Experimental Research of Line Power Unloading Automatics With Its Tripping Characteristics Correction

Abstract

In conditions of complicated structure of modern power grids, a special emphasis is given to the issues of ECA failure-free operation. This article is concerned with the problems of increasing sensitivity and selectivity of line power unloading automatics because its correct operation plays an important role in ensuring energy security and survivability of power systems.
 
 Within the framework of this paper, the full cycle of development of ECA algorithm is considered. ECA is performing the functions of line power unloading automatics. The development cycle includes the tasks of tentative assessment of electrical equipment operating modes, rationale for choosing the automatics tripping characteristics, algorithm design and programmable logic controller (PLC) based implementations. It also includes the laboratory testing with the use of real-time hardware and software complex.
 
 The calculation data of steady-state and transient operating modes of power electrical equipment presented in the article were carried out in software complexes RastrWin, Rustab. The power facilities of the interconnected power systems of Urals, Siberia and Kazakhstan were considered as modeled objects of power systems. In accordance with the obtained results, the tripping characteristics of device being developed were determined.
 
 Based on the results of mathematical simulation of electrical equipment transient operating modes, the major disadvantages of device algorithm, which controls the active-power flow through the line, were determined. Besides, methods focused on increasing the sensitivity and selectivity of such automatics are proposed.
 
 The developed algorithm controls the active-power flow over a given cross section. Measurements of electrical parameters are carried out at one of the lines in cross section. The total value of active-power flow over the cross section is calculated according to the equivalent circuit. To increase the sensitivity and selectivity of automatics, the algorithm uses the action time adjustment. It is determined depending on the previous operating mode of transmission line.
 
 The algorithm for line power unloading automatics described in this article was implemented on a PLC system in accordance with the IEC 61131 standard. The obtained device was successfully tested on the real-time hardware and software complex. This paper presents the results of the carried out device performance tests, and the characteristics of the used mathematical simulation.