考虑参数自适应的直流微电网DC/DC变换器虚拟惯性控制策略研究

相对于交流微网,直流微网电能变换环节少,接入分布式电源及直流负荷更为高效可靠,但传统的下垂控制无法解决直流微网系统小惯性及母线电压受功率波动影响大的问题。对此,类比同步发电机转子特性和一次调频特性,提出了一种直流微电网DC/DC变换器改进虚拟惯性控制策略,以提高直流微电网的惯性,解决直流母线电压波动问题。首先根据系统发生功率波动时的响应特性,分析获取扰动发生时所需系统控制参数的变化情况,据此提出了虚拟惯性系数及阻尼系数自适应的控制策略;同时,建立小信号模型对DC/DC变换器在所提直流微电网虚拟惯性、阻尼系数自适应控制策略下的响应特性进行了分析,并讨论了关键控制参数对系统响应特性及系统稳定性的影响。最后在PSCAD/EMTDC中建立了直流微电网模型进行仿真分析,对比结果验证了所提控制策略的正确性和有效性。

Research on Virtual Inertial Control Strategy of DC/DC Converter in DC Microgrid Considering Self-adaptive Parameters

Compared with AC micro-grid, DC micro-grid has fewer power conversion links, and it is more efficient and reliable to connect with distributed generation and DC load. But traditional droop control cannot solve the problems of small inertia and bus voltage being greatly affected by power fluctuation in DC micro-grid system. In order to improve the inertia of DC microgrid and solve the problem of DC bus voltage fluctuation, an improved virtual inertia control strategy of DC/DC converter in DC microgrid is proposed by analogizing the rotor characteristics and primary frequency modulation characteristics of synchronous generators. Firstly, according to the response characteristics of power fluctuation, the variation of the system control parameters needed to obtain the disturbance is analyzed. The response characteristics of DC/DC converter under the proposed virtual inertial damping coefficient self-adaption control strategy for DC micro-grid are analyzed by signal model, and the influences of key control parameters on system response characteristics and system stability are discussed. Finally, a DC microgrid model is built in PSCAD/EMTDC, and the simulation results verify the correctness and effectiveness of the proposed control strategy.