Wu Wenchuan

A Hybrid Fault Event Detection Algorithm Using Fault Recorder Data

When fault occurs in power grid, a lot of alarms and records are generated in substations. These are secondary circuit signals, fault recorder and PMU data. Fault recorder data contains the details of fault evolution, which can be used for diagnosis fault occurrence time, circuit breaker operation events. It is crucial for power grid diagnosis and intelligent alarm functions. However, the analysis and utility of fault record data for diagnosis purpose require the operators participate and is time consuming. In this paper we design a two stages fault diagnosis mode for future development of IEC61850 and digital substation. Based on this, we propose a hybrid algorithm to analyze fault recorder data with abrupt change detection which can obtain major events during a fault, including fault occurrence, circuit breaker operation time. We use a simulated example to prove correctness and efficiency of our proposed algorithm. The algorithm proposed in this paper can be used as intelligent alarm functions for future power grid fault diagnosis.

Observability analysis in power system state estimation based on the solvable condition of power flow

In order to overcome the difficulty in merging and extending observable islands formed by branch flow criteria by using injection measurements, a novel theory and a new topologic algorithm are proposed for observability analysis in power system state estimation. By the idea of equivalence, the nodes of interior network in the islands are ignored during the combination of islands. The sub-networks formed by branches connecting different islands and their terminal nodes called boundary nodes are taken as our research objects. Several rules and the solvability condition of power flow are considered to judge the combination of islands. The validity and efficiency of the method are verified.

An intelligent checking system for power system operation tickets

The automatic generation for power system operation tickets is strongly welcomed in the control center. An intelligent checking system for generated operation series is proposed in this paper. In order to improve the robustness and maintainability of the system, three key technologies, including the recognition of objects, the topological analysis and the organization of knowledge rules, are developed in this paper. This system is embedded in a practical EMS platform and supported by EMS information.

Modelling and Application of Secondary Circuit Signals for Power Grid Intelligent Alarm

Power grid intelligent alarm and fault diagnosis program mainly use breaker and relay action alarms. However, there may be misoperations existed in relays, which could leads to incorrect diagnosis results. With the development of digital substation and application of IEC61850, the secondary circuit signals are available from integrated automation system in substation. These signals may imply control or interlock relationship between relay alarms, which can be used to get rid of misoperation alarms in intelligent alarm functions. This paper mainly concerns about how to integrate these signals into power grid diagnosis procedure. Firstly, we survey the available secondary circuit signals for diagnosis purpose. Secondly, a model of secondary circuit signals is proposed which is an extension of IEC61850. Then, the diagnosis methods considering secondary circuit signals are presented. Lastly, an example is presented to illustrate the proposed methods practical.