Modern techniques for Protecting Busbars in HV networks

Transcription

1 101 Modern techniques for Protecting Busbars in HV networks Zoran Gajic * (Convenor, ABB, Sweden), Philip Beaumont (Toshiba, UK), Hans-Werner Funk (Siemens AG, Germany), Ljubomir A. Kojovic (Cooper Power Systems, USA), Kenneth Opskar (Statnett, Norway), Andre dos Santos (REN, Portugal), Damien Tholomier (AREVA, France), Juergen Westerfeld (ABB, Switzerland), Jose Miguel Yarza (ZIV, Spain) AK Gupta (National Thermal Power Corporation, India), Yong-Cheol Kang (Chonbuk National University, Korea), Sugunan Pillai Raghavan (TNB, Malaysia) This paper summarizes the CIGRE SC B5 WG16 draft report entitled, Modern Techniques for Protecting Busbars in HV Networks Error! No se encuentra el origen de la referencia.. The paper is organized into three sections. Section 1 presents general practices for the selection of busbar protection (BBP) designs and describes centralized and de-centralized digital (numerical) busbar protection solutions. Section 2 describes common features of modern busbar protections. Busbar protection schemes utilise sophisticated algorithms to provide reliable performance during substantial CT saturation, resulting in low CT requirements. A disconnector replica implemented in relay software eliminates the need for switching in CT secondary circuits and trip circuits. Protection functions such as breaker failure protection, end fault protection, and overcurrent feeder protection can be implemented into the BBP. Built-in self-supervision improves BBP reliability. Communication enables remote access to relevant information available within the BBP. Other features presented include disturbance recording (oscillography) and an event list that provides improved evaluation of BBP protection operation. Section 3 addresses advanced features of modern busbar protection designs. Feasibility of using new types of current sensors for current measurements is presented. Also described is integration of other protection functions such as feeder protection within the individual bay units of a de-centralized BBP arrangement. Furthermore, the impact of IEC on busbar protection design and operation is considered describing the use of GOOSE messages and their influence on scheme design, as well as blocking of autoreclosing after BBP operation. Finally, issues regarding the integration of BBP schemes into modern substations using an IEC process bus approach conclude the discussion. Relay Protection, Busbar Protection, IEC 61850, Power System. * zoran.gajic@se.abb.com 1

2 102 An Innovative Template Design for Low Impedance Bus Zone Protection Muhsin Ally / Barrie Moor (Powerlink Queensland, Australia) This paper will describe the process of developing a template based design to effect a versatile low impedance bus zone scheme, its application to isolator switched substations, its flexibility, and the development and use of a specialised testing tool. Powerlink Queensland, the Transmission Network Service Provider for the State of Queensland, Australia found that this approach removed the complexity usually associated with the implementation of low impedance bus zone schemes and significantly reduced the problems associated with field testing and commissioning. By applying innovative techniques and solid engineering knowledge, the low impedance bus zone scheme has significantly helped in improving the performance and reliability of our isolator switched busbar substations, making them viable well into the future. Terminal is synonymous with feeder and the two words are frequently interchanged. N/O normally open & N/C - normally closed. 2

3 103 Communication and synchronization methods for distributed bus protection Wu Qian / Gu Xinxin / Shi Yuxiang / Le xiufan (Nanjing Automation Research Institute. No.8 of NARI Road, Nanjing, P.R.China) Abstract Bus protection is the main protection for power system. When modern substation and power plant scale become larger and short circuit current become heavier, traditional centralized principle of bus protection shows some disadvantage. New distributed bus protection principle based on microcomputer and communication network operates in power system in recent years. According to this principle the whole bus protection system is divided into a number of bus protection units that installed each on one power circuit connected to the bus. These bus protection units are connected together by communication network, so that each unit obtains the current data of all the circuits connected. An effective communication protocol is needed to meet high speed operated for bus protection. Another important technique in distributed bus protection system is synchronization between each unit sampling data. This paper proposes some new communication and synchronization methods. The communication method is to applying a cycle-push method within each protection unit by using a simple optic-fiber double-looped communication network. This thesis also works out the communication speed required by the method and offers a supplementary method. Distributed protection units can meet the bus differential protection requirement in synchronous sampling and data transmitting. The proposed communication network possesses the following advantages: simple and reliable structure, convenient modifying, low requirement in communication speed and high performance. The synchronous sampling and the anti-ta saturation method are also presented. bus protection; distributed; optic fiber communication; synchronous sampling; cycle-push; TA saturation; non-periodic component. 3

4 104 Trends in 400 kv Busbar Protection at RTE Jean-Luc Chanelière 1 (RTE-EDF Transport, France) For 20 years, the 400 kv busbar protection scheme used in RTE's substations has consisted of a busbar differential protection, a time-delayed ring opening protection that trips bus couplers and switched busbar circuit breakers (based on impedance measurements), and in some substations that are important for the safety of the power network, a simplified supervision differential protection that trips couplers and switched busbar circuit breakers. Following recent work to update stability studies for nuclear units connected to the French network, 400 kv substations were classified on a three-tier scale, based on the risks arising due to an unscheduled outage of the busbar differential protection system (anomaly with blocking, risk of failure to trip when triggered): Level 1: system safety is not threatened. No special preventive measures are required for these substations. Level 2: the risk to system safety is high. However, simple topological counter-measures (ring opening) combined with unit restrictions is sufficient to eliminate the risk to system safety. Level 3: the risk to system safety is extremely high. Consequently, the faulty protection system or zone protection parameters need to be dealt with urgently. The existing busbar protection system is poorly suited to dealing with the risks identified: For level 3 substations, the simplified supervision protection system is not sufficient to eliminate the risk. For level 2 substations, the risk is substantial with busbar differential protection systems that do not signal anomalies. Moreover, the risks identified make it more problematic to arrange scheduled outages of busbar differential protection systems (for maintenance). It is worth noting that whilst topological countermeasures cost RTE nothing, the same is not true of restrictions placed on generating units. Consequently, RTE is looking at possible changes to the protection systems for its 400 kv busbars, as follows: 1 jean-luc.chaneliere@rte-france.com 4

5 For all 400 kv substations, installing a busbar differential protection system and a time-delayed ring opening protection that trips couplers and switched busbar circuit breakers (based on impedance measurements), For level 2 substations, gradually replacing the busbar differential protection systems with digital self-checked protection systems, For level 3 substations, doubling-up the busbar differential protection by installing a second, digital self-checked differential protection system. Protection, busbar, extremely high voltage grid. 5

6 105 Numerical Busbar Protection: Benefits of Numerical Technology and IEC61850 Damien Tholomier (Areva T&D Automation, Canada) Henri Grasset (Areva T&D Automation, France) Mark Stockton (Areva T&D Automation, UK) Abstract In many networks, bus protection has been applied sparingly due to the difficulties experienced with early bus protection schemes in achieving satisfactory performance in term of stability, speed and sensitivity. Numerical technologies provide new solutions for bus protection schemes that are improving the performance of the scheme itself and the power system operation. This paper describes some of the new techniques being implemented. Busbar protection, Numerical, Reliability, Performance, IEC

7 106 Measures against CT Saturation for Busbar Protection in Japan Jirou Tsukida (Tokyo Electric Power Co., Japan), Hisanori Itou (Chubu Electric Power Co., Japan), Katsuhiko Kawai (Electric Power Development Co., Japan), Chikashi Komatxu (Hitachi, Ltd, Japan), Isao Chihara (Fuji Electric Systems Co., Japan) This paper describes three major measures against CT saturation in busbar protective relays in Japan. Detection system during the unsaturation period of a CT (applied to phase-fault protective current differential relays) Positive/negative AND system (applied to ground-fault protective current differential relays) Air-core CT system Busbar protection, Current transformer saturation, Rogowski current transformer. 7

8 107 Busbar Differential Protection in Conjunction with A CT Compensation Algorithm Yong-Cheol Kang*/Jae-Sung Yun/Byung-Eun Lee/Sung-Il Jang, (Chonbuk National University, Korea) Yong-Gyun Kim, (Hankook IED Inc., Korea) Il-Dong Kim, (Doowon Technical College, Korea) This paper describes the design, evaluation, and implementation of a busbar differential protection relay that operates in conjunction with a current transformer (CT) compensating algorithm. Prior to saturation, the secondary current of a CT is not compensated. The compensating algorithm detects the start of first saturation based on the third-difference function of the current and estimates the core flux at the first saturation start by inserting the negative value of the third-difference function of the current into the magnetisation curve of a CT. Thereafter, it calculates the core flux and then the corresponding magnetising current in conjunction with the magnetisation curve. The calculated magnetising current is added to the measured secondary current to obtain the correct secondary current. The algorithm can estimate the correct current irrespective of the level of the remanent flux. In the proposed busbar protection scheme, a current differential relay with the single-slope operating characteristic is used based on the compensated current of the saturated CT. Test results indicate that the relay shows satisfactory performance for the various external and internal faults with CT saturation, particularly in the case of a progressive fault from a feeder fault to a busbar fault. The algorithm is implemented in a prototype relay based on a digital signal processor. The relay achieves greater stability on external faults, enhanced sensitivity on internal faults, and fast operation on internal faults with CT saturation. Busbar protection, Compensation, CT saturation, Magnetisation curve, Remanent flux, Sensitivity. 8

9 108 Fast and simple busbar protection for HV substation multiple busbar arrangements Bernard Glowocz / Jacek Manczak (ZPrAE, Poland) Adam Babs (Institute of Power Engineering, Poland) This paper describes the cost-effective solution of the busbar protection based on the well-known criteria of differential current and phase-comparison. The way in which these criteria have been implemented makes this solution very attractive from the point of view of availability, maintenance and economy. The paper also answers the question of how existing IEC communication solution can be expressed in terms of the IEC standard. Detailed specifications of data model and communication services are described together with practical implementation. Keyword Busbar protection, phase-comparison method, IEC gateway. 9

10 109 Distributed Bus Differential Protection as Integral Protection and Control System I. Ojanguren (Iberdrola Distribucion, Spain) A, Garcia / R. Quintanilla (ZIV Aplicaciones y Tecnología, S.A., Spain) As a result of the development of digital technology, a new step on protection and control integration may be reached. Bay Protection and control functions integrated with the differential bus bar protection, possible locations (type of substations), and advantages and difficulties are presented below from the point of view of the electrical utility (Iberdrola is installing nowadays the first equipment). The article provides new possibilities to play with cost reductions, reliability, commissioning and maintenance to increase the protection functionality at particular substations. A description of the progression from present to new design is shown from the manufacturer s point of view. Integration Protection Control Bus Bar Differential Protection (BBP) Subtransmission Refurbishment Cost Reduction. 10

11 110 Engineering and application improvements using a numerical Bus protection system Juan Carlos Sánchez (Red Eléctrica, Spain) Jorge Cardenas / Rosana Osorio (GE Multilin, Spain) Abstract The engineering and application of a new Bus Protection system in a Substation presents many and big challenges, particularly when the installation is made on an existing Substation that is normally in service. This paper presents the complete process of how a Utility establishes the different requirements for a new Bus Protection system in new and existing installations. The requirements are based not only on the replacement of the old equipment, but also on the advantages for replacement of other existing functions (such as Breaker Failure, Undervoltage, etc.) and the possibility to add new functions to improve the overall scheme. Other advantages are the flexibility that allows an implementation of nearly 80% of the projects with a single design, with the corresponding standardization of manufacturing and field testing. Finally, an analysis of the engineering time and cost reduction is made, among other added benefits as the reliability improvement, errors reduction in the process and flexibility in the change of the system from one substation to another one. Because the basic design is common and independently of the substation, minimum spare requirements are needed and the knowledge interchange for operation is improved. With the appropriate definition, it appears the possibility to have a live design that allows modifications with minimum changes and a dramatic reduction of the time needed for installation and testing. All these advantages minimize the outage time needed of the installation in case of replacement of old bus protection systems or implementation of the system in Substations that are in Operation. 11

12 111 Verification of Utility Requirements on Modern Numerical Busbar Protection by Dynamic Simulation Z. Gajić (ABB, Sweden) JP Wang / PW Gong / YS Xu (ABB China) ZX Zhou (CERPI, China) Power utilities are aware of the specific characteristics and requirements for their network. For this reason, they may require additional functionalities from the protective devices and secondary systems included in their power network. Therefore State Grid Cooperation of China (SG) requires a number of specific tests to be conducted on the protection system proposed for a particular application to prove the suitability of the proposed protection system for the specific application. Only when all of these tests are successfully passed, the protection system is certified for use in State Grid s network which has 70% of total installed capacity of China. China Electric Power Research Institute (CEPRI) is given the tasks for carrying on this type of dynamic tests to check if the protection system can fulfil SG s requirement by using the power system dynamic simulator in CEPRI s test centre. Relay Protection, Busbar Protection, Differential Protection. 12