Electromagnetic transient simulation method and system for alternating-current and direct-current hybrid power grid

Abstract

The invention discloses an electromagnetic transient simulation method and system for an AC-DC hybrid power grid, and the method comprises the steps: carrying out the load flow calculation of an electromechanical transient simulation model of an AC system containing a DC equivalent point, and obtaining an AC load flow result at an AC-DC connection point; converting the electromechanical transient simulation model into an electromagnetic transient simulation model; then, a clamping voltage source is connected to an alternating-current access point of the electromagnetic transient simulation model of the direct-current system; adjusting parameters of the electromagnetic transient simulation model of the direct current system; and finally, splicing the electromagnetic transient simulation model of the alternating current and direct current system, and simulating the alternating current and direct current hybrid electromagnetic transient simulation model. And when the power fluctuation occurs in the simulation result, adjusting the parameters of the direct current system, and performing simulation again until the power fluctuation does not occur or the maximum number of iterations is reached. According to the method, automatic access of the direct current system is realized on the premise that the alternating current system is not adjusted, and the electromagnetic transient simulation model of the alternating current and direct current hybrid power grid suitable for electromagnetic transient simulation is formed.

Description

Technical Field

[0001] The invention relates to electromagnetic transient simulation, in particular to an electromagnetic transient simulation method and system for an AC / DC hybrid power grid. Background Art

[0002] With the rapid development of new power system construction, the scale and total transmission capacity of new energy installations and DC transmission are increasing, and the operating characteristics of the power system are undergoing profound changes. Electromagnetic transient simulation can accurately simulate the action process of power electronic equipment such as DC and new energy, and is a key technology to fully understand and master the dynamic characteristics of new power systems.

[0003] The interconnection of AC and DC power grids is the basis of electromagnetic transient simulation of AC / DC hybrid power grids and a prerequisite for various dynamic analyses. However, the existing electromagnetic transient simulation methods of AC / DC hybrid power grids do not consider the automatic access of DC electromagnetic transient simulation models, resulting in low efficiency in evaluating the impact of DC system access on the electromagnetic transient results of the existing AC system. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide an electromagnetic transient simulation method and system for an AC / DC hybrid power grid that can realize automatic access of a DC system without adjusting an AC system.

[0005] Technical solution: The electromagnetic transient simulation method of the AC / DC hybrid power grid of the present invention comprises the following steps:

[0006] Perform power flow calculation on the electromechanical transient simulation model of the AC system with DC equivalent points to obtain the AC power flow results at the AC / DC connection points;

[0007] Convert the electromechanical transient simulation model of the AC system into an electromagnetic transient simulation model;

[0008] A clamping voltage source is connected to the AC access point of the electromagnetic transient simulation model of the DC system;

[0009] Adjust the parameters of the electromagnetic transient simulation model of the DC system according to the AC power flow results;

[0010] The electromagnetic transient simulation model of the AC system and the DC system is spliced ​​to obtain the electromagnetic transient simulation model of the AC / DC hybrid system;

[0011] Simulate the electromagnetic transient simulation model of AC / DC hybrid system. When the power of the DC system reaches the power value in the AC power flow result, exit the clamping voltage source.

[0012] When power fluctuation occurs in the simulation results, the parameters of the DC system are adjusted and the AC / DC hybrid electromagnetic transient simulation model is re-simulated until no power fluctuation occurs or the maximum number of iterations is reached.

[0013] Furthermore, adjusting the parameters of the electromagnetic transient simulation model of the DC system according to the AC power flow results includes:

[0014] Adjust the transformation ratio of the converter transformer on the AC access side so that the voltage level of the converter transformer winding is consistent with the voltage level of the DC access point in the AC system;

[0015] According to the ratio of the voltage levels before and after the converter transformer is adjusted, the impedance of the converter transformer AC access side winding, the impedance of the filter and the admittance of the filter are modified.

[0016] Furthermore, adjusting the parameters of the electromagnetic transient simulation model of the DC system according to the AC power flow results includes:

[0017] Adjust the setting value of the DC system current regulator according to the ratio of the DC system rated power to the active power of the DC access point in the AC power flow result.

[0018] Furthermore, converting the electromechanical transient simulation model of the AC system into an electromagnetic transient simulation model comprises:

[0019] If the electromagnetic transient simulation method is full electromagnetic transient simulation, the electromechanical transient simulation model of the AC system is converted into an electromagnetic transient simulation model including generators, lines, transformers and loads;

[0020] If the electromagnetic transient simulation method is an electromechanical-electromagnetic hybrid simulation, the electromechanical transient simulation model of the AC system is converted into a Thevenin equivalent model.

[0021] Furthermore, if power fluctuation occurs in the simulation result, adjusting the parameters of the DC system includes: adjusting line parameters and reactive power compensation parameters of the DC system.

[0022] Furthermore, the reactive compensation parameter adjustment method is as follows: if the DC reactive power is greater than the AC / DC switching requirement, the reactance value is increased or the susceptance is decreased to reduce the DC reactive power; if the DC reactive power is less than the AC / DC switching requirement, the reactance value is decreased or the susceptance is increased to increase the DC reactive power, until the deviation between the DC reactive power and the reactive power of the DC access point in the AC power flow result is less than a preset threshold.

[0023] Furthermore, the AC power flow results include voltage level, voltage amplitude, voltage phase angle, active power and reactive power values.

[0024] The electromagnetic transient simulation system of the AC / DC hybrid power grid of the present invention comprises:

[0025] The power flow calculation module is used to perform power flow calculation on the electromechanical transient simulation model of the AC system containing the DC equivalent point, and obtain the AC power flow results at the AC / DC connection point;

[0026] A model conversion module, used to convert the electromechanical transient simulation model of the AC system into an electromagnetic transient simulation model;

[0027] A DC model adjustment module is used to connect a clamp voltage source to an AC access point of an electromagnetic transient simulation model of a DC system; and to adjust parameters of the electromagnetic transient simulation model of a DC system according to AC power flow results;

[0028] A splicing module, used for splicing electromagnetic transient simulation models of an AC system and a DC system to obtain an AC / DC hybrid electromagnetic transient simulation model;

[0029] The electromagnetic transient simulation module is used to simulate the electromagnetic transient simulation model of AC / DC hybrid. When the power of the DC system reaches the power value in the AC power flow result, the clamping voltage source is exited.

[0030] The result verification module is used to adjust the parameters of the DC system when power fluctuation occurs in the simulation results, and re-simulate the AC / DC hybrid electromagnetic transient simulation model until no power fluctuation occurs or the maximum number of iterations is reached.

[0031] The electronic device described in the present invention includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is loaded into the processor, the electromagnetic transient simulation method of the AC / DC hybrid power grid is implemented.

[0032] The computer-readable storage medium of the present invention stores a computer program, and when the computer program is executed by a processor, the electromagnetic transient simulation method of the AC / DC hybrid power grid is implemented.

[0033] Beneficial effect: Compared with the prior art, the advantages of the present invention are: the present invention modifies the transformer, filter, reactive compensation model parameters and current regulator setting values ​​of the DC system to meet the voltage and power requirements of the AC access point, and performs electromagnetic transient simulation verification by splicing the electromagnetic transient simulation model of the AC and DC systems through switches, and can realize automatic access of the DC system without adjusting the AC system, forming an electromagnetic transient simulation model of the AC / DC hybrid power grid suitable for electromagnetic transient simulation. The method of the present invention can provide technical support for electromagnetic transient simulation analysis of AC / DC hybrid power grids. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The figure is a flow chart of the electromagnetic transient simulation method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0036] like Figure 1 As shown, the electromagnetic transient simulation method of the AC / DC hybrid power grid of the present invention includes the following steps.

[0037] 1) Perform power flow calculation on the electromechanical transient simulation model of the AC system containing the DC equivalent point to obtain the AC power flow results at the AC / DC connection point;

[0038] Specifically, the AC power flow results at the AC / DC connection point to be obtained include voltage level, voltage amplitude, voltage phase angle, active power and reactive power values.

[0039] 2) Electromechanical transient simulation model of AC system based on voltage, active and reactive conversion of components in AC system;

[0040] Specifically, if it is a full electromagnetic transient simulation, it is converted into a detailed electromagnetic transient simulation model containing models such as generators, lines, transformers, and loads; if it is an electromechanical and electromagnetic hybrid simulation, it is converted into a Thevenin (Norton) equivalent model.

[0041] 3) Connect a clamped voltage source with a switch to the AC access point of the electromagnetic transient simulation model of the DC system;

[0042] Specifically, the standard DC system refers to the CIGRE standard DC system, in which a closed-loop constant current control method is adopted on the rectifier side, and a control method combining closed-loop constant current control and fixed turn-off angle control is adopted on the inverter side.

[0043] Specifically, the naming rules for each node in the electromagnetic transient simulation model of the DC system are as follows: the node name consists of 6 characters, the first and second digits are filled with "DC" to indicate the DC system node; the third, fourth and fifth digits are filled with "0", "1", "2", ..., "9", "A", "B", ..., "Z" respectively, where the third digit is used to indicate the DC system ID, and the combination of the fourth and fifth digits is used to indicate the node number, with a total of 1296 combinations; the sixth digit is filled with "A", "B", "C", representing A, B, and C phases respectively.

[0044] Specifically, the voltage amplitude of the clamped voltage source is U s , phase angle θ s The value method is:

[0045]

[0046] Where: U s0 ,θ s0 are the voltage amplitude and phase angle at the AC / DC interface in the AC power flow results.

[0047] 4) Adjust the electromagnetic transient simulation model of the DC system according to the AC power flow results;

[0048] Specifically include:

[0049] a) Adjust the transformer and filter model parameters

[0050] Adjust the transformation ratio of the converter transformer on the AC access side so that the voltage level of the converter transformer winding on the AC access side is consistent with the voltage level of the DC access point in the AC system.

[0051] Modify the impedance of the AC access side winding of the converter transformer and the impedance of the filter according to the following formula:

[0052]

[0053] Wherein: Z0 is the impedance of the AC access side winding of the converter transformer or the impedance of the filter before modification; Z is the impedance of the AC access side winding of the converter transformer or the impedance of the filter after modification; U0 is the voltage level of the AC access side of the converter transformer before modification; U is the voltage level of the AC access side of the converter transformer after modification.

[0054] Modify the filter's admittance as follows:

[0055]

[0056] Where: Y0, Y are the admittance of the filter before and after modification respectively.

[0057] b) Adjust the setting value of the current regulator in the control model

[0058] Adjust the setting value of the DC system current regulator according to the following formula so that the deviation between the active power of the DC system and the active power of the DC access point in the AC power flow result is less than a preset threshold;

[0059]

[0060] Where: I N , I are the rated value and modified value of the setting value of the DC system current regulator respectively; P N , P are the rated power of the DC system and the active power of the DC access point in the AC power flow results respectively.

[0061] 5) Connect the AC and DC connection points through switches and splice the AC and DC electromagnetic transient simulation models;

[0062] 6) Perform electromagnetic transient simulation on the AC / DC hybrid electromagnetic transient simulation system, and when the DC system power rises to the power value in the AC power flow result, disconnect the switch to exit the clamping voltage source;

[0063] 7) Check the electromagnetic transient simulation results. If power fluctuation occurs, adjust the DC system line parameters and the reactive power compensation parameters of the DC system. If no power fluctuation occurs or the maximum number of iterations is reached, terminate this method.

[0064] Power fluctuation refers to the power fluctuation range exceeding 10% of the rated capacity.

[0065] Among them, the method for adjusting reactive power supplement is: if the DC reactive power is greater than the demand for AC / DC exchange, then increase the reactance value or reduce the susceptance to reduce the DC reactive power; if the DC reactive power is smaller than the demand for AC / DC exchange after electromagnetic transient simulation, then reduce the reactance value or increase the susceptance to increase the DC reactive power until the deviation between the DC reactive power and the reactive power of the DC access point in the AC power flow result is less than the preset threshold.

[0066] The electromagnetic transient simulation system of the AC / DC hybrid power grid of the present invention comprises:

[0067] The power flow calculation module is used to perform power flow calculation on the electromechanical transient simulation model of the AC system containing the DC equivalent point, and obtain the AC power flow results at the AC / DC connection point;

[0068] A model conversion module, used to convert the electromechanical transient simulation model of the AC system into an electromagnetic transient simulation model;

[0069] A DC model adjustment module is used to connect a clamp voltage source to an AC access point of an electromagnetic transient simulation model of a DC system; and to adjust parameters of the electromagnetic transient simulation model of a DC system according to AC power flow results;

[0070] A splicing module, used for splicing electromagnetic transient simulation models of an AC system and a DC system to obtain an AC / DC hybrid electromagnetic transient simulation model;

[0071] The electromagnetic transient simulation module is used to simulate the electromagnetic transient simulation model of AC / DC hybrid. When the power of the DC system reaches the power value in the AC power flow result, the clamping voltage source is exited.

[0072] The result verification module is used to adjust the parameters of the DC system when power fluctuation occurs in the simulation results, and re-simulate the AC / DC hybrid electromagnetic transient simulation model until no power fluctuation occurs or the maximum number of iterations is reached.

[0073] The electronic device described in the present invention includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is loaded into the processor, the electromagnetic transient simulation method of the AC / DC hybrid power grid is implemented.

[0074] The computer-readable storage medium of the present invention stores a computer program, and when the computer program is executed by a processor, the electromagnetic transient simulation method of the AC / DC hybrid power grid is implemented.

[0075] The computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other medium that can be used to store program code in the form of instructions or data structures and that can be accessed by a computer.

[0076] The processor is used to execute the computer program stored in the memory to implement each step of the method involved in the above embodiment.

Claims

1. An electromagnetic transient simulation method for an AC / DC hybrid power grid, characterized in that: The steps include: Perform power flow calculation on the electromechanical transient simulation model of the AC system with DC equivalent points to obtain the AC power flow results at the AC / DC connection points; Convert the electromechanical transient simulation model of the AC system into an electromagnetic transient simulation model; A clamping voltage source is connected to the AC access point of the electromagnetic transient simulation model of the DC system; Adjust the parameters of the electromagnetic transient simulation model of the DC system according to the AC power flow results; The electromagnetic transient simulation model of the AC system and the DC system is spliced ​​to obtain the electromagnetic transient simulation model of the AC / DC hybrid system; Simulate the electromagnetic transient simulation model of AC / DC hybrid system. When the power of the DC system reaches the power value in the AC power flow result, exit the clamping voltage source. When power fluctuation occurs in the simulation results, the parameters of the DC system are adjusted and the AC / DC hybrid electromagnetic transient simulation model is re-simulated until no power fluctuation occurs or the maximum number of iterations is reached.

2. The electromagnetic transient simulation method of the AC / DC hybrid power grid according to claim 1 is characterized in that: The method of adjusting the parameters of the electromagnetic transient simulation model of the DC system according to the AC power flow results includes: Adjust the transformation ratio of the converter transformer on the AC access side so that the voltage level of the converter transformer winding is consistent with the voltage level of the DC access point in the AC system; According to the ratio of the voltage levels before and after the converter transformer is adjusted, the impedance of the converter transformer AC access side winding, the impedance of the filter and the admittance of the filter are modified.

3. The electromagnetic transient simulation method of the AC / DC hybrid power grid according to claim 1, characterized in that: The method of adjusting the parameters of the electromagnetic transient simulation model of the DC system according to the AC power flow results includes: Adjust the setting value of the DC system current regulator according to the ratio of the DC system rated power to the active power of the DC access point in the AC power flow result.

4. The electromagnetic transient simulation method of the AC / DC hybrid power grid according to claim 1, characterized in that: The converting of the electromechanical transient simulation model of the AC system into the electromagnetic transient simulation model comprises: If the electromagnetic transient simulation method is full electromagnetic transient simulation, the electromechanical transient simulation model of the AC system is converted into an electromagnetic transient simulation model including generators, lines, transformers and loads; If the electromagnetic transient simulation method is an electromechanical-electromagnetic hybrid simulation, the electromechanical transient simulation model of the AC system is converted into a Thevenin equivalent model.

5. The electromagnetic transient simulation method of the AC / DC hybrid power grid according to claim 1, characterized in that: If power fluctuation occurs in the simulation result, adjusting the parameters of the DC system includes: adjusting the line parameters and reactive power compensation parameters of the DC system.

6. The electromagnetic transient simulation method of the AC / DC hybrid power grid according to claim 5, characterized in that: The reactive power compensation parameters are adjusted as follows: if the DC reactive power is greater than the AC / DC exchange requirement, the reactance value is increased or the susceptance is reduced to reduce the DC reactive power; if the DC reactive power is less than the AC / DC exchange requirement, the reactance value is reduced or the susceptance is increased to increase the DC reactive power until the deviation between the DC reactive power and the reactive power of the DC access point in the AC power flow result is less than the preset threshold.

7. The electromagnetic transient simulation method of the AC / DC hybrid power grid according to claim 1, characterized in that: The AC power flow results include voltage level, voltage amplitude, voltage phase angle, active power and reactive power values.

8. An electromagnetic transient simulation system for an AC / DC hybrid power grid, characterized in that: include: The power flow calculation module is used to perform power flow calculation on the electromechanical transient simulation model of the AC system containing the DC equivalent point, and obtain the AC power flow results at the AC / DC connection point; A model conversion module, used to convert the electromechanical transient simulation model of the AC system into an electromagnetic transient simulation model; A DC model adjustment module is used to connect a clamp voltage source to an AC access point of an electromagnetic transient simulation model of a DC system; and to adjust parameters of the electromagnetic transient simulation model of a DC system according to AC power flow results; A splicing module, used for splicing electromagnetic transient simulation models of an AC system and a DC system to obtain an AC / DC hybrid electromagnetic transient simulation model; The electromagnetic transient simulation module is used to simulate the electromagnetic transient simulation model of AC / DC hybrid. When the power of the DC system reaches the power value in the AC power flow result, the clamping voltage source is exited. The result verification module is used to adjust the parameters of the DC system when power fluctuation occurs in the simulation results, and re-simulate the AC / DC hybrid electromagnetic transient simulation model until no power fluctuation occurs or the maximum number of iterations is reached.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the computer program is loaded into a processor, the electromagnetic transient simulation method for an AC / DC hybrid power grid is implemented according to any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the electromagnetic transient simulation method for an AC / DC hybrid power grid is implemented according to any one of claims 1 to 7.

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