电压源、电流源混合型直流输电的运行机理研究

发布时间：2018-03-21 03:46

本文选题：电网换相换流器　切入点：电压源换流器　出处：《华北电力大学》2014年硕士论文　论文类型：学位论文

【摘要】：电网换相型高压直流(Line Commutated Converter High Voltage Direct Current, LCC-HVDC)在我国已经广泛应用,具有输送功率大、输电距离远的特点,但换相失败问题仍亟待解决。近年来以全控型器件为基础的电压源换流器型高压直流输电(Voltage Source Converter based High Voltage Direct Current, VSC-HVDC)迅速发展,具有控制灵活、可以供电无源网络等优势。一端为LCC另一端为VSC构成的电压源、电流源混合型直流输电(Hybrid-HVDC),可以结合两种换流器的优势,构成一种具有广泛应用前景的新型拓扑,具有深入研究的价值。首先阐述了Hybrid-HVDC的特点与适用领域,分析了其拓扑结构和接线方式,分别研究了两端换流站的参数设计和控制方法。然后研究了整流侧和逆变侧分别为LCC和VSC的混合直流输电结构,两种仿真模型均在PSCAD/EMTDC环境中进行了仿真验证。对于整流侧为LCC、逆变侧为VSC的混合直流输电系统,设计了合理的启动与控制方法,并使用Simplex算法对直流侧LC参数与控制器PI参数进行了优化,得到更好的运行特性；并研究了混合直流输电系统向无源网络供电的情况。对于整流侧为VSC、逆变侧为LCC的混合直流输电系统,针对其逆变侧容易发生换相失败的情况,对比了不同控制策略的优略,并在此基础上提出了新的抑制换相失败的协调控制方法,在逆变侧包含低压限流(Voltage Dependent Current Order Limiter, VDCOL)的定直流电流控制的基础上加入了定关断角备用控制,在整流侧定直流电压的基础上加入低压限压控制(Voltage Dependent Voltage Order Limiter, VDVOL),仿真结果验证了协调控制方法可以降低换相失败的概率,并改善了系统的故障恢复特性。
[Abstract]:The commutation Commutated Converter High Voltage Direct current (LCC-HVDC) has been widely used in China, which has the characteristics of large transmission power and long transmission distance. In recent years, voltage Source Converter based High Voltage Direct current (VSC-HVDC), which is based on full-control devices, has developed rapidly and has flexible control. It can supply the advantages of passive network, one end is a voltage source composed of LCC and the other end is VSC, and the hybrid current source hybrid direct current transmission can combine the advantages of two converters to form a new topology with wide application prospects. It has the value of further study. Firstly, the characteristics and application fields of Hybrid-HVDC are described, and its topology and connection mode are analyzed. The parameter design and control methods of the converter stations are studied respectively. Then the hybrid DC transmission structures with rectifier side and inverter side are studied, which are LCC and VSC respectively. The two simulation models are verified in PSCAD/EMTDC environment. For the hybrid DC transmission system with rectifier side and inverter side as VSC, reasonable start-up and control methods are designed. The LC parameters of DC side and Pi parameters of controller are optimized by Simplex algorithm. For the hybrid DC transmission system with rectifier side and inverter side as LCC, the inverter side is prone to commutative failure, and the advantages and disadvantages of different control strategies are compared. Based on this, a new coordinated control method to suppress commutation failure is proposed. Based on the constant DC current control with low voltage current limiting Dependent Current Order limiter (VDCOL) in the inverter side, a fixed turn-off angle standby control is added. The voltage Dependent Voltage Order limiter (VDVOL) is added to the fixed DC voltage of the rectifier side. The simulation results show that the coordinated control method can reduce the probability of commutation failure and improve the fault recovery characteristics of the system.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM721.1

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