针对并联接入系统的电压型逆变器提出一种专用于抑制次同步振荡的次同步电压调制策略。基于复转矩系数法推导了采用该方式抑制由串补引发的次同步谐振时提供的近似电气阻尼。分析结果表明，当接入点系统电压与电压型逆变器输出的次同步电压之间的相位差满足一定条件时，可使得逆变器提供正的电气阻尼。分析了影响此正的电气阻尼大小的相关因素。利用dq变换对电压型逆变器的控制器进行了设计，通过解耦控制，实现了抑制次同步振荡、维持逆变器直流侧电压的目的。测试信号法及时域仿真法的仿真结果表明，这种基于并联电压型逆变器的次同步电压调制策略能够有效阻尼系统的次同步振荡。%Subsynchronous voltage modulation strategy for voltage source inverter (VSI) in parallel with system is presented, which is exclusively for subsynchronous oscillation (SSO) mitigation use. Approximate electrical damping provided by the strategy for suppressing subsynchronous resonance (SSR) induced by fixed series capacitor (FSC) is formulated by complex torque coefficient approach. The analysis result demonstrates that when the phase difference between system voltage of access point and subsynchronous voltage output of VSI satisfies some condition, VSI can provide positive electrical damping. And the related elements which influence the size of this positive electrical damping are analyzed. The controller of VSI is designed by dq transformation, which can mitigate SSO and maintain voltage on DC side of inverter by decoupled control. The simulation result with the methods of test signal and time domain simulation reveals that the subsynchronous voltage modulation strategy based on VSI in parallel can damp SSO effectively.
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