KeyWord : reliability ; real - time performance ; two kinds of algorithms for real - time topology analysis of power networks ; Wei Wei ; Mu Daqing ; Department of Electric Power Engineering ; Changsha University of Electric Power ;
The function of the power network topology analysis is to judge the structure of the power grid (that is, topology) according to the switching state of the power grid, that is, to put various devices (such as generators, load feeders, shunt reactors, transformers, transmission lines, etc.) according to the state of the switch. The connected power grid is represented as a node model that can be used for power system analysis and calculation, and identifies mutually isolated subsystems. It is the basis of power system simulation and analysis calculations.
The topological analysis of power networks requires high real-time performance and reliability. In this paper, two topological analysis procedures have been programmed using breadth-first and depth-first methods, and they have been run on a provincial power grid simulation system. Good results have been achieved.
1 The two algorithms of topology analysis are grouped. The first step is the wiring analysis of the plant station. According to the state of the switch in the plant station, all the bus sections connected by the closed switch (herein the bus section is referred to as a node, such as the nodes 1 to 20) are grouped into one node by searching. The second step is system network analysis, using the same search method, according to the branch (line or transformer) connection, the entire system of nodes from the operational branch into several subsystems. As shown in the model system of the three plant stations, in the current switch state, there are six nodes through the plant station wiring analysis, and the characteristics of the power network topology are not changed in the case of the system network branch plant station. Network Topology Analysis Fast local network topology correction method. The special requirements of DTS were analyzed and a fast and reliable topology analysis method for DTS was introduced.
Although these methods are different in the processing method of the electric network model, they all have the basic process of connected search. The essence of topology analysis is the connectivity problem of the solution graph. There are two algorithms that are suitable for power network topology analysis, namely depth-first method and breadth-first method. The depth-first method starts from a certain vertex and searches for the end of a path along the connected branch, and then reverses back to the branch node to search for other paths until all the connected branches and nodes are searched. The breadth-first method is based on a certain node as a starting point, and the nodes that are connected to the starting point and have the same path and have a path length of 1, 2, ... are accessed in layers. This paper aims at an actual power grid simulation system and introduces the implementation of two algorithms based on the electrical network model.
2 Implementation of Two Algorithms 2.2 Implementation of Breadth First Method The implementation of the breadth first method is shown.
The results of a calculation example The grid size of a certain province is: plant number 98, number of generators 58, total number of switches 164 switches 882, number of branches 498, number of nodes 391. I use these two procedures for a certain provincial power grid at a certain moment The power grid topology was analyzed in the switch state. The hardware platform for running the program is the RISC workstation Sunsparc20. The software platform is the Unix operating system and the Panda real-time data management system. The results of the program running are shown in Table 1. Table 1. Results of the program execution method Number of searched nodes Number of subsystems Time (ms) Depth-first method Breadth-first search N -1 times, The total number of searched nodes is much more than the actual number of network points However, it is less than 2 times the number of network nodes; the number of nodes searched by the breadth-first method is exactly the number of network nodes, and the selection of initial vertices will not have any effect on the number of searches. Therefore, the breadth-first method is faster and more reliable. The topology analysis of the power grid is the basis of dynamic power flow, safety analysis, dynamic simulation and other modules. The two algorithms implemented in this paper are the basic algorithms for power network topology analysis.
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