23 rd International Conference on Electricity Distribution Lyon, 15-18 June 2015 Paper 0676 CIRED 2015 1/5 DESIGN & ANALYSIS OF AN IMPROVED FAULT LOCALIZATION SCHEME FOR SECONDARY SUBSTATION AUTOMATION Daniel SCHACHT Gonca GÜRSES Hendrik VENNEGEERTS FGH e.V. – Germany FGH e.V. – Germany FGH e.V. - Germany daniel.schacht@fgh-ma.de gonca.gürses@fgh-ma.de hendrik.vennegeerts@fgh-ma.de Björn KEUNE Manuel GREULICH Robert FRINGS TU Dortmund University – Germany ABB AG – Germany INFRAWEST GmbH - Germany bjoern.keune@tu-dortmund.de manuel.greulich@de.abb.com robert.frings@infrawest.de ABSTRACT The increasing penetration of inverter-based, volatile dispersed generation units in distribution level creates technical challenges for a secure and reliable power supply. The modernization of secondary substation technology represents a prominent technical solution in order to master the effects of this trend. This paper presents the joined research results of an intelligent secondary substation design including improved methods for voltage control, fault detection and localization. Thereby the work’s focus is on the novel secondary substation’s characteristic function and its impact on the fault clearance process in medium voltage level. Simulation results emphasize its benefits for modern grid operation. INTRODUCTION The expanding deregulation of electricity market along with the advent of power generation from renewable energy sources lead to a widespread promotion of distributed generation units. However, the increasing penetration with distributed generation in low and medium voltage level causes new technical challenges for voltage control, grid loading and reliability. While system operators are bound to optimize their grids and thus reduce existing costs, an appropriate grid reliability, which in general requires corresponding equipment and staff, is an essential requirement by quality regulation [1]. These constraints lead to a conflict within the grid optimization process. In this context a collaborative research project promoted by the German federal ministry for economic affairs and energy investigates solutions for an intelligent secondary substation. The focus of the project lies in part on the improvement of grid reliability through newly developed functionalities to detect and to locate faults. Although the intelligent secondary substation can be connected to the information and communication network of the grid operator, the newly developed functionalities work exclusively with information available inside the substation to detect and to locate faults. This characteristic of the new functionalities enables the implementation in substations with and without a communication link to the regional operating centre and give the grid operator thereby more flexibility in its grid planning process. In this paper the newly developed functionalities of the intelligent secondary substation will be introduced as well as an algorithm to simulate the benefit of these new functionalities. Special attention will be paid to the accuracy of the functionalities and the benefit, which arises from these for the fault clearance process in specific grid configurations. CURRENT PROCESS OF FAULT DETECTION, LOCATION AND CLEARANCE IN MEDIUM VOLTAGE GRIDS The medium voltage (MV) grid shows two significant differences compared to the high voltage (HV) grid during the fault clearance process. First redundancy can in most cases only be realized by switching operations and second the protection concept based on protection relays and switch gear facilitates no direct selective disconnection of faulty equipment. In medium voltage grids fault detection and localization are therefore of much importance. To determine the faulty equipment or fault location a fault area will be defined at first. By using this method the number of possible fault locations shall be reduced significantly. The fault locating is completed as soon as the fault can be linked to a specific equipment or group of equipment. Those groups of equipment can be differentiated in groups determined by a protection area and groups determined by a work clearance area (see figure 1). The work clearance area is delimited by isolating switches and the protection area is determined by combinations of protection relays and circuit breakers. Since common secondary substations are usually not equipped with protection relays and circuit breakers, the protection area includes several work clearance areas in most cases. In common grids overcurrent relays are placed in primary substations to ensure selectivity on a high level and will trigger in case the measured current exceeds a pre-set threshold. Thereby short circuit indicators will allow to evaluate the fault’s direction. Technical staff will then manually inspect the short circuit indicators in secondary substations within the effected feeder to identify the faulty equipment and work clearance area [2].