摘要
提出一种基于状态空间法的高压直流(HVDC)输电简化模型的解析算法,用于模拟逆变侧交流故障下直流系统的暂态响应。首先利用准稳态模型对HVDC系统的整流侧做简化;然后把不同工况下的换流器写成统一的形式,并把简化后的HVDC系统模型用一个分时段线性的非齐次微分方程组来描述;最后,通过引入辅助变量,将非齐次方程转化为齐次,从而使计算复杂度大大降低,同时简化后的系统可以用解析算法求解。控制系统用微分-代数方程组描述,用变步长数值积分法求解。在Matlab里编写相应程序实现所提简化模型的解析算法,并与PSCAD里搭建的双端电磁暂态模型进行比较,以验证所提算法的准确性。
In this paper, an analytic solution for simplified high voltage direct current(HVDC)system based on state space method is proposed, which is mainly used to simulate the transient response of DC system under AC fault on the inverter side. Firstly, the rectifier side of HVDC system is simplified using quasi-steady model. Secondly, the converter under different conditions is described as a uniformed express, and the simplified HVDC system is described by a piecewise linear inhomogeneous differential equations. Finally, the inhomogeneous differential equations are transformed into homogeneous ones by introducing auxiliary variables, which greatly reduces the computational complexity. Meanwhile, the simplified system can be accurately solved by analytical algorithm. The control system is described with differential-algebraic equations and solved by the variable-step numerical integration method. According to the analytical solution of the simplified model proposed in this paper, the corresponding program is coded in Matlab and compared with the double-terminal HVDC model built in PSCAD to verify the accuracy of the proposed solution.
引文
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