大规模电网分层分区解耦的最优潮流

发布时间：2018-08-29 13:01

【摘要】：随着电力系统规模不断扩大,以及各区域电网的互联工程的推进,造成传统的集中式全网最优潮流越来越难以满足在线分析与实时控制的要求;同时集中式串行计算方式存在数据外泄风险高,数据传输量大,计算“维数灾”等问题。快速、高效、稳定的分区解耦分布式算法已成为解决大规模OPF的关键。为实现分区解耦计算,首先需要利用分区方法将一个大的电力系统分为多个区域系统,接着利用分解协调算法对多区域系统进行解耦分布式计算。因此,本文研究主要涉及两个主要内容,一是分区方法,二是分解协调算法。在电网分区方法上,本文提出了与分层分区结构相适应的电压分区方法。500kV/220kV电磁环网会给电力系统运行带来诸多的不利影响,打开电磁环网形成分层分区网架结构将是电网的发展方向。基于分层分区结构的特点,提出了以220kV电压等级为依据的分区方法,将大电网划分为500kV及以上电压等级的输电网和多个220kV及以下电压等级的高中压配电网。这样的分区方式能得到几个规模适中、区域间连接耦合较弱的子网,也与现实基于电压等级的电力调度相适应。在将全网数据按区域进行归类的实现上,提出了节点注入电流法。在求解多区域系统的最优潮流问题中,采用了两种高效的分解协调算法——分解协调内点法、改进近似牛顿方向法。分解协调内点法通过对边界节点“一分为二”及增加耦合约束条件,实现了多区域模型的等价转换,并利用鲁棒性好的现代内点法进行求解,使各区域的内部变量保持相互独立,只需要边界变量信息的传递协调,从而实现了分区解耦后的最优潮流分布式计算;改进近似牛顿方向法是在近似牛顿方向法的基础上,保留了简约修正方程中潮流方程的梯度部分,使获得的近似牛顿方向更好地逼近于纯牛顿方向,使其对较强耦合系统也能实现完全解耦。所提的两种分解协调算法都具有一个显著的特征,其修正方程都具有对角加边的结构。利用对角加边结构可实现修正方程的降阶解耦,大大减少了修正方程的维数,提高了计算速度和减少了计算机内存占用,同时也实现了分区解耦计算。通过搭建多个具有分层分区结构的电力系统,首先利用所提出的节点注入电流法实现电力系统的快速分区,进而对分区后形成的多区域系统运用两种分解协调算法进行最优潮流的计算验证,所得计算结果表明这两种解耦算法都能很好的提高计算效率,实现大网架的分区解耦计算。这种解耦计算方式对于其他大规模优化问题也具有广泛的应用前景。
[Abstract]:With the expansion of power system scale and the promotion of regional power network interconnection project, the traditional centralized optimal power flow becomes more and more difficult to meet the requirements of on-line analysis and real-time control. At the same time, there are some problems such as high risk of data leakage, large amount of data transmission, calculation of "dimension disaster" and so on. Fast, efficient and stable partition decoupling distributed algorithm has become the key to solve large scale OPF. In order to realize the divisional decoupling computation, a large power system should be divided into several regional systems by using the partition method, and then the distributed decoupling computing of the multi-area system is carried out by using the decomposition and coordination algorithm. Therefore, this paper mainly involves two main contents, one is partition method, the other is decomposition and coordination algorithm. In the area of power grid partition, this paper proposes a voltage partition method. 500kV / 220kV electromagnetic ring network, which is suitable for the hierarchical partition structure, will bring a lot of adverse effects to the power system operation. It will be the development direction of the power network to open the electromagnetic ring network to form a layered and partitioned grid structure. Based on the characteristics of hierarchical partition structure, a partition method based on 220kV voltage grade is proposed. The large power grid is divided into transmission networks with 500kV and above voltage levels and high voltage distribution networks with multiple 220kV and voltage levels below. In this way, several subnets with moderate scale and weak coupling between regions can be obtained, which are also suitable for power dispatching based on voltage level in reality. In the realization of classifying the whole network data by region, the nodal injection current method is proposed. In order to solve the optimal power flow problem for multi-region systems, two efficient decomposition and coordination algorithms, the decomposition coordinated interior point method, are used to improve the approximate Newton direction method. By dividing the boundary nodes into two and adding the coupling constraints, the decomposition and coordination interior point method realizes the equivalent transformation of the multi-region model, and uses the robust modern interior point method to solve the problem. The internal variables of each region are kept independent of each other, only the information of boundary variables is transferred and coordinated, thus the distributed optimal power flow calculation after partition decoupling is realized, and the improved approximate Newton direction method is based on the approximate Newton direction method. The gradient part of the power flow equation is preserved in the reduced correction equation, which makes the obtained approximate Newton direction approach to the pure Newton direction better, and it can also achieve complete decoupling for the strongly coupled system. Both of the proposed decomposition and coordination algorithms have a remarkable characteristic, and the modified equations have diagonal edge structure. The diagonal triangulation structure can be used to reduce the order decoupling of the modified equation, which greatly reduces the dimension of the modified equation, improves the computing speed and reduces the computer memory consumption, and also realizes the partition decoupling calculation. Firstly, the proposed node injection current method is used to realize the fast partitioning of power system. Then, two decomposition and coordination algorithms are used to verify the optimal power flow of the multi-area system formed after partitioning. The results show that the two decoupling algorithms can improve the efficiency of calculation and realize the partition decoupling calculation of large grid. This decoupling method also has a wide application prospect for other large-scale optimization problems.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM744

【参考文献】