一种适用于小干扰分析的在线负荷建模方法

An Online Load Modeling Approach for Small Signal Stability Analysis

负荷模型对小干扰稳定分析影响很大,然而目前的负荷建模方法利用大扰动的响应数据建立负荷模型,由于负荷具有时变性,大扰动时刻建立的负荷模型不能等效于替他时刻的负荷模型,故不适用于其他时刻的小干扰稳定分析。为解决上述问题,基于子空间法提出一种适用于小干扰分析的在线负荷建模方法。首先选择时时存在的类噪声信号作为辨识信号,并采用子空间法在线辨识负荷的状态空间模型,旨在通过在线建模解决由负荷时变性导致负荷模型不准确的问题。但是子空间法建立的负荷状态空间模型并不是实际负荷的状态空间模型,二者存在未知的线性变换,采用解析的方法证明了上述未知线性变换不影响小干扰分析的结果,从而说明所提出的负荷建模方法适用于小干扰分析。最后,在10机39节点系统验证了方法的有效性。

Due to inaccuracy of load modeling caused by time variation, the result of on-line small signal stability analysis is inaccurate. In order to solve above problem, a load modeling method based on subspace method suitable for on-line small signal stability is proposed in this paper. Firstly,always existing ambient signal is selected as identification signal and state space model of load is identified with subspace method. On-line load modeling is accomplished to solve the inaccuracy problem caused by load time variation. Since the state space model is not unique, an unknown linear transformation exists between state space load model identified with subspace method and real state space model of load. It is proved that the unknown linear transformation has no influence on the result of small signal stability evaluation. Simulation result demonstrates correctness of the proposed method.