Relay Protection Algorithms Research Articles

Prony filter vs conventional filters for distance protection relays: An evaluation

This article presents a performance evaluation of Prony method vs conventional digital filters in distance relay protection algorithms, and characterizes the error when asynchronous frequency components (subharmonics or interharmonics) are embedded in voltage and current signals during fault period when conventional digital filters of distance relay algorithms (cosine or Fourier filter) are used to estimate the fundamental frequency phasors. First, the signal processing overview of conventional distance relays is presented. Then, the effects of line series compensation in distance relay estimation during the fault period are presented by analyzing two events of recorded data signals in a laboratory test system of a series compensated line and using a mho operation characteristic. Next, Prony method and its considerations for the implementation in distance relay algorithms are described. Then, the performance of Prony method using simulated signals is evaluated. Lastly, an assessment of Prony as a digital filter in distance relay algorithm is performed by analyzing two fault events in a laboratory test system using a quadrilateral operation characteristic, and the results of Prony vs conventional digital filters in distance relay algorithms are presented.

A Test Rig for Smart Substation Training System

The concept of smart substations has been widely used in power systems. Since the variation in interfaces and communication manner, the operating& maintenance methods for smart stations have changed a lot compared with the traditional substations. In this paper , a training system based on virtual substation primary equipment combined with real secondary devices is developed for accident management and operating work in smart substations. The training system is also used to test the relay protection algorithms、Ethernet switch functions、fault recorder actions ,and so on.

Application of Fuzzy Neural Network in Relay Protection

This paper present a relay protection algorithm based on fuzzy neural network theory. FZZ makes full use of the strong structural knowledge express ability of fuzzy logic as well as self-learning and direct quantitative data processing ability of neural network. Hence the robustness and self-learning of FZZ are improved. At the end of this paper, we use a relay protection working case to certify the application.