First Exploration On Reactive Voltage Control Technology Of Ultra-high-voltage Ac-current Half-wave Length System

In recent years,environmental pressure is growing,the traditional coal-based power development model has become increasingly difficult to sustain.China's vast territory,the distribution of resources is extremely uneven,the rapid development of power industry,in order to meet the central and eastern regions of the load center of the power needs,urgent need to solve the ultra-long distance,large capacity transmission technology.In addition,according to the United Nations Climate Development Summit "Paris Agreement" requirements,between countries and more power transmission technology,transmission distance will be more than3000 km,half-wavelength AC transmission with its remarkable technical and economic advantages in the super Remote point-to-point transmission mode,with strong competitiveness and broad application prospects.For UHV AC transmission technology,the conventional medium-long lines,short-circuit electrical characteristics in the transmission line length reaches a certain value will change,transmission lines along the voltage,current and other electrical power will produce very obvious changes.In this paper,the theory of uniform transmission line is used as the theoretical basis,and the related problems of ultrahigh-distance transmission-UHV AC half-wavelength transmission technology are studied with reference to the demonstration project of UHV AC transmission line which has been completed and successfully put into operation.Analyzes the current situation of long-distance transmission,and compares the advantages and disadvantages of the technology,and puts forward the corresponding technical route.Based on the natural power,the relationship between the transmission power and the voltage along the line is simulated.The waveforms of the voltage and current with the transmission power are simulated and the two key indexes of natural power and wave impedance are proposed.The results show that the impedance of the half-wavelength line is valid.By using the conclusions drawn from the first and second chapters,the variation of the voltage and current along the line is obtained.Terminal power of the parameters of the equation and the static stability of the two aspects of the half-wavelength transmission line transmission power limit;from the power transmission mechanism and electrical resonance of the two aspects of the power transmission on the line of the impact of the proposed economic operation of which The line loss rate,by gradually increasing the transmission power obtained in the line transmission of natural power line loss rate of the lowest conclusion;by setting different locations of different short-circuit fault type,obtained along the level of over-voltage And the reason of the non-fault phase voltage rise in the fault is analyzed,and the corresponding simulation curve is made.,Through the reactive powerto a large extent determine the operation of UHV transmission line economy,in order to make the operation of the economy is optimal,must make the corresponding through the reactive power minimum,it will break through the reactive power,and find the various parts Through the reactive power and the terminal voltage ratio of the equation.The optimal solution is obtained by using the peak of the line voltage,the reactive power compensation capacity of the UHV semi-wavelength system and the lower network as the constraint of the inequality or equation,and the control algorithm is proved compared with the ordinary control strategy The validity of the.But also for the actual operation of the site to provide a useful reference.