B Impact of new functionalities on substation design

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1 21, rue d'artois, F Paris B3-208 Session 2004 CIGRÉ Impact of new functionalities on substation design P. Bosshart J. Finn C. Di Mario M. Osborne P. Wester ABB High Voltage VA Tech GRTN National Grid NUON Technologies Transco Switzerland U.K Italy U.K. Netherlands. Submitted to CIGRE Session 2004 On behalf of Cigré WG B3-01 Substation Concepts Summary One of the consequences of implementing emerging new functionalities and technologies is the demand for application guidance and recommendations related to the design and construction impact for substations. This paper outlines the strategy for addressing the subject and provides a framework to organize the screening of design impacts: it proposes a scope of new functionalities addressing today s important demands of the utilities and introduces a matrix-based approach to present the results of the analysis. These results will be given in a technical brochure planned for Key words: Substation, Construction, Design, Interface-Definition, Modular-Design, System- Analysis, FACTS, Screening-Technique, technology suitability. 1 Introduction The purpose of the strategy (Electra) paper is to describe the reasons driving the application of new functionalities. This will be supported with recommendation on the impact on substation design and construction. The assessment will be performed by applying a number of supporting management technologies like mind mapping and design structure analysis matrices. The strategy will be succeeded by a brochure covering all the specific results of the management technologies applied. The mind-map, as shown in figure 1 (last page), visualizes the scope of different aspects and items involved in this highly interdisciplinary task. The rapid development of power electronics materials technology not only provides opportunities to develop new power system functionalities, it also generates questions regarding integration into substations and then the subsequent optimization regarding demands in the energy & distribution organization process. As most of the functionality is integrated within the substation boundary the guidance provides key-information for future substation design e.g. a more modular and flexible design approach. The outcome of this investigation will therefore be of importance to designers, project companies, original equipment manufacturers and, the Standards community, which will also have to be aware of the needs and requirements when adopting this technology. This supporting paper follows the structure of the strategy paper in order to give explanatory support where that seems relevant. As such the main focus is directed at the key demands, solution overview, design impact, implementation and cross-relations. 1 Peter Bosshart, ABB High Voltage Technologies, Brown Boveri Strasse 5, 8050 Zurich, Switzerland, peter.bosshart@ch.abb.com

2 2 Key demands The generic elements which are believed to affect most substations are the basis for a further investigation of the impact of new technologies. Based upon the mind mapping results these are considered to be: Reduction of substation environmental impact, expressing the pressure on the designer to deliver a solution which is acceptable both from a social (minimising impact on neighbours) and environmental (safety, green parties) perspective. Pressure of cost reductions, forcing utilities to review the architecture of their networks such that a more flexible approach to asset management can be achieved. Volatile daily and seasonal load profiles and composition, reflecting the impact of end-user technology. Green energy may see electric cars and public transport taking a higher priority, especially as countries try to meet their CO 2 reduction targets for 2010 and beyond. Compatibility of dispersed generation, resulting from opening up of the energy markets may result in unmanaged non-centrally dispatching. The lack of large-scale energy storage and inconsistency of the weather will make the balancing of the network a more complex activity as dispersed generation proliferates unchecked without coordination of the long-term system security. The more process based issues surrounding asset management and resourcing, whilst very critical to the business, will not be addressed within the scope of this work. 3 Overview of solutions The strategy paper and brochure are aimed at identifying and introducing solutions for the problems occurring, when applying the new demands, to the substations. Generally solutions applied are based upon combinations of measures in the technology, commercial or process area. Given its background the working group will focus on technology based solutions like: Flexible AC transmission systems (FACTS) Voltage and current source converters based on silicon switching provide variety of new control possibilities [4]. Energy storage systems Super-conducting magnetic storage (SMES), chemical energy storage, (Redox-flow, fuel cells, NaS battery) and flywheels. Fault current limiter Current limiters allow a low-impedance, stiff system with a low fault-current level. Economic solutions are based on high temperature superconductors. Power quality support Dynamic voltage restoration (DVR), active filtering and solid-state transfer switch to ensure uninterruptible supply. Flywheel technology. Other state-of-the-art technology Integrated and modular packaging, special transformers/reactors such as thyristor controlled phase shifter, saturated reactor and phase shifting transformer. New combinations with integral optical CT s on circuit breakers, integral support/surge arresters, combined CB/disconnectors should be included. Information technology and substation automation Monitoring systems/sensor in equipment [5], www-technology for substation automation, application of standard protocols, e.g. IEC to ensure interoperability of sensor/actors, real-time voltage/current phasor GPS-based wide area measurement allowing new wide area protection. Protection and control systems with self-adapting or learning capabilities. The strategy paper and brochure will not only be based on the knowledge of the present WG B3-02 2

3 members. The work and investigations of other international organizations (EPRI, IEEE) addressing similar questions and technologies will be covered. Moreover a liaison to Cigre SC B4 will assure the link between our more application approach and the design of power semiconductors. 4 Impact on substation design The impacts of these new functionalities upon substation design can be considered in three stages. Basic system changes. The new functionalities are either fundamentally designed to control the basic parameters of the system (to give control over voltage, fault level, power flow or even short term frequency support), or in the case of distributed generation inherently make major changes to the way in which an existing distribution system will behave. Impact on the single line diagram: factors like the short circuit rating, increase in harmonics on the network, all different solutions which cause the application of new devices incl. their protection arrangements and maintenance consequences in the substation area. Detailed substation design including consideration of the detailed design requirements for installation and operation. This considers not only the requirements regarding physical design covering clearances, oil containment, AC/DC voltage supplies (to mention a few), but also the introduction of these new functionalities may have an impact upon the design requirements of many of the conventional plant items. Factors like the fault rating of circuit breakers, load switching of disconnectors and protection schemes and insulation coordination. Especially the design of the earthing system should ensure safety whilst avoiding interference into control circuits and avoiding large circulating currents from flowing due to electromagnetic induction. 5 Guidelines for the successful implementation The strategy paper and brochure will contain a more extensive description and summary of the impacts on substation design These guidelines will be covered by the brochure in the form of a checklist to help the designer to identify the actual impacts affecting the substation under design. The guidelines will start by looking firstly at what type of functionality is being introduced. The results of the studies will enable the substation designer to finalize the SLD of the substation taking into account the availability, control and protection requirements. The guidelines will provide advice on all specific design items including the identification of the key interfaces which the substation designer needs to take into account and provide a logical and controlled way of dealing with these. 6 Cross-relationships Value is added to the brochure by making the design impact of a new technology transparent. This information could be further used as a base for: Setting up the guidelines for implementation Optimizing solution and design process by easier tracking of relevant parts Establishing a general framework for future/periodic updates and screening of design knowledge data-bases, expert systems, and configuration rules related to substation design. Thus an approach for setting up the brochure has been identified that addresses the following questions: How can a contributor capture and present the design impacts of a new technology? Which format is suited to capture design impacts? How can contributions be worked out independently from each other and be easily integrated later into a big picture? An assessment tool based on a method called Design Structure Matrix (DSM) [6] has been identified 3

4 to support such a task. It uses a matrix representation to capture technical relationships among design/project steps, e.g. design and dimensioning of technical parts. The essential feature of the DSM method provides a measure to qualify relationships. This feature could be applied directly to describe design impacts. Following this method contributors have guidance and a format to describe design impacts: critical path items, complex interactions between a new technology and a substation are broken-up into simpler relationships following the DSM. A new technology is checked against substation design issues as given in chapter 4 one by one. This approach greatly helps collecting design impacts independently from other contributions while providing a common format to harmonize and compile the big picture. The technique is useful for developing an understanding of the system engineering needs which arise because of complex interactions between substations components and new required functionalities/technologies. 7 References [1] T. Sato: Effects of many dispersed generations installed in customers on power systems. Extracted from ETRA report Substation technology towards the 21 st century, Vol. 58, part 2, July [2] IEEE : IEEE Guide for the Design, Construction, and Operation of Electric Power Substations for Community Acceptance and Environmental Compatibility. [3] Technical Brochure 161: General guidelines for the design of outdoor AC substations. CIGRE 23-03, August [4] Y.H. Song and A.T. Johns: Flexible AC transmission systems (FACTS), IEE, London UK, [5] Technical Brochure 167: User guide for the application and diagnostic techniques for switching equipment for rated voltages of 72.5 kv and above, Cigré working group 13.09, August [6] Massachusetts Institute of Technology (MIT) & University of Illinois at Urbana-Champaign (UIUC): An introduction to the DSM Method

5 Fig. 1 : Initial mind map of involved areas and issue 5