多直流馈入受端电网电压特性分析与控制策略研究
发布时间：2019-04-03 10:03
【摘要】：随着高电压、大容量电力电子技术的发展,高压直流输电在长距离输电、异步电网互联、可再生能源发电并网等方面得到广泛应用。由于直流逆变站落点密集,负荷中心电网形成多直流馈入的网架结构。以半控型晶闸管为换流器件的高压直流输电系统的运行需要受端交流电网的强力支撑,若受端电网较弱,将引发安全稳定问题。在多直流馈入受端电网中,由于各直流馈入子系统之间相互影响,电网某处故障可能引起多回直流逆变站同时换相失败,严重时将导致一馈或多馈直流闭锁,使受端电网失去大电源,.引起系统失稳,造成巨大的停电损失。研究多直流馈入系统特性及控制策略,对保持电网稳定运行具有重要的理论意义与应用价值。本文围绕多直流馈入受端电网的电压特性及控制策略开展研究,主要工作与研究成果如下:(1)多直流馈入受端电网静态电压稳定性评估。分析影响多直流馈入受端电网静态电压稳定性的主要因素,即受端交流系统强度、各直流之间电压耦合程度,提取量化指标并进行信息压缩。采用多元回归分析方法,建立以静态电压稳定性指标为因变量,受端交流系统强度指标、多直流之间电压耦合程度指标为自变量的回归分析模型。对算例系统进行了仿真,验证了所提评估方法的有效性。(2)多直流馈入系统协同二级电压控制。建立多直流馈入系统二级电压控制模型,该模型能够应用于由电网换相型高压直流输电(LCC-HVDC)和电压源型高压直流输电(VSC-HVDC)构成的混合多直流馈入系统。提出基于一致性算法的多直流馈入系统协同二级电压控制策略,采用Lagrange乘子法推导一致项与修正项。基于H2性能标准,建立协同二级电压控制策略的通信网络优化模型,并采用混合整数规划法进行求解。对算例系统进行了仿真,验证了所提控制策略的有效性。(3)多直流馈入系统换相失败免疫能力分析与提高。提出基于电磁暂态仿真的直流换相失败免疫能力指标的计算方法。考虑受端电网的无功、电压分布特性,推导能够适应系统运行方式变化的电压关联因子的解析表达式,应用电压关联因子及临界电压关联因子,提出识别多直流馈入系统发生同时换相失败区域的方法。采用电磁暂态仿真,分析多种动态无功补偿装置对提高直流换相失败免疫能力的作用,在此基础上,提出动态无功补偿装置的配置方案,以提高多直流馈入系统换相失败免疫能力,消除同时换相失败区域。对算例系统进行了仿真,验证了所提分析方法及配置方案的有效性。
[Abstract]:With the development of high-voltage and large-capacity power electronics technology, HVDC transmission has been widely used in long-distance transmission, asynchronous grid interconnection, renewable energy generation grid connection and so on. Due to the dense drop point of DC inverter station, a multi-DC feed-in grid structure is formed in the load center network. The operation of HVDC system with semi-controlled thyristor as commutator needs strong support from AC network. If the terminal grid is weak, it will lead to security and stability problems. In the multi-DC feed-into-the-receiving power grid, due to the interaction among the DC-fed subsystems, some faults in the power network may cause the simultaneous commutation failure of the multi-circuit DC inverter station, which will lead to one-feed or multi-feed DC lock-up in serious cases. Loss of large power supply to the receiving end of the grid. Causes the system instability, causes the huge blackout loss. The research on the characteristics and control strategy of multi-DC feed-in system is of great theoretical significance and application value for maintaining the stable operation of the power network. In this paper, the voltage characteristics and control strategies of multi-DC feed into the receiving power grid are studied. The main work and achievements are as follows: (1) the static voltage stability evaluation of the multi-DC feed into the receiving power grid. This paper analyzes the main factors affecting the stability of the static voltage of the multi-DC-fed power grid, that is, the strength of the AC system at the receiving end, the voltage coupling degree between the DC and the receiver, and the quantitative index is extracted and the information compression is carried out. By using multiple regression analysis method, a regression analysis model is established, which takes static voltage stability index as dependent variable, receiving terminal AC system strength index and voltage coupling degree index between multiple DC currents as independent variables. The simulation results show the effectiveness of the proposed method. (2) Multi-DC feed systems cooperate with two-stage voltage control. A two-stage voltage control model for multi-feed-in system is established, which can be applied to hybrid multi-DC feed-in system composed of commutated HVDC transmission (LCC-HVDC) and voltage source HVDC (VSC-HVDC). A coordinated two-stage voltage control strategy based on consistency algorithm for multi-DC feed-in system is proposed. The uniform and modified terms are derived by using the Lagrange multiplier method. Based on H _ 2 performance standard, the communication network optimization model of cooperative two-stage voltage control strategy is established, and the mixed integer programming method is used to solve the problem. The simulation results show the effectiveness of the proposed control strategy. (3) the immune capability of commutation failure of multi-DC feed system is analyzed and improved. The calculation method of DC commutation failure immunity index based on electromagnetic transient simulation is presented. Considering the reactive power and voltage distribution characteristics of the receiving power grid, the analytical expression of the voltage correlation factor which can adapt to the change of the operation mode of the system is derived, and the voltage correlation factor and the critical voltage correlation factor are applied. A method is proposed to identify the simultaneous commutation failure area of a multi-DC feed-in system. The electromagnetic transient simulation is used to analyze the effect of various dynamic reactive power compensation devices on improving the immunity of DC commutation failure. On this basis, the configuration scheme of the dynamic reactive power compensation device is put forward. In order to improve the ability of commutation failure immunity of multi-DC feed-in system, the area of simultaneous commutation failure is eliminated. An example system is simulated to verify the effectiveness of the proposed analysis method and configuration scheme.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM721.1
[Abstract]:With the development of high-voltage and large-capacity power electronics technology, HVDC transmission has been widely used in long-distance transmission, asynchronous grid interconnection, renewable energy generation grid connection and so on. Due to the dense drop point of DC inverter station, a multi-DC feed-in grid structure is formed in the load center network. The operation of HVDC system with semi-controlled thyristor as commutator needs strong support from AC network. If the terminal grid is weak, it will lead to security and stability problems. In the multi-DC feed-into-the-receiving power grid, due to the interaction among the DC-fed subsystems, some faults in the power network may cause the simultaneous commutation failure of the multi-circuit DC inverter station, which will lead to one-feed or multi-feed DC lock-up in serious cases. Loss of large power supply to the receiving end of the grid. Causes the system instability, causes the huge blackout loss. The research on the characteristics and control strategy of multi-DC feed-in system is of great theoretical significance and application value for maintaining the stable operation of the power network. In this paper, the voltage characteristics and control strategies of multi-DC feed into the receiving power grid are studied. The main work and achievements are as follows: (1) the static voltage stability evaluation of the multi-DC feed into the receiving power grid. This paper analyzes the main factors affecting the stability of the static voltage of the multi-DC-fed power grid, that is, the strength of the AC system at the receiving end, the voltage coupling degree between the DC and the receiver, and the quantitative index is extracted and the information compression is carried out. By using multiple regression analysis method, a regression analysis model is established, which takes static voltage stability index as dependent variable, receiving terminal AC system strength index and voltage coupling degree index between multiple DC currents as independent variables. The simulation results show the effectiveness of the proposed method. (2) Multi-DC feed systems cooperate with two-stage voltage control. A two-stage voltage control model for multi-feed-in system is established, which can be applied to hybrid multi-DC feed-in system composed of commutated HVDC transmission (LCC-HVDC) and voltage source HVDC (VSC-HVDC). A coordinated two-stage voltage control strategy based on consistency algorithm for multi-DC feed-in system is proposed. The uniform and modified terms are derived by using the Lagrange multiplier method. Based on H _ 2 performance standard, the communication network optimization model of cooperative two-stage voltage control strategy is established, and the mixed integer programming method is used to solve the problem. The simulation results show the effectiveness of the proposed control strategy. (3) the immune capability of commutation failure of multi-DC feed system is analyzed and improved. The calculation method of DC commutation failure immunity index based on electromagnetic transient simulation is presented. Considering the reactive power and voltage distribution characteristics of the receiving power grid, the analytical expression of the voltage correlation factor which can adapt to the change of the operation mode of the system is derived, and the voltage correlation factor and the critical voltage correlation factor are applied. A method is proposed to identify the simultaneous commutation failure area of a multi-DC feed-in system. The electromagnetic transient simulation is used to analyze the effect of various dynamic reactive power compensation devices on improving the immunity of DC commutation failure. On this basis, the configuration scheme of the dynamic reactive power compensation device is put forward. In order to improve the ability of commutation failure immunity of multi-DC feed-in system, the area of simultaneous commutation failure is eliminated. An example system is simulated to verify the effectiveness of the proposed analysis method and configuration scheme.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM721.1
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