Voltage Management And Control Method For Medium Voltage Distribution Network And Its Application

The unreasonable planning of distribution system,i.e.long power supply radius and the inability of power supply capacity to meet the rapid growth of load,and the lack of information and intelligence in distribution system,has long plagued voltage-sensitive power users and power suppliers.Using modern information technology and artificial intelligence technology to control the voltage level of key nodes in distribution network is of great significance to ensure the safe and stable operation of power equipment,efficient operation of people's production activities,people's living quality and realize energy saving and efficiency enhancement in the whole society.In traditional voltage regulation methods,capacitors are favoured for their simple switching operation,low cost and perfect configuration.Normally,the effect of voltage on output reactive power is neglected in the calculation and engineering application of capacitor switching.This approximation has some limitations.Based on this,the influence of voltage on output power of capacitors is considered in this dissertation.And voltage management and control strategies based on the sensitivity of voltage to capacitance under different intellectualization levels of distribution system are also proposed.First,from the prospections that the power of a capacitor is proportional to the square of its voltage and other grid-connected capacitors may be influenced by a group of capacitors' putting into operation or removing from the network,the necessity of studying the relationship between voltage and capacitance is analysed.Then,the mathematical model of dendritic distribution network with fully known parameters is given.Through this model,the expression of the sensitivity matrix of voltages of distribution system to capacitance is further derived,and the physical meaning as well as characteristics of the sensitivity matrix are given.Next,the feasibility of using capacitors to regulate voltage is analysed.Second,the capacitors' remote switching control strategy for low voltage distribution capacitors using local information is proposed in this dissertation under the condition that some transformer areas are equipped with intelligent terminals.Aiming at the problem of incomplete line parameters in an actual distribution system engineering drawing of a city,firstly,the missing line parameters are supplemented using the idea of system identification and then the distribution network model is established.Next,the simulation of the strategy is carried out to verify the effectiveness and rationality of the proposed strategy.Third,after fully equipped with intelligent terminals,each transformer area is defined as an Agent,and then an improved contract network method based on sensitivity matrix under the multi-agent system framework is proposed.The method is simulated in the same distribution system as the above mentioned.The simulation results show that the coordinated voltage regulation of transformer areas can effectively raise the voltage of the low voltage transformer area under the interactive information environment.Moreover,this method can deal with the phenomenon of low voltage in many branches of a distribution system in parallel,which can improve the efficiency of voltage management and control.This research is supported by the scientific and technological project Integrated Management System for Low Voltage Distribution Network(0002200000019184)of Yunnan Power Grid Co.,Ltd.