高压直流输电换相失败解决方法的研究

发布时间：2018-09-04 13:20

【摘要】：随着我国“西电东送、南北互供、全国联网”的电力发展战略的实施,电力系统的发展越来越快。在大电网时代,高压直流输电拥有输电距离远,输电容量大,输电灵活优点,直流输电作为交流输电的有力补充,因而在大容量远距离电力输送中应用越来越广泛。随着高压直流输电传输容量,在电网中所占的比例越来越大,直流输电为受端交流系统提供电力的同时,换流站消耗的无功功率是直流系统所传输有功功率的40%-60%,因为换流站的无功功率消耗,换流站的交流母线电压波动将会给系统的稳定运行带来较大的影响。因此,本文重点针对换流站交流母线电压的波动问题,对高压直流输电系统换相失败故障的解决方法进行了研究,具体研究内容如下：首先本文针对高压直流输电系统换流站的一、二次构成,对高压直流输电系统常见的直流闭锁故障进行概述,特别对换相失败发生的机理以及影响进行了分析,给出了换相失败的预防控制措施。针对交流母线电压波动的问题,利用高压直流输电系统中换流站交流母线电压稳定的判据,对换流器的不同控制方式的作用进行分析,针对系统运行时受扰动的问题,整流器和逆变器选择不同的控制策略,其中逆变侧主要采用定电压控制；针对换流站无功消耗问题,分析了无功补偿的必要性,针对逆变侧交流母线电压波动问题,无功补偿装置选择定电压控制,能实时调整控制器的输出导纳值,快速的调节晶闸管的触发角,使其能快速的调节控制器的无功功率输出,达到稳定电压的目的。最后在PSCAD/EMTDC中搭建仿真平台,对逆变侧的定电压控制和换流站进行无功补偿进行仿真,仿真结果验证了上述控制和无功补偿的有效性和可行性。
[Abstract]:With the implementation of the electric power development strategy of "power transmission from west to east, power supply from north to south, and national interconnection", the power system is developing more and more rapidly. In the era of large power grid, HVDC transmission has the advantages of long transmission distance, large transmission capacity and flexible transmission. As a powerful complement of AC transmission, HVDC is more and more widely used in large capacity long-distance power transmission. With the transmission capacity of HVDC transmission, the proportion of HVDC transmission in the power network is increasing. At the same time, the DC transmission provides power to the receiving AC system. The reactive power consumed by the converter station is 40 to 60 percent of the active power transmitted by the DC system. Because of the reactive power consumption in the converter station and the fluctuation of the AC bus voltage in the converter station, the stable operation of the system will be greatly affected. Therefore, aiming at the voltage fluctuation of AC bus in converter station, this paper studies the solution of commutation failure in HVDC transmission system. The specific research contents are as follows: firstly, aiming at the primary and secondary components of HVDC system converter station, the common DC lock-in faults of HVDC transmission system are summarized in this paper. Especially, the mechanism and influence of commutation failure are analyzed, and the prevention and control measures of commutation failure are given. Aiming at the problem of voltage fluctuation of AC busbar, using the criterion of voltage stability of AC bus in HVDC transmission system, this paper analyzes the function of different control mode of converter, aiming at the problem that the system is disturbed when it is running. The rectifier and inverter choose different control strategies, in which the inverter side mainly adopts constant voltage control, aiming at the problem of reactive power consumption in converter station, the necessity of reactive power compensation is analyzed, and the voltage fluctuation of AC bus on inverter side is analyzed. The reactive power compensation device can adjust the output admittance of the controller in real time and the trigger angle of the thyristor quickly, so that the reactive power output of the controller can be adjusted quickly, and the stable voltage can be achieved. Finally, a simulation platform is built in PSCAD/EMTDC to simulate the constant voltage control of inverter side and reactive power compensation of converter station. The simulation results verify the effectiveness and feasibility of the above control and reactive power compensation.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM721.1

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