1. 1 Engr. Jonathan U. Ndiagwalukwe Executive Director (S/O), TCN STRATEGIES FOR MITIGATING INCIDENCE OF SYSTEM COLLAPSE By Enugu Power Summit 11 th -12th May, 2012

2. ● Introduction OUTLINE 2 ● The Grid System ● System Frequency Management ● System Collapses in Retrospect ● System Collapse Mitigation Strategies ● Concluding Remarks ● Causes of System Collapse ● Grid Instability

3. ● A system is an inter-related set of components that work together within an identifiable boundary, as a coherent whole, to achieve an overall goal. INTRODUCTION 3 ● In the case of a power system, when all or some of the functional components have failed as a result of perturbations,System Collapse is said to have occurred. ● The scope of failure determines whether the collapse is total or partial.

4. ● System Operation States INTRODUCTION (CONT’D) 4 ► Normal State: The power system operates in normal state when system frequency and voltages are close to their nominal values. There is adequate generation to cope with load demand. ► Alert State: It is the state of an electric power system in which an event will result in loss of load, stressing of system components beyond their ratings, bus voltages and system frequency outside tolerances, cascading voltage instability etc. The Grid Code stipulates that the grid has to be in the normal state at least 90% of the time, This is hardly the case with our grid

5. ● An electric power grid is a system of power generation plants, transmission substations and lines interconnected in a mesh for efficient delivery of electricity The Grid System 5

6. TO SAKETE ONITSHA KAINJI JEBBA/GS JEBBA/TS SHIRORO Ikeja Akure Uyo Birnin Kebbi Minna Kaduna Abuja Jos Bauchi Gombe Damaturu Maiduguri Kano IIorin Ado Ekiti Enugu Akwa Ibadan Sokoto Gusau Katsina Hadejia Jalingo Yola Abakaliki Calabar JIGAWA KANO KATSINA SOKOTO ZAMFARA KEBBI KWARA KADUNA NIGER NASSARAWA TARABA YOBE PLATEAU EBONYI CROSS RIVER OSUN BAYELSA EDO DELTA ONDO OYO IMO ADAMAWA BORNO GOMBE BAUCHI EKITI LAGOS ATLANTIC OCEAN NIGER REPUBLIC OF BENIN REPUBLIC OF CAMEROON REPUBLIC OF CHAD SAPELE P/ST. DELTA POWER ST. OGUN Osogbo NIGERIA Potiskum Niamey 132 kV Mambila Bali AFAM POWER ST. Asaba Benin EGBIN P/ST. Lokoja ABUJA AJAOKUTA Lafia Makurdi MAKURDI BENUE KOGI ENUGU Aliade ABIA AKWA IBOM Owerri AN AMBRA Port Harcourt RIVERS Umuahia 22222 2 2 4 3 TRANSMISSION LINE LEGEND BULK SUPPLY POINT HYDROELECTRIC POWER STATION THERMAL POWER STATIONS 330 KV H 330KV LINES (EXISTING) – MULTIPLE CIRCUITS 330KV LINES - EXISTING 2 2 2 330KV LINES (FGN) – MULTIPLE CIRCUITS 330KV LINES (PROPOSED PROJECT) – MULTIPLE CIRCUITS 330KV LINES (NIPP) – MULTIPLE CIRCUITS 330KV LINES - FGN 330KV LINES - NIPP 330KV LINES - PROPOSED PROJECT 2 Nigerian Power Grid: Existing 330KV Lines Network ALAGBADO Abeokuta Olorunsogo B1T T4A

7. An electric power grid can be rendered unstable by the following: System faults at busbar sections or on Transmission lines Loss of generation Loss of large loads Switching of large loads A power system is therefore considered stable if in the event of any or a combination of the above factors, the entire network is able to remain in synchronism. This is hardly the case with the Nigerian grid. Any of the above events can throw the system out of synchronism and result in the shutdown of the grid. Grid Instability 7

8. SYSTEM FREQUENCY MANAGEMENT 8 ● A nominal frequency of 50Hz is achieved when active power generation in the system equals the total demand. ● In practice, we seek to achieve this balance through manual load shedding/generation scheduling or by the appropriate application of under-frequency relays. ● The SCADA/EMS facility, through its Load Frequency Control (LFC) function, offers an automated means for frequency management.

9. SYSTEM COLLAPSES IN RETROSPECT 9 YEARGENERATIONTRANSMISSION INDERTERMINAT E 2000290 20019100 200219220 200314390 200420320 200515210 20068220 20073240 20088322 20098310 20109294 20110172

10. 10 SYSTEM COLLAPSES IN RETROSPECT………

11. 2012 SYSTEM COLLAPSES TO DATE SUMMARY OF MAJOR SYSTEM DISTURBANCES IN 2012 S/No DATE/ MONTH TYPE OF DISTURBANCE IN THE GRID IMMIDIATE CAUSE/REMARKS TOTALPARTIAL 116/03/2012X The tripping of Benin/Onitsha 330KV line (CCT B1T) at both ends 223/03/2012 X (1) Explosion of the red phase CT of the primary side of 150MVA 330/132/33kV transformer at Benin TS. 325/03/2012 XBus Zone protective relay operation at Benin T/S 428/03/2012X The tripping of Benin/Onitsha line (cct B1T) 502/04/2012 XTripping of Benin - Onitsha line (CCT B1T) at both ends. 603/04/2012 XTripping of Benin - Onitsha line (CCT B1T) at both ends. 712/04/2012X The simultaneous tripping of Benin/Onitsha 330kV line (cct B1T) and Onitsha /Alaoji 330kV line (cct T4A) 8 30/04/12 XThe tripping of Onitsha/Alaoji 330kV line (cct T4A) 907/05/2012X (1) Tripping of Jebba Units (2G1 & 3) on fault 1009/05/2012X Indeterminate 1110/05/2012X Indeterminate

12. Graphical representation of 2012 system collapses to Date 12 No.

13. Causes of system collapse System collapse can result from: Generation Transmission Load Management GENERATION: Grossly inadequate generation Sudden loss of generation Absence of/or inadequate operating reserve TRANSMISSION: Tripping of critical 330KV lines (especially the single circuit lines) Indiscriminate operation of line protection relays Transmission equipment failure 13

14. Causes of system collapse........contd. LOAD MANAGEMENT – Grid indiscipline - Reluctance to adhere to load allocation – Lack of a functional SCADA/EMS system, necessitating manual operation which is fraught with human error 14

15. Generation Profile (Mar’11 – April’12) 15 MONTH AVERAGE ACTUAL GEN. CAPABILITY (MW) PEAK GEN. (MW) AVERAGE GEN. (MW) MAR 20114450.143851.603324.62 APR 20114627.513943.603501.11 MAY 20114195.033635.902945.25 JUN 20114359.043354.002790.33 JUL 20114571.533607.002970.51 AUG 20114421.463839.703363.06 SEPT 20114684.334003.803352.65 OCT 20114899.554054.203078.07 NOV 20115039.383627.773280.36 DEC 20114768.914089.303338.36 JAN 20124788.264162.203531.69 FEB 20124959.014086.203465.29 MAR 20125171.003744.203096.49 APR 20125338.683698.302936.67 Collapse Free Months with average Spinning Reserve of 280MW

16. System Collapse Mitigation Strategies 16 ● Elimination of all encumbrances on all Transmission lines. ► Short Term Strategies: ● Review of the operation of Under-frequency Load Disconnection scheme. ● Procurement of additional operating reserve capability for effective frequency management. ● Timely completion of on-going SCADA/EMS reactivation project for real-time Grid management and supervisory control. ● Review of the entire system protection scheme is required to ensure proper and reliable operation ● Manpower shortage in system operations is now acute needs to addressed.

17. System Collapse Mitigation Strategies (Cont’d) 17 ● It is imperative to strengthen the Grid to satisfy N-1 reliability assessment criteria. ► Long Term Strategies: ● Increased generation is an absolute necessity for stable grid operation. ● Creation of closed loops in the network. ● Network compensating devices, such as the Static Var Compensators (SVC) should be deployed for efficient voltage control.

18. Nigerian Power Grid: Existing, On-going and Proposed 330KV Lines Network TO SAKETE ONITSHA KAINJI JEBBA/GS JEBBA/TS SHIRORO Ikeja Akure Uyo Birnin Kebbi Minna Kaduna Abuja Jos Bauchi Gombe Damaturu Maiduguri Kano IIorin Ado Ekiti Enugu Akwa Ibadan Sokoto Gusau Katsina Hadejia Jalingo Yola Abakaliki Calabar JIGAWA KANO KATSINA SOKOTO ZAMFARA KEBBI KWARA KADUNA NIGER NASSARAWA TARABA YOBE PLATEAU EBONYI CROSS RIVER OSUN BAYELSA EDO DELTA ONDO OYO IMO ADAMAWA BORNO GOMBE BAUCHI EKITI LAGOS ATLANTIC OCEAN NIGER REPUBLIC OF BENIN REPUBLIC OF CAMEROON REPUBLIC OF CHAD SAPELE P/ST. DELTA POWER ST. OGUN Osogbo NIGERIA Potiskum Niamey 132 kV Mambila Bali AFAM POWER ST. Asaba Benin EGBIN P/ST. Lokoja ABUJA AJAOKUTA Lafia Makurdi MAKURDI BENUE KOGI ENUGU Aliade ABIA AKWA IBOM Owerri AN AMBRA Port Harcourt RIVERS Umuahia 2 222222 222 2222 222 2 2 2 111 4 2 2222 2 2 222 2 22222 2 2 4 3 ALAGBADO Abeokuta 2 Olorunsogo TRANSMISSION LINE LEGEND BULK SUPPLY POINT HYDROELECTRIC POWER STATION THERMAL POWER STATIONS 330 KV H 330KV LINES (EXISTING) – MULTIPLE CIRCUITS 330KV LINES - EXISTING 2 2 2 330KV LINES (FGN) – MULTIPLE CIRCUITS 330KV LINES (PROPOSED PROJECT) – MULTIPLE CIRCUITS 330KV LINES (NIPP) – MULTIPLE CIRCUITS 330KV LINES - FGN 330KV LINES - NIPP 330KV LINES - PROPOSED PROJECT 2

19. CONCLUDING REMARKS Increased Generation,expanded grid network with redundancies and functional grid management tools will launch the system into an era of stability and a collapse free operation. 19

20. THANK YOU 20