Research On Operational Flexibility Analysis And Optimal Dispatching Of Power System

In recent years,the shortage of fossil energy and environmental pollution have become increasingly serious.A broad consensus has been reached on the green and low-carbon transformation of energy consumption,and the basic framework to promote the green and low-carbon transformation of global energy is being formed.In this context,renewable energy power generation represented by wind and photovoltaic is developing rapidly,and the proportion of wind power and photovoltaic installed capacity is increasing rapidly.But such as wind power,photovoltaic intermittent renewable energy generation has the characteristics of uncertainty,volatility and correlation,their access put forward higher requirements for the flexible operation of the power system,which brings the power system flexibility problems.In order to study the flexibility of power system,we need to sort out the research connotation and balance mechanism of flexibility.Combined with the analysis of the current power system operation,this paper explores the connotation of flexible demand and flexible supply,and studies the causes of the flexibility problem from these two levels.Starting from the power balance,this paper deduces the balance mechanism of power system flexibility,which lays a foundation for the quantification of flexible demand and flexible dispatching.Flexibility requirement quantification is the key to solve the problem of flexibility.The establishment of a quantitative method of power system flexibility demand is the basis of applying flexibility theory to system optimal dispatch and configuration.Therefore,from the operational level,this paper carries out in-depth research on the quantification of the flexibility demand of power system with large-scale wind power and photovoltaic.Firstly,according to the uncertainty and volatility of random sources,the probability model is established;according to the correlation between random sources,the covariance matrix is used to quantify;then,using the model of uncertainty,volatility and correlation,a set of quantitative method of flexibility demand is proposed.There are six steps in the method,which can comprehensively consider the uncertainty,volatility and correlation of multiple random sources in the system.The method describes the multi-dimensional joint fluctuation domain of random sources by multidimensional envelopes,which is regarded as the flexibility requirement of the system.At the same time,the spatial distribution of flexibility requirements can be quantified by projecting the multidimensional envelopes in different directions.Flexible optimal scheduling is the goal of flexibility research.For the flexible optimal scheduling problem,this paper establishes a rolling scheduling model considering the spatial distribution constraints of flexible requirements.The model is based on the running state of the system at the current time,and the prediction window is set.The flexibility demand of the system in the prediction window time is quantified by using the flexibility demand quantification model.By projecting the multidimensional envelopes in different directions,the spatial distribution of the flexibility demand is calculated,which is added to the power balance constraint and line transmission power constraint of the system.Through interval optimization method,the model can give a generation scheduling scheme that meets the flexibility requirements under a given confidence.The simulation results on IEEE 3 9-bus system and Northwest China grid show that the proposed optimal scheduling method can reduce new energy power abandonment and improve the flexibility of system operation.