Voltage control method for the low-voltage side bus of the step-up transformer in new energy power plants

Abstract

This invention relates to the field of new energy technology and is a method for controlling the low-voltage bus voltage of a step-up transformer in a new energy power plant. The method includes the following steps: determining the AVC status and control mode; collecting the grid connection point voltage, grid-connected circuit breaker status, and low-voltage bus voltage of the step-up transformer; verifying the availability of the data and confirming the correctness of the received master station commands; determining the current control zone; formulating a voltage control strategy for the low-voltage bus of the step-up transformer; generating and executing AVC substation control commands; and adjusting the data several times until the control target is achieved. This invention can reduce the sensitivity of the low-voltage bus voltage, mitigate various adverse effects caused by maintaining the grid connection point voltage, and provide important guidance for improving the control strategy of the automatic voltage control substation in new energy power plants. It can also improve the low-voltage bus voltage qualification rate, reduce voltage fluctuations between power plants, and reduce reactive power loss.

Description

Technical Field

[0001] This invention relates to the field of new energy technology and is a method for controlling the low-voltage bus voltage of a booster transformer in a new energy power station. Background Technology

[0002] The Automatic Voltage Control (AVC) substation at a renewable energy power station receives commands from the master station or local commands and generates control commands through software algorithms to coordinate and control various reactive power equipment within the station. When operating in a remote closed-loop manner, the AVC substation uses meeting the master station's requirements for grid connection voltage as its control objective. When operating in a local closed-loop manner, it uses meeting the limits issued by the dispatching agency for the voltage of each bus as its control objective.

[0003] In practice, under both control modes, the voltage of the low-voltage side bus of the step-up transformer is adjusted to prioritize meeting the grid connection voltage. Under these circumstances, new energy power plants generally face difficulties in coordinating the control of the low-voltage side bus voltage with the grid connection voltage. This manifests primarily as overshooting of the low-voltage side bus voltage even when the grid connection voltage is within acceptable limits, or frequent adjustments to the AVC substation due to fluctuations in the low-voltage side bus voltage.

[0004] The above problems will lead to the blocking of reactive power generation equipment in the station due to exceeding the status limit, increased voltage fluctuations between stations, or equipment aging. Summary of the Invention

[0005] This invention provides a method for controlling the low-voltage bus voltage of the step-up transformer in a new energy power plant, which overcomes the shortcomings of the prior art and can effectively solve the problem of difficult voltage control at the grid connection point for the low-voltage bus voltage of the step-up transformer in a new energy power plant.

[0006] The technical solution of this invention is achieved through the following measures: a method for controlling the low-voltage side bus voltage of a booster transformer in a new energy power station, comprising the following steps: Determine the AVC status, which includes the engaged state and the disengaged state; Determine the AVC control mode, which includes remote closed-loop control or local closed-loop control; Collect the voltage at the grid connection point of the new energy power station, the status of the grid-connected circuit breaker, and the voltage of the low-voltage side bus of the step-up transformer; verify the availability of the data; and check the correctness of the received master station commands. Determine the current regulatory zone; A voltage control strategy for the low-voltage side bus of the step-up transformer is formulated, and AVC substation control commands are generated and executed. After several adjustments, the control target is achieved.

[0007] The following are further optimizations and / or improvements to the above-mentioned technical solution: The aforementioned control zones can be determined according to the effective value of the low-voltage side bus voltage of the boost transformer in the new energy power station, and are, in order from low to high, the upward pullback zone, the upward blocking zone, the normal adjustment zone, the downward blocking zone, and the downward pullback zone.

[0008] The voltage regulation strategy for the low-voltage side bus of the aforementioned step-up transformer can be specifically as follows: When the low-voltage side bus voltage of the step-up transformer is in the normal regulation range, the AVC substation responds normally to the master station control commands. When the voltage on the low-voltage side bus of the step-up transformer enters the upward or downward blocking zone, the AVC substation blocks all directional control. After the voltage returns to normal, the blocking is automatically released. When the voltage on the low-voltage side bus of the step-up transformer enters the upward or downward pullback zone, the AVC substation blocks the over-limit direction adjustment control and simultaneously adjusts in the opposite direction until the voltage returns to the normal adjustment zone. After the voltage returns to normal, the blocking is automatically released. When the voltage on the low-voltage side bus of the step-up transformer exceeds the upper or lower directional pullback zone, the AVC substation blocks all directional control. Once the voltage returns to normal, the blockage is automatically released.

[0009] AVC substation control commands can be formed by combining AVC master station commands, current reactive power equipment control strategies, and the control strategies for the current voltage of the low-voltage side bus mentioned above.

[0010] The above-mentioned normal adjustment range limits can be set according to -3% to 7% of the nominal voltage of the low-voltage side bus of the step-up transformer.

[0011] The maximum values ​​of the aforementioned upward and downward blocking zones can be set from -4% to 8% of the nominal voltage of the low-voltage side busbar of the step-up transformer.

[0012] The maximum values ​​of the above-mentioned upward and downward pullback zones can be set from -10% to 10% of the nominal voltage of the low-voltage side bus of the step-up transformer.

[0013] This invention addresses the difficulty of controlling the voltage at the grid connection point of the low-voltage side bus of the step-up transformer in new energy power plants. It provides a method for controlling the voltage of the low-voltage side bus of the step-up transformer in new energy power plants. Based on existing AVC (Automatic Voltage Control) substation hardware, it formulates a voltage control strategy for the low-voltage side bus of the step-up transformer in the AVC substation, modifies the control commands of the AVC substation to the controlled object, reduces the sensitivity of the low-voltage side bus voltage, and mitigates various adverse effects caused by maintaining the grid connection point voltage. This invention also provides a method for dividing the low-voltage side bus voltage zones, as well as control strategies and limits for each zone. This information is fed back to the AVC substation to assist in the next round of reactive power and voltage regulation across the entire plant. This invention provides important guidance for improving the control strategy of the automatic voltage control substation in new energy power plants, increasing the low-voltage side bus voltage qualification rate, reducing voltage fluctuations between power plants, and lowering reactive power losses. Attached Figure Description

[0014] Appendix Figure 1 This is a schematic diagram of the voltage regulation range of the low-voltage side bus of the booster station according to an embodiment of the present invention.

[0015] Appendix Figure 2 This is a flowchart illustrating the voltage control strategy for the low-voltage side bus of the booster transformer in a new energy power station, according to an embodiment of the present invention. Detailed Implementation

[0016] 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.

[0017] In this invention, for ease of description, the relative positional relationships of each component are described according to the layout of the accompanying drawings. For example, the positional relationships of front, back, top, bottom, left, right, etc., are determined according to the layout direction of the accompanying drawings.

[0018] The present invention will be further described below with reference to embodiments and accompanying drawings: Example 1: As shown in the attached document Figure 1 , 2 As shown, the voltage control method for the low-voltage side bus of the step-up transformer in a new energy power station includes the following steps: determining the AVC status, which includes both active and deactivated states; determining the AVC control mode, which includes remote closed-loop control or local closed-loop control; collecting the grid connection point voltage, grid-connected circuit breaker status, and low-voltage side bus voltage of the new energy power station through an automation system or independent device, verifying the availability of the data, and checking the correctness of the received master station commands; determining the current control zone based on the effective value of the low-voltage side bus voltage of the step-up transformer; formulating a voltage control strategy for the low-voltage side bus of the step-up transformer for the AVC substation, forming and executing the AVC substation control commands, and adjusting several times until the control target is achieved. The control zone is determined according to the effective value of the low-voltage side bus voltage of the step-up transformer in the new energy power station, from low to high as follows: upward pullback zone, upward blocking zone, normal adjustment zone, downward blocking zone, and downward pullback zone.

[0019] In this embodiment, the voltage regulation strategy for the low-voltage side bus of the step-up transformer is as follows: When the voltage of the low-voltage side bus of the step-up transformer is in the normal adjustment zone, the AVC substation responds normally to the master station control command; when the voltage of the low-voltage side bus of the step-up transformer enters the upward or downward blocking zone, the AVC substation blocks all directional control, and automatically releases the blocking after the voltage returns to normal; when the voltage of the low-voltage side bus of the step-up transformer enters the upward or downward correction zone, the AVC substation blocks the adjustment control in the over-limit direction and adjusts in the opposite direction until the voltage returns to the normal adjustment zone, and automatically releases the blocking after the voltage returns to normal; when the voltage of the low-voltage side bus of the step-up transformer exceeds the upward or downward correction zone, the AVC substation blocks all directional control, and automatically releases the blocking after the voltage returns to normal.

[0020] In this embodiment, under the current control mode, the next round of AVC substation control commands are formed by combining the AVC master station commands, the current reactive power equipment control strategy, and the control strategy of the current voltage of the low-voltage side bus.

[0021] In this embodiment, the voltage limits for each zone of the low-voltage side busbar of the step-up transformer in the new energy power station can be set as follows: the normal adjustment zone limit is set at -3% to 7% of the nominal voltage of the low-voltage side busbar of the step-up transformer. The maximum limits for the upward and downward blocking zones are set at -4% to 8% of the nominal voltage of the low-voltage side busbar of the step-up transformer. The maximum limits for the upward and downward pullback zones are set at -10% to 10% of the nominal voltage of the low-voltage side busbar of the step-up transformer.

[0022] This invention addresses the difficulty of controlling the voltage at the grid connection point of the low-voltage side bus of the step-up transformer in new energy power plants. It provides a method for controlling the voltage of the low-voltage side bus of the step-up transformer in new energy power plants. Based on existing AVC (Automatic Voltage Control) substation hardware, it formulates a voltage control strategy for the low-voltage side bus of the step-up transformer in the AVC substation, modifies the control commands of the AVC substation to the controlled object, reduces the sensitivity of the low-voltage side bus voltage, and mitigates various adverse effects caused by maintaining the grid connection point voltage. This invention also provides a method for dividing the low-voltage side bus voltage region, as well as control strategies and limits for each region. This information is fed back to the AVC substation to assist in the next round of reactive power voltage regulation across the entire plant. This invention provides important guidance for improving the control strategy of the automatic voltage control substation in new energy power plants, increasing the low-voltage side bus voltage qualification rate, reducing voltage fluctuations between power plants, and reducing reactive power losses.

[0023] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A method for controlling the low-voltage side bus voltage of a booster transformer in a new energy power station, characterized in that... Includes the following steps: Determine the AVC status, which includes the engaged state and the disengaged state; Determine the AVC control mode, which includes remote closed-loop control or local closed-loop control; Collect the voltage at the grid connection point of the new energy power station, the status of the grid-connected circuit breaker, and the voltage of the low-voltage side bus of the step-up transformer; verify the availability of the data; and check the correctness of the received master station commands. Determine the current control zone; formulate a voltage control strategy for the low-voltage side bus of the step-up transformer, generate and execute AVC substation control commands, and adjust several times until the control target is achieved; the control zone is determined according to the effective value of the voltage of the low-voltage side bus of the step-up transformer in the new energy power station, and from low to high, it is as follows: upward pullback zone, upward blocking zone, normal adjustment zone, downward blocking zone, and downward pullback zone; The specific voltage regulation strategy for the low-voltage side bus of the step-up transformer is as follows: When the low-voltage side bus voltage of the step-up transformer is in the normal regulation range, the AVC substation responds normally to the master station control commands. When the voltage on the low-voltage side bus of the step-up transformer enters the upward or downward blocking zone, the AVC substation blocks all directional control. After the voltage returns to normal, the blocking is automatically released. When the voltage on the low-voltage side bus of the step-up transformer enters the upward or downward pullback zone, the AVC substation blocks the over-limit direction adjustment control and simultaneously adjusts in the opposite direction until the voltage returns to the normal adjustment zone. After the voltage returns to normal, the blocking is automatically released. When the voltage on the low-voltage side bus of the step-up transformer exceeds the upper or lower directional pullback zone, the AVC substation blocks all directional control. Once the voltage returns to normal, the blockage is automatically released.

2. The method for controlling the low-voltage busbar voltage of the booster transformer in a new energy power station according to claim 1, characterized in that... AVC substation control commands are formed by combining AVC master station commands, current reactive power equipment control strategies, and control strategies for the current voltage of the low-voltage side bus.

3. The method for controlling the low-voltage busbar voltage of the booster transformer in a new energy power station according to claim 1 or 2, characterized in that... The normal adjustment range limit is set to -3% to 7% of the nominal voltage of the low-voltage side bus of the step-up transformer.

4. The method for controlling the low-voltage busbar voltage of the booster transformer in a new energy power station according to claim 1 or 2, characterized in that... The maximum limits for the upper and lower blocking zones are set to -4% to 8% of the nominal voltage of the low-voltage side busbar of the step-up transformer.

5. The method for controlling the low-voltage busbar voltage of the booster transformer in a new energy power station according to claim 3, characterized in that... The maximum limits for the upper and lower blocking zones are set to -4% to 8% of the nominal voltage of the low-voltage side busbar of the step-up transformer.

6. The method for controlling the low-voltage busbar voltage of the booster transformer in a new energy power station according to claim 1, 2, or 5, characterized in that... The maximum values ​​of the upper and lower pullback zones are set to -10% to 10% of the nominal voltage of the low-voltage side bus of the step-up transformer.

7. The method for controlling the low-voltage side bus voltage of the booster transformer in a new energy power station according to claim 3, characterized in that... The maximum values ​​of the upper and lower pullback zones are set to -10% to 10% of the nominal voltage of the low-voltage side bus of the step-up transformer.

8. The method for controlling the low-voltage busbar voltage of the booster transformer in a new energy power station according to claim 4, characterized in that... The maximum values ​​of the upper and lower pullback zones are set to -10% to 10% of the nominal voltage of the low-voltage side bus of the step-up transformer.

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