Research On Interruptible Load Model Considering Load Reactive Power

As the social demand for electricity continues to rise and the uncertain factors of market transactions increase,the probability of transmission congestion is greatly increased,which will damage the economy of operation and the fairness of the market.Therefore,reasonable and efficient congestion management has become an urgent demand of power grid operation departments.At present,there are three ways to eliminate congestion:adjust the power generation output,change the network structure and cut off the load.When the first two methods cannot eliminate the congestion,the interruptible load can only be used to solve the congestion.Interruptible load has always been the research focus of congestion management,but the classical interruptible load model only involves the discussion of load active power,without considering the impact of load reactive power on congestion management.In fact,this paper analyzes the relationship between line injection power and load power with the help of transmission gain.Through simulation,it is found that not only cutting off the load active power has the function to reduce the line injection power,but also adjusting the load reactive power can make the injection power on the line change slightly.It can be seen that adjusting load reactive power can also alleviate line congestion to a certain extent.Although the adjustment function of load reactive power is very limited,and it can not eliminate congestion by implementing it alone,if it is used as an auxiliary means of congestion management,and the load reactive power is adjusted while the load active power is removed,it will certainly improve the efficiency of congestion management.Therefore,this paper proposes an interruptible load model involving load reactive power for pool mode,the model is based on adjusting generator output,reducing load active power and adjusting load reactive power.Its core idea is to control the change of load reactive power by switching capacitor or inductor at the load node,and take the switched capacitor and inductor value as one of the decision variables of the interruptible load model.The model contains two objective functions:one is to minimize the total amount of outage load;The second is to introduce willingness-to-pay on the basis of maximum social benefits.Willingness-to-pay is the cost that users are willing to pay to avoid their unit load reduction.Obviously,the higher the efficiency of users,the greater the reported willingness-to-pay in order to minimize their own load reduction.Therefore,the willingness-to-pay can reflect the benefit of user’s unit load.The introduction of willingness-to-pay has two functions:first,when calculating social benefits,it is difficult to know the real load benefit function of users,so willingness-to-pay can be used to replace the benefit function;Second,the willingness-to-pay represents the user’s willingness to interrupt,and its inclusion in the model can guide users to actively participate in congestion management.The new model proposed in this paper participates in the process of congestion management:if there is no congestion,it will be cleared normally.In case of congestion,each user conduct willingness-to-pay bidding first,and after the dispatcher summarizes the information,the new model is called for congestion management.Taking the improved IEEE39 system as an example,the traditional interruptible model and the interruptible model proposed in this paper are compared.The analysis results show that the model considering load reactive power is superior to the traditional model,whether it is optimized according to objective function 1 or according to objective function 2.