多换流器直流系统的虚拟惯性评估与控制参数协调设计

Virtual Inertia Evaluation and Coordinated Design of Control Parameters for Multi-converter DC System

针对基于类虚拟同步发电机(AVSG)的多换流器直流系统遇到的非预期虚拟惯性问题,提出了一种多换流器直流系统虚拟惯性通用分析方法,有效修正了系统级等效AVSG外特性。首先,将多个AVSG控制回路等效为一个等值AVSG控制回路,建立了直流系统的等值单台AVSG模型。其次,提出了一种系统级虚拟惯性评估方法,从等值单台AVSG模型的输出阻抗频域响应特性角度对系统级虚拟惯性进行评估。然后,讨论了电压比例-积分(PI)控制参数对虚拟惯性特性的影响,并开展了电压PI控制参数和虚拟惯性系数间的协调设计。最后,在PLECS仿真软件及RT-BOX硬件在环实验平台上搭建了多换流器直流系统的开关模型,通过多种实验工况验证了等值单台AVSG模型和控制参数协调设计的有效性和可行性。

Aiming at the unintended virtual inertia problems in the multi-converter DC systems based on the analogous virtual synchronous generator(AVSG),a general analysis method for virtual inertia of the multi-converter DC systems is proposed,which effectively corrects the system-level external characteristics of the equivalent AVSG.Firstly,multiple control loops of AVSG are equated to one equivalent control loop of AVSG,and an equivalent single AVSG model of the DC system is established.Secondly,a system-level virtual inertia evaluation method is proposed to evaluate the system-level virtual inertia from the perspective of frequency-domain response characteristics of the output impedance of the equivalent single AVSG model.Thirdly,the influence of the voltage proportional-integral(PI)control parameters on the virtual inertia characteristics is discussed.And the coordinated design between the voltage PI control parameters and the virtual inertia coefficients is carried out.Finally,a switching model of the multi-converter DC system is built on the PLECS simulation software and RT-BOX hardware-in-the-loop experimental platform.The effectiveness and feasibility of the equivalent single AVSG model and the coordinated design of control parameters are verified in various experimental conditions.