Staged voltage control method and system for alternating current and direct current system under high wind power permeability

Abstract

The invention belongs to the field of intelligent power grids, and provides a staged voltage control method and system for an alternating current and direct current system under high wind power permeability. In an emergency control stage, the voltage control variable of an area in the next step is determined through prediction and inter-area communication; and voltage control is carried out through model predictive control with minimum voltage deviation and control cost as objective functions. In a preventive voltage control stage, reactive replacement is performed on quick response equipment by using a generator set and a parallel capacitor in the area, so that the standby margin of the quick response equipment is increased, and the ability of the system to deal with sudden accidents is improved. A simulation result shows that the strategy can improve the calculation efficiency of long-term voltage control and optimize the reactive standby of the system.

Description

technical field [0001] The invention belongs to the field of smart grids, and in particular relates to a method and system for phase-by-stage voltage control of AC and DC systems under high wind power penetration rates. Background technique [0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art. [0003] With the construction and operation of large-scale offshore wind farms in my country, how to reasonably accept offshore wind power has become one of the urgent problems to be solved in the power system. The connection mode between the wind farm and the AC system is an important factor affecting the stability of the AC voltage. The existing connection methods are divided into AC access, traditional DC (LCC-HVDC) access and multi-terminal flexible DC access (VSC-MTDC). VSC-MTDC has become the best choice for the existing wind power grid because of its advantages such as indepe...

AI Technical Summary

Problems solved by technology

[0005] According to the knowledge of the inventors, the following problems exist in the current distributed voltage control method of AC and DC systems under high wind power penetration rate: (1) At present, in order to deal with the uncertainty of renewable energy output, the main research is on the internal voltage regulation of wind farms and the voltage fed into the grid Control and reactive power optimization, but there are few studies on long-term voltage control of AC and DC grids under high wind power penetration

(2) Existing research only considers the emergency voltage control after the fault, and does not consider the optimization of the reactive power backup of the system after the voltage enters the safe range

After emergency voltage control, the fast response reactive power reserve drops significantly. If no reactive power replacement is performed, the system will not have sufficient fast response reactive power reserve in the next control, which will reduce the voltage stability of the system.

(3) In the existing long-term voltage instability control scheme, for the scenario where the wind farm is connected to the AC grid through VSC-MTDC, the control characteristics of flexible DC cannot be fully utilized, which reduces the long-term voltage stability of the system

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