Analyzing TRV of CBs on Mato Grosso Transmission System (ELETRONORTE) due to the Fixed Series Compensation installation

Transcription

1 1 Analyzing TRV of CBs on Mato Grosso Transmission System (ELETRONORTE) due to the Fixed Series Compensation installation A. L. P. de Oliveira Abstract FACTS is the acronym for Flexible AC Transmission Systems and it refers to a group of resources used to overcome certain limitations in the static and dynamic transmission capacity of electrical networks. The main purpose of these systems is to supply the network as quickly as possible with inductive or capacitive reactive power that is adapted to its particular requirements, while also improving the transmission quality and the efficiency of the Power Transmission System. The objective of this paper is to present the criteria and conclusions of the Transient Recovery Voltage (TRV) studies realized for the installation and operation of 03 (three) Fixed Series Compensation (FSC) at Barra do Peixe 230 kv Substation, integrated at the Mato Grosso Transmission System (ELETRONORTE). The simulations were accomplished through detailed representations of the power transmission system, as well as the FSCs protection and control system, using as simulation tools the programs Alternative Transient Program (ATP) and PSS Network Torsion Machine (NETOMAC). Index Terms Equipment, High Voltage (HV), Circuit Breaker, Transient Recovery Voltage (TRV), Fixed Series Compensation (FSC), Flexible AC Transmission System (FACTS), Power Transmission System. C I. INTRODUCTION onsidering the environmental and economical difficulties to construction of new transmission lines, the use of Fixed Series Compensation (FSC) has turned into a common practice of power transmission companies in Brazil. The series compensation is presented as the best choice, because not only it makes possible increasing power transmission capacity as well as it stabilizes the interconnected energy nets through reduction of the impedance of the transmission line. The presence of FSCs usually causes rise of the Transient Recovery Voltage (TRV) in the circuit breakers of transmission lines (TL). To be able to assess the impact of the FSCs on the installation of equipment in these circuits, studies of electromagnetic transients simulations were conducted using the programs Alternative Transient Program (ATP) [1] and PSS Network Torsion Machine (NETOMAC) [2]. The 03 (three) FSCs have the following characteristics: André Luiz Pereira de Oliveira is with Siemens Ltda. Energy Sector Power Transmission - Power Transmission Solutions (E T PS), Avenida Mutinga, 3.800, 2 o Floor Pirituba São Paulo/SP ZIP CODE Brazil ( andreluiz.oliveira@siemens.com). FSC C2 [230 kv / 35 MVAr (CD 30%)] installed at Barra do Peixe Rondonópolis 230 kv TL Circuit 1; FSC C3 [230 kv / 120 MVAr (CD 50%)] installed at Barra do Peixe Rondonópolis 230 kv TL Circuit 2; FSC C4 [230 kv / 37 MVAr (CD 30%)] installed at Barra do Peixe Rio Verde 230 kv TL Circuit 1. The main purpose of the realized studies is to verify the adequacy of the high voltage circuit breakers of 03 (three) transmission lines (TLs) of Barra do Peixe 230 kv Substation, that received the installation of these 03 (three) new FSCs. A comparison was made in the power system configurations of all the values obtained without the presence of the new FSCs against the values obtained with the presence of the new FSCs (inserted in the TLs). Several types of faults in different locations of the TLs were simulated, aiming to analyze the higher voltage stresses (worst cases) to the HV circuit breakers. The severity of TRV effect is evaluated through the simulation of the circuit breakers opening for eliminating of defects in the power system. II. TRANSIENT RECOVERY VOLTAGE (TRV) Upon the faults occurrence in the electrical system, during the high voltage circuit breakers s contacts separation to interrupt the short-circuit current, the fault current does not stop instantly due to the presence of an electric arc between the contacts that guarantee the continuity of this current. The industrial frequency sinusoidal component of the short-circuit current has natural crossings through zero, during which this electric arc will be extinguished. The re-ignition of this electric arc may or may not occur during the next semi-cycle of the sinusoidal component, depending on the speed of the dielectric between the contacts recovers the insulating properties [3]-[4]. If the voltage developed across the high voltage circuit breakers contacts during this semi-cycle exceeds the dielectric insulating capacity, the electric arc re-ignition will occur, which will remain in the system until the next zero current crossing. The voltage developed between the circuit breakers contacts after the short-circuit current interruption is known as Transient Recovery Voltage (TRV). Due to the inductive and capacitive system s characteristics, the TRV has, during the initial, high frequency components superimposed on the

2 2 fundamental component, which typically decays within a few cycles. Such components are particularly responsible for exceeding the dielectric capabilities in the circuit breaker contacts [4]. While several academic examples of TRV calculation consider the electrical system represented by RLC circuits, to determine the higher frequency components present in the voltage initial growth period, elements that presents a high complexity degree should be represented, which does not permit a simple RLC network modeling [4]. Naturally the larger the number of information concerning the transmission system under study, the more detailed the representation in simulation tools and more accurate results will be obtained from the TRV. III. MATO GROSSO TRANSMISSION SYSTEM (ELETRONORTE) The Mato Grosso Transmission System (ELETRONORTE) was analyzed in two different configurations, first in the year of Fixed Series Compensation (FSC) energization configuration (in the year of 2007) and second in the future configuration (in the year of 2014). In these two configurations a detailed modeling of 500 kv and 230 kv voltage levels were used, and the external system was modeled by Thevénin equivalents, with the power capacity calculated with the use of specific computer programs. Fig. 1 presents the Configuration 2007 and Fig. 2 presents the Configuration 2014, both highlighting in red color the transmission lines where the Barra do Peixe 230 kv FSCs were installed [5]. Fig. 1. Mato Grosso Transmission System in Configuration 2007 The Configuration 2014 was basically the same as Configuration 2007, but presenting the following main important modifications on the Mato Grosso Transmission System [5]: New 500kV transmission circuit between the Cuiabá Ribeirãozinho Intermediária and Hydroelectric Power Plant Itumbiara (approximated 808 km extension); Insertion of the Hydroelectric Power Plant (HPP) Agua Limpa (13.8 kv / 170 MVA) interconnected to the Barra do Peixe 230 kv Substation; Insertion of the Hydroelectric Power Plant (HPP) Torixoréu (13.8 kv / 102 MVA) interconnected to the Barra do Peixe 230 kv Substation; Insertion of the Hydroelectric Power Plant (HPP) Couto Magalhães (13.8 kv / 72 MVA) interconnected to the Couto Magalhães 230 kv Substation. Fig. 2. Mato Grosso Transmission System in Configuration 2014 IV. TRANSIENT RECOVERY VOLTAGE ANALYSIS: CRITERION AND METHODOLOGY The Transient Recovery Voltage (TRV) analysis has the objective to verify if during the faults occurrence on the electrical system at critical operation conditions, the shortcircuit currents values are sufficient for the Spark Gaps trigger and bypass of the Fixed Series Compensation (FSC). Likewise, we want to examine whether these values in situations where minimum trigger currents do not occur, the high voltage circuit breakers are required to withstand the defects elimination. A. Initial considerations of TRV Analysis Upon the most severe Transmission Line s (TL) internal short-circuits where the FSCs are installed, the protection system will take off (isolate) the FSCs through the Spark Gap trigger and subsequent bypass (circuit breakers closing). In the simulations realized are considered that internal faults near (terminal and Kilometric) to the FSCs where the currents reach the minimum trigger values, the Spark Gaps and bypass breakers will act within milliseconds, whereas the TLs protections and their respective circuit breakers will act at least 02 (two) to 03 (three) cycles, this means tens of milliseconds. This means that the TL s circuit breakers will therefore face the condition of FSC out of the network when eliminating the defects. For more distant faults in relation to the FSCs location (remote), if the minimum trigger current values do not occur, the TL s circuit breakers should support this operational condition and eliminate the internal defects. B. Minimal Short-Circuit Currents for Spark-Gaps Trigger The minimal short-circuit currents for Spark Gap trigger were defined in the FSCs project and are presented below [6]:

3 3 FSC C2 [230 kv / 35 MVAr (CD 30%)]: 1.28 ka; FSC C3 [230 kv / 120 MVAr (CD 50%)]: 1.24 ka; FSC C4 [230 kv / 37 MVAr (CD 30%)]: C. types applied for TRV analysis 1.21 ka. The following fault types were applied to the analysis of Transient Recovery Voltage (TRV) [6]-[7]: Terminal s: those faults very close to the substation where the FSC is installed. In these cases three pole () faults and three pole ground () faults were simulated, because they are defects that provide the most severe demands for the TL s circuit breakers; Kilometric s: those faults just a few Kilometric away (up to 5 km) to the substation where the FSC is installed. In these cases single pole () faults were simulated, because it was possible to coordinate the faults elimination with the TL s circuit breakers last pole opening, thus maximizing the requests severity; Remote s: those faults away from the substation where the FSC is installed. In these cases all fault types were simulated for TL s circuit breakers verification. In the simulations it was considered that all faults are applied to stead state operation and the poles opening is realized for the waveforms analysis. This procedure does not consider the transients that occur immediately after shortcircuits, because the influence of these occur in very specific situations, for example, faults in very short TLs [8]. D. Circuit Breakers Table I presents the TL s circuit breakers nominal data [7]: 230 kv Transm Lines Nomina l Current Short Circuit First Pole Factor TABLE I TRANSMISSION LINES NOMINAL DATA B. Peixe- Rond. C1 (1x636MCM ) B. Peixe- Rond. C2 (2x795MCM ) B. Peixe-Rio Verde C1 (1x556MCM ) A A A 31.5 ka 31.5 ka 31.5 ka 1,3 1,5 1,5 E. TRV according to ABNT NBR IEC :2006 The values of Transient Recovery Voltage (TRV) used as reference for the analysis are the presumed on the standard ABNT NBR IEC :2006 [9] and presented in Tables II and III. TABLE II TRV PRESUMED VALUES FOR TERMINAL FAULTS AT 245 KV Short Circuit Current [%] First ref. Voltage [kv] 100% 60% 30% 10% 195 kv 195 kv Time [µs] 98 µs 65 µs TRV [kv] 364 kv 390 kv 400 kv 398 kv Time [µs] 392 µs 390 µs 80 µs 57 µs Growing Rate [kv/µs] 2 kv/µs 3 kv/µs 5 kv/µs 7 kv/µs TABLE III TRV PRESUMED VALUES FOR KILOMETRIC FAULTS AT 245 KV Short Circuit Current [%] 100% First ref. Voltage [kv] 150 kv Time [µs] 75 µs TRV [kv] 280 kv Time [µs] 300 µs Growing Rate [kv/µs] 2 kv/µs OBS: for kilometric faults ABNT estabilishes an unique TRV value at initial moments, associated to the first voltage levels at the Transmission Lines. V. TRANSIENT RECOVERY VOLTAGE ANALYSIS: THE MATO GROSSO TRANSMISSION SYSTEM RESULTS For the Transient Recovery Voltage (TRV) analysis a 4 (four) parameters representation was used [9]: U1 = first reference voltage in kilovolts (kv); t1 = time to reach the first reference voltage in microseconds (µs); Uc = second reference voltage (TRV peak value) in kilovolts (kv); t2 = time to reach the second reference voltage in microseconds (µs). These parameters determine the TRV waveforms and provide a measure of its severity to the TL s circuit breakers. If the waveform obtained is less than the ABNT Standard definitions (Tables II and III), the circuit breakers are dimensioned to withstand the TRV demands. The 2 (two) Mato Grosso Transmission System s configurations were considered (Fig. 1 - Configuration 2007 and Fig. 2 - Configuration 2014) [5]. Besides the normal system condition of the system (no emergencies), emergencies situations were analyzed in order to verify TRV requests in a system degraded

4 4 condition, reducing the short circuit capacity [7]. The emergencies conditions (informed by ELETRONORTE) were: 2007 Configuration: absence of 230 kv TL Ribeirãozinho Barra do Peixe (double circuit) = ; 2014 Configuration: absence of 230 kv TL Ribeirãozinho Barra do Peixe (double circuit) = ; 2014 Configuration: absence of the future Hydroelectric Power Plant (HPP) Torixoréu (13.8 kv / 102 MVA) =. The short-circuit currents were calculated to verify the Spark Gap trigger and the consequent FSCs bypass. For terminals and kilometric faults the short-circuit currents were sufficient to trigger, and the circuit breakers didn t suffer TRV problems to the defects elimination. Tables IV to VI present the TRV values for the cases which the remote faults calculation didn t reach the minimum Spark Gap trigger current, meaning that the TL s circuit breakers would be required to eliminate the defects with the FSC inserted in the TLs, in both 2007 and 2014 configurations [6] - [7]- [8]. TABLE IV TRV FOR REMOTE FAULTS IN THE 230 KV TL BARRA DO PEIXE RONDONÓPOLIS CIRCUIT 1 - FSC C2 [230 KV / 35 MVAR (CD 30%)] DGF TL stretch [km] until 180 km After 120 km After 120 km Icc [kap] TRV [kvp] Operat. Cond. 2,14 kap 459 kvp ,22 kap 470 kvp ,34 kap 417 kvp ,23 kap 482 kvp ,24 kap 494 kvp ,54 kap 408 kvp ,58 kap 400 kvp ,16 kap 499 kvp ,17 kap 501 kvp ,36 kap 449 kvp ,28 kap 516 kvp ,29 kap 518 kvp ,38 kap 458 kvp 2014 until 195 km 2,31 kap 496 kvp ,93 kap 434 kvp ,33 kap 435 kvp ,42 kap 436 kvp 2014 TABLE V TRV FOR REMOTE FAULTS IN THE 230 KV TL BARRA DO PEIXE RONDONÓPOLIS CIRCUIT 2 - FSC C3 [230 KV / 120 MVAR (CD 50%)] TL stretch [km] After 110 km After 110 km After 110 km until 115 km After 185 km After 185 km After 155 km After 80 km After 200 km After 200 km Icc [kap] TRV [kvp] Operat. Cond. 3,76 kap 605 kvp ,79 kap 607 kvp ,36 kap 512 kvp ,78 kap 663 kvp ,81 kap 666 kvp ,84 kap 563 kvp ,45 kap 568 kvp ,38 kap 569 kvp ,31 kap 496 kvp ,67 kap 471 kvp ,73 kap 682 kvp ,79 kap 684 kvp ,16 kap 636 kvp ,13 kap 470 kvp ,66 kap 439 kvp ,51 kap 613 kvp ,54 kap 614 kvp ,33 kap 492 kvp 2014

5 5 After 80 km until 110 km 4,36 kap 540 kvp ,86 kap 472 kvp 2014 TABLE VI TRV FOR REMOTE FAULTS IN THE 230 KV TL BARRA DO PEIXE RIO VERDE CIRCUIT 1 - FSC C4 [230 KV / 37 MVAR (CD 30%)] TL stretch [km] until 185 km until 241 km After 140 km until 170 km After 140 km until 175 km until 220 km until 220 km until 210 km until 210 km After 140 km until 190 km After 170 km After 170 km until 190 km Icc [kap] TRV [kvp] Operat. Cond. 2,21 kap 469 kvp ,23 kap 471 kvp ,26 kap 483 kvp ,28 kap 498 kvp ,22 kap 511 kvp ,26 kap 505 kvp ,36 kap 481 kvp ,32 kap 517 kvp ,33 kap 518 kvp ,38 kap 482 kvp ,31 kap 500 kvp ,33 kap 495 kvp ,42 kap 461 kvp 2014 The simulations results presented that the Fixed Series Compensation (FSCs) should be bypassed for three pole () remote faults, three pole to ground () remote faults, double pole to ground () remote faults and single pole () faults. Tables VII and VIII presents the TRV results evaluation due to the FSCs installation [10]. TABLE VII TRV EVALUATION DUE TO THE FIXED SERIES COMPENSATIONS (FSCS) INSTALLATION AT 230KV TLS 2007 CONFIGURATION (FIG. 1) 230 kv TL description B.Peixe Ron Stretch with Stretch without (TRV problem) 0 until 145km until 145km until 120km 120 until 180 km 0 until 145km until 145km until 110km until 110km until 140km 140 until 185 km 0 until 140km 140 until 190 km TABLE VIII TRV EVALUATION DUE TO THE FIXED SERIES COMPENSATIONS (FSCS) INSTALLATION AT 230KV TLS 2014 CONFIGURATION (FIG. 2) 230 kv TL description B.Peixe Ron Stretch with Stretch without (TRV problem) 0 until 165km until 165km until 155km until 150km until 185km until 185km until 160km until 155km until 80km 80 until 110 km 0 until 160km 160 until 220 km 0 until 160km 160 until 220 km 0 until 150km 150 until 210 km

6 6 VI. CONCLUSIONS The Brazilian Transmission System is very peculiar, covering great territorial extension and presenting an expressive predominance of the hydroelectric power generation. Those conditions enlarge the transmission importance, which is responsible for the integration between power generation sources and distant load centers. The power transmission systems make possible to gain advantage of diversities, providing energy optimization, increasing system safety and reducing the need of investments in new power generation. Flexible AC Transmission Systems (FACTS) is a technology that responds to these needs. It significantly alters the way power transmission systems are developed and controlled together with improvements in asset utilization, systems flexibility and performance The main purpose of this paper was to present the criteria and conclusions of the Transient Recovery Voltage (TRV) studies realized for the installation and operation of 03 (three) Fixed Series Compensation (FSC) at Barra do Peixe 230 kv Substation, integrated at the Mato Grosso Transmission System (ELETRONORTE). The analysis of the TRV calculation results generated the following conclusions: High Voltage Circuit Breakers of Barra do Peixe Rondonópolis 230 kv Transmission Line - Circuit 1 [FSC C2 / 230 kv / 35 MVAr (CD 30%)]: it is necessary the Spark Gap trigger and FSC bypass before the transmission line circuit breaker trip command, always when three pole () remote faults or double pole () remote faults in both power system configurations (2007 and 2014); \ High Voltage Circuit Breakers of Barra do Peixe Rondonópolis 230 kv Transmission Line - Circuit 2 [FSC C3 / 230 kv / 120 MVAr (CD 50%)]: it is necessary the Spark Gap trigger and FSC bypass before the transmission line circuit breaker trip command, always when three pole () remote faults or double pole () remote faults in both power system configurations (2007 and 2014) and single pole () fault due to HPP Torixoréu and/or duplication of the Itumbiara-Intermediária-Ribeirãozinho-Cuiabá 500 kv Transmission Line on configuration 2014; High Voltage Circuit Breakers of Barra do Peixe Rio Verde 230 kv Transmission Line - Circuit 1 [FSC C4 / 230 kv / 37 MVAr (CD 30%)]: it is necessary the Spark Gap trigger and FSC bypass before the transmission line circuit breaker trip command, always when three pole () remote faults or double pole () remote faults in both power system configurations (2007 and 2014). Logics and delays were inserted in the transmission lines s (TLs) protection system that ensured the Spark Gap trigger and FSCs bypass on the situations above described before the TLs trip command and HV circuit breakers opening. This action was implemented independent of the FSCs Protection and Control System functioning. So there was no need to change the HV circuit breakers already installed in the TLs. Through the 03 (three) new FSCs installation at Barra do Peixe 230 kv Substation, the Mato Grosso Transmission System (ELETRONORTE) had the transmission capacity increased and improved system stability. VII. REFERENCES [1] M. C. D. Tavares, P G. Campos, P. Prado, Alternative Transient Program (ATP) - Practical Summarized Guide (in Portuguese), UNICAMP - Universidade Estadual de Campinas / Faculdade de Engenharia Elétrica e de Computação FEEC / Departamento de Sistemas de Controle e Energia - DSCE, Campinas-SP-Brasil, [2] SIEMENS AG, PSS NETOMAC Professional Network Planning Software Instruction Manual, Power Transmission and Distribution, Erlangen, Germany, [3] ABNT (Brazilian Technical Standards Association) - High Voltage Circuit Breakers, ABNT Standard NBR: 7118:1994, Brazil [4] M. C. Lima, F. R. Alves, S. Henschel, L. Kirschner, Transient Electromagnetic Studies for Impact Assessment of 500 kv Series Capacitor Banks regarding the Transient Recovery Voltage imposed at Operation Equipments (in Portuguese), XVII SNPTEE Seminário Nacional de Produção e Transmissão de Energia Elétrica, Curitiba-PR- Brasil, [5] Norte Sul Engenharia, Mato Grosso (Brazil) Transmission System Barra do Peixe SS 230 kv Fixed Series Compensations Electrical Data and System Parameters (in Portuguese), Norte Sul Engenharia / ELETRONORTE - Centrais Elétricas do Norte do Brasil S.A., Brasília DF Brazil, [6] S. Henschel, G. Khun, M. Moraes, A. L. P. de Oliveira, Eletromagnetic Studies for the Barra do Peixe Power System ELETRONORTE - Brazil, Power Transmission and Distribution Service Power Technologies International PTD SE PTI, Erlangen - Germany, [7] Norte Sul Engenharia, Mato Grosso (Brazil) Transmission System Barra do Peixe SS 230 kv Fixed Series Compensations Studies of Transient Recovery Voltage (TRV) associated to the FSCs (in Portuguese), Norte Sul Engenharia / ELETRONORTE - Centrais Elétricas do Norte do Brasil S.A., Brasília DF Brazil, [8] J. T. Honda, W. S. Pinto, A. D`Juz, C. Machado Junior, E. H. Rose, Evaluation of Transient Recovery Voltage (TRV) for 550 kv Circuit Breakers of HPP Tucuruí Second Phase (in Portuguese), XV SNPTEE Seminário Nacional de Produção e Transmissão de Energia Elétrica, Foz do Iguaçu-PR-Brasil, [9] ABNT (Brazilian Technical Standards Association) - High Voltage Equipments Part 100: HVAC Circuit Breakers, ABNT Standard NBR IEC :2006, Brazil [10] Norte Sul Engenharia, Barra do Peixe SS 230 kv Fixed Series Compensations Minimal Short-Circuits Currents for Spark-gaps Triggers (in Portuguese), Norte Sul Engenharia / ELETRONORTE - Centrais Elétricas do Norte do Brasil S.A., Brasília DF Brazil, VIII. BIOGRAPHY André Luiz Pereira de Oliveira was born in São José do Rio Preto/SP, Brazil in He received his BSEE degree in electrical engineering from the Federal Engineering School of Itajubá (EFEI), Brazil, in Obtained Specialist's title in Power Systems Protection and MSc in Electrical Engineering in 2003 and 2007 respectively, from Federal University of Itajubá (UNIFEI), Brazil. Project Management Professional (PMP ) certified by the Project Management Institute - PMI of the United States of America (USA) since He works at SIEMENS Ltda. as a Project Manager since 2001 at the Energy Sector Power Transmission - Power Transmission Solutions (E T PS), responsible for the supplying of "turn-key" High Voltage Direct Current Systems (HVDC), High Voltage Substations, Protection, Control and Supervision Systems, and Power Compensation Systems (FACTS).