Generalized droop control strategy for power grid support type inverter

Abstract

The invention discloses a generalized droop control strategy of a voltage control type power grid support inverter, and belongs to the field of grid-connected inverter control research. The method isused for solving the problem that traditional droop control and VSG control cannot have good power tracking performance while providing rotational inertia. According to the method, an active power loop controller is more flexible in design, and the method is different from a traditional droop control active power loop which is only a proportional control and low-pass filter and is also different from VSG control which completely simulates parameters of a synchronous generator. By reasonably designing generalized droop controller parameters, the generalized droop control can enable the output power of the inverter to quickly change along with the instruction value of the inverter when the power instruction value changes, does not have large oscillation and overshoot, and is superior to VSGcontrol; and meanwhile, rotational inertia can be provided for the system and is superior to traditional droop control. And a good reference value is provided for engineering application.

Description

technical field [0001] The invention belongs to the research field of grid-connected inverter control, and in particular relates to a generalized droop control strategy for grid-connected inverters. Background technique [0002] With the deepening of environmental and energy crises, distributed generation has received more and more attention and applications. These distributed generation units are usually composed of renewable energy, DC bus and two-stage converters; different types of renewable Energy sources have different forms of input-side converters, but grid-side converters are usually inverters. The control performance of the grid-connected inverter will have an important impact on the stability of the power generation system and the grid. According to the operation mode of grid-connected inverters, inverters can be divided into grid-feeding inverters, grid-forming inverters, and grid-supporting inverters. The existing control strategies of grid-supported inverters...

AI Technical Summary

Problems solved by technology

With the traditional droop control distributed power generation unit, when the grid is connected, the actual output power of the inverter can quickly follow the change of the command value, but when it is running in an island, it cannot support the moment of inertia of the system. When the load power changes or the disturbance occurs, the system Frequency changes drastically, unable to meet ROCOF regulations

On the contrary, the distributed power generation unit controlled by VSG can provide the moment of inertia when it is running in an island, but when the power command changes step by step when it is connected to the grid, the actual output power of the inverter will have a large oscillation and overshoot. It may even cause the inverter to trigger protection and stop

Therefore, neither the VSG control nor the traditional droop control can achieve good control performance in the grid-connected mode and the island mode at the same time, that is, it cannot provide the moment of inertia and have good power following characteristics at the same time

Images