Research On Under Frequency Load Shedding Strategy Of Power Grid Under High Renewable Energy Proportion

The increase in the proportion of renewable energy in the power grid and the successive commissioning of UHV DC have brought serious challenges to the frequency stability of the power grid,increasing the probability of grid breakdown and frequency collapse accidents.Low-frequency load shedding devices are an important part of the third line of defense in the power grid and are widely used in the power grid.With the increasing development of renewable energy,the frequency characteristics of the power grid have deteriorated,and the study of low-frequency load shedding schemes is of great significance to the improvement of the frequency stability of the power grid.On the basis of summarizing and drawing on the existing research results of scholars at home and abroad,this paper mainly studies the optimization scheme of low-frequency load shedding under the condition of high proportion of renewable energy,and analyzes the frequency characteristics and Control method to improve frequency stability and safety.This article has mainly achieved research results:The influence of primary frequency modulation parameters such as adjustment coefficient,dead zone,and rotation reserve capacity on the frequency stability of the power grid is analyzed,and the frequency characteristics of the hydropower high-ratio grid and new energy high-ratio grid are studied.Based on the analysis of the water hammer effect of the turbine unit and the volume effect of the steam turbine unit,a dynamic model of the system frequency that reflects the different proportions of hydropower and thermal power is built.One-time frequency modulation capability method.According to the actual situation of the power grid in a certain area,the research on a variety of power sources and interruptible load lifting process frequency stability coordination control method is studied,and a "multi-round,small-level difference" frequency stability coordination control scheme is proposed for it.The basic principles of low-frequency load shedding design and the method of determining key parameters are summarized.Aiming at the problem of low-frequency load shedding of hydropower high-proportion power grids that are easy to overshoot,a low-frequency load shedding optimization scheme with increased level difference is proposed,and a small frequency of inertia for high-power grids of new energy The problem of too fast decline proposes a low-frequency load shedding optimization idea that predicts the power deficit based on the slope and performs blocking in advance.The adaptability of the low-frequency load shedding scheme of an actual regional power grid was evaluated,and an optimized scheme was proposed.