Research on VSC-LVDC with DC Energy Storage to Improve the Stability of Microgrid Connected to Grid Operation

含直流储能的双端柔性直流输电技术提高微网并网稳定运行能力的研究

Received: 1 September 2017

Abstract

In order to improve stability of the microgrid operation connected to distribute network, the power flow fluctuations are smoothed. In this paper, a kind of flexible interconnection interface was studied in this paper, based on voltage source converter low voltage direct current(VSC-LVDC) containing energy storage. According to the mathematical model of VSC-LVDC and battery, a dual vector decoupling three-loop control strategy consisted of stages charging is proposed, and the battery charging and discharging switch control is offered, for charging and discharging of the energy storage, the bidirectional power transmission and suppressing power fluctuations. A simulation model is built that microgrid connected to distribute network using the flexible interconnection interface, and the conditions of power fluctuation, battery charging and discharging switch and the short-circuit fault at the microgrid side AC bus are simulated. The simulation results show that the control strategy effectively suppresses the power fluctuations of point of common coupling(PCC), guarantee the stability of the power flow.

摘要

为了提高微网并网时稳定运行能力，平抑配电网公共连接点的功率波动与维持功率潮流分布，研究了一种含直流储能的柔性直流输电并网接口系统，根据柔性直流输电和蓄电池数学模型，以直流侧储能单元的充放电与双端功率传输控制和平抑微网并网扰动为目标，提出了基于两段式充电的矢量解耦三环控制及蓄电池的充放电切换控制策略，构建了以蓄电池为储能元件的微网并网系统仿真模型，针对微网内功率变化、蓄电池充放电切换和微网交流系统短路故障等情况进行了仿真分析，结果表明控制策略在保证储能单元的充放电与双端功率传输的基础上，有效地抑制了公共连接点的功率波动，保证了电网潮流分布的稳定。