一种用于电磁暂态仿真的两电平电压源型换流器解耦模型

Two-level Voltage Source Converter Decoupling Model for Electromagnetic Transient Simulation

由于电压源型换流器(voltage source converter,VSC)电磁暂态详细模型导纳矩阵时变,因此对含大规模新能源场站的大电网进行仿真时,仿真效率低下。针对这一问题,该文基于半隐式延迟解耦原理,提出一种解耦电路简单、导纳矩阵恒定、可计及换流器内部特性的解耦模型。首先从VSC换流器的状态方程出发,利用矩阵分裂和延迟技术,分别构建直流侧电容接地VSC换流器和直流侧电容不接地VSC换流器的半步时延模型,实现交直流侧的解耦;然后利用VSC上下桥臂纵向换流互斥导通的特点,简化解耦模型参数计算,从而使得系统导纳矩阵恒定,进一步提高计算速度。算例结果表明了所提方法在保持较高精度的同时提升了计算速度。

Due to the time-varying nodal matrix of the electromagnetic transient detailed model of the VSC converter,the simulation efficiency is usually low when simulating a large power grid of a large-scale new energy station. To solve this problem, based on the principle of semi-implicit latency decoupling, a decoupling model with the characteristics of uncomplicated decoupled electric circuit, invariable nodal admittance matrix and convenient parallel computing is proposed. Firstly, according to the state equation of the two-level VSC converter and with the methods of matrix splitting and latency technology, the half-step time latency decoupling models of the DC-side capacitor-grounded VSC converter and the DC-side capacitor-ungrounded VSC converter respectively are constructed, realizing the decoupling and parallelization of the AC and DC sides. Then using the characteristics of the longitudinal commutation and mutually exclusive conduction of the upper and lower arms of the VSC to simplify the calculation of the decoupling model parameters so that the system admittance matrix remains constant and further improves the calculation efficiency. In addition, the method in this paper accurately retains the internal information of the converter. The accuracy and effectiveness of the proposed method is verified by the results of simulation examples.