考虑海缆充电功率的海上风电场无功补偿协调控制策略研究

Study on Coordinate Control Strategy for Reactive Power Compensation of Offshore Wind Farm Considering Cable Charging Power

针对海上风电场的特点,研究其有效利用风电机组无功调节能力的无功补偿协调控制策略。海上风电场并网的电压稳定性分析主要分为两个方面:海缆充电功率对并网系统电压稳定性的影响;如何有效地利用风机无功调节能力来改善系统的电压稳定性。针对上述问题,首先利用灵敏度分析法及Q-V曲线法分析了海缆充电功率对海上风电场并网系统电压薄弱点的影响,并分析出最薄弱点为海缆末端母线;其次,选择STATCOM作为海上风电场无功补偿设备,并对双馈风机两侧变流器及STATCOM的无功控制环节进行研究;最后,提出以海缆末端母线电压为控制目标的三者无功协调控制策略,从而更为有效地利用风机自身的无功能力,显著减小STATCOM的安装容量。通过软件DIg SILENT建立CIGRE B4-39标准风电场并网系统,利用此系统进行暂态故障仿真分析,验证该无功协调控制策略的有效性。

For the characteristics of offshore wind farms, study on coordinate control strategy about reactive power compensation, which would effectively use reactive regulating ability of wind turbine. This analysis on the voltage stability of offshore wind farm was divided into two areas： charging power of sea cable and the wind turbine reactive regulating ability. In order to solve these problems, firstly the impacts about charging power of sea cable on the voltage weak point of offshore wind farm was analyzed through the sensitivity analysis method and Q-V curve, and it showed that the weakest point was the end bus of sea cable ; Secondly, choosed the STATCOM as offshore wind farm reactive power compensation equipment, then two sides converter of the doubly-fed wind turbine and STATCOM reactive power control aspects were studied; Lastly, coordinate control strategy of three parts for reactive power with the target of voltage for the end bus of sea cable was presented. This strategy could effectively used reactive power adjusting capability of DFIG, and save installation capacity of STATCOM. CIGRE B4-34 system through the software of DIgSILENT was built and used this system for transient fault simulation. The effectiveness of this strategy was verified.