Probabilistic Evaluation Of Available Transfer Capability Evaluation Methods Considering Wind Power Correlation

In recent years,with the large-scale integration of renewable energy into the grid,due to the characteristics of its output randomness and volatility.There is a risk that the transmission capacity of the renewable energy transmission system is limited due to too many operating conditions or the safety and stability level of the system is reduced due to insufficient operating conditions.At the same time,it brings new challenges to accurately evaluate the available transfer capability（ATC）between regions of the system.The output of each wind farm station has a certain probability distribution,and the output of different wind farms in the same area has a strong spatial correlation.Therefore,it is urgent to accurately evaluate the inter-regional available transmission capacity of the system from the perspective of spatial correlation of wind power output,so as to improve the delivery capacity of renewable energy,alleviate the problem of wind curtailment and power limit,and provide powerful conditions for the delivery of renewable energy and the subsequent renewable energy grid connection.In this paper,the spatial correlation model of wind power output is established,and inter-regional ATC calculation method based on spatial correlation is proposed.Finally,the renewable energy gathering area in the west of Jilin Power Grid is taken as the research object to analyze the control strategy for improving the transmission capacity of the renewable energy transmission system of Jilin Power Grid.The main contents are as follows:1)In order to accurately evaluate the inter-regional ATC under uncertain conditions,a probabilistic evaluation method of ATC taking into account the spatial correlation of wind power is proposed.Firstly,the conditional probability principle is used to process the historical data,and the Copula function is used to model the wind power correlation.Secondly,the assessment process of inter-regional ATC involves the calculation of the maximum transmission capacity and the existing transmission protocol.Therefore,a two-level optimization model of ATC is proposed.On this basis,the karush-kuhn-tucker（KKT）optimal conditions are used.The two-layer model is a mathematica program with equilibrium constraint（MPEC）model.Thirdly,the MPEC model is transformed into a mixed integer second-order cone programming problem.Finally,monte carlo simulation was used to evaluate the probability of inter-regional ATC including wind power correlation.Taking IEEE 30-node system as an example,the influence of wind power correlation on inter-regional ATC was analyzed to verify the correctness and effectiveness of the proposed model.2)In order to evaluate inter-regional ATC more accurately,a conditional value-at-risk（CVa R）and wind power correlation probabilistic evaluation method for inter-regional ATC of power system is proposed.A double-level optimization evaluation model of ATC probability evaluation is proposed to maximize the inter-regional ATC of power system under the premise of minimum generation cost and risk cost in ground state.On this basis,the lower layer model is transformed,and the two-level model is transformed into MPEC model.Thirdly,the MPEC model is transformed into a mixed integer second-order cone programming problem,and the probabilistic evaluation process of ATC is proposed.Finally,an example of PJM-5 node system is given to verify the effectiveness of the proposed method.3)In order to improve the transmission capacity of the key section of the system,the control function between the feeder and the receiver groups is first introduced,and then a two-level optimization model of the transmission capacity of the wind power delivery system is established.The upper model minimizes the abandoned electricity of wind power by optimizing the control function between the feeder and receiver groups.The lower level model solves the probability assessment of the transmission capacity of the wind power delivery system under the constraints of the given feeder and terminal cluster.At the same time,the maximum inter-regional transmission capacity is determined,the abandoned electricity is minimized.Within the limits of safe and stable operation of the system,the problem of wind abandoning and power limiting in high-permeability wind power gathering areas is solved.Finally,on the premise of satisfying the safe and stable operation of the power grid,the purpose of improving the power transmission capacity of the wind power delivery system is achieved by reducing the amount of electricity discarded by wind power.The PJM-5 bus system and an actual system in Jilin province are analyzed to verify the effectiveness and practicability of the method.