Voltage and current double closed loop control method and device of adjustable invertor inertial effect

Abstract

The present invention discloses a voltage and current double closed loop control method and device of an adjustable invertor inertial effect. In the frame of the routine voltage and current double closed loop control, the inertial current component is added in an inverter current inner ring instruction to realize the equivalent control of the inverter inertia property and is indirectly generated through an inertial control system connected in parallel on the voltage outer ring. The inertial control system is formed by three parts connected in series, wherein the three parts include a low pass filter, a proportional controller and a differential arithmetical unit. The size of the inertial current component and the intensity level of the grid-connected inverter inertial effect can be flexibly controlled through the proportional controller in the inertial control system. The voltage and current double closed loop control method of the adjustable invertor inertial effect does not need to change the hardware portion of the current grid-connected inverter system, completely maintains the current basic control frame of the software portion, has good compatibility, can be applied to a double-fed wind turbine system and a photovoltaic power generation system, and has good engineering application values.

Description

technical field [0001] The invention belongs to the technical field of grid-connected inverter control, and in particular relates to an improved voltage-current double-closed-loop control technology capable of adjusting the inertia effect of a grid-connected inverter. Background technique [0002] With the increasing penetration of new energy sources such as photovoltaics and wind power, grid-connected inverters characterized by low inertia and weak damping are connected to the power system on a large scale. The conventional rotary synchronous generator (Rotational Synchronous Generator, RSG) The proportion of installed capacity gradually decreases, resulting in a relative reduction in the rotating reserve capacity and moment of inertia in the power system; on the other hand, new energy power represented by wind energy and solar energy has low-density dispersion on the spatial scale and strong random fluctuations on the time scale Large-scale new energy access will lead to s...

AI Technical Summary

Problems solved by technology

However, the conventional droop control strategy can only be used for the grid-connected inverter of the voltage source type DC power supply, otherwise the grid-connected inverter cannot achieve the stability of the capacitor voltage on the DC side

[0004] 2) When the grid-connected inverter is connected to the end of the grid and the high-penetration power electronic grid, the short-circuit capacity of the grid is significantly reduced, and the dynamic support capability is significantly weakened

Since the VSG control strategy is implemented on the grid-connected inverter, the VSG control cannot ensure the stability of the capacitor voltage on the DC side, so it is only applicable to the grid-connected inverter of the voltage source DC power supply

In addition, the VSG control strategy must be equipped with a certain amount of reserves (including energy storage converters), which is less economical and difficult for industrial applications

At the same time, VSG control does not take full advantage of the huge potential of the primary energy source and its converter in inertia / damping characteristic simulation

[0006] The above-mentioned methods and corresponding devices all have some obvious deficiencies, which are not conducive to large-scale application. The ideal grid-connected inverter inertia control technology should: try not to change the hardware part of the grid-connected inverter system, and can basically By retaining the basic framework of the existing control strategy, it is convenient to adjust the inertia effect of the grid-connected inverter flexibly and equivalently, that is, it has good economic benefits, excellent technical performance and convenient operability

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