Wind power converter control methods and systems for reducing the risk of transient voltage instability in wind power collection stations

Abstract

This invention relates to the field of power system stability control technology, and is a wind power converter control method and system for reducing the risk of transient voltage instability at wind power collection stations. The method includes: establishing a transient voltage model of the wind power collection station in the renewable energy sending-end grid after a DC bipolar blocking fault; establishing a reactive power control model of the wind power converter under the transient voltage control mode based on active power output; and setting transient voltage instability limits for the wind power collection station in the renewable energy sending-end grid after a DC bipolar blocking fault. This invention can fully leverage the rapid reactive power control advantages of the wind power converter when the transient voltage instability risk of the wind power collection station is caused by the UHVDC bipolar blocking in the renewable energy sending-end grid, thereby reducing the peak transient voltage of the wind power collection station, preventing the wind farm units connected to the wind power collection station from tripping and disconnecting from the grid due to high voltage ride-through failure, thus reducing the risk of transient voltage instability at the wind power collection station and improving the transient voltage stability of the system.

Description

Technical Field

[0001] This invention relates to the field of power system stability control technology, and in particular to a wind power converter control method and system for reducing the risk of transient voltage instability at wind power collection stations. Background Technology

[0002] Against the backdrop of my country's vigorous promotion of the "dual-carbon" strategy, the centralized integration of a high proportion of renewable energy into the power system has become a development trend in regions rich in renewable energy resources. Long-distance, large-capacity transmission of a high proportion of renewable energy via ultra-high-voltage direct current (UHVDC) has become a typical operating mode for renewable energy consumption. However, for the sending-end grid of a high-proportion renewable energy UHVDC system, the centralized integration of large-scale wind power into the grid leads to problems such as reduced system inertia, decreased short-circuit capacity, and insufficient dynamic reactive power support. This can cause a large amount of reactive power to be fed back to the sending-end AC grid during a bipolar blocking fault in the UHVDC system, resulting in a sudden surge in transient voltage in the AC grid and posing a significant challenge to grid operation.

[0003] According to the "Technical Regulations for Wind Farm Connection to Power Systems," wind power collection stations or wind farm stations must have high-voltage ride-through capability. In actual operation, if the transient voltage of the wind power collection station exceeds 1.3 pu, it will cause the wind farm to trip and disconnect from the grid due to exceeding the high-voltage ride-through capability. In severe cases, it will trigger a chain of grid disconnection accidents, causing transient voltage instability and threatening the safe and stable operation of the power grid.

[0004] Traditional dynamic reactive power compensation devices such as SVC, SVG, and synchronous condensers can provide voltage support, but they suffer from high investment costs, insufficient configuration, and limited response speed. Wind power converters themselves have the potential for rapid reactive power regulation and can respond to system voltage changes within milliseconds. However, wind farms currently generally use constant power factor control, which cannot actively provide voltage support based on reactive power control during system transients, and therefore cannot effectively suppress transient voltage instability.

[0005] Therefore, for a high proportion of new energy UHVDC transmission grid, giving full play to the rapid and active transient voltage regulation capability of the wind power converter itself, and quickly responding to and suppressing the excessively high peak transient voltage of the wind power collection station during the transient process, can effectively reduce the risk of transient voltage instability of the wind power collection station in the new energy DC transmission grid. Summary of the Invention

[0006] This invention provides a wind power converter control method and system for reducing the risk of transient voltage instability in wind power collection stations. It overcomes the shortcomings of the prior art and can effectively solve the problem of transient voltage instability caused by the disconnection of wind farms connected to the DC sending-end grid wind power collection station due to excessively high transient voltage after a DC fault.

[0007] To address the above problems, one of the technical solutions of this invention is achieved through the following method: a wind power converter control method for reducing the risk of transient voltage instability in wind power collection stations, comprising the following steps: Establish a transient voltage model of the wind power collection station at the new energy sending-end power grid after a DC bipolar blocking fault. Establish a reactive power control model for wind power converters based on the transient voltage control mode of active power output; Set transient voltage instability limits for wind power collection stations at the new energy sending-end grid after a DC bipolar blocking fault. Set threshold values ​​for transient voltage control actions of wind power converters to reduce the risk of transient voltage instability at wind power collection stations; Establish a transient voltage model for wind power collection stations in which wind power converters participate in transient voltage control; Calculate the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station after a DC bipolar blocking fault, and determine whether the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station is greater than or equal to zero. Therefore, it is determined that the wind power collection station is at risk of transient voltage instability, that is, the wind power collection station may experience transient voltage instability after a DC bipolar blocking fault. After adopting the transient voltage control action threshold of the wind power converter, based on the transient voltage model of the wind power collection station with the participation of the wind power converter in transient voltage control, the difference between the transient voltage of the wind power collection station and the transient voltage instability limit is calculated, and it is determined whether the difference between the transient voltage of the wind power collection station and the transient voltage instability limit is less than zero. Therefore, it is determined that there is no risk of transient voltage instability at the wind power collection station, that is, the risk of transient voltage instability at the wind power collection station is reduced after the wind power converter is used to participate in transient voltage control.

[0008] The aforementioned establishment of a transient voltage model for the wind power collection station at the renewable energy sending-end grid after a DC bipolar blocking fault includes: The transient voltage model of the wind power collection station is as follows: , , , In the formula, Transient voltage of wind power collection station, For the steady-state voltage of the wind power collection station, For the transient voltage increment of the wind power collection station, For the AC line reactor from the main grid to the collection station, For AC main grid transient voltage, The active power sent to the wind power collection station by the main grid. The reactive power sent to the wind power collection station by the main grid.

[0009] The aforementioned establishment of a transient voltage model for the wind power collection station at the renewable energy sending-end grid after a DC bipolar blocking fault includes: The reactive power control calculation formula under transient voltage control mode is as follows: , , , , Constraints: , In the formula, This represents the sum of the reactive power control power of the wind turbine converters at the collecting station under transient voltage conditions. This represents the sum of the maximum apparent power of the wind turbine converters at the collecting station under transient voltage conditions. For the first collection station under transient voltage i Maximum apparent power of typhoon generator converter; For the first collection station i The rated apparent power of the typhoon generator converter. for based on The increase factor This is the sum of the active power output of the wind turbine generators at the collection station. For the first collection station i The active power output of the typhoon generator converter.

[0010] The aforementioned transient voltage instability limits for wind power collection stations at the renewable energy sending-end grid after a DC bipolar blocking fault include: The calculation method for transient voltage instability limits is as follows: , In the formula, This is the limit for transient voltage instability. This is the rated voltage of the collection station.

[0011] The aforementioned threshold values ​​for wind power converter transient voltage control actions to reduce the risk of transient voltage instability at wind power collection stations include: The transient voltage control action threshold for the wind power converter is set as follows: , In the formula, The threshold for transient voltage control action of the wind power converter. This is the rated voltage of the wind power collection station.

[0012] The aforementioned establishment of a transient voltage model for wind power collection stations involving wind power converters in transient voltage control includes: , , , , , , In the formula, Transient voltage of wind power collection station, For the steady-state voltage of the wind power collection station, This refers to the transient voltage increment at the wind power collection station. For the AC line reactor from the main grid to the collection station, For AC main grid transient voltage, The active power sent to the wind power collection station by the main grid. To supply reactive power to the wind power collection station for the main grid, For the short-circuit capacity of the wind power collection station, This refers to the reactive power control increment of the wind power converter under transient voltage at the collection station. This represents the sum of the reactive power control power of the wind turbine converters at the collecting station under transient voltage conditions. For the first wind power collection station under transient voltage i Reactive power control of typhoon generator converter; This represents the sum of the reactive power of the wind turbine converters in the wind power collection station before the DC fault. The first wind power collection station before the DC fault i Reactive power of typhoon generator converter.

[0013] The above calculation of the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station after a DC bipolar blocking fault includes: The calculation method is as follows: , In the formula, This is the difference between the expected transient voltage and the transient voltage instability limit of the new energy collection station. This represents the expected transient voltage value of the new energy collection station after a DC bipolar blocking fault. This is the limit for transient voltage instability.

[0014] The above-mentioned reactive power control increment of the wind power converter after applying the transient voltage control action threshold is input into the transient voltage model of the wind power collection station to calculate the difference between the transient voltage of the wind power collection station and the transient voltage instability limit, including: The transient voltage of the wind power collection station after the wind power converter participates in transient voltage control is calculated as follows: , , In the formula, The steady-state voltage control threshold for the collection station. The reactive power sent to the aggregation station from the main AC network. The active power sent from the main network to the aggregation station. For the AC line reactor from the main grid to the collection station, The transient voltage of the collecting station in which the wind power converter participates in transient voltage control. For AC main grid transient voltage, For the short-circuit capacity of the wind power collection station, This is the sum of the reactive power control increments of the wind turbine converters under transient voltage at the collecting station. For the first wind power collection station under transient voltage i Incremental reactive power control of typhoon generator converter; The difference between the transient voltage at the collection station and the transient voltage instability limit at the wind power collection station after the wind power converter participates in transient voltage control is calculated as follows: , In the formula, This is the difference between the transient voltage of the new energy collection station and the transient voltage instability limit of the wind power collection station after the wind power converter participates in transient voltage control.

[0015] The second technical solution of this invention is achieved through the following means: a wind power converter control system for reducing the risk of transient voltage instability in wind power collection stations, comprising: A transient voltage unit for blocking faults is established to create a transient voltage model of the wind power collection station at the new energy sending end of the power grid after a DC bipolar blocking fault. A reactive power control model unit is established to create a reactive power control model for a wind power converter based on the transient voltage control mode of active power output. Voltage instability limit setting unit, sets transient voltage instability limit of wind power collection station of new energy sending end grid after DC bipolar blocking fault; The voltage control threshold setting unit sets the transient voltage control action threshold of the wind power converter to reduce the risk of transient voltage instability in the wind power collection station. Transient voltage unit of wind power converter: Establish transient voltage model of wind power collection station in which wind power converter participates in transient voltage control; The transient voltage difference calculation unit before the wind power converter participates in control calculates the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station after the DC bipolar blocking fault, and determines whether the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station is greater than or equal to zero. The transient voltage instability risk assessment unit responds by determining that the wind power collection station has a transient voltage instability risk, that is, the wind power collection station may have transient voltage instability after the DC bipolar blocking fault. The transient voltage difference calculation unit after the wind power converter participates in the control uses the transient voltage control action threshold of the wind power converter and, based on the transient voltage model of the wind power collection station with the wind power converter participating in the transient voltage control, calculates the difference between the transient voltage of the wind power collection station and the transient voltage instability limit, and determines whether the difference between the transient voltage of the wind power collection station and the transient voltage instability limit is less than zero. The transient voltage instability risk reduction judgment unit responds, and then determines that there is no transient voltage instability risk in the wind power collection station, that is, the transient voltage instability risk of the wind power collection station is reduced after the wind power converter participates in transient voltage control.

[0016] Compared with the prior art, the present invention has the following advantages: This invention first establishes a transient voltage model of the wind power collection station in the renewable energy sending-end grid after a DC bipolar blocking fault; secondly, it establishes another transient voltage model of the wind power collection station in the renewable energy sending-end grid after a DC bipolar blocking fault; based on this, it sets transient voltage instability limits for the wind power collection station in the renewable energy sending-end grid after a DC bipolar blocking fault and sets a control mode switching threshold for the wind power converter to reduce the risk of transient voltage instability in the wind power collection station; thirdly, it establishes a transient voltage model of the wind power collection station in which the wind power converter participates in transient voltage control; and then, it calculates... The difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station after a DC bipolar blocking fault is calculated to assess the transient voltage instability risk of the wind power collection station. Finally, after the transient voltage control threshold of the wind power converter is activated, based on the transient voltage model of the wind power collection station with the wind power converter participating in transient voltage control, the difference between the transient voltage and the transient voltage instability limit of the wind power collection station after a DC bipolar blocking fault is calculated to assess the control effect of reducing the transient voltage instability risk of the wind power collection station, thereby confirming the effectiveness of reducing the transient voltage instability risk.

[0017] The method described in this invention can fully leverage the reactive power rapid control advantage of wind power converters when the risk of transient voltage instability at wind power collection stations is caused by the bipolar blocking of ultra-high voltage DC transmission lines at the new energy sending-end grid. This reduces the peak transient voltage of wind power collection stations, prevents wind farm units connected to the wind power collection stations from tripping and disconnecting from the grid due to high voltage ride-through failure, thereby reducing the risk of transient voltage instability at wind power collection stations and improving the stability of system transient voltage. Attached Figure Description

[0018] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0019] Figure 1 This is a flowchart of the method in Embodiment 1 of the present invention.

[0020] Figure 2 This is an equivalent schematic diagram of the wind power collection station wiring in Embodiment 1 of the present invention.

[0021] Figure 3 This is a system block diagram of Embodiment 2 of the present invention.

[0022] Figure 4 This is a graph showing the high-voltage ride-through requirements for wind farms in Embodiment 3 of the present invention.

[0023] Figure 5 This is a circular diagram showing the power operation of the wind power converter in Embodiment 3 of the present invention.

[0024] Figure 6 This is a schematic diagram of the power grid wiring in Embodiment 3 of the present invention.

[0025] Figure 7 This is a comparison curve of transient voltages in Embodiment 3 of the present invention. Detailed Implementation

[0026] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0027] Example 1: As Figure 1 As shown in the figure, this invention discloses a wind power converter control method to reduce the risk of transient voltage instability in wind power collection stations, including the following steps: S101, Establish a transient voltage model of the wind power collection station of the new energy sending-end power grid after a DC bipolar blocking fault; S102, Establish a reactive power control model for wind power converter based on transient voltage control mode of active power output; S103, set the transient voltage instability limit of the wind power collection station of the new energy sending end grid after a DC bipolar blocking fault. S104, set the threshold for transient voltage control action of wind power converter to reduce the risk of transient voltage instability in wind power collection stations; S105, Establish a transient voltage model for wind power collection stations in which wind power converters participate in transient voltage control; S106, calculate the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station after a DC bipolar blocking fault, and determine whether the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station is greater than or equal to zero. S107, in response, it is determined that there is a risk of transient voltage instability at the wind power collection station, that is, after the DC bipolar blocking fault, the wind power collection station may experience transient voltage instability. S108. After adopting the transient voltage control action threshold of the wind power converter, based on the transient voltage model of the wind power collection station with the participation of the wind power converter in transient voltage control, calculate the difference between the transient voltage of the wind power collection station and the transient voltage instability limit, and determine whether the difference between the transient voltage of the wind power collection station and the transient voltage instability limit is less than zero. S109, in response, it is determined that there is no risk of transient voltage instability at the wind power collection station, that is, the risk of transient voltage instability at the wind power collection station is reduced after the wind power converter is used to participate in transient voltage control.

[0028] In step S101 above, such as Figure 2 The equivalent wiring diagram of the wind power collection station is shown. A transient voltage model of the wind power collection station at the renewable energy sending-end grid is established after a DC bipolar blocking fault, including: The transient voltage model of the wind power collection station is as follows: , , , In the formula, Transient voltage of wind power collection station, For the steady-state voltage of the wind power collection station, For the transient voltage increment of the wind power collection station, For the AC line reactor from the main grid to the collection station, For AC main grid transient voltage, The active power sent to the wind power collection station by the main grid. The reactive power sent to the wind power collection station by the main grid.

[0029] In step S102 above, establishing a transient voltage model for the wind power collection station of the renewable energy sending-end grid after a DC bipolar blocking fault includes: The reactive power control calculation formula under transient voltage control mode is as follows: , , , , Constraints: , In the formula, This represents the sum of the reactive power control power of the wind turbine converters at the collecting station under transient voltage conditions. This represents the sum of the maximum apparent power of the wind turbine converters at the collecting station under transient voltage conditions. For the first collection station under transient voltage i Maximum apparent power of typhoon generator converter; For the first collection station i The rated apparent power of the typhoon generator converter. for based on The increase factor This is the sum of the active power output of the wind turbine generators at the collection station. For the first collection station i The active power output of the typhoon generator converter.

[0030] In step S103 above, setting the transient voltage instability limit for the wind power collection station of the new energy sending-end grid after a DC bipolar blocking fault includes: The calculation method for transient voltage instability limits is as follows: , In the formula, This is the limit for transient voltage instability. This is the rated voltage of the collection station.

[0031] In step S104 above, setting the transient voltage control action threshold of the wind power converter to reduce the risk of transient voltage instability in the wind power collection station includes: The transient voltage control action threshold for the wind power converter is set as follows: , In the formula, The threshold for transient voltage control action of the wind power converter. This is the rated voltage of the wind power collection station.

[0032] In step S105 above, establishing a transient voltage model for the wind power collection station with the wind power converter participating in transient voltage control includes: , , , , , , In the formula, Transient voltage of wind power collection station, For the steady-state voltage of the wind power collection station, This refers to the transient voltage increment at the wind power collection station. For the AC line reactor from the main grid to the collection station, For AC main grid transient voltage, The active power sent to the wind power collection station by the main grid. To supply reactive power to the wind power collection station for the main grid, For the short-circuit capacity of the wind power collection station, The reactive power control increment of the wind power converter under transient voltage at the collection station (the first wind power collection station under transient voltage). i (sum of reactive power control increments of typhoon generator converters) This represents the sum of the reactive power control power of the wind turbine converters at the collecting station under transient voltage conditions. For the first wind power collection station under transient voltage i Reactive power control of typhoon generator converter; This represents the sum of the reactive power of the wind turbine converters in the wind power collection station before the DC fault. The first wind power collection station before the DC fault i Reactive power of typhoon generator converter.

[0033] In step S106 above, the calculation of the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station after a DC bipolar blocking fault includes: The calculation method is as follows: , In the formula, This is the difference between the expected transient voltage and the transient voltage instability limit of the new energy collection station. This represents the expected transient voltage value of the new energy collection station after a DC bipolar blocking fault. This is the limit for transient voltage instability.

[0034] In step S108 above, after adopting the transient voltage control action threshold of the wind power converter, based on the transient voltage model of the wind power collection station with the wind power converter participating in transient voltage control, the difference between the transient voltage of the wind power collection station and the transient voltage instability limit is calculated, including: The transient voltage of the wind power collection station after the wind power converter participates in transient voltage control is calculated as follows: , , In the formula, The steady-state voltage control threshold for the collection station. The reactive power sent to the aggregation station from the main AC network. The active power sent from the main network to the aggregation station. For the AC line reactor from the main grid to the collection station, The transient voltage of the collecting station in which the wind power converter participates in transient voltage control. For AC main grid transient voltage, For the short-circuit capacity of the wind power collection station, This is the sum of the reactive power control increments of the wind turbine converters under transient voltage at the collecting station. For the first wind power collection station under transient voltagei Incremental reactive power control of typhoon generator converter; The difference between the transient voltage at the collection station and the transient voltage instability limit at the wind power collection station after the wind power converter participates in transient voltage control is calculated as follows: , In the formula, This is the difference between the transient voltage of the new energy collection station and the transient voltage instability limit of the wind power collection station after the wind power converter participates in transient voltage control.

[0035] Example 2: As Figure 3 As shown, this invention discloses a wind power converter control system for reducing the risk of transient voltage instability in wind power collection stations, comprising: A transient voltage unit for blocking faults is established to create a transient voltage model of the wind power collection station at the new energy sending end of the power grid after a DC bipolar blocking fault. A reactive power control model unit is established to create a reactive power control model for a wind power converter based on the transient voltage control mode of active power output. Voltage instability limit setting unit, sets transient voltage instability limit of wind power collection station of new energy sending end grid after DC bipolar blocking fault; The voltage control threshold setting unit sets the transient voltage control action threshold of the wind power converter to reduce the risk of transient voltage instability in the wind power collection station. Transient voltage unit of wind power converter: Establish transient voltage model of wind power collection station in which wind power converter participates in transient voltage control; The transient voltage difference calculation unit before the wind power converter participates in control calculates the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station after the DC bipolar blocking fault, and determines whether the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station is greater than or equal to zero. The transient voltage instability risk assessment unit responds by determining that the wind power collection station has a transient voltage instability risk, that is, the wind power collection station may have transient voltage instability after the DC bipolar blocking fault. The transient voltage difference calculation unit after the wind power converter participates in the control uses the transient voltage control action threshold of the wind power converter and, based on the transient voltage model of the wind power collection station with the wind power converter participating in the transient voltage control, calculates the difference between the transient voltage of the wind power collection station and the transient voltage instability limit, and determines whether the difference between the transient voltage of the wind power collection station and the transient voltage instability limit is less than zero. The transient voltage instability risk reduction judgment unit responds, and then determines that there is no transient voltage instability risk in the wind power collection station, that is, the transient voltage instability risk of the wind power collection station is reduced after the wind power converter participates in transient voltage control.

[0036] This invention first establishes a transient voltage model of the wind power collection station in the renewable energy sending-end grid after a DC bipolar blocking fault; secondly, it establishes another transient voltage model of the wind power collection station in the renewable energy sending-end grid after a DC bipolar blocking fault; based on this, it sets transient voltage instability limits for the wind power collection station in the renewable energy sending-end grid after a DC bipolar blocking fault and sets a control mode switching threshold for the wind power converter to reduce the risk of transient voltage instability in the wind power collection station; thirdly, it establishes a transient voltage model of the wind power collection station in which the wind power converter participates in transient voltage control; and then, it calculates... The difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station after a DC bipolar blocking fault is calculated to assess the transient voltage instability risk of the wind power collection station. Finally, after the transient voltage control threshold of the wind power converter is activated, based on the transient voltage model of the wind power collection station with the wind power converter participating in transient voltage control, the difference between the transient voltage and the transient voltage instability limit of the wind power collection station after a DC bipolar blocking fault is calculated to assess the control effect of reducing the transient voltage instability risk of the wind power collection station, thereby confirming the effectiveness of reducing the transient voltage instability risk.

[0037] The method described in this invention can fully leverage the reactive power rapid control advantage of wind power converters when the risk of transient voltage instability at wind power collection stations is caused by the bipolar blocking of ultra-high voltage DC transmission lines at the new energy sending-end grid. This reduces the peak transient voltage of wind power collection stations, prevents wind farm units connected to the wind power collection stations from tripping and disconnecting from the grid due to high voltage ride-through failure, thereby reducing the risk of transient voltage instability at wind power collection stations and improving the stability of system transient voltage.

[0038] Example 3: This example is based on a real regional power grid. The power grid wiring diagram is attached. Figure 6 As shown in the attached figure, the high-voltage ride-through requirements for wind farms are as follows. Figure 4 As shown in the attached figure, the steady-state and transient power operation characteristics of the wind power converter are as follows. Figure 5 As shown, the total output of new energy sources in this region's power grid is 16000MW, of which Ganguangliang Wind G1, Ganguangliang Wind G2, and Ganliu Wind G1 each output 95MW, the load of Gantianshui Well is 60+j20MVA, and the DC transmission power is the rated transmission power of 8000MW. Assume the rated voltage of "Ganhongliu 31" is... The normal operating voltage range of "Gan Hong Liu 31" is ,in, This refers to the upper limit of the allowable steady-state operating voltage range for "Gan Hong Liu 31". This is the lower limit of the allowable steady-state operating voltage range for "Gan Hongliu 31". At time t=1.0s, a bipolar blockage fault occurred between Ganqilianhuan 71 and Hunan Zhuzhou 51 UHVDC lines.

[0039] Take the upper limit of steady-state voltage of the wind power collection station Transient voltage control action threshold The apparent power enhancement factor of wind power converters Transient voltage instability limits The apparent power enhancement factor of wind power converters .

[0040] Simulation calculations were performed on the transient voltage of the wind power collection station after a DC double-acting blockade fault, with and without the wind power converter participating in transient voltage control. The calculation results before and after the wind power converter participates in transient voltage control are shown in Table 1. The transient voltage comparison curves of the wind power collection station are attached. Figure 7 As shown.

[0041] Table 1 Comparison of results before and after wind power converters participate in transient voltage control As shown in Table 1, the wind power converter did not participate in transient voltage control. When the transient voltage of the collecting station increased, the reactive power absorbed by the wind power converter was 0.0491 pu. However, there is a risk of transient instability. After the wind power converter participates in transient voltage control, the reactive power absorbed by the wind power converter is 0.4699 pu when the transient voltage of the collecting station rises, which significantly increases the reactive power absorption capacity. There is no risk of transient instability, indicating that the risk of transient voltage instability has been significantly reduced.

[0042] Verification conclusion: The transient voltage of the wind power collection station after implementation of the method proposed in this invention is less than the set transient voltage instability limit, thus eliminating the risk of transient voltage instability of the wind power collection station and significantly reducing the risk of transient voltage instability of the wind power collection station.

[0043] As can be seen from Examples 1 and 3, by using wind power converters to participate in transient voltage control and setting transient voltage control thresholds for wind power converters, the reactive power regulation space of wind power converters under transient conditions can be fully utilized, the excessively high peak value of transient voltage can be quickly suppressed, and the wind farm units connected to the wind power collection station can be prevented from tripping and disconnecting from the grid due to high voltage ride-through failure, thereby reducing the risk of transient voltage instability at the wind power collection station and improving the stability of the system transient voltage.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the pending claims.

Claims

1. A wind power converter control method for reducing the risk of transient voltage instability in wind power collection stations, characterized in that, Includes the following steps: Establish a transient voltage model of the wind power collection station at the new energy sending-end power grid after a DC bipolar blocking fault. Establish a reactive power control model for wind power converters based on the transient voltage control mode of active power output; Set transient voltage instability limits for wind power collection stations at the new energy sending-end grid after a DC bipolar blocking fault. Set threshold values ​​for transient voltage control actions of wind power converters to reduce the risk of transient voltage instability at wind power collection stations; Establish a transient voltage model for wind power collection stations in which wind power converters participate in transient voltage control; Calculate the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station after a DC bipolar blocking fault, and determine whether the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station is greater than or equal to zero. Therefore, it is determined that the wind power collection station is at risk of transient voltage instability, that is, the wind power collection station may experience transient voltage instability after a DC bipolar blocking fault. After adopting the transient voltage control action threshold of the wind power converter, based on the transient voltage model of the wind power collection station with the participation of the wind power converter in transient voltage control, the difference between the transient voltage of the wind power collection station and the transient voltage instability limit is calculated, and it is determined whether the difference between the transient voltage of the wind power collection station and the transient voltage instability limit is less than zero. Therefore, it is determined that there is no risk of transient voltage instability at the wind power collection station, that is, the risk of transient voltage instability at the wind power collection station is reduced after the wind power converter is used to participate in transient voltage control.

2. The wind power converter control method for reducing the risk of transient voltage instability in wind power collection stations according to claim 1, characterized in that, The establishment of the transient voltage model for the wind power collection station at the new energy sending-end grid after a DC bipolar blocking fault includes: The transient voltage model of the wind power collection station is as follows: ， ， ， In the formula, Transient voltage of wind power collection station, For the steady-state voltage of the wind power collection station, For the transient voltage increment of the wind power collection station, For the AC line reactor from the main grid to the collection station, For AC main grid transient voltage, The active power sent to the wind power collection station by the main grid. The reactive power sent to the wind power collection station by the main grid.

3. The wind power converter control method for reducing the risk of transient voltage instability in wind power collection stations according to claim 1, characterized in that, The establishment of the transient voltage model for the wind power collection station at the new energy sending-end grid after a DC bipolar blocking fault includes: The reactive power control calculation formula under transient voltage control mode is as follows: ， ， ， ， Constraints: ， In the formula, This represents the sum of the reactive power control power of the wind turbine converters at the collecting station under transient voltage conditions. This represents the sum of the maximum apparent power of the wind turbine converters at the collecting station under transient voltage conditions. For the first collection station under transient voltage i Maximum apparent power of typhoon generator converter; For the first collection station i The rated apparent power of the typhoon generator converter. for based on The increase factor This is the sum of the active power output of the wind turbine generators at the collection station. For the first collection station i The active power output of the typhoon generator converter.

4. The wind power converter control method for reducing the risk of transient voltage instability in wind power collection stations according to claim 1, characterized in that, The setting of transient voltage instability limits for wind power collection stations at the renewable energy sending-end grid after a DC bipolar blocking fault includes: The calculation method for transient voltage instability limits is as follows: ， In the formula, This is the limit for transient voltage instability. This is the rated voltage of the collection station.

5. The wind power converter control method for reducing the risk of transient voltage instability in wind power collection stations according to claim 1, characterized in that, The threshold values ​​for setting transient voltage control actions of wind power converters to reduce the risk of transient voltage instability at wind power collection stations include: The transient voltage control action threshold for the wind power converter is set as follows: ， In the formula, The threshold for transient voltage control action of the wind power converter. This is the rated voltage of the wind power collection station.

6. The wind power converter control method for reducing the risk of transient voltage instability in wind power collection stations according to claim 1, characterized in that, The establishment of a transient voltage model for wind power collection stations involving wind power converters in transient voltage control includes: ， ， ， ， ， ， In the formula, Transient voltage of wind power collection station, For the steady-state voltage of the wind power collection station, For the transient voltage increment of the wind power collection station, For the AC line reactor from the main grid to the collection station, For AC main grid transient voltage, The active power sent to the wind power collection station by the main grid. To supply reactive power to the wind power collection station for the main grid, For the short-circuit capacity of the wind power collection station, This refers to the reactive power control increment of the wind power converter under transient voltage at the collection station. This represents the sum of the reactive power control power of the wind turbine converters at the collecting station under transient voltage conditions. For the first wind power collection station under transient voltage i Reactive power control of typhoon generator converter; This represents the sum of the reactive power of the wind turbine converters in the wind power collection station before the DC fault. The first wind power collection station before the DC fault i Reactive power of typhoon generator converter.

7. The wind power converter control method for reducing the risk of transient voltage instability in wind power collection stations according to claim 1, characterized in that, The calculation of the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station after a DC bipolar blocking fault includes: The calculation method is as follows: ， In the formula, This is the difference between the expected transient voltage and the transient voltage instability limit of the new energy collection station. This represents the expected transient voltage value of the new energy collection station after a DC bipolar blocking fault. This is the limit for transient voltage instability.

8. The wind power converter control method for reducing the risk of transient voltage instability in wind power collection stations according to claim 1, characterized in that, After adopting the transient voltage control action threshold of the wind power converter, based on the transient voltage model of the wind power collection station with the participation of the wind power converter in transient voltage control, the difference between the transient voltage of the wind power collection station and the transient voltage instability limit is calculated, including: The transient voltage of the wind power collection station after the wind power converter participates in transient voltage control is calculated as follows: ， ， In the formula, The steady-state voltage control threshold for the collection station. The reactive power sent to the aggregation station from the main AC network. The active power sent from the main network to the aggregation station. For the AC line reactor from the main grid to the collection station, The transient voltage of the collecting station in which the wind power converter participates in transient voltage control. For AC main grid transient voltage, For the short-circuit capacity of the wind power collection station, This is the sum of the reactive power control increments of the wind turbine converters under transient voltage at the collecting station. For the first wind power collection station under transient voltage i Incremental reactive power control of typhoon generator converter; The difference between the transient voltage at the collection station and the transient voltage instability limit at the wind power collection station after the wind power converter participates in transient voltage control is calculated as follows: ， In the formula, This is the difference between the transient voltage of the new energy collection station and the transient voltage instability limit of the wind power collection station after the wind power converter participates in transient voltage control.

9. A wind power converter control system for reducing the risk of transient voltage instability in wind power collection stations, characterized in that, include: A transient voltage unit for blocking faults is established to create a transient voltage model of the wind power collection station at the new energy sending end of the power grid after a DC bipolar blocking fault. A reactive power control model unit is established to create a reactive power control model for a wind power converter based on the transient voltage control mode of active power output. Voltage instability limit setting unit, sets transient voltage instability limit of wind power collection station of new energy sending end grid after DC bipolar blocking fault; The voltage control threshold setting unit sets the transient voltage control action threshold of the wind power converter to reduce the risk of transient voltage instability in the wind power collection station. Transient voltage unit of wind power converter: Establish transient voltage model of wind power collection station in which wind power converter participates in transient voltage control; The transient voltage difference calculation unit before the wind power converter participates in control calculates the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station after the DC bipolar blocking fault, and determines whether the difference between the expected transient voltage and the transient voltage instability limit of the wind power collection station is greater than or equal to zero. The transient voltage instability risk assessment unit responds by determining that the wind power collection station has a transient voltage instability risk, that is, the wind power collection station may have transient voltage instability after the DC bipolar blocking fault. The transient voltage difference calculation unit after the wind power converter participates in the control uses the transient voltage control action threshold of the wind power converter and, based on the transient voltage model of the wind power collection station with the wind power converter participating in the transient voltage control, calculates the difference between the transient voltage of the wind power collection station and the transient voltage instability limit, and determines whether the difference between the transient voltage of the wind power collection station and the transient voltage instability limit is less than zero. The transient voltage instability risk reduction judgment unit responds, and then determines that there is no transient voltage instability risk in the wind power collection station, that is, the transient voltage instability risk of the wind power collection station is reduced after the wind power converter participates in transient voltage control.

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