A grid simulator network type control method, device, system and medium

Abstract

A grid-type control method for a power grid simulator includes the following steps: establishing a mathematical model of the inverter side of the energy conversion unit of the power grid simulator; designing the power outer loop in the inverter side based on the established mathematical model; and designing the voltage and current inner loop on the inverter side based on the designed power outer loop. The power grid simulator is designed using VSG control rather than V‑F control, which realizes the simulation of the transient and steady-state characteristics of the power grid, derives the frequency response characteristics of the system when the active power changes, and analyzes the influencing factors of the transient and steady-state characteristics; and designs a parallel QPR structure to control the power quality of the power grid simulator. The method of the present invention has high accuracy, fills the gap in the transient and steady-state and power quality control of the power grid simulator, and provides a new idea for the grid connection test of renewable energy power generation.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a grid simulator networking control method, device, system and medium. Background Art

[0002] With the exploitation and application of fossil energy and the growing demand for energy, environmental pollution and energy problems are becoming increasingly prominent. Therefore, the application of new energy such as photovoltaics and wind power has received more and more attention and support from countries around the world. Due to the dispersion and intermittency of new energy, it is often developed and utilized through distributed power generation systems. In the development stage of distributed power generation systems with small capacity, when the power grid fails, the distributed power generation is required to cut off the connection with the power grid within a specified time. The penetration rate of new energy grid connection increases year by year, and more and more new energy will inevitably be connected to the power grid through distributed power generation technology. With the increase in the capacity of distributed power generation connected to the power grid, once the power grid fails, large-scale distributed power generation will be disconnected from the power grid, which will cause the stable power grid voltage to fluctuate and even cause the power grid to collapse. For this reason, more stringent requirements are put forward for distributed power generation systems. When the power grid fails, the distributed power generation system can still continue to connect to the grid and provide certain support. Before the distributed power generation system is connected to the grid, it is necessary to test the grid adaptability of the system. However, since the power grid usually operates in a stable state, it is impossible to use the power grid for various tests. Therefore, special power grid simulation equipment is required to test the necessary working conditions of the distributed power generation system.

[0003] The current research on power grid simulators mainly focuses on the optimization of topological structures and the improvement of control methods, and there are certain limitations. At the same time, there are few literatures that study the inertial characteristics of power grids. In addition, the output voltage of the power grid simulator needs to meet the conditions of multiple harmonics and frequency offsets. The PI regulator used in the existing power grid simulator cannot effectively control the AC time-varying components, and in the two-phase rotating coordinate system, PI control still cannot effectively control the harmonic components. Since the three-phase AC time-varying components are still AC time-varying components in the two-phase rotating coordinate system, it can be seen from the internal model principle that the PR controller can effectively control the fundamental and harmonic components. However, PR control at the resonant frequency ω 0 The bandwidth of the frequency band near ω is too narrow, and 0 The gain at is too high, resulting in low system stability. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies of the above-mentioned prior art by providing a grid simulator configuration control method, which can provide support for various grid-connected adaptability tests of new energy power generation equipment.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A grid configuration control method for a power grid simulator comprises the following steps:

[0007] Establish a mathematical model of the inverter side of the energy conversion unit of the power grid simulator;

[0008] Design the power outer loop in the inverter side based on the established mathematical model;

[0009] Based on the designed power outer loop, the voltage and current inner loop on the inverter side is designed.

[0010] The mathematical model of the inverter side of the energy conversion unit of the power grid simulator is established as follows:

[0011] According to Kirchhoff's law, the AC side circuit equation in the three-phase coordinate system is:

[0012]

[0013] Among them, e j (j=a, b, c) represents the virtual internal potential of the inverter; u oj (j=a,b,c) represents the output voltage; L 2 Represents the filter inductance; i L2j (j=a,b,c) represents the current in the inductor; i oj (j=a,b,c) represents the output current; C 2 Represents filter capacitor;

[0014] The AC side circuit equation in the three-phase coordinate system is transformed into the two-phase rotating coordinate system αβ, and Laplace transformation is performed to obtain the AC side circuit equation in the two-phase rotating coordinate system αβ:

[0015]

[0016] Among them, e α represents the virtual internal potential of the inverter α axis; u oα Represents the output voltage of the α-axis; L 2 Represents the filter inductance; i L2α represents the inductor current on the α-axis; i oα Indicates output current; C 2 Represents filter capacitor.

[0017] The power outer loop in the inverter side is designed based on the established mathematical model, as follows:

[0018] The rotor characteristics of the synchronous generator are simulated by active power-frequency control, and the excitation regulation characteristics of the synchronous generator are simulated by reactive power-voltage control;

[0019] The rotor characteristics of a synchronous generator obey the following second-order swing equation:

[0020]

[0021] Where, ω is the output angular velocity of the synchronous generator, ω n is the rated angular velocity of the power grid, T m and T e is the mechanical torque and electromagnetic torque, J is the rotor moment of inertia, D is the damping coefficient of the system, P ref is the reference active power input to the system, P e is the active power actually output by the system;

[0022] Synchronous generator output active power P e and reactive power Q e The calculation formula is as follows:

[0023]

[0024] Among them, in the formula, 1 / (1+T f s) is the first-order low-pass filter transfer function, T f is the time constant, u od 、u oq 、i od 、i oq is the fundamental wave output voltage U at the grid connection point oabc ,I oabc Voltage and current components in the dq coordinate system;

[0025] The integral control link is introduced to simulate the reactive power-voltage droop characteristics of the synchronous generator exciter, so that the reactive power can track the reference value without difference. The reactive power-voltage relationship expression is:

[0026]

[0027] Among them, K represents the proportional coefficient of the integral link, Q ref Indicates the input reactive power reference value, Q e Indicates the actual reactive power of the system, U n It represents the effective value of the rated phase voltage, and E is the amplitude of the virtual internal potential;

[0028] The transfer function between the output angular frequency error and the output power error of the power grid simulator is:

[0029]

[0030] It can be seen from the formula that when the system output active power suddenly increases, the output frequency change of the power grid simulator with synchronous generator characteristic simulation can slowly decrease, showing a certain inertia characteristic, and finally reaching a steady-state value.

[0031] Based on the designed power outer loop, the voltage and current inner loop on the inverter side is designed as follows:

[0032] The QPR controller is used to control the voltage and current inner loop;

[0033] The transfer function of QPR control is shown below:

[0034]

[0035] Among them, K P is the proportionality coefficient; K R is the resonance coefficient; ω c is the cut-off frequency; ω 0 is the resonant frequency;

[0036] Let s = jω r Substituting into the above formula, the gain of QPR control at the fundamental frequency can be obtained as:

[0037]

[0038] When multiple resonant controllers are connected in parallel, the expression is as follows:

[0039]

[0040] In the formula, K P is the proportionality coefficient, K Rm is the resonance coefficient of the mth harmonic; ω c is the cut-off frequency; ω 0 is the fundamental frequency; m is the harmonic number.

[0041] A grid-building control device for a power grid simulator, comprising:

[0042] A model building module, wherein the model building module is used to establish a mathematical model of the inverter side of the energy conversion unit of the power grid simulator;

[0043] A power outer loop design module, wherein the power outer loop design module is used to design a power outer loop in the inverter side based on an established mathematical model;

[0044] The voltage and current inner loop design module is used to design the voltage and current inner loop on the inverter side based on the designed power outer loop.

[0045] Model building models are specifically used for:

[0046] According to Kirchhoff's law, the AC side circuit equation in the three-phase coordinate system is:

[0047]

[0048] Among them, ej (j=a, b, c) represents the virtual internal potential of the inverter; u oj (j=a,b,c) represents the output voltage; L 2 Represents the filter inductance; i L2j (j=a,b,c) represents the current in the inductor; i oj (j=a,b,c) represents the output current; C 2 Represents filter capacitor;

[0049] The AC side circuit equation in the three-phase coordinate system is transformed into the two-phase rotating coordinate system αβ, and Laplace transformation is performed to obtain the AC side circuit equation in the two-phase rotating coordinate system αβ:

[0050]

[0051] Among them, e α represents the virtual internal potential of the inverter α axis; u oα Represents the output voltage of the α-axis; L 2 Represents the filter inductance; i L2α represents the inductor current on the α-axis; i oα Indicates output current; C 2 Represents filter capacitor.

[0052] The power outer loop design module is specifically used for:

[0053] The rotor characteristics of the synchronous generator are simulated by active power-frequency control, and the excitation regulation characteristics of the synchronous generator are simulated by reactive power-voltage control;

[0054] The rotor characteristics of a synchronous generator obey the following second-order swing equation:

[0055]

[0056] Where, ω is the output angular velocity of the synchronous generator, ω n is the rated angular velocity of the power grid, T m and T e is the mechanical torque and electromagnetic torque, J is the rotor moment of inertia, D is the damping coefficient of the system, P ref is the reference active power input to the system, P e is the active power actually output by the system;

[0057] Synchronous generator output active power P e and reactive power Q e The calculation formula is as follows:

[0058]

[0059] Among them, in the formula, 1 / (1+Tf s) is the first-order low-pass filter transfer function, T f is the time constant, u od 、u oq 、i od 、i oq is the fundamental wave output voltage U at the grid connection point oabc ,I oabc Voltage and current components in the dq coordinate system;

[0060] The integral control link is introduced to simulate the reactive power-voltage droop characteristics of the synchronous generator exciter, so that the reactive power can track the reference value without difference. The reactive power-voltage relationship expression is:

[0061]

[0062] Among them, K represents the proportional coefficient of the integral link, Q ref Indicates the input reactive power reference value, Q e Indicates the actual reactive power of the system, U n It represents the effective value of the rated phase voltage, and E is the amplitude of the virtual internal potential;

[0063] The transfer function between the output angular frequency error and the output power error of the power grid simulator is:

[0064]

[0065] It can be seen from the formula that when the system output active power suddenly increases, the output frequency change of the power grid simulator with synchronous generator characteristic simulation can slowly decrease, showing a certain inertia characteristic, and finally reaching a steady-state value.

[0066] The voltage and current inner loop design module is specifically used for:

[0067] The QPR controller is used to control the voltage and current inner loop;

[0068] The transfer function of QPR control is shown below:

[0069]

[0070] Among them, K P is the proportionality coefficient; K R is the resonance coefficient; ω c is the cut-off frequency; ω 0 is the resonant frequency;

[0071] Let s = jω r Substituting into the above formula, the gain of QPR control at the fundamental frequency can be obtained as:

[0072]

[0073] When multiple resonant controllers are connected in parallel, the expression is as follows:

[0074]

[0075] In the formula, K P is the proportionality coefficient, K Rm is the resonance coefficient of the mth harmonic; ω c is the cut-off frequency; ω 0 is the fundamental frequency; m is the harmonic number.

[0076] A power grid simulator network control system, comprising: a computer-readable storage medium and a processor;

[0077] The computer-readable storage medium is used to store executable instructions;

[0078] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the power grid simulator networking control method.

[0079] A non-transitory computer-readable storage medium stores a computer program, which, when executed by a processor, implements the grid configuration control method of a power grid simulator.

[0080] Aiming at the application scenario of new energy grid connection test, the present invention proposes a grid-type power grid simulator transient and steady-state characteristics and power quality control strategy. The grid simulator is designed with VSG control instead of VF control, which realizes the simulation of the transient and steady-state characteristics of the power grid, derives the frequency response characteristics of the system when the active power changes, and analyzes the influencing factors of transient and steady-state characteristics; a parallel QPR structure is designed to control the power quality of the grid simulator. The proposed method is effective and has high accuracy, filling the gap in transient and steady-state control and power quality control of the grid simulator, and providing a new idea for the grid connection test of new energy power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 This is a flow chart of a grid-type control strategy of a power grid simulator with inertia and power quality regulation functions according to an embodiment of the present invention;

[0082] Figure 2 is a structural diagram of an energy conversion unit according to an embodiment of the present invention;

[0083] Figure 3 This is the inverter side topology structure of an embodiment of the present invention;

[0084] Figure 4 is a mathematical model of an inverter according to an embodiment of the present invention;

[0085] Figure 5 is an active power-frequency control block diagram of an embodiment of the present invention;

[0086] Figure 6 is a Bode diagram of QPR and PR control according to an embodiment of the present invention;

[0087] Figure 7 is a Bode diagram of QPR control at different parameter values ​​at the fundamental frequency of an embodiment of the present invention;

[0088] Figure 8 is a Bode diagram of QPR control at different angular frequencies according to an embodiment of the present invention;

[0089] Fig. 9 It is a block diagram of the inner loop control of an embodiment of the present invention. DETAILED DESCRIPTION

[0090] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0091] See also Figure 1 The embodiment of the present invention provides a grid simulator network control strategy with inertia and power quality regulation functions. The method establishes a grid simulator with grid inertia function and high-order harmonic simulation function. Figure 2 In order to use the inverter control framework of this strategy, since the existing power grid simulator lacks the power grid inertia function and the high-order harmonic simulation function, the power grid simulator control strategy designed by the present invention is proposed, which includes the following steps:

[0092] Establish mathematical model of AC side;

[0093] See also Figure 2 The overall structure of the energy conversion unit model adopts a three-phase unified control main circuit topology, where L 1 , C 1 Respectively represent the filter inductor and filter capacitor on the rectifier side; U abc ,I L1abc Respectively represent the capacitor voltage and inductor current of the rectifier bridge; L 2 , C 2 Respectively represent the filter inductor and filter capacitor on the inverter side; I L2abc , U Oabc ,I Oabc Respectively represent the inductor current, output voltage and output current on the output side of the inverter bridge; C dc Represents the voltage stabilizing capacitor of the rectifier output; U dcIndicates the output voltage of the rectifier bridge and the input voltage of the inverter bridge.

[0094] The rectifier bridge and inverter bridge are controlled by two separate controllers, in which the input voltage U abc 、Input current I L1abc And the output voltage U dc As the input signal of the rectifier side controller, the control signal of the rectifier bridge is obtained through the action of the controller; similarly, the inductor current I L2abc , output voltage U Oabc , output current I Oabc The control signal of the inverter is obtained through the action of the inverter-side controller.

[0095] like Figure 3 The topology structure of the inverter side of the power grid simulator designed by the present invention is shown as follows. The rectifier side is a constant DC power output by the rectifier side. Here, the DC source U dc Instead. 2 and C 2 The LC filter is formed, and PCC is the common coupling point. According to Kirchhoff's law, the inverter side circuit equation is:

[0096]

[0097] Among them, e j (j=a, b, c) represents the virtual internal potential of the inverter; u oj (j=a,b,c) represents the output voltage; L 2 Represents the filter inductance; i L2j (j=a,b,c) represents the current in the inductor; i oj (j=a,b,c) represents the output current; C 2 Represents filter capacitor; u oj (j=a, b, c) represents the output voltage.

[0098] Transform the circuit equation in the above three-phase coordinate system to the two-phase rotating coordinate system αβ and perform Laplace transformation to obtain the following circuit equation:

[0099]

[0100] refer to Figure 4 The figure shows the mathematical model of the inverter in a two-phase rotating coordinate system. Figure 4 (a) is the mathematical model of the inverter of the α axis. Figure 4 (a) in the figure is the mathematical model of the inverter of the β axis.

[0101] Design the power outer loop in the inverter side based on the established mathematical model;

[0102] The present application enables the power grid simulator to have the characteristics of a synchronous generator by adopting VSG control in the power outer loop control. The power outer loop includes active-frequency control and reactive-voltage control. The rotor characteristics of the synchronous generator are simulated by active-frequency control, and the excitation regulation characteristics of the synchronous generator are simulated by reactive-voltage control.

[0103] From the rotor characteristics of the synchronous generator, it can be seen that the rotor motion follows the second-order swing equation of the following formula:

[0104]

[0105] Where, ω is the output angular velocity of the synchronous generator, ω n is the rated angular velocity of the power grid, T m and T e is the mechanical torque and electromagnetic torque, J is the rotor moment of inertia, D is the damping coefficient of the system, P ref is the reference active power input to the system, P e It is the active power actually output by the system.

[0106] like Figure 5 The active power-frequency control block diagram is shown in Figure 1. When the synchronous generator is running with load, the system power will fluctuate at a low frequency, affecting the output characteristics of the system. In engineering, digital low-pass filters are generally used for power filtering to slow down the fluctuation of system power. The synchronous generator outputs active power P e and reactive power Q e The calculation formula is as follows:

[0107]

[0108] Among them, in the formula, 1 / (1+T f s) is the first-order low-pass filter transfer function, T f is the time constant. od 、u oq 、i od 、i oq is the fundamental output voltage U oabc ,I oabc Voltage and current components in the dq coordinate system.

[0109] Reactive power-voltage control is used to generate voltage reference amplitude. In order to simulate the reactive power-voltage droop characteristics of synchronous generator exciter and enable reactive power to track reference value without error, an integral control link is introduced to obtain the reactive power-voltage relationship expression as shown in the following formula:

[0110]

[0111] Among them, K represents the proportional coefficient of the integral link, Q refIndicates the input reactive power reference value, Q e Indicates the actual reactive power of the system, U n It represents the effective value of the rated phase voltage, and E is the amplitude of the virtual internal potential.

[0112] For the power grid, the voltage generally remains stable or changes slightly. The output voltage of the power grid simulator is adjusted according to the reactive power-voltage characteristic curve, and the regulation rule is similar to the active power-frequency. The transfer function between the output angular frequency error and the output power error of the power grid simulator can be obtained as:

[0113]

[0114] It can be seen from the formula that when the system output active power suddenly increases, the output frequency change of the power grid simulator with the synchronous generator characteristic simulation can slowly decrease, showing a certain inertia characteristic, and finally reach a steady-state value; similarly, when the system frequency undergoes a step change, the addition of the synchronous generator characteristics makes the output power show a certain damping characteristic, and the power grid simulator system power change can respond slowly. It can be seen that the power grid simulator with the synchronous generator characteristic simulation has a smoother system frequency regulation process and better stability. And unlike the damping and inertia of the synchronous generator, which are determined by the material and structure, the power grid simulator can adjust the system inertia by setting the inertia and damping parameters.

[0115] Based on the designed power outer loop, the voltage and current inner loop on the inverter side is designed;

[0116] This application uses the QPR controller to control the inner loop. Fig. 9 is the inner loop control block diagram, H v(s) is a parallel QPR controller, and H i(s) Proportional control is adopted. The transfer function of QPR control is shown as follows:

[0117]

[0118] Among them, K P is the proportionality coefficient; K R is the resonance coefficient; ω c is the cut-off frequency; ω 0 is the resonant frequency.

[0119] Let s = jω r Substituting into the above formula, the gain of QPR control at the fundamental frequency can be obtained as:

[0120]

[0121] According to the requirements of the power grid simulator, it is necessary to output a voltage containing a harmonic signal. Therefore, the output voltage contains multiple angular frequency signals. In order to realize the control of multiple angular frequency signals, the present invention designs multiple resonant controllers in parallel. The expression is as follows:

[0122]

[0123] In the formula, K P is the proportionality coefficient, K Rm is the resonance coefficient of the mth harmonic; ω c is the cut-off frequency; ω 0 is the fundamental frequency; m is the harmonic number.

[0124] The functions of the power grid simulator include simulating dynamic voltage faults of the power grid such as voltage drop, frequency offset, etc., so the inverter is required to be able to quickly track the given voltage or frequency signal. The present invention selects a dual closed-loop control strategy of voltage outer loop and current inner loop. The voltage outer loop adopts a QPR controller to control the three-phase output voltage and harmonics, and the current inner loop adopts a proportional controller for control. The three-phase voltage signal expected to be output is transformed into a two-phase coordinate system as the given signal of the voltage outer loop, and the actual system output voltage instantaneous value is used as the feedback signal of the voltage outer loop. The difference between the given signal of the voltage outer loop and the feedback signal is passed through a modified QPR regulator as the given signal of the current inner loop. The instantaneous value of the filtered inductor current is used as the feedback signal of the current inner loop, and the difference after comparison with the given signal of the current inner loop is passed through a proportional regulator as the control signal of the inverter.

[0125] refer to Figure 6 middle, Figure 6 (a) is the Bode diagram of the phase under QPR and PR control strategies. Figure 6 (b) in the figure is the Bode diagram of the phase under the QPR and PR control strategies. It can be seen that the use of QPR control avoids the problem of infinite gain of PR control at the fundamental frequency, thereby avoiding the stability problem caused by infinite gain of PR control.

[0126] When QPR control is used, three parameters K in the transfer function need to be studied: P , K R and ω c The influence of the controller performance on the performance of the controller is to select the appropriate parameters. The Bode diagram when the parameters take different values ​​is as follows Figure 7 As shown, Figure 7 (a) is the Bode diagram of the phase under the QPR control strategy with different parameter values. Figure 7 (b) in the figure is the Bode diagram of the phase under the QPR control strategy for different parameter values.

[0127] The functions of the power grid simulator include simulating dynamic voltage faults of the power grid, such as voltage drop, frequency deviation, etc., so the inverter is required to quickly track the given voltage or frequency signal. The present invention selects a dual closed-loop control strategy of voltage outer loop and current inner loop. The voltage outer loop adopts a QPR controller to control the three-phase output voltage and harmonics, and the current inner loop adopts a proportional controller for control. Figure 8 It can be seen that when m is 1, 2, 3, and 4, the gain of QPR at a specific frequency is large, while the gain in other frequency bands decreases rapidly. Therefore, the designed QPR controller can well control the output of different frequencies and meet the requirements of the power grid simulator. Figure 8 (a) is the Bode diagram of the phase under the QPR control strategy at different angular frequencies. Figure 8 (b) in the figure is the Bode diagram of the phase under the QPR control strategy at different angular frequencies.

[0128] The optimization method of the present invention is to reduce the impact of the grid-connected inverter on the grid when switching between grid and off-grid, improve the safety of the grid, comprehensively consider the operation mode of the grid-connected inverter and the pre-synchronization control strategy of the phase angle, formulate a smooth grid-connected strategy of adaptive model predictive control, dynamically simulate the grid-connected inverter switching between grid and off-grid on the MATLAB / Simulink simulation platform, study the impact of the proposed control strategy on the power system after the grid-connected and off-grid switching, and verify the feasibility and effectiveness of the proposed strategy. The present invention considers adding an attenuation phase 2ω based on PR control. c s obtains the QPR controller to control the inner loop. Aiming at the problem that the power grid simulator is insufficient in simulating the power grid inertia, a power grid simulator control structure based on VSG+QPR is proposed, and the harmonic simulation method of the power grid simulator is analyzed in detail. The power grid simulator proposed in the present invention has the basic functions of a general power grid simulator and has the functions of power grid inertia and high-order harmonic simulation. The results show that the power grid simulator control strategy proposed in the present invention can realize basic functions such as power grid fault simulation, and at the same time has the ability of power grid inertia simulation and high-order harmonic simulation, which has certain practical significance and use value.

[0129] The embodiment of the present invention further provides a grid simulator network control device, comprising:

[0130] A model building module, wherein the model building module is used to establish a mathematical model of the inverter side of the energy conversion unit of the power grid simulator;

[0131] A power outer loop design module, wherein the power outer loop design module is used to design a power outer loop in the inverter side based on an established mathematical model;

[0132] The voltage and current inner loop design module is used to design the voltage and current inner loop on the inverter side based on the designed power outer loop.

[0133] Model building models are specifically used for:

[0134] According to Kirchhoff's law, the AC side circuit equation in the three-phase coordinate system is:

[0135]

[0136] Among them, e j (j=a, b, c) represents the virtual internal potential of the inverter; u oj (j=a,b,c) represents the output voltage; L 2 Represents the filter inductance; i L2j (j=a,b,c) represents the current in the inductor; i oj (j=a,b,c) represents the output current; C 2 Represents filter capacitor;

[0137] The AC side circuit equation in the three-phase coordinate system is transformed into the two-phase rotating coordinate system αβ, and Laplace transformation is performed to obtain the AC side circuit equation in the two-phase rotating coordinate system αβ:

[0138]

[0139] Among them, e α represents the virtual internal potential of the inverter α axis; u oα Represents the output voltage of the α-axis; L 2 Represents the filter inductance; i L2α represents the inductor current on the α-axis; i oα Indicates output current; C 2 Represents filter capacitor.

[0140] The power outer loop design module is specifically used for:

[0141] The rotor characteristics of the synchronous generator are simulated by active power-frequency control, and the excitation regulation characteristics of the synchronous generator are simulated by reactive power-voltage control;

[0142] The rotor characteristics of a synchronous generator obey the following second-order swing equation:

[0143]

[0144] Where, ω is the output angular velocity of the synchronous generator, ω n is the rated angular velocity of the power grid, T m and T e is the mechanical torque and electromagnetic torque, J is the rotor moment of inertia, D is the damping coefficient of the system, Pref is the reference active power input to the system, P e is the active power actually output by the system;

[0145] Synchronous generator output active power P e and reactive power Q e The calculation formula is as follows:

[0146]

[0147] Among them, in the formula, 1 / (1+T f s) is the first-order low-pass filter transfer function, T f is the time constant, u od 、u oq 、i od 、i oq is the fundamental wave output voltage U at the grid connection point oabc ,I oabc Voltage and current components in the dq coordinate system;

[0148] The integral control link is introduced to simulate the reactive power-voltage droop characteristics of the synchronous generator exciter, so that the reactive power can track the reference value without difference. The reactive power-voltage relationship expression is:

[0149]

[0150] Among them, K represents the proportional coefficient of the integral link, Q ref Indicates the input reactive power reference value, Q e Indicates the actual reactive power of the system, U n It represents the effective value of the rated phase voltage, and E is the amplitude of the virtual internal potential;

[0151] The transfer function between the output angular frequency error and the output power error of the power grid simulator is:

[0152]

[0153] It can be seen from the formula that when the system output active power suddenly increases, the output frequency change of the power grid simulator with synchronous generator characteristic simulation can slowly decrease, showing a certain inertia characteristic, and finally reaching a steady-state value.

[0154] The voltage and current inner loop design module is specifically used for:

[0155] The QPR controller is used to control the voltage and current inner loop;

[0156] The transfer function of QPR control is shown below:

[0157]

[0158] Among them, K P is the proportionality coefficient; K R is the resonance coefficient; ω c is the cut-off frequency; ω 0 is the resonant frequency;

[0159] Let s = jω r Substituting into the above formula, the gain of QPR control at the fundamental frequency can be obtained as:

[0160]

[0161] When multiple resonant controllers are connected in parallel, the expression is as follows:

[0162]

[0163] In the formula, K P is the proportionality coefficient, K Rm is the resonance coefficient of the mth harmonic; ω c is the cut-off frequency; ω 0 is the fundamental frequency; m is the harmonic number.

[0164] Another embodiment of the present invention provides a power grid simulator network control system, including: a computer-readable storage medium and a processor;

[0165] The computer-readable storage medium is used to store executable instructions;

[0166] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the power grid simulator networking control method.

[0167] Another embodiment of the present invention provides a non-transitory computer-readable storage medium having a computer program stored thereon, which implements the power grid simulator networking control method when executed by a processor.

[0168] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0169] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0170] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0171] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0172] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A grid configuration control method for a power grid simulator, characterized in that: The steps include: Establish a mathematical model of the inverter side of the energy conversion unit of the power grid simulator; Design the power outer loop in the inverter side based on the established mathematical model; Based on the designed power outer loop, the voltage and current inner loop on the inverter side is designed; The power outer loop in the inverter side is designed based on the established mathematical model, as follows: The rotor characteristics of the synchronous generator are simulated by active power-frequency control, and the excitation regulation characteristics of the synchronous generator are simulated by reactive power-voltage control; The rotor characteristics of a synchronous generator obey the following second-order swing equation: Where, ω is the output angular velocity of the synchronous generator, ω n is the rated angular velocity of the power grid, T m and T e is the mechanical torque and electromagnetic torque, J is the rotor moment of inertia, D is the damping coefficient of the system, P ref is the reference active power input to the system, P e is the active power actually output by the system; Synchronous generator output active power P e and reactive power Q e The calculation formula is as follows: Among them, in the formula, 1 / (1+T f s) is the first-order low-pass filter transfer function, T f is the time constant, u od 、u oq 、i od 、i oq is the fundamental wave output voltage U at the grid connection point oabc , and output current I oabc Voltage and current components in the dq coordinate system; The integral control link is introduced to simulate the reactive power-voltage droop characteristics of the synchronous generator exciter, so that the reactive power can track the reference value without difference. The reactive power-voltage relationship expression is: Among them, K represents the proportional coefficient of the integral link, Q ref Indicates the input reactive power reference value, Q e Indicates the actual reactive power of the system, U n It represents the effective value of the rated phase voltage, and E is the amplitude of the virtual internal potential; The transfer function between the output angular frequency error and the output power error of the power grid simulator is: It can be seen from the formula that when the system output active power suddenly increases, the output frequency change of the power grid simulator with synchronous generator characteristic simulation can slowly decrease, showing a certain inertia characteristic, and finally reaching a steady-state value; Based on the designed power outer loop, the voltage and current inner loop on the inverter side is designed as follows: The QPR controller is used to control the voltage and current inner loop; The transfer function of QPR control is shown below: Among them, K P is the proportionality coefficient; K R is the resonance coefficient; ω c is the cut-off frequency; ω0 is the resonant frequency; Let s = jω r Substituting into the above formula, the gain of QPR control at the fundamental frequency can be obtained as: When multiple resonant controllers are connected in parallel, the expression is as follows: In the formula, K P is the proportionality coefficient, K Rm is the resonance coefficient of the mth harmonic; ω c is the cut-off frequency; ω0 is the fundamental frequency; m is the harmonic number.

2. A grid simulator configuration control method according to claim 1, characterized in that: The mathematical model of the inverter side of the energy conversion unit of the power grid simulator is established as follows: According to Kirchhoff's law, the AC side circuit equation in the three-phase coordinate system is: Among them, e j (j=a, b, c) represents the virtual internal potential of the inverter; u oj (j=a,b,c) represents the output voltage; L2 represents the filter inductor; i L2j (j=a,b,c) represents the current in the inductor; i oj (j=a,b,c) represents the output current; C2 represents the filter capacitor; The AC side circuit equation in the three-phase coordinate system is transformed into the two-phase rotating coordinate system αβ, and Laplace transformation is performed to obtain the AC side circuit equation in the two-phase rotating coordinate system αβ: Among them, e α represents the virtual internal potential of the inverter α axis; u oα represents the output voltage of the α axis; L2 represents the filter inductance; i L2α represents the inductor current on the α-axis; i oα Represents output current; C2 represents filter capacitor.

3. A grid simulator control device, characterized in that: include: A model building module, wherein the model building module is used to establish a mathematical model of the inverter side of the energy conversion unit of the power grid simulator; A power outer loop design module, wherein the power outer loop design module is used to design a power outer loop in the inverter side based on an established mathematical model; A voltage and current inner loop design module, which is used to design the voltage and current inner loop of the inverter side based on the designed power outer loop; The power outer loop design module is specifically used for: The rotor characteristics of the synchronous generator are simulated by active power-frequency control, and the excitation regulation characteristics of the synchronous generator are simulated by reactive power-voltage control; The rotor characteristics of a synchronous generator obey the following second-order swing equation: Where, ω is the output angular velocity of the synchronous generator, ω n is the rated angular velocity of the power grid, T m and T e is the mechanical torque and electromagnetic torque, J is the rotor moment of inertia, D is the damping coefficient of the system, P ref is the reference active power input to the system, P e is the active power actually output by the system; Synchronous generator output active power P e and reactive power Q e The calculation formula is as follows: Among them, in the formula, 1 / (1+T f s) is the first-order low-pass filter transfer function, T f is the time constant, u od 、u oq 、i od 、i oq is the fundamental wave output voltage U at the grid connection point oabc , and output current I oabc Voltage and current components in the dq coordinate system; The integral control link is introduced to simulate the reactive power-voltage droop characteristics of the synchronous generator exciter, so that the reactive power can track the reference value without difference. The reactive power-voltage relationship expression is: Among them, K represents the proportional coefficient of the integral link, Q ref Indicates the input reactive power reference value, Q e Indicates the actual reactive power of the system, U n It represents the effective value of the rated phase voltage, and E is the amplitude of the virtual internal potential; The transfer function between the output angular frequency error and the output power error of the power grid simulator is: It can be seen from the formula that when the system output active power suddenly increases, the output frequency change of the power grid simulator with synchronous generator characteristic simulation can slowly decrease, showing a certain inertia characteristic, and finally reaching a steady-state value; The voltage and current inner loop design module is specifically used for: The QPR controller is used to control the voltage and current inner loop; The transfer function of QPR control is shown below: Among them, K P is the proportionality coefficient; K R is the resonance coefficient; ω c is the cut-off frequency; ω0 is the resonant frequency; Let s = jω r Substituting into the above formula, the gain of QPR control at the fundamental frequency can be obtained as: When multiple resonant controllers are connected in parallel, the expression is as follows: In the formula, K P is the proportionality coefficient, K Rm is the resonance coefficient of the mth harmonic; ω c is the cut-off frequency; ω0 is the fundamental frequency; m is the harmonic number.

4. A grid-type control device for a power grid simulator according to claim 3, characterized in that: Model building models are specifically used for: According to Kirchhoff's law, the AC side circuit equation in the three-phase coordinate system is: Among them, e j (j=a, b, c) represents the virtual internal potential of the inverter; u oj (j=a,b,c) represents the output voltage; L2 represents the filter inductor; i L2j (j=a,b,c) represents the current in the inductor; i oj (j=a,b,c) represents the output current; C2 represents the filter capacitor; The AC side circuit equation in the three-phase coordinate system is transformed into the two-phase rotating coordinate system αβ, and Laplace transformation is performed to obtain the AC side circuit equation in the two-phase rotating coordinate system αβ: Among them, e α represents the virtual internal potential of the inverter α axis; u oα represents the output voltage of the α axis; L2 represents the filter inductance; i L2α represents the inductor current on the α-axis; i oα Represents output current; C2 represents filter capacitor.

5. A power grid simulator network control system, characterized in that: include: A computer readable storage medium and a processor; The computer-readable storage medium is used to store executable instructions; The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the grid configuration control method of the power grid simulator according to any one of claims 1-4.

6. A non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the grid configuration control method of a power grid simulator as described in any one of claims 1-2.

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