基于可变下垂线的变速风电机组参与微网频率调节控制

Variable Speed Wind Turbine Micro-grid Frequency Regulation Control Based on Variable Droop

随着风电在电网中所占比例的提高,当电网频率变化过大时希望风电机组改变输出功率参与电网频率调节,改善频率的动态特性。为了应用电力系统中广泛采用的有功功率–频率下垂控制策略,依据风电机组输出功率和微网频率为风电机组参与频率调节构筑下垂线,当风速变化引起风电机组输出功率变化时下垂线随之改变。微网频率在正常范围内波动时风电机组采用常规最大功率点跟踪或者限功率模式运行,频率变化过大时风电机组切换至频率支撑控制模式,频率支撑期间风电机组输出功率目标值基于构筑的下垂线根据微网频率计算求得,频率支撑结束后,通过逐渐改变风电机组输出功率使机组恢复至频率支撑前的正常运行模式。采用HAWC2和MATLAB/Simulink搭建包含变速风电机组的集成仿真模型,仿真结果对所提出控制策略的有效性进行验证,并且对执行提出的控制策略对风电机组结构载荷的影响进行分析。

With the increase of wind energy penetration in power system, wind turbine is expected to change its output power to participate in the grid frequency regulation to improve the frequency dynamic characteristic when grid frequency changes suddenly. In order to use the active power-frequency droop control strategy widely used in power system, a droop is built for wind turbine micro-grid frequency regulation control according to the wind turbine output power and micro-grid frequency. The change of wind speed results in the change of wind turbine output power, and the droop is regulated accordingly. When micro-grid frequency fluctuates within normal range, wind turbine operates in the normal maximum power point tracking or de-load mode. Once micro-grid frequency is detected to change suddenly, wind turbine control is switched to the frequency support mode. During frequency support period, wind turbine output power reference is calculated according to micro-grid frequency and the droop built. After frequency support, wind turbine control is switched back to the former normal mode by reducing wind turbine output power gradually. HAWC2 and MATLAB/Simulink are used to build an integrated simulation model including variable speed wind turbinel The effectiveness of the proposed control strategy is verified and the influence on the wind turbine structural loads is also studied with the simulation results.