基于最近电压稳定临界点的发电机无功备用优化方法

目前发电机的无功备用优化方法均基于固定的负荷增长方式,而当考虑负荷、新能源出力预测误差之后,这种优化方法无法有效评估最危险负荷增长方式下的无功备用水平。针对这一问题,文中提出基于最近电压稳定临界点的发电机无功备用优化非线性二层规划模型,上层问题在给定基态节点注入功率的情况下,将求取最近电压稳定临界点及对应的最危险负荷增长方式化为极限曲面二次近似和连续潮流校正的两层迭代格式,而下层模型则求解该最危险负荷增长方式下的无功备用问题,并将修正的基态节点注入功率返回上层模型。为证明该模型的有效性,首先在若干假设的前提下证明了最优解的存在性和充分必要条件,进一步分析表明所提方法可考虑节点负荷增长方式的不确定性,有效提升最危险负荷增长方式下系统的无功备用水平,提高系统的电压稳定裕度,保障系统的安全运行。

An Optimization Approach to Generator Reactive Power Reserve Based on Closest Critical Point of Voltage Stability Limit Surface

Conventional optimization approaches to generator reactive power reserve are mostly based on the deterministic load increase pattern. However, this pattern is unable to effectively evaluate the reactive power reserve level under the most critical load increase pattern when the forecast errors of load and renewable energy output are taken into account. To address this problem, a nonlinear bilevel programming model of optimal generator reactive power reserve dispatch method based on the closest critical point of voltage stability limit surface is proposed. The upper model transforms the solution of critical point and its load increase pattern into the iteration process of second-order approximation of limit surface and continuation power flow under the given nodal power injection. The lower model solves the reactive power reserve under the critical load increase pattern, while the modified power injections are returned to the upper level. To demonstrate the validity of the proposed method, first the existence of optimal solution and the effectiveness of convergence criteria are verified. Further, it is shown by an analysis of the numerical simulation that the proposed method is able to improve reactive power level and enhance the voltage stability margin of power system under the critical load increase pattern considering the uncertainties of load increase pattern. This work is supported by the Key Program of National Natural Science Foundation of China(No. 51337005)and National Basic Research Program of China(973 Program)(No. 2014CB23903).