Research On A General-purpose System Of Relay Protection Setting Calculation

Protection device is an important part of power system, its ability of correct action directly affects the safe and stable operation of power system. With the development of power system, grid-scale and grid-structure become more complex. The difficulty of setting calculation is greatly increased, and the corresponding request becomes more and more complex. It is important to improve the efficiency of setting calculation and reduce the burden of staff by developing setting calculation software with high accuracy, versatility, and high scalability.This paper conducted needs analysis on the system, described the function of each module, introduced the Unified Modeling Language (UML), and modeled the system using UML. Based on the model, system was developed by Visual Studio 2008 platform with Oracle database.This paper improved the virtual-port-based fault calculation, and derived the virtual port parameter formula in the case of short circuit, break, and cross-line fault. It can simulate network operation, handle multi-circuit zero-sequence mutual inductance problem, and take into account the line-to-ground capacitor and the transformer phase shift. It increases the calculation accuracy. It improved setting calculation module to enable users freely to add a protection device and setting principle and edit their own formulas with operator and variables. The system's versatility and scalability was greatly improved.