MAXIMIZATION OF ENERGY GENERATED AT THE POWER PLANTS

Transcription

1 MAXIMIZATION OF ENERGY GENERATED AT THE POWER PLANTS OF THE NORTHERN REGION OF THE BRAZILIAN INTERCONNECTED POWER SYSTEM THROUGH THE SPECIAL PROTECTION SYSTEM - SPS ASSOCIATED TO XINGU - ESTREITO HVDC LINK S.L.A. Sardinha G.Cardoso Junior E.F. Oliveira A.F.C. de Aquino A.G. Massaud A.M. Silva P.E.M. Quintão R.S. Gomes L.C. Soares F.M. Silva M.A.N. Silveira A.R. Nunes S.B. Martins R.V. Faria V.G.C. Salles M.F. Silva L.D. Penna F.C.S. Araujo J.M.F. Ferreira J.C. Oliveira R. Treistman 1 / 25

2 In order to minimize dispatch restrictions at this plant and to enable the first direct current bipolar to be commissioned at the beginning of Introduction The integration of Belo Monte Hydro Power Plant to the Brazilian Interconnected Power System (BIPS) occurred without the planned expansion of the AC transmission system, due to the delay in important transmission facilities under the responsibility of ABENGOA agent, which would establish an alternative path for the generation of the power plants of the Northern region, especially for Belo Monte HPP. Belo Monte HPP 18 x 611 MW In order to minimize dispatch limitations to Belo Monte HPP and to enable the commissioning of the HVDC link connecting Xingu (PA) and Estreito (MG) substations at the beginning of 2018, ONS has developed preoperational studies considering this new configuration of the BIPS with parallel AC and DC interconnections, which led to the definition of control and systemic protection actions, based on a Special Protection System. Label of author s Company 2 / 25

3 Investigated Contingencies For the development of the Special Protection System, the following set of contingencies was analyzed and their corresponding logics defined: Single outages (Logic 1) and double outage (Logic 2) of 500 kv Xingu Tucuruí transmission line; Logic 5 Logics 1 and 2 Bipole 1 blocking (Logic 3); Double outages at the North-Southeast interconnection (Logic 4); Logic 3 Logic 4 Tripping of generating units of Belo Monte HPP (Logic 5) Label of author s Company 3 / 25

4 Logic 3 - Bipole 1 blocking (blocking of the last pole) In the Exporting North scenario (power flow from Xingu to Estreito), the blocking of Bipole 1 will produce an increase of the power flow in the North-Southeast interconnection, that may lead to the loss of synchronism between the systems of the North / Northeast and South / Southeast regions, with the consequent actuation of the out-of-step protections of the North-Southeast and Southeast-Northeast interconnections. In this case, the only possible action is the generation drop in the power plants of the Northern region. In this way, the necessary generation drop at Belo Monte HPP was identified through simulations as a function of the power order in Bipole 1, so as to guarantee the stability of the system. For this, the application of a short-circuit in the DC line followed by blocking of the bipole with the drop of generating units at Belo Monte HPP after 150 ms were used as assumptions. It should be emphasized that the selection of the generating units to be dropped, as well as eventual priority changes in the dropping row, can be performed through Belo Monte HPP HMI. 4 / 25

5 Logic 3 - Bipole 1 blocking (blocking of the last pole) In order to optimize the generation drop, two communication channels were implemented for the transmission of digital signals from the Master PLC at Serra da Mesa substation, informing the power flow level in the North-Southeast interconnection (FNS) to the "Station Control" of Bipole 1 located at Xingu substation, thus defining three operational ranges: Bits generated by the Master PLC at Serra da Mesa Substation Power Flow in the North-Southeast Interconnection Canal 1 Canal FNS 1000 MW MW < FNS 2000 MW 0 0 FNS > 2000 MW Obs.: If one or both channels are lost, signal 0 (zero) will be assumed, so that the highest generation drop will be conservatively executed. Label of author s Company 5 / 25

6 Logic 3 - Bipole 1 blocking (blocking of the last pole) The following table summarizes the Logic of generation drop according to the power order of Bipole 1 and the transmission level in the North-Southeast interconnection (FNS), for the Exporting North scenario. Power Order Generation Drop (nº of GU at Belo Monte HPP) (MW) FNS 1000 MW 1000 < FNS 2000 MW 2000 < FNS 4000 MW > Logic 3 is automatically disabled if both circuits of the 500 kv Xingu-Tucuruí LT are unavailable absent (Belo Monte HPP connected asynchronously to the SIN). In the Exporting Southeast scenario (power flow Estreito Xingu) there is no possible action in case of Bipole loss, so it is necessary to impose an operative restriction for the sum of Bipole 1 power order and the total power flow in the circuits of the 500 kv Miracema Colinas TL (FMCCO). Label of author s Company 6 / 25

7 Logic 3 - Bipole 1 blocking (blocking of the last pole) At the end of the wet season in the Northern region, Belo Monte Hydroelectric Plant, due to its run-of-river characteristic, is prone to operate with its generating units converted to synchronous compensators, while Tucuruí HPP, due to the storage capacity of its reservoir, will still continue with some generation capacity. If the number of generating units operating as generators at Belo Monte HPP is not sufficient to meet the necessary generation drop, Logic 3 will promote a complementary trip of machines at Tucuruí HPP. Considering that 2 units of Tucuruí HPP correspond approximately to 1 generating unit of Belo Monte HPP, the following strategy was adopted: - when the difference between the number of units to be dropped at Belo Monte HPP and the number of its units operating as generators is equal to 1, a digital signal is sent to make a complementary trip of 2 generating units at Tucuruí HPP - when the difference between the number of units to be dropped at Belo Monte HPP and the number of its units operating as generators is greater than 1, a digital signal is sent to make a complementary trip of 4 generating units at Tucuruí HPP. Tucuruí. 7 / 25

8 Logics 1 and 2 - Single and double outages of 500 kv Xingu Tucuruí transmission line 1) Exporting North Scenario (Power flow Xingu Estreito) - Power flow from Xingu to Tucuruí - Single outages at 500 kv Xingu-Tucuruí (Logic 1.a.1) This Logic performs a Run-up action on the bipole in order to limit the loading of the Fixed Series Capacitor of the remaining circuit to 2600 MW to meet its 2723 MVA overload limit. The Run-up action will be complemented by generation drop at Belo Monte HPP: - in case of exhaustion of the bipole overload capacity (33%) or other limitations in the AC / DC systems - if the telecontrol between Bipole Interface 2 and the Station Control is unavailable 8 / 25

9 Label of author s Company 9 / 25

10 Logics 1 and 2 - Single and double outages of 500 kv Xingu Tucuruí transmission line 1) Exporting North Scenario (Power flow Xingu Estreito) - Power flow from Xingu to Tucuruí - Single outages at 500 kv Xingu-Tucuruí TL (Logic 1.a.1) Should generation drop be executed, in addition to the Run-up action, if the amount of power to be dropped (Delta Power) does not correspond to an exact number of machines, Logic 1 uses the "over-trip" option. In case of total unavailability of Bipole 1, only generation drop action is performed. Label of author s Company 10 / 25

11 Logics 1 and 2 - Single and double outages of 500 kv Xingu Tucuruí transmission line 1) Exporting North Scenario (Power flow Xingu Estreito) - Power flow from Xingu to Tucuruí - Double outage of circuits at 500 kv Xingu-Tucuruí TL (Logic 2.a.1) This Logic performs a Run-up action on the bipole, in an amount equal to the total previous power flow on the circuits of Xingu-Tucuruí TL. If Bipole 1 does not have enough margin to fully perform the Run-up action, either due to the exhaustion of its overload capacity (33%) or limitations in the AC / DC systems, or if the telecontrol between Bipole Interface 2 and the Station Control is unavailable, the Run-up action will be complemented by generation drop at Belo Monte HPP. 11 / 25

12 Logics 1 and 2 - Single and double outages of 500 kv Xingu Tucuruí transmission line 1) Exporting North Scenario (Power flow Xingu Estreito) - Power flow from Xingu to Tucuruí - Double outage of circuits at 500 kv Xingu-Tucuruí TL (Logic 2.a.1) Should generation drop be executed, in addition to the Run-up action, if the amount of power to be dropped (Delta Power) does not correspond to an exact number of machines, Logic 2 uses the under-trip option. In case of total unavailability of Bipole 1, only generation drop action is performed. Obs.: Once both circuits of Xingu-Tucuruí TL are opened, the generation drop actions at Belo Monte HPP promoted by Logic 3 and the Run-up / generation drop actions promoted by Logic 4 are inhibited, since they would be innocuous, as Xingu substation and, as a consequence, Belo Monte HPP will be separated from the Brazilian Label of author s Interconnected Power System. Company 12 / 25

13 Logics 1 and 2 - Single and double outages of 500 kv Xingu Tucuruí transmission line 1) Exporting North Scenario (Power flow Xingu Estreito) - Power flow from Tucuruí to Xingu - Single outages at 500 kv Xingu-Tucuruí TL (Logic 1.a.2) This Logic performs a Run-back action on the bipole in order to limit the loading on the Fixed Series Capacitor of the remaining circuit to 2600 MW to meet its 2723 MVA overload limit. This action is limited to the minimum power order of the bipole (10% P nom ). If the telecontrol between Bipole 2 Interface and the Station Control is unavailable, there will be no Run-back action. In this case, the total power flow in the circuits of 500 kv Xingu-Tucuruí TL, from Tucuruí to Xingu, should be limited to 2600 MW through Operating Instructions. Label of author s Company 13 / 25

14 Logics 1 and 2 - Single and double outages of 500 kv Xingu Tucuruí transmission line 1) Exporting North Scenario (Power flow Xingu Estreito) - Power flow from Tucuruí to Xingu - Double outage of circuits at 500 kv Xingu-Tucuruí TL (Logic 2.a.2) This Logic performs a Run-back action on the bipole, in an amount equal to the total previous power flow on the circuits of Xingu-Tucuruí TL. Since the minimum power order of the Bipole is equal to 10% Pnom, if the difference between Bipole power order and the total power flow in Xingu-Tucuruí TL is less than this minimum value or if the telecontrol between Bipole 2 Interface and the Station Control is unavailable, the Run-back action cannot be fully performed and the Bipole 1 will be blocked. - If Bipole Tuc-Xgu < 10% P nom : Bipole blocking - If Bipole Tuc-Xgu 10% P nom : Run-back equal to the total previous power flow in the circuits of Xgu-Tuc TL Note: In order to guarantee the stability of the N-SE interconnection, if Tucuruí-Xingu power flow exceeds 400 MW, 2 generating units are tripped at Tucuruí HPP. If it exceeds 600 MW, 4 generating units are tripped at Tucuruí HPP. Label of author s Company 14 / 25

15 Logics 1 and 2 - Single and double outages of 500 kv Xingu Tucuruí transmission line 2) Exporting Southeast Scenario (Power flow Estreito Xingu) - Power flow from Xingu to Tucuruí In this scenario, the power flow at 500 kv Xingu-Tucuruí TL will always run from Xingu to Tucuruí. - Single outages at 500 kv Xingu-Tucuruí (Logic 1.b.1) This Logic performs a Run-back action on the bipole in order to limit the loading on the Fixed Series Capacitor of the remaining circuit to 2600 MW to meet its 2723 MVA overload limit. This action is limited to the minimum power order of the bipole (10% P nom ). If the telecontrol between Bipole 2 Interface and the Station Control is unavailable or if there is no communication between Xingu and Estreito terminals, there will be no Run-back action. In this case, the total power flow at the circuits of 500 kv Xingu-Tucuruí TL, from Xingu to Tucuruí, should be limited to 2600 MW through Operating Instructions. 15 / 25

16 Logics 1 and 2 - Single and double outages of 500 kv Xingu Tucuruí transmission line 2) Exporting Southeast Scenario (Fluxo Estreito Xingu) - Power flow from Xingu to Tucuruí - Double outage of circuits at 500 kv Xingu-Tucuruí TL (Logic 2.b.1) This Logic performs a Run-back action on the bipole, in an amount equal to the total previous power flow on the circuits of Xingu-Tucuruí TL. Since the minimum power order of the Bipole is equal to 10% Pnom, if the difference between Bipole power order and the total power flow in Xingu-Tucuruí TL is less than this minimum value or if the telecontrol between Bipole 2 Interface and the Station Control is unavailable, the Run-back action cannot be fully performed and the Bipole 1 will be blocked. - If Bipole Xgu-Tuc < 10% P nom : Bipole blocking - If Bipole Xgu-Tuc 10% P nom : Run-back equal to the total previous power flow in the circuits of Xgu-Tuc TL 16 / 25

17 Logic 4 Double outages at the North Southeast Interconnection Currently, an Emergency Control Scheme is implemented in the North - Southeast interconnection, composed of a network of PLC installed in several substations on its path and a Master PLC located at Serra da Mesa substation. Since Bipole 1 is embedded in the AC transmission system, running in parallel with the North-Southeast interconnection, it offers the possibility of contributing to the pre-existing Emergency Control Scheme, through a Run-up action, for the elimination of overloads on the remaining circuits for contingencies in any of its segments. Thus, should double outages occur in the North-Southeast interconnection (or single outages in case of unavailability of circuits), Logic 4 promotes the following actions, in complement to the previously mentioned Emergency Control Scheme: - In the Exporting North Scenario (from Xingu to Estreito): Run-up in the Bipole/ generation drop at Belo Monte - In the Exporting Southeast Scenario (from Estreito to Xingu): Run-up in the Bipole.. Scenario Digital Signal (Pulse) (MW) Logic 4 Action Exp N Type Run-up / Gen Drop (*) Type Run-up Exp SE Type Run-up (*) the actions of Run-up and generation drop (if the Run-up margin is not sufficient) are executed simultaneously 17 / 25

18 Logic 4 Double outages at the North Southeast Interconnection 1) Exporting North Scenario (Power flow Xingu Estreito) 1.A Double outages at the North Southeast Interconnection As previously mentioned, its is currently implemented in the North - Southeast interconnection an Emergency Control Scheme, composed of a network of PLC installed in several substations on its path and a Master PLC located at Serra da Mesa substation. This ECS promotes generation drop actions at Serra da Mesa, Tucuruí, Estreito, Lajeado and Peixe Angical Hydro Power Plants, in addition to the tripping of one generating unit at Belo Monte HPP. With the installation of Bipole 1, the current tripping of 4 generating units at Tucurui HPP was maintained and a Run-up action was implemented to replace the generation drop at Belo Monte HPP (Type 1 signal). The generation drop at Belo Monte HPP by Logic 4 will only be executed in case of unavailability of the bipole or if the remote control between Bipole 2 Interface and the Station Control is unavailable. 18 / 25

19 Logic 4 Double outages at the North Southeast Interconnection 1) Exporting North Scenario (Power flow Xingu Estreito) 1.B Loss of large generation blocks in the Southeastern and Southern regions The loss of large generation blocks in the Southeastern and Southern regions (e.g., loss of bipole from the Madeira River Complex or 765 kv transmission elements associated with Itaipu HPP) may lead to the opening of the North / Southeast and North /Northeast interconnections. In order to reduce the energy transfer limitations from the Northern subsystem (Exporting North scenario), an additional logic was implemented, consisting on the implementation and activation of an Out-of-Step Protection on circuit C1 of the 500kV Gurupi - Serra da Mesa TL, at Gurupi substation, sending a signal to trip four generating units at Tucuruí HPP. This signal was also incorporated into Logic 4 of the SPS (Type 1 signal). 19 / 25

20 Logic 4 Double outages at the North Southeast Interconnection 2) Exporting Southeast Scenario (Power flow Estreito Xingu) In order to face the single outage of elements of the North-Southeast interconnection, the total power flow at Miracema-Colinas 500 kv TL circuits (FMCCO) was limited to 4000 MW. In the event of a double outage in this interconnection (or a single outage being one circuit unavailable), depending on the transmitted power level, a Run-up action on the Bipole 1 will be necessary in order to limit the loading on the Fixed Series Capacitor of the remaining circuit of 500 kv Colinas Miracema TL to 1950 MVA (50% overload), so that it does not evolve to a triple loss. In order to optimize the Run-up action, two communication channels were implemented for the transmission of digital signals from the Master PLC at Serra da Mesa substation, informing the power flow level in the North-Southeast interconnection (FMCCO) to the "Station Control" of Bipole 1 located at Xingu substation,. 20 / 25

21 Logic 4 Double outages at the North Southeast Interconnection 2) Exporting Southeast Scenario (Power flow Estreito Xingu) Notes: 1) In this scenario, if the bipole is out of operation, the generation drop action promoted by Logic 4 at Belo Monte HPP should be inhibited so as not to compromise the stability of the North - Southeast interconnection. Thus, when this scenario is configured and bipole is out of operation, Logic 4 must be disabled by means of a switch accessible in the HMI, following an Operation Instruction. 2) In order to avoid that the blocking of the bipole may cause an undesirable actuation of the out-of-step protection installed on circuit C1 of 500 kv Gurupi-Serra da Mesa TL, tripping four generating units at Tucuruí HPP, a communication channel between Xingu and Tucuruí substations was used to inhibit for 10 s this generation tripping. This delay was defined based on dynamic simulations to identify the excursion time of the electric center within the out-of-step protection characteristic when the blocking of the bipole occurs. 21 / 25

22 Logic 5 - Tripping of generating units of Belo Monte HPP When both 500 kv Xingu-Tucuruí LT circuits are out of operation, Manaus / Macapá area, together with Belo Monte HPP, stay connected asynchronously to the Brazilian Interconnected Power System through Bipole 1. In this configuration, in the event of tripping of generating units of Belo Monte HPP, Logic 5 executes a Run-back action on Bipole 1 in an amount equal to the lost generation, in order to reestablish the load- generation balance in the islanded area. In this configuration, until the AC interconnection is re-established, the generation drop actions promoted by Logic 3 and Run-up / generation drop promoted by Logic 4 will be unnecessary and should therefore be inhibited.. 22 / 25

23 Logic 5 - Tripping of generating units of Belo Monte HPP As previously mentioned, in case of double outage of circuits of 500 kv Xingu-Tucuruí TL, with the power flow running from Xingu to Tucuruí, a Run-up action will be promoted in Bipole 1 (Logic 2.a.1) and, if there is not enough margin for the execution of this action, it wiil be complemented with generation drop at Belo Monte HPP. In order to prevent this generation drop from giving rise to an undue Run-back action by Logic 5, a 10 s delay was introduced when the double loss of Xingu-Tucuruí is characterized. 23 / 25

24 Implementation Aspects and Field Tests of the Special Protection System Given the urgency of the Xingu - Estreito HVDC link start-up and the short time available for the implementation of the Special Protection System, it was necessary to find solutions based on the existing infrastructure, involving, consequently, numerous installations, with the participation of several generation and transmission agents (FURNAS, ELETRONORTE, TAESA, TBE, ISOLUX / LXTE, BMTE and NESA). With this objective, the PLC network installed along the North - Southeast interconnection and the existing communication infrastructure starting from Marabá substation was used. It is worth mentioning the enormous effort and praiseworthy proactivity of the Agents to overcome obstacles to the achievement of this objective. The five Logics that make up the Special Protection System were tested on the Real Time Simulator and commissioned in the field, through exhaustive tests carried out on December 08 and 09, As a result of these tests and due to the complementary dynamic studies developed, improvements were introduced, which were once again tested on RTDS and field-tested in the period from March 17 to 19, 2000, comprising 34 tests. This SEP will be expanded to incorporate the 2nd bipole (Xingu - Rio Terminal). 24 / 25

25 Thanks. 25 / 25