two are compared to obtain the PWM wave drive signal.

7. The control method for the virtual synchronous generator system according to claim 6, characterized in that, The comparison process of the hysteresis comparator includes: defining the current difference. ,in This is the current reference value. For the actual line current, the hysteresis band half-width is set to... ; when When, it means The hysteresis comparator outputs a second PWM trigger signal, causing the inverter to switch to a switching state that reduces the output current, thereby reducing current error; when When, it means The hysteresis comparator outputs a first PWM trigger signal, causing the inverter to switch to a switching state that increases the output current, thereby reducing current error; when At this time, keep the previous switching state unchanged to stabilize the current at the reference value. Inside the belt.

8. The control method for the virtual synchronous generator system according to claim 1, characterized in that, The optimization of the particle swarm optimization algorithm based on the rated capacity includes: Initialize particle swarm parameters, including those based on rated capacity. Determine the rated value of the controlled variable and set the search boundary for the PID parameters; Calculate and update PID parameters; Initialize local and global optimal values; Perform particle fitness evaluation to determine whether the iteration meets the termination condition; If the termination condition is met, the process ends; if the termination condition is not met, the inertia weights are updated. After updating the inertia weights, the particle velocity and position are updated, and then the particle fitness evaluation step is returned.

9. The control method for the virtual synchronous generator system according to claim 8, characterized in that, The method for updating the inertia weight is as follows: ； in, Indicates inertia weight; Indicates inertia weight The maximum value; Indicates inertia weight The minimum value; Indicates the number of algorithm iterations; This indicates the maximum number of iterations the algorithm can perform.

10. A control system for a virtual synchronous generator, characterized in that, The control system uses the control method for a virtual synchronous generator system as described in any one of claims 1-9, and the control system includes: Measurement unit, the measurement unit being used to measure the mains voltage Grid current and power grid frequency ; The comparison feedback unit is used to obtain an active power reference value. Reactive power reference value and respectively compared with the actual active power With reactive power By comparison, the deviations were obtained respectively. , And based on this, a virtual potential is generated. and related control quantities; The rotor equation calculation and integration unit is used to calculate the virtual electric angular velocity based on the frequency deviation. The virtual rotor angle is obtained by integration. The rotor equation calculation and integration unit outputs the calculation results to the current hysteresis control unit. A proportional-integral-derivative (PI-DE) control unit is used to adjust the error signal; Current hysteresis control unit, used to determine the current hysteresis control unit based on the current hysteresis control unit. and The comparison result generates the PWM trigger signal for the inverter IGBT; The filtering unit is used to filter the transient potential and voltage reference to suppress high-frequency components.

Images