柴发机组与逆变器并联运行暂稳态功率均分控制方法

Transient and steady-state power sharing control method for parallel operation of diesel generator set and inverter

柴发机组和逆变器并联供电为独立微电网的典型供电结构。通常工作于电流源模式的逆变器难以快速响应系统电压频率动态,在负载扰动时不平衡功率由柴发机组承担,给系统电压和频率稳定性带来挑战。本文提出一种新的控制方法解决异构电源间功率均分问题:逆变器基于锁相环检测系统频率变化,通过有功调频下垂控制支撑系统频率,逆变器检测并网点电压幅值变化,通过无功电压下垂控制支撑电网电压。进一步地,基于对系统动态性能分析,对逆变器电流指令外环控制进行改进优化,使其在负载扰动下具备与柴发机组类似的动态响应过程,从而实现柴发机组与逆变器间的暂稳态有功功率及无功功率均分,改善负荷突变下的系统动态性能。最后,通过仿真验证了所提方法的有效性。

The parallel operation of diesel generator set(DGS) and inverter is a typical power supply structure of isolated microgrid. Since the inverter usually operates in current source mode, it can not respond quickly to system voltage and frequency dynamics. Then the unbalanced power is mainly borne by DGS under disturbance, bringing the risk of voltage and frequency instability. A novel control method was proposed to address the power sharing issue between heterogeneous power sources. Through PLL, the system frequency dynamics can be detected. And the system frequency was supported by introducing active frequency modulation control. By detecting the voltage amplitude variation of PCC, the grid voltage was supported by introducing reactive voltage regulation control. Further, based on performance analysis of system dynamics, the current outer loop control of inverter was improved. And the inverter can have similar dynamical response under disturbance. Then the transient and steady-state power sharing between the DGS and inverter can be achieved. And the system dynamic performance under sudden changes of load can be improved. Finally, effectiveness of proposed method is verified by the simulation.