提高暂态电压稳定水平的紧急控制策略研究

发布时间：2019-06-05 05:45

【摘要】：随着科技的迅速发展,电力系统相应发生许多变化:大容量发电机组普遍应用,电力系统互联、电网电压等级升高,负荷容量相对集中,直流输电和新型电力电子控制装置的应用等,但受环境和建设成本的限制,电网结构却相对薄弱,发电设备储备量较少,系统常运行在重负荷条件下,现代敏感负荷所占比例越来越大,这些现状使得电压稳定问题日益突出。本文在“广东电网动态无功补偿装置优化配置”研究课题上,深入研究暂态电压稳定及暂态电压稳定紧急控制措施。暂态电压紧急控制是一种事故后控制,当电力系统处于紧急状态下,通过采取适当的措施,使电力系统恢复到正常状态或者暂时进入恢复状态的控制。常见的改善措施分为两类:一类是安装以静止同步补偿器为代表的动态无功补偿装置,另一类是紧急切负荷控制。针对两种措施,分别搭建优化模型,考虑电压稳定约束的同时控制成本最低,接着以电压暂降概率为改善目标,协调控制无功补偿和紧急切负荷。本文主要工作如下:首先,本文考虑暂态电压稳定,提出紧急切负荷优化控制模型。以控制成本为优化单目标函数。引入轨迹灵敏度法,将复杂非线性优化控制模型转化为静态的线性整数规划模型以简化优化难度。为了寻找最优解,使用启发式算法,提出Lsi指标,通过该数值的大小排序判断各节点切负荷的改善程度,从而判断切负荷地点和切负荷容量,通过实例仿真表明,该方法简化计算的同时不存在迭代问题。然后,本文提出动态无功容量优化模型。从敏感负荷角度出发,把电压暂降指标做为电压改善目标。本文基于蒙特卡洛理论搭建故障模型,随机生成故障发生类型和故障发生时间,统计并生成电压暂降概率表。搭建电压暂降费用模型,同时计及系统有功损耗费用和STATCOM补偿装置投资费用,生成年总支出费用建立优化模型。通过曲线拟合方式求取暂降费用与容量函数关系,方便后续容量优化计算。通过实例仿真,验证方法的正确性和有效性。最后,本文提出紧急电压协调控制策略。以电压暂降概率指标为改善对象,同时考虑紧急切负荷控制和STATCOM动态无功补偿,优先进行STATCOM无功补偿,如果不满足要求再考虑紧急切负荷控制,协调配合,最大限度降低电压暂降发生概率。通过实例仿真验证得出电压暂降发生概率大大降低,效果明显。
[Abstract]:With the rapid development of science and technology, many changes have taken place in the power system: large capacity generating sets are widely used, power systems are connected, the voltage level of the power grid is increased, and the load capacity is relatively concentrated. The application of DC transmission and new power electronic control devices, but limited by the environment and construction cost, the power grid structure is relatively weak, the storage of power generation equipment is less, and the system often runs under heavy load conditions. The proportion of modern sensitive load is increasing, which makes the problem of voltage stability more and more prominent. In this paper, based on the research topic of "optimal configuration of dynamic reactive Power compensation device in Guangdong Power Grid", the transient voltage stability and emergency control measures of transient voltage stability are deeply studied. Transient voltage emergency control is a kind of post-accident control. When the power system is in a state of emergency, appropriate measures are taken to make the power system return to the normal state or temporarily enter the recovery state. The common improvement measures are divided into two categories: one is the installation of dynamic reactive power compensation devices represented by static synchronous compensators, the other is emergency load cutting control. According to the two measures, the optimization model is built respectively, and the control cost is the lowest considering the voltage stability constraint. Then, taking the voltage sag probability as the improvement goal, the reactive power compensation and emergency load shedding are coordinated and controlled. The main work of this paper is as follows: firstly, considering transient voltage stability, an emergency load shedding optimization control model is proposed. Take the control cost as the optimization single objective function. The trajectory sensitivity method is introduced to transform the complex nonlinear optimal control model into a static linear integer programming model to simplify the difficulty of optimization. In order to find the optimal solution, the heuristic algorithm is used to propose the Lsi index, and the improvement degree of load shedding of each node is judged by the order of the numerical value, so as to judge the load shedding place and load cutting capacity. This method simplifies the calculation and does not have the iterative problem at the same time. Then, a dynamic reactive capacity optimization model is proposed. From the point of view of sensitive load, the voltage sag index is taken as the target of voltage improvement. In this paper, based on Monte Carlo theory, the fault model is built, the fault occurrence type and fault occurrence time are randomly generated, and the voltage sag probability table is counted and generated. The voltage sag cost model is built, and the system active power loss cost and the investment cost of STATCOM compensation device are taken into account at the same time, and the annual total expenditure cost is generated to establish the optimization model. The relationship between sag cost and capacity function is obtained by curve fitting, which is convenient for subsequent capacity optimization calculation. The correctness and effectiveness of the method are verified by an example. Finally, an emergency voltage coordinated control strategy is proposed. Taking the probability index of voltage sag as the improvement object, considering the emergency load shedding control and STATCOM dynamic reactive power compensation, priority should be given to STATCOM reactive power compensation, and if the requirements are not met, the emergency load shedding control should be considered and coordinated. Minimize the probability of voltage sag. The simulation results show that the probability of voltage sag is greatly reduced and the effect is obvious.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM712

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