Evaluating Phase Over-current Protection Philosophies for Medium-voltage Feeders Applying Let-through Energy and Voltage Dip Minimization. Issue 2 (20th January 2016)

• Record Type: Journal Article
• Authors: Slabbert, Martin J.; van Zyl, Stuart J.; Naidoo, Raj; Bansal, Ramesh C.
• Is Part Of: Electric power components and systems. Volume 44:Issue 2(2016)
• Page Start: 206
• Page End: 218
• Publication Date: 2016-01-20
• Subjects: let-through energy -- medium voltage -- protection -- radial feeder -- reliability -- sensitivity -- voltage dip; Electric machinery -- Periodicals; 621.3104205
• DOI: 10.1080/15325008.2015.1107862
• Languages: English
• ISSNs: 1532-5008

Abstract

Abstract: The effectiveness of phase over-current protection cannot be evaluated by using time-current graphs alone. This article develops a method to evaluate and optimize the phase over-current protection on a radial medium-voltage distribution feeder, which can reduce the risk at the point of fault and improves the overall reliability of the feeder. The method is based on the evaluation of protection operating time, let-through energy, pickup sensitivity, and extent of the voltage dips experienced at the point of common coupling due to network faults under high- and low-source impedance conditions. A Microsoft Excel-based software application (Microsoft, Redmond, WA, USA) is developed that incorporates the four evaluation measures under user-definable network criteria. The application illustrates the results in unique, special forms across the analyzed path and allows the benefits of small changes in protection settings to be quantified. The method and software applications are applied in two case studies on an actual distribution network. The results confirm that it is possible to evaluate the effectiveness of the phase over-current protection philosophy using the aforementioned criteria.