Connecting the voltage source converters (VSCs) to various types of AC systems results in different operation characteristics and core problems associated with traditional control strategies. Therefore, it is necessary to optimize the control strategies of the VSCs according to the types of AC systems. For the VSCs connected to islanded renewable power plants, a voltage/frequency (V/f) droop control strategy is proposed to damp fluctuations of AC voltage and frequency in the island, which is vital for bipolar VSC control. In addition, a multi-branch impedance equivalent method for renewable power plants is proposed, with which large-scale renewable power plants can be modeled accurately in the frequency domain to prevent wide-band oscillation. For the VSCs connected to strong AC systems, smart AC voltage and coordinated frequency transient control strategies are proposed, which can improve AC system transient stability. For the VSCs connected to weak AC systems, the relationship between the system stability and strength is analyzed, and then the control strategy of inner-loop control parameter optimization and outer-loop power limiting (if necessary) is proposed to improve the stability of the allied system. The proposed strategies are verified by both software simulation and field commissioning.

中文翻译：

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连接各种交流系统的电压源变换器的控制策略优化

将电压源转换器（VSC）连接到各种类型的AC系统会导致不同的操作特性以及与传统控制策略相关的核心问题。因此，有必要根据AC系统的类型来优化VSC的控制策略。对于连接到岛上可再生能源发电厂的VSC，提出了一种电压/频率（V / f）下垂控制策略，以抑制岛中AC电压和频率的波动，这对于双极VSC控制至关重要。此外，提出了一种针对可再生能源发电厂的多分支阻抗等效方法，利用该方法可以在频域中对大型可再生能源发电厂进行精确建模，以防止宽带振荡。对于连接到强大交流系统的VSC，提出了一种智能的交流电压和协调频率瞬态控制策略，可以提高交流系统的瞬态稳定性。对于连接弱交流系统的VSC，分析了系统稳定性和强度之间的关系，然后提出了内环控制参数优化和外环功率限制（如有必要）的控制策略，以提高系统的稳定性。联盟系统。软件仿真和现场调试都验证了所提出的策略。然后提出了内环控制参数优化和外环功率限制（必要时）的控制策略，以提高联盟系统的稳定性。软件仿真和现场调试都验证了所提出的策略。然后提出了内环控制参数优化和外环功率限制（必要时）的控制策略，以提高联盟系统的稳定性。软件仿真和现场调试都验证了所提出的策略。