防止过载连锁跳闸的保护与紧急控制方案研究

发布时间：2018-10-30 16:56

【摘要】：随着电网规模的不断扩大和结构的日益复杂,由过负荷所导致的大停电事故的发生严重威胁着系统的安全稳定运行和供电的可靠性。当线路出现过负荷时,应准确识别过负荷,将其与线路故障区分,避免有关保护误动对系统造成进一步的冲击,防止连锁跳闸导致大停电事故发生。在识别线路过负荷并确保保护不误动后,为了从根源上避免大停电事故的发生,需要选择合适的切机、切负荷控制节点及相应的控制量,对过负荷线路进行紧急控制减载,保证系统的安全稳定运行。针对上述问题,本文主要进行了以下几个方面的研究工作：提出一种基于复合相量平面的自适应过负荷识别方法。先根据不同运行工况下量测相量的几何分布特性,建立虚拟电压降落方程,并求解自适应整定系数,构造距离保护III段自适应过负荷识别判据,然后,将该判据与传统距离保护III段的动作特性相结合,以识别过负荷与对称故障。该方法采用本地信息处理,不依赖于通信,决策快速,易于实现,且克服了过负荷识别简单闭锁后出现保护死区的问题,在过负荷情况下,保护仍能正确动作。IEEE10机39节点系统仿真结果验证了该方法的正确性和有效性。提出一种基于虚拟电压方程的自适应距离保护。该方法同样先根据量测相量的几何分布特性,建立虚拟电压降落方程,求解自适应整定系数,构造自适应距离保护判据,在此基础上,针对过渡电阻对距离保护的干扰问题,借助负序和零序分量的测量,确定过渡电阻电压偏移角,求取过渡电阻补偿系数,从而显著提高了该自适应距离保护的抗过渡电阻干扰能力。通过PSCAD500kV两机系统验证了该方法的有效性和高抗过渡电阻能力。提出一种基于源荷协同系数的线路过负荷紧急控制策略。该策略在线路出现过负荷后,根据系统实时运行方式更新源荷支路协同系数及源荷分配协同系数,并由源荷支路协同系数确定切机、切负荷控制节点集合。根据线路过负荷情况和控制节点集合,以系统经济损失最小为目标,利用双适应度粒子群算法优化搜寻控制策略减载。在此基础上,为了保证供电的可靠性,在不造成新的线路重新过载的条件下,依据源荷分配协同系数选择一部分未参与切机控制的发电机增加出力,带动部分所切负荷,恢复供电,提高整体策略的经济性。IEEE10机39节点系统仿真验证了该策略可以在保证系统安全稳定运行的前提下,有效降低过载线路的负载,并且具有很高的经济性。
[Abstract]:With the continuous expansion of power network scale and the increasing complexity of the structure, the blackout caused by overload seriously threatens the safe and stable operation of the system and the reliability of power supply. When the line is overloaded, the overload should be accurately identified and distinguished from the line fault so as to avoid the further impact on the system caused by the maloperation of the protection, and to prevent the chain tripping resulting in a major blackout. After identifying the line overload and ensuring that the protection is not accidentally operated, in order to avoid the occurrence of the blackout accident from the source, it is necessary to select the appropriate cutting machine, the load cutting control node and the corresponding control quantity, and carry on the emergency control and load reduction to the overload line. Ensure the safe and stable operation of the system. In order to solve the above problems, this paper mainly studies the following aspects: a novel adaptive overload recognition method based on compound phasor plane is proposed. According to the geometric distribution characteristics of the measured phasor under different operating conditions, the virtual voltage drop equation is established, and the adaptive setting coefficient is solved, and the adaptive overload identification criterion for the III section of distance protection is constructed. The criterion is combined with the action characteristics of the III section of the traditional distance protection to identify overload and symmetric faults. This method uses local information processing, does not depend on communication, makes decision fast and easy to realize, and overcomes the problem of protection dead zone after overload identification. The IEEE10 39-bus system simulation results show that the method is correct and effective. An adaptive distance protection based on virtual voltage equation is proposed. Based on the geometric distribution of the measured phasor, the virtual voltage drop equation is established, the adaptive tuning coefficient is solved, and the adaptive distance protection criterion is constructed. On this basis, the interference of the transition resistance to the distance protection is discussed. With the help of the measurement of negative sequence and zero sequence component, the offset angle of transition resistance voltage is determined, and the compensation coefficient of transition resistance is obtained, which improves the ability of the adaptive distance protection to resist the interference of transition resistance. The effectiveness of the method and the ability of high impedance transition resistance are verified by PSCAD500kV two-machine system. This paper presents an emergency control strategy for line overload based on source load synergy coefficient. After the line is overloaded, the cooperative coefficient of source load branch and the cooperative coefficient of source load distribution are updated according to the real-time operation mode of the system, and the cutting machine is determined by the coordination coefficient of source load branch and the set of load control nodes is set. According to the overload of the line and the set of control nodes, aiming at the minimum economic loss of the system, the dual fitness particle swarm optimization algorithm is used to optimize the search control strategy for load reduction. On this basis, in order to ensure the reliability of the power supply, under the condition of not causing the new line to overload again, according to the source load distribution synergy coefficient, select a part of the generator not taking part in the cutting machine control to increase the output force, drive part of the cut load. The IEEE10 39-bus system simulation shows that the strategy can effectively reduce the overload load of the over-loaded line under the premise of ensuring the safe and stable operation of the system, and has a high economy.
【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】：TM732

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