Parallel control of inverter and generator provides technical basis for independent power system
With the development of new energy technologies, independent power systems such as remote mountainous areas and islands are increasingly using hybrid power generation equipment and diesel generators.
The functional requirements for the separate power supply of the new energy inverter in this type of system and the parallel supply of the diesel generator are based on the voltage source control when the inverter is separately powered and the current source control when connected in parallel with the diesel generator. Inverter control mode switching and diesel generator quasi-synchronous parallel control strategy to solve the control problem of inverter and diesel generator parallel process, electromagnetic transient time domain simulation and 1:1 prototype physical experiment verify the control The effectiveness of the strategy.
Independent power system refers to the power system that operates independently in the area separated from the large power grid. It is often used in remote mountainous areas and isolated islands. Traditional independent power systems use rotary generators such as diesel generator sets and light gas turbine generator sets, which have disadvantages such as high noise, environmental pollution, and difficulty in refueling in remote areas.
With the development of new energy power generation technology, independent power systems are increasingly powered by new energy power generation devices such as wind power and solar energy, or power supply in parallel with conventional generators to improve power generation economy and reduce environmental pollution. Enhance self-sufficiency in power supply in remote areas.
However, inverters and generators have large differences in voltage and frequency control methods, output port impedance characteristics, electromechanical inertia, and anti-interference ability, resulting in difficulty in parallel control of inverters and generators. The parallel connection of the transformer and the grid-connected control strategy are difficult to solve the parallel control problem between the inverter and the generator. Therefore, it is necessary to carry out research on parallel control strategy of inverter and generator, and provide technical basis for operation and control of independent power system based on new energy generation.
According to different parallel objects, inverter parallel control can be divided into three types: inverters are connected in parallel, inverters are integrated into the grid, and inverters are connected in parallel with generators. Up to now, domestic and foreign scholars have achieved fruitful research results in the control of the first two parallel systems. Among them, the control strategies of the parallel connection between the inverters mainly include the master-slave control method, the droop control method, and the distributed control method.
The grid connection of the inverter has realized the grid connection of the voltage source and the current source. In the parallel control of the inverter and the generator, the research on the grid operation of the generator and the parallel operation of the inverter are similar to the case of the inverter connected to the grid, and the related research has been relatively mature. Therefore, this paper only discusses the control strategy of the inverter running in the grid and the generators being put into parallel operation.
In this research, a seamless switching control method for a diesel generator and a battery energy storage device connected by an inverter is proposed. However, in addition to the local controllers of the two devices, this document also needs to add an upper control unit to achieve coordinated control of the two, which increases the complexity of the system control, and does not carry out 1:1 prototype experimental research. The practicality of the control algorithm has yet to be further verified.
This paper takes a hybrid power supply system of a new energy generation inverter and a diesel generator set as the research object. Based on the introduction of the operation mode of the system, the control mode of the generator and the inverter, the inverter is combined with the load and the diesel. The control strategy of the combination of inverter voltage source and current source control mode switching and diesel generator quasi-synchronous operation is proposed.