A control method and system for improving the fault ride-through performance of a new energy power station

Abstract

The application provides a control method and system for improving the fault ride-through performance of a new energy power station, wherein parameters of the new energy power station are substituted into a pre-constructed new energy power station model, the grid frame consumption reactive current of the new energy power station is calculated by using the model, the grid frame consumption reactive current is added to the reactive current output of the new energy power station, and the grid-connected voltage of the new energy power station is controlled. The control method provides effective compensation for the support voltage recovery of the new energy power station during fault ride-through, solves the problem that the reactive response of the photovoltaic inverter is inaccurate and does not meet the requirements of the power grid, improves the fault ride-through capability of the new energy power station, has strong operability and low cost, and can be realized by upgrading and updating the software of the existing power station inverter.

Description

Technical Field

[0001] This invention relates to the field of control technology for new energy power generation systems, and specifically to a control method and system for improving the fault ride-through performance of new energy power plants. Background Technology

[0002] As the installed capacity of new energy storage power stations continues to increase, their impact on the power grid is growing. To ensure the safe operation of the power grid, power grid companies require new energy power stations to meet relevant requirements, including specific requirements for their fault ride-through performance.

[0003] The fault ride-through capability of photovoltaic (PV) power plants is primarily provided by PV inverters, while that of wind farms is mainly provided by wind turbines. The fault ride-through capability of either the inverter or the wind turbine directly determines the fault ride-through capability of the entire renewable energy power plant. Taking a PV power plant as an example, the inverter responds reactively based on the sensed voltage. Currently, the voltage sensed by the PV power plant inverter is the inverter output point, while the reference point is the grid connection point. Reactive power consumption exists between the grid connection point and the inverter output point. A PV power plant that relies solely on the inverter output point for fault response cannot properly support the reactive power demand of the grid and cannot meet the grid's requirements. Therefore, developing a convenient, cost-effective, and efficient fault ride-through control method is a pressing issue that needs to be addressed. Summary of the Invention

[0004] To address the issues of inaccurate reactive power response and insufficient grid fault ride-through capability of current renewable energy power plants, this invention proposes a control method to improve the fault ride-through performance of renewable energy power plants, including:

[0005] Obtain parameters of new energy power plants;

[0006] The parameters of the new energy power station are substituted into a pre-built new energy power station model, and the reactive power consumption of the new energy power station during fault ride is obtained using the pre-built new energy power station model.

[0007] Using the reactive power consumption as the target response power, the reactive power response power of the inverter of the new energy power station is controlled by the pre-constructed new energy power station model.

[0008] The pre-built new energy power plant model is constructed based on the electrical topology of the new energy power plant and takes into account the power consumption of the grid.

[0009] Preferably, the step of substituting the parameters of the new energy power station into a pre-built new energy power station model and using the pre-built new energy power station model to obtain the reactive power consumption during fault ride-through of the new energy power station includes:

[0010] Substitute the parameters of the new energy power station into the pre-built new energy power station model, and use the pre-built new energy power station model to calculate the standard reactive current and grid-consumpted reactive current when the new energy power station experiences a fault ride-through.

[0011] The sum of the standard reactive current and the reactive current consumed by the grid is used as the reactive current required when the new energy power station experiences a fault ride, and the reactive power consumed when the new energy power station experiences a fault ride is obtained from the reactive current.

[0012] Preferably, the reactive current consumed by the grid structure is calculated using the following formula:

[0013]

[0014] Among them, I Q2 The reactive current consumed by the grid structure is U, the difference between the inverter output voltage and the grid connection point voltage is U, the resistance between the inverter output and the grid connection point is R, and the reactance between the inverter output and the grid connection point is X.

[0015] Preferably, the standard reactive current is calculated using the following formula:

[0016] I Q1 =1.5×(0.9-U T In

[0017] Among them, I Q1 For standard reactive current, U T In represents the per-unit value of the inverter output drop voltage during fault ride-through at a new energy power plant, where In is the rated output current of the inverter.

[0018] Preferably, the acquisition of parameters of the new energy power station includes: acquiring the resistance and reactance between the inverter outlet and the grid connection point of the new energy power station, the voltage drop at the inverter outlet when the new energy power station experiences a fault ride-through, and the voltage at the grid connection point.

[0019] Preferably, the step of substituting the parameters of the new energy power station into a pre-built new energy power station model and using the pre-built new energy power station model to obtain the reactive power consumption during fault ride-through of the new energy power station further includes:

[0020] Substitute the parameters of the new energy power station into the pre-built new energy power station model, and use the pre-built new energy power station model to obtain the reactive power consumption of each inverter in the new energy power station under different power generation and voltage levels.

[0021] A reactive power consumption database for the new energy power plant is established based on the reactive power consumption of each inverter under different power generation and voltage levels.

[0022] The pre-built new energy power plant model calls the corresponding data in the reactive power consumption database based on the voltage level when the new energy power plant experiences a fault ride-through, and uses the corresponding data in the reactive power consumption database as the reactive power consumption.

[0023] Based on the same inventive concept, this invention also proposes a control system for improving the fault ride-through performance of new energy power plants, comprising:

[0024] The acquisition module is used to acquire parameters of new energy power plants;

[0025] The reactive power calculation module is used to substitute the parameters of the new energy power station into a pre-built new energy power station model, and use the pre-built new energy power station model to obtain the reactive power consumption power of the new energy power station when a fault ride occurs.

[0026] The response module is used to control the grid connection point voltage of the new energy power station by using the reactive power consumption power as the target response power and outputting the reactive power response power using the pre-built new energy power station model.

[0027] The pre-built new energy power plant model is constructed based on the electrical topology of the new energy power plant and takes into account the power consumption of the grid.

[0028] Preferably, the reactive power calculation module includes:

[0029] The reactive current unit is used to calculate the reactive current of the new energy power station when a fault ride occurs using the pre-built new energy power station model.

[0030] The reactive power consumption unit is used to convert the reactive current into reactive power consumption when the new energy power station experiences a fault ride-through.

[0031] Preferably, the reactive current unit includes:

[0032] A standard reactive current subunit is used to calculate the standard reactive current of the new energy power station during fault ride-through using the pre-built new energy power station model.

[0033] The grid reactive current consumption sub-unit is used to calculate the grid reactive current consumption when the new energy power station experiences a fault ride using the pre-built new energy power station model.

[0034] Preferably, the reactive current consumed by the grid structure is calculated using the following formula:

[0035]

[0036] Among them, I Q2 The reactive current consumed by the grid structure is U, the difference between the inverter output voltage and the grid connection point voltage is U, the resistance between the inverter output and the grid connection point is R, and the reactance between the inverter output and the grid connection point is X.

[0037] Preferably, the standard reactive current is calculated using the following formula:

[0038] I Q1 =1.5×(0.9-U T In

[0039] Among them, I Q1 For standard reactive current, U T In represents the per-unit value of the inverter output drop voltage during fault ride-through at a new energy power plant, where In is the rated output current of the inverter.

[0040] Based on the same inventive concept, the present invention also proposes a computer device, comprising: one or more processors;

[0041] The processor is used to store one or more programs;

[0042] When the one or more programs are executed by the one or more processors, the control method provided by the present invention is implemented.

[0043] Based on the same inventive concept, the present invention also proposes a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, it implements the control method provided by the present invention.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] This invention provides a control method and system for improving the fault ride-through performance of new energy power plants. By calculating the reactive current consumed by the grid of the new energy power plant and using the sum of the grid-consumed current and the minimum consumption current as the output reactive current of the photovoltaic inverter, it provides effective compensation for the recovery of the support voltage during fault ride-through of the new energy power plant. This solves the problem of inaccurate reactive response of the photovoltaic inverter and failure to meet grid requirements, and improves the fault ride-through capability of the new energy power plant. Attached Figure Description

[0046] Figure 1 A flowchart illustrating the control method for improving the fault ride-through performance of new energy power plants provided by the present invention;

[0047] Figure 2 This is a schematic diagram of the structure of a photovoltaic power station provided by the present invention;

[0048] Figure 3 This is a schematic diagram of a photovoltaic power station model provided by the present invention;

[0049] Figure 4 This invention provides an equivalent model of the transformer and lines between the inverter outlet and the grid connection point of a photovoltaic power station.

[0050] Figure 5 This is a further simplified equivalent model of the transformer and line between the inverter outlet and the grid connection point of the photovoltaic power station provided by the present invention.

[0051] Figure 6 A schematic diagram of the inverter control method during fault ride-through in a new energy power plant.

[0052] Figure 7 A schematic diagram of the inverter control method for considering grid consumption of new energy power plants provided by the present invention. Detailed Implementation

[0053] Example 1:

[0054] This embodiment discloses a control method for improving the fault ride-through performance of new energy power plants, such as... Figure 1 As shown, it includes:

[0055] Step 1: Obtain the parameters of the new energy power station;

[0056] Step 2: Substitute the parameters of the new energy power station into the pre-built new energy power station model, and use the pre-built new energy power station model to obtain the reactive power consumption when the new energy power station experiences a fault ride-through.

[0057] Step 3: Using reactive power consumption as the target response power, control the reactive power response power of the inverter of the new energy power plant using a pre-built new energy power plant model.

[0058] This method provides effective compensation for the recovery of support voltage during fault ride-through in renewable energy power plants, thereby improving their fault ride-through capability. This method is applicable to improving the fault ride-through performance of renewable energy storage power generation systems such as photovoltaic power plants and wind farms.

[0059] This embodiment takes a photovoltaic power station as an example. Before step 1, it also includes pre-constructing a mathematical model of the photovoltaic power station based on the electrical topology of the photovoltaic power station and taking into account the power consumption of the grid.

[0060] The electrical structure of a photovoltaic power station is as follows Figure 2As shown, the voltage sensed by the inverter in the photovoltaic power station is point B, the inverter output point, and point A is the grid connection point. There are lines and transformers between points A and B, resulting in reactive power loss. A photovoltaic power station that uses point B as a reference point for fault response cannot meet the requirements of the power grid.

[0061] A complete mathematical model of the photovoltaic power station is established. This modeling process can be implemented using power system simulation software such as PSASP. Figure 3 As shown, a mathematical model of a photovoltaic power station is established using PSASP software. The transformer and lines between points A and B of the photovoltaic power station are treated equivalently, such as... Figure 4 As shown, nodes M and N correspond to points B and A in ±2, respectively, and R... L X is the line resistance. L B is the line reactance, R is the charging susceptance, and R is the charging susceptance. T X is the line resistance. T For line reactance, T k This refers to the transformer's turns ratio. Figure 4 With further simplification and equivalence, it can be transformed into, for example: Figure 5 The structure shown is as follows: R is the resistance between the inverter output and the grid connection point, X is the reactance between the inverter output and the grid connection point, U is the difference between the inverter output voltage and the grid connection point voltage, and I is the current between the inverter output point and the grid connection point. A schematic diagram of the inverter control method during fault ride-through in a photovoltaic power station is shown below. Figure 6 As shown.

[0062] The specific steps of this method are explained in detail below:

[0063] Step 1: Obtain the parameters of the photovoltaic power station, including the impedance between the output of each photovoltaic inverter and the grid connection point of the photovoltaic power station, the actual output voltage of each photovoltaic inverter, and the rated output power of the photovoltaic power station.

[0064] The parameters of a photovoltaic power station also include other grid parameters, such as transformer parameters (e.g., capacity of the main transformer and unit transformers, high-voltage side voltage, short-circuit loss, short-circuit current, no-load loss, no-load current, etc.); collector line parameters (e.g., conductor type and length); photovoltaic inverter parameters (e.g., inverter type, capacity, control parameters during normal operation, control parameters during faults, and control parameters after fault recovery); and reactive power compensation device parameters (e.g., reactive power compensation device type, capacity, control parameters during normal operation, control parameters during faults, and control parameters after fault recovery, etc.).

[0065] Step 2: Substitute the parameters obtained in Step 1 into the pre-built photovoltaic power station model to calculate the reactive current of the photovoltaic power station.

[0066] Reactive current consists of two parts: grid current consumption and minimum current consumption.

[0067] The current consumption of the space frame is calculated using the following formula:

[0068]

[0069] Among them, I Q2 U is the current consumed by the grid structure, U is the actual output voltage of the photovoltaic inverter, R is the resistance between the output of the photovoltaic inverter and the grid connection point, and X is the reactance between the output of the photovoltaic inverter and the grid connection point.

[0070] In this embodiment, the relevant parameters are given in per-unit value. Assuming the rated output power of the photovoltaic power station is 1 p.u., when the grid connection point voltage drops to 0.4 p.u., it is determined by I. Q2 The calculation formula can be used to obtain the current I consumed by the grid structure between points A and B. Q2 It is 0.135 pu.

[0071] The minimum current consumption of a photovoltaic inverter is calculated using the following formula:

[0072] I Q1 =1.5*(0.9-0.4)U

[0073] Among them, I Q1 U is the minimum current consumption of the photovoltaic inverter, and U is the actual output voltage of the photovoltaic inverter given in per-unit value.

[0074] byI Q1 The calculation formula shows that the minimum current consumption of the photovoltaic inverter is 0.75 pu.

[0075] Therefore, the reactive current of the photovoltaic inverter is I. Q1 +I Q2 That is, 0.75pu + 0.135pu, and the reactive current is 0.885pu.

[0076] Step 3: Use the reactive current of the photovoltaic inverter obtained in Step 2 as the output current of the photovoltaic inverter to control the grid-connected voltage of the photovoltaic power station.

[0077] The flowchart of the inverter control method considering grid consumption provided in this embodiment is shown below. Figure 7 As shown in the figure. Under this control strategy, the grid voltage is restored from 0.4 pu to 0.44 pu, meeting the grid demand.

[0078] If the current consumption of the grid structure is not taken into account, the minimum current consumption of the photovoltaic inverter is 0.75 pu. Due to line and transformer losses, the recovery voltage at the grid connection point is (0.75 pu - 0.135 pu), which is 0.615 pu. This does not meet the actual grid demand. Therefore, it can be seen that the technical solution of this invention can significantly improve the voltage support capability of the photovoltaic power station to the grid.

[0079] Furthermore, the grid current consumption and minimum current consumption of each photovoltaic inverter can be calculated using a photovoltaic power station model under different power generation and voltage levels. This allows for the acquisition of reactive current for each photovoltaic inverter at different power generation and voltage levels, establishing a reactive current database for each photovoltaic inverter. This database can be accessed during fault ride-through in the photovoltaic power station, significantly improving control efficiency. Typical power generation and voltage values ​​can be selected as 0, 0.2 pu, 0.4 pu, 0.6 pu, 0.8 pu, and 1 p.u.

[0080] Example 2:

[0081] Based on the same inventive concept, this embodiment provides a control system for improving the fault ride-through performance of new energy power plants, including:

[0082] The acquisition module is used to acquire parameters of new energy power plants;

[0083] The reactive power calculation module is used to input the parameters of the new energy power plant into a pre-built new energy power plant model and use the pre-built new energy power plant model to obtain the reactive power consumption power when the new energy power plant experiences a fault ride-through.

[0084] The response module is used to control the grid connection point voltage of the new energy power plant by using the reactive power consumption power as the target response power and outputting the reactive power response power using a pre-built new energy power plant model.

[0085] The control system also includes a model building module, which is used to pre-build a model of the new energy power station based on the electrical topology of the new energy power station and taking into account the power consumption of the grid.

[0086] The reactive power calculation module includes:

[0087] The reactive current unit is used to calculate the reactive current when a new energy power station experiences a fault ride-through, using a pre-built model of the new energy power station.

[0088] The reactive power consumption unit is used to convert reactive current into reactive power consumption power when a new energy power station experiences a fault ride-through.

[0089] The reactive current unit includes:

[0090] The standard reactive current sub-unit is used to calculate the standard reactive current when a new energy power station experiences a fault ride-through using a pre-built model of the new energy power station.

[0091] The grid reactive current consumption sub-unit is used to calculate the grid reactive current consumption when a new energy power station experiences a fault ride, using a pre-built new energy power station model.

[0092] The reactive current consumed by the grid structure is calculated using the following formula:

[0093]

[0094] Among them, I Q2 The reactive current consumed by the grid structure is U, the difference between the inverter output voltage and the grid connection point voltage is U, the resistance between the inverter output and the grid connection point is R, and the reactance between the inverter output and the grid connection point is X.

[0095] Standard reactive current is calculated using the following formula:

[0096] I Q1 =1.5×(0.9-U T In

[0097] Among them, I Q1 For standard reactive current, U T In represents the per-unit value of the inverter output drop voltage during fault ride-through at a new energy power plant, where In is the rated output current of the inverter.

[0098] Example 3:

[0099] Based on the same inventive concept, this invention also provides a computer device, which includes a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer memory. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, and is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in a computer storage medium to realize the corresponding method flow or corresponding function, so as to realize the steps of the control method for improving the fault ride-through performance of a new energy power station in Embodiment 1 above.

[0100] Example 4:

[0101] Based on the same inventive concept, this invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the control method for improving the fault ride-through performance of a new energy power plant in Embodiment 1 above.

[0102] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied 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.

[0103] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0104] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0105] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0106] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A control method for improving the fault ride-through performance of new energy power plants, characterized in that, include: Obtain parameters of new energy power plants; The parameters of the new energy power station are substituted into a pre-built new energy power station model, and the reactive power consumption of the new energy power station during fault ride is obtained using the pre-built new energy power station model. Using the reactive power consumption as the target response power, the reactive power response power of the inverter of the new energy power station is controlled by the pre-constructed new energy power station model. The pre-built new energy power plant model is constructed based on the electrical topology of the new energy power plant and takes into account the power consumption of the grid structure. The step of substituting the parameters of the new energy power station into a pre-built new energy power station model and using the pre-built new energy power station model to obtain the reactive power consumption during fault ride-through of the new energy power station includes: Substitute the parameters of the new energy power station into the pre-built new energy power station model, and use the pre-built new energy power station model to calculate the standard reactive current and grid-consumpted reactive current when the new energy power station experiences a fault ride-through. The sum of the standard reactive current and the reactive current consumed by the grid is taken as the reactive current required when the new energy power station experiences a fault ride, and the reactive power consumed when the new energy power station experiences a fault ride is obtained from the reactive current. The reactive current consumed by the grid structure is calculated using the following formula: in, To dissipate reactive current for the grid structure R is the difference between the inverter output voltage and the grid connection point voltage, R is the resistance between the inverter output and the grid connection point, and X is the reactance between the inverter output and the grid connection point. The standard reactive current is calculated using the following formula: 1.5×(0.9-UT)In in, UT represents the standard reactive current, UT represents the per-unit value of the inverter output drop voltage when a fault occurs at the new energy power station, and In represents the rated output current of the inverter.

2. The control method as described in claim 1, characterized in that, The parameters obtained from the new energy power station include: the resistance and reactance between the inverter outlet and the grid connection point of the new energy power station, the voltage drop at the inverter outlet when the new energy power station experiences a fault ride-through, and the voltage at the grid connection point.

3. The control method as described in claim 2, characterized in that, The step of substituting the parameters of the new energy power station into a pre-built new energy power station model and using the pre-built new energy power station model to obtain the reactive power consumption during fault ride-through of the new energy power station also includes: Substitute the parameters of the new energy power station into the pre-built new energy power station model, and use the pre-built new energy power station model to obtain the reactive power consumption of each inverter in the new energy power station under different power generation and voltage levels. A reactive power consumption database for the new energy power plant is established based on the reactive power consumption of each inverter under different power generation and voltage levels. The pre-built new energy power plant model calls the corresponding data in the reactive power consumption database based on the voltage level when the new energy power plant experiences a fault ride-through, and uses the corresponding data in the reactive power consumption database as the reactive power consumption.

4. A control system for improving the fault ride-through performance of new energy power plants, characterized in that, include: The acquisition module is used to acquire parameters of new energy power plants; The reactive power calculation module is used to substitute the parameters of the new energy power station into a pre-built new energy power station model, and use the pre-built new energy power station model to obtain the reactive power consumption power of the new energy power station when a fault ride occurs. The response module is used to control the grid connection point voltage of the new energy power station by using the reactive power consumption power as the target response power and outputting the reactive power response power using the pre-built new energy power station model. The pre-built new energy power plant model is constructed based on the electrical topology of the new energy power plant and takes into account the power consumption of the grid structure. The reactive power calculation module includes: The reactive current unit is used to calculate the reactive current of the new energy power station when a fault ride occurs using the pre-built new energy power station model. The reactive power consumption unit is used to convert the reactive current into reactive power consumption when the new energy power station experiences a fault ride-through. The reactive current unit includes: A standard reactive current subunit is used to calculate the standard reactive current of the new energy power station during fault ride-through using the pre-built new energy power station model. The grid reactive current consumption sub-unit is used to calculate the grid reactive current consumption when the new energy power station experiences a fault ride using the pre-built new energy power station model. The reactive current consumed by the grid structure is calculated using the following formula: in, To dissipate reactive current for the grid structure R is the difference between the inverter output voltage and the grid connection point voltage, R is the resistance between the inverter output and the grid connection point, and X is the reactance between the inverter output and the grid connection point. The standard reactive current is calculated using the following formula: 1.5×(0.9-UT)In in, UT represents the standard reactive current, UT represents the per-unit value of the inverter output drop voltage when a fault occurs at the new energy power station, and In represents the rated output current of the inverter.

5. A computer device, characterized in that, include: One or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, the control method as described in any one of claims 1-3 is implemented.

6. A computer-readable storage medium, characterized in that, It contains a computer program, which, when executed, implements the control method as described in any one of claims 1-3.

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