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506 NEW INTELLIGENT FEATURES DURING REFURBISHMENT OF SUBSTATIONS Maarten VAN RIET NUON Technical Projects Consultancy The Netherlands Maarten van Riet N Frans PROVOOST Eindhoven University of Technology The Netherlands F Provoost Tue nl Frans VAN ERP NUON Technical Projects Consultancy The Netherlands Frans vau Erp N SUMMARY The moment of substation refurbishment is the cxcellent time to install new features and ideas It has proven that it is better to wait a few years for refurbishment than to act without well thought ideas Nuon stands on an important moment where many substations have to he upgraded with new protections controls and innovative features Our main goal is to upgrade old substations towards tomorrow s state of the art using only some hundred thousands euros To reach this goal many things have to he combined There is no doubt about merging of protection and control But there is also a need that one single protection and control box has to serve more than one feeder Recent success stories about super fast tripping via a simple Ethernet bus frees the possibilities of combining many protection software devices into one computer So our vision about a future substation is becoming more and more realistic The last 25 years everybody was focused on benefits from HV automation But our opinion is that on this moment we can reach much more starting with the low and medium voltage In our pilot project for refurbishing the 150110 kV substation Zalthommel we realized not only state of the art protection and control but also a fully integrated Power Quality measurement for all 20 outgoing feeders Also we realized a medium voltage fault locator which detects 2 and 3 phase faults with an accuracy of less than 100 meter and single phase to ground faults in soft grounded network with an accuracy of 500 meters Because of the distance between MV houses this accuracy is more than sufficient to know where to start switching for network restoration We reached several successes in PLC communication over low and medium voltage networks opening a new world in information and control handling This involves not only the communication to our customers e g automatic meter reading hut also the total grid management information between substation and the low voltage connections Our goal is to reach total transparent and simple substation automation system within 10 years As a consequence the costs for substation automation refurbishment must be decreased by 90 INTRODUCTION Nuon is one of the major power utilities in the Netherlands supplying gas water and electricity to 5 million customers in five provinces including the capital city of Amsterdam From the 150 110 50 kV high voltage network about 340 medium voltage networks 10 kV are fed Refurbishment of such a substation is the excellent time for adding new state of the art features From the beginning of the seventies many effort was put in automation of the high voltage side of the substation The opening of the electricity market and the rise of vulnerable power electronic equipment both in industry as households set more requirements on the quality of supply especially on outages voltage dips harmonics and grounding philosophy Medium voltage automation is necessary to meet these requirements Due to the large number of feeders this kind of automation needs simple cheap and intelligent standard solutions The fast developments in information technology require visionary thinking and ideas for which manufactures don t have a proper solution yet New ideas towards the end state can be proven in pilots and implemented as standard solutions in future refurbishment Nuon has already published several ideas during major conferences All ideas show that everything deals with everything and that only overall solution will reach to success The final goal for this moment is a simple intelligent MV automation consisting of smart measuring devices communicating with a smart centralized system containing in principle only 2 computing systems REQUIREMENTS FOR MV AUTOMATION For a good working system requirements come from operators customers and management Customers require a high standard of reliability and quality This means that outage times have to he as short as possible Power Quality aspects have to meet standards stated by the regulator and international standards Operators need to act as fast as possible and want to have more data from the network in order to monitor the performance of the grid and the attitude of the customers Management 0 2004 The Institution of Electrical Engineers Printed and published by the IEE Michael Faraday House Six Hills Way Stevenage SGI 2AY 507 is always interested in doing more with less money Therefore the total automation system has to fulfill Fast acting on disturbances in the network both protection and restoration Constant monitoring of Power Quality parameters and alarming when thresholds are exceeded Good communication links between substation dispatch centre and the rest of the world EMC proven solutions Less depending on human errors Simple MMl s Getting more information from the network like loads deeper in the grid and state estimation also for the medium voltage Modularity and central supporting software Reducing future investments and costs of network operation All these requirements form the dilemma of the modem substation automation For solving the puzzle there is cooperation with the part Intelligent Networks of the Dutch innovative research program IOP EMVT I The highlights of this program sponsored by the Dutch government are the influence of large amount of dispersed generation on stability in large scale high voltage networks design of manageable distribution grids and control schemes for autonomous controlled medium voltage grids This project was stated during Cired2003 in Barcelona 2 TECHNICAL END STATE The technical end state within a horizon of 5 years is shown in figure I Figure I Protection and control in 2006 The substation consists of smart components and smart measuring devices communicating over glass fiber with the centralized protection and control system Smart components are conventional devices like circuit breakers and switches which are supplied with a lot of electronics for operating diagnostics and storage of all kind of information about the device itself Smart measuring devices like current and voltage transformers produce digital signals instead of analogue signals like voltage and current The protection and control system is fully integrated in two computers The input consists of information from the smart devices The output consists of control signals towards the smart components and information about the network towards the dispatch centre and other interested parties In this concept the physical distance between protection and smart components is no longer of interest In this concept it has to be accepted that even the out command of circuit breakers is running over the substation communication bus and no longer over physical copper wires There is no longer a clear separation between protection and control The smart measuring devices deliver continuous on line information about current and voltage for monitoring When a short circuit occurs in the MV network the control system is able to detect that something is changing and sets alarms within the first period After one period there is enough information to calculate the type of fault and the distance between substation and fault If switching in the substation is necessary an out signal will be send to the appropriate circuit breaker Information ahout the faulted feeder type of fault and distance is sent to the dispatch centre The glass fiber is not only necessary for EMC purposes but also to prevent damages to the central system in case of open arcs and other disasters with the primary installation An example of such a disaster occurred in one of our old fashioned automated substations An open arc in a bushar system transferred high voltage to the secondary system of a current transformer and from there towards a protection device which was in a copper wired communication with the substation automation system Half of the centralized automation system was totally lost PILOTS To reach the final goal pilots are necessary In these pilots there is good cooperation with manufacturers For Nuon itself it is valuable to split the project in several manageable parts For manufacturers it gives a good opportunity to test their new developments in real practice The goal of every pilot must he that thinking meets reality The pilots started already in 1997 and new pilots will be started up Some examples will be explained below Intelligent faultlocation The aim of this pilot was fast location of faults in MV grids This locating had to result in reduction of customer minutes out The principle was proved in a pilot with ABB in substation Zaltbommel and published on Cired 1999 Nice 3 The realization 508 was not yet feasible due to too high costs of hardware and unavailable suitable software Merging faultlocation protection and control The aim of this pilot was to show the financial feasibility of a proper automatic functioning faultlocator in combination wits substation protection and control This pilot also showed the possibility of reducing the volume for the necessary Darts of substation eauioment as shown in figure 2 Figure 2 Protection and control o f men5 MVfeedersfits in 5 cabinets The pilot in cooperation with GE Calgary and Phase to Phase was implemented in substation Zaltbommel The first results were published in Cired 2003 in Barcelona 4 51 PLC communication The aim of this pilot was to show the possibility of suitable and reliable communication between low voltage customers and the WAN connected to the substation as shown in figure 3 h Figure 3 The pilot was divided into two stages The first stage was communication between the customer and the low voltage side of the MV LV transformer in a MV house For this the Enel concept was The two stage PLC communication between house and WAN proven The second stage will consist of communication between the MV houses and the substation For this we realized a patented cheap solution just 25 euros for a direct capacitive coupling to the core of the MV cable Because of the waiting time for the patent nothing has been published yet Cuprum copper project for redesign unified media communication The aim of this project is to show the possibility of a modem communication system over all HV substations The system works both with glass fibers and copper wires Each connection is able to communicate with at least 2 MBitisec This hybrid WAN includes the direct routed connections for protection devices like distance and differential protection including the possibility of predefined rerouting The system is based on the ABB fox 515 concept MV test grid in substation Zuiderveld A part of the MV grid of substation Zuidetveld will be placed at disposal of the research program on intelligent networks in order to prove development results At this moment the PLC communications between the MV houses are installed This gives possibility for simultaneous measurements on loads and Power Quality aspects In future we hope to develop this test grid into an autonomous controlled network which is coupled to the outside network by means of power electronics In this network it is possible to test completely new adaptive protection and control systems Also state estimation in the MV grid will be performed Results will be continuously published by the involved PhD students Grounding philosophy using global earthing The reliability of a substation is no longer dependent on reliability of a component in itself hut of the immunity of the used substation components for EMC disturbances The advantages of a global earthing system were published in the dissertation of Jeroen van Waes 6 A new protection philosophy for MV grids New protection systems will consist of existing conventional protection devices in the grid and intelligent adaptive protection in the substation The aim of this system is not only to switch off the fault but also to limit dips due to two and three phase faults and to reduce safety risks due to phase to earth faults This solution requires intelligent selectivity of