基于概率法的并网双馈风电场次同步相互作用及其抑制措施

Sub-synchronous Interaction and Its Suppression Measurement Caused by Grid-integration of DFIG-based Wind Farms Using Probabilistic Method

双馈风电场经串补线路接入电力系统,小扰动情况下会出现次同步控制相互作用形式的次同步振荡现象。针对这一问题,由于系统运行方式的变化会对次同步控制相互作用产生影响,考虑了电力系统中风电场出力、同步发电机出力以及负荷的随机不确定性,首次采用概率法研究多运行方式下含风电场系统次同步振荡的统计属性,利用参与因子分析参与次同步控制相互作用的模式。提出基于附加阻尼控制的SVC抑制措施,研究其为相应次同步模式提供阻尼转矩以改善系统的阻尼特性。并以含双馈风电场系统为例进行时域仿真和概率次同步稳定研究,结果表明安装附加阻尼控制器的SVC能为系统振荡模式提供阻尼,阻尼常数的概率密度曲线向左半平面移动,且概率阻尼比明显增大,动态稳定性得到改善,时域仿真也验证了该次同步抑制措施的有效性。

The sub-synchronous oscillation （SSO） in the form of sub-synchronous control interaction （SSCI） may appear under small perturbation while doubly fed wind induction generator （DFIG） is connected to power grid via series compensation. The variation of the system operating conditions will affect the SSCI. Considering the random uncertainties of wind farm output, synchronous generators output, and stochastic fluctuations of loads in the power system, we applied a probabilistic method for the first time to study SSO statistical attribute in the system with the wind farms integrated under multi-operating conditions, and utilized participation factors to analyze the SSCI modes. Based on the additional damping controller of static var compensator （SVC）, a suppression measure against SSCI is proposed to study the damping torque which is provided to the corresponding oscillation modes for improving the damping character in the system. Time domain simulation and probabilistic sub-synchronous stability research are illustrated based on a test system with DFIG-based wind farm integrated. The results show that SVC in the presence of an additional damping controller can provide extra damping for the system oscillation modes, the probabilistic density function of damping constant moves to the left-half plane, and the value of probabilistic damping ratio is increased greatly, which means the dynamic stability is much improved. The effectiveness of the sub-synchronous suppression measure is also verified by the results of the time-domain simulation.