适用于复杂拓扑结构混合直流电网的实用机电 暂态建模仿真方法

为提升混合直流输电系统模型的适应性和计算效率，提出一种基于电流源思想的混合直流输电系统机电暂态建模方法。由电网换流器(line commutated converter, LCC)、电压源换流器的准稳态模型推导其电流源模型，并通过差分化直流支路的微分方程，形成直流电网的通用化电流源模型。采用多速率混合积分算法分别求解交直流系统，并结合步长回退、积分方法切换等，解决LCC电流反向、开关闭合与开断等特殊情形下的数值问题。在国内通用的机电暂态仿真程序中实现了上述模型，并以白鹤滩-江苏混合直流输电工程为例，与电磁暂态仿真工具进行了对比测试。仿真结果验证了该方法的有效性和准确性。该方法较好地平衡了仿真精度和计算速度的矛盾，为提升大规模交直流混联电网的仿真能力提供了有力工具。

A practical electromechanical transient simulation method for complicated topological hybrid HVDC grids

To improve the adaptability and computational efficiency of hybrid DC transmission system models, an electromechanical transient modeling method for a hybrid DC transmission system is proposed based on the idea of current source. The current source models of a line commutated converter (LCC) and a voltage source converter (VSC) are derived from their quasi-steady state models, and the general current source model of a DC grid is formed based on the differential equations of DC branches. A multi-rate hybrid integration algorithm is used to solve the AC and DC power systems, and the numerical problems in special cases, e. g., LCC reverse current, breaker closing and opening, are solved by combining integration step rollback and integral method switching. The above model is developed in a domestic general electromechanical transient simulation program. Simulation analysis on the Baihetan-Jiangsu hybrid HVDC transmission system is compared with an electromagnetic transient simulation. It verifies the effectiveness and accuracy of the proposed method, which well balances simulation accuracy and calculation speed, and provides a powerful tool to improve the simulation ability for a large-scale hybrid AC/DC power grid. This work is supported by the Beijing Natural Science Foundation (No. 3172015).