抑制大规模连锁脱网的风电汇集区域电压预防控制策略

风电场连锁脱网事故给风电并网带来了新的挑战。传统无功优化虽能得到较好的优化控制量,但当风电场N-1脱网,并且在风电场慢无功补偿设备未能快速动作的情况下,系统潮流重新进行分布,从而导致节点电压不能满足安全约束条件。因此,文中建立了带风电场安全约束条件的无功优化模型,以最大化风电安全接纳量和最小化系统网损为目标,保证系统电压在正常情况下和N-1脱网后均能满足安全性要求。其次,采用Benders分解算法求解该优化模型,将优化模型分为主问题和若干子问题,通过主、子问题的交互迭代得到最优解。采用某风电基地9个风电场的实际算例对所提方法进行验证和分析,与传统无功优化的对比结果表明安全约束无功优化能保证系统正常和故障下的电压安全性,是抑制风电场连锁脱网的一种有效预防控制措施。此外,详细分析了风电场容量、风电机组无功调节容量与最大风电接纳量间的关系,为风电场运行调度提供支持。

A Voltage Control Strategy for Preventing Cascading Trips of Large-scale Wind Power in Centralized Area

A New challenge of cascading wind farms has been brought to wind power integration. Traditional reactive power optimization could give a desirable result, but voltage security violation usually happens after N-1 contingency because of the redistribution of power flow and slow Var compensator having been cut off in time. Therefore, reactive power optimization model for wind farm has been set up with security constraints, guaranteeing the voltage within the security region under both normal condition and N-1 contingency. Besides, Benders decomposition method has been employed for solving the complex model, dividing into one master and some slave problems. Iterative method is used between master and slave problems to obtain the optimal solution. Practical power grid with nine wind farms has been tested, and the comparison of security constrained optimal power flow (SCOPF) and traditional optimal power plow shows that the SCOPF has better effect, which can guarantee the voltage security under both normal condition and N-1 contingency. So it is an effective method for mitigating the cascading faults of multiple wind farms integrated into power grid. Finally, the relationship of curtailment, wind farm capacity and Var capacity of wind units is fully studied to provide certain help for the operation of wind farm.