考虑缓冲回路的HVDC系统状态空间模型与求解算法

为了提高基于状态空间法的高压直流输电系统仿真计算精度，提出了一种考虑缓冲回路的HVDC系统仿真计算方法。以晶闸管的阀电流和缓冲电流作为状态变量对晶闸管进行建模，将换流变压器不同工况下的电压变换关系通过关联矩阵表示为统一的形式，建立换流器和换流变压器的状态空间模型，结合直流线路模型推导HVDC系统一次设备状态空间表达式。进一步，分析了控制系统的触发信号生成方法以及一次系统与控制系统的数据交互过程，实现了HVDC系统数学模型高精度求解。最后将Matlab实现的算法结果与PSCAD仿真结果进行对比，一次系统求解精度可达99.99%。

State-space model and solution algorithm of an HVDC system considering a snubber circuit

To improve the accuracy of the simulation calculation of an HVDC transmission system based on state-space method, a method for an HVDC system considering a snubber circuit is proposed. Valve current and snubber current are used as state variables to model a thyristor. The voltage transformation relation of a converter transformer under different working conditions is expressed as a unified form by a correlation matrix, so as to establish the state-space model of converter and converter transformer, from which the state-space expression of primary equipment in an HVDC system is derived simultaneously with the DC line model. Also, a calculation method of trigger angle in the control system is proposed. A data interaction process between the primary equipment system and the control side system is introduced. As a result, a high-precision solution of the mathematical model of an HVDC system is realized. Finally, algorithm results realized by Matlab are compared with the simulation results of PSCAD, and the solving accuracy of the primary system can reach 99.99%. This work is supported by the Science and Technology Project of Southern China Power Grid (No. ZBKJXM20180104).