Research On The Distributed Generation System Of Microgrid And Its Control Method

Distributed generation (DG) can effectively take advantage of a variety of distributedenergy, improve energy efficiency and reduce emissions to protect the environment.Electronic devices are mainly applied to power conversion and power output control ofdistributed power, therefore the study of inverter control is an important basis forimproving the applicability of distributed power.Referring to the research of DG control in micro grid, this paper first made models ofthree-phase voltage source inverter circuit. Considering the standard three-phase varyingsinusoidal voltage as inverter output, the work used dq transformation to transferthree-phase varying parameters in static coordinate system to dq parameters insynchronous rotating coordinate system for the convenience of varying parameters control,though that the relationships between different parameters was carded, as well asfoundation of control system design laid.And then it focused on PQ inverter control system design for DGs on a feeder lineunder the state of grid connection mainly composed by power control loop and currentcontrol loop. In order to effectively control DGs’ inverter output, quickly respond to agiven reference value and ensure supplied power quality satisfying criteria, it designedpower control loop and current control loop. The former independently regulated theactive and reactive power through decoupling control separately, while the latter was usedto control inductor current of LC filter on the line, which ensured the balance ofthree-phase output current.Finally, the paper established distribution network of a the feeder whose capacity is5MVA as an example in MATLAB/SIMULINK. By Observing the impact to power gridcaused by power changes, adjustment and response acted by PQ inverter control systemchange caused by power changes changes of DGs’ output, the example verified thecorrectness of the design. The result of simulation example shows that DG can quicklymake adjustments referring to the reference power value with transient time short and theharmonic content low, parameters containing changes of active and reactive power,dynamic adjustment processes of voltage, current, frequency, etc., as well as the power quality of inverter system output are all in line with expectation, even national standards.