基于储能型准Z源逆变器的VSG并网控制策略的研究

随着光伏发电装机容量的增加,以传统控制策略并网的分布式光伏电源会大幅度降低电网惯性,使电网稳定性减弱。针对该问题,结合准Z源逆变器的优点,在准Z源网络中引入储能单元,提出基于储能型准Z源逆变器的虚拟同步发电机(VSG)并网控制策略。分析了储能型准Z源的工作模态。采用VSG技术控制系统输出功率,调节直通占空比使光伏功率钳位在最大功率点,蓄电池自动弥补功率缺额。讨论考虑VSG暂态响应时蓄电池的配置问题,并推导直通占空比与VSG转动惯量和阻尼系数的关系,为储能型准Z源逆变器在VSG控制参数设计方面提供参考标准。最后仿真和实验验证了所提策略的有效性。

Research on VSG grid-controlled strategy based on energy-storaged quasi-Z-source inverter

With the increase of installed capacity of photovoltaic power generation, the distributed photovoltaic power grid with traditional grid-connected control strategy would greatly reduce the inertia of power grid and undermine the stability of power grid.Given the advantages of quasi-Z-source inverter, this paper presents a Virtual Synchronous Generator (VSG) grid-connected control scheme based on energy-storaged quasi-Z-source inverter to solve the problem, in which the energy storage unit is inserted.Firstly, this paper analyzes the working mode of the energy-storaged quasi-Z-source. Then the VSG technology is used to control the output power of the system, and the PV power is clamped at the maximum power point by regulating the shoot-through duty ratio so that the battery automatically compensates for the power shortage. In addition, this paper discusses the problem of the battery configuration considering the transient response of VSG, and deduces the relationship between shoot-through duty ratio and moment of inertia as well as damping coefficient of VSG, which provides criterion for the parameter design of quasi-Z-source inverter with VSG control. The simulation and experiment results verify the effectiveness of the method proposed in this paper. This work is supported by National Natural Science Foundation of China (No. 51407122).