微电网自适应电流保护原理完善及其新算法研究

摘要

Due to its characteristics like the variation of the operation mode and the difference with traditional power grid on network topology structure, micro grid needs to be provided a new protection principle. To a tee, the real-time characteristic of adaptive current protection is consistent with the problem. This paper firstly proves that the existing adaptive protection principle applying to those micro grid which may arise two-way short circuit current in the same line when a fault occurred was prone to error, and carries on a principle to be more perfect. Then, a new algorithm of adaptive current protection is tried the—— key parameter (the equivalent impedance) is calculated by using the intersection point of three impedance circle, added with the adaptive mutation algorithm, to avoid the problem that the original algorithm is prone to be disturbed. Afterwards, through the PSCAD model simulation of typical micro grid, the results validate that the protection has the ability to correct the mistakes of the original principle using in certain situations, and demonstrate its better stability and accuracy than the original algorithm.%微电网由于其运行模式及网络拓扑结构多变等与传统电网的特征差异,需要提供适应其特性的新的保护原理.自适应保护的实时性等特点与该问题恰好契合.首先分析了原有自适应电流保护原理在应用于故障时可能在同一线路出现双向短路电流的微电网中时容易出现的错误,并对此进行了原理完善.其次尝试新的自适应电流保护算法,用三阻抗圆交点的方法计算出等效阻抗这一关键参数,再加入自适应突变量算法,以规避原有算法易受扰动而导致动作错误的问题.而后采用PSCAD对典型微电网进行建模仿真,算例结果验证了该保护能纠正原有原理在特定情况下出现的错误,比原算法更好的稳定性与准确性.