互联电网的多端等值方法及其误差分析

为满足含多馈入直流的交直流电力系统等值分析需要，提出了多端等值法。对等值过程中可能出现的误差进行了分类和分析，揭示了多端等值法的2类非线性误差产生机理：系统状态量变化可引起非线性误差和外网注入功率变化可引起非线性误差。提出了减小误差的改进方案，并在广东电网等值分析中得到应用。基于PSCAD/EMTDC平台搭建了等值模型，对等值前后系统进行了潮流和短路计算对比分析，验证了所提方法的正确性和有效性。

Multi-terminal Equivalence Method of Interconnected Power System and Improvement Based on Its Error Analysis

To meet the demand of equivalent anlysis of AC/DC hybrid power grid involving muiti-infeed DC system, a multi-terminal equivalent method is proposed. The errors that possibly appear during the equivalence process are classified and analyzed, and the mechanism making two kinds of nonlinar errors in multi-terminal equivalence is revealed, that is, the variations of both system state variables and injected power from external power network lead to nonlinear errors. A scheme to reduce the errors is put forward and has been applied in the equivalent analysis of Guangdong power grid. Based on the platform of PSCAD/EMTDC an equivalent model is constructed, by which the comparative analysis on power flow and short-circuit calculation before and after the equivalence is performed. Comparison results verify the correctness and effectiveness of the proposed mehtod.