INCENTIVE FOR TRANSMISSION EFFICIENCY

Transcription

1 INCENTIVE FOR TRANSMISSION EFFICIENCY - T. UMESH, SEE, RETD. KPTCL - & - N. RAGHUPRAKASH, EE, RA, KPTCL

2 IN THIS SESSION Brief introduction to Transmission System Efficiency Parameters in Transmission Activity Transmission Loss & its calculation System Availability & its calculation Incentive Calculation by KERC.

3 INTRODUCTION TO TRANSMISSION NETWORK Transmission Voltages in Karnataka Transmission System Elements AC/ DC lines Power Transformers ( ICTs) STATIC VAR Compensators BUS REACTORS

4 TRANSMISSION SYSTEM EFFICIENCY Measured in terms of Transmission loss Transmission system availability

5 TRANSMISSION LOSS MYT Regulation, clause 3.4 deals with treatment of losses. In the tariff order KERC stipulates the normative transmission losses to be achieved by KPTCL during MYT period. If the loss is less, then incentive is allowed. This gain is to be shared in the ratio of 70: 30 between STU and the users of transmission system. SLDC works out the Transmission loss month on month based on the input to the transmission system and the quantum of energy supplied to ESCOMs at the Inter Face points. This information is furnished to KERC based on which the Order for sharing of loss / gain on account of Transmission loss is issued.

6 INCENTIVE FOR TRANSMISSION EFFICIENCY KERC vide its MYT Regulations Order dated has stipulated that KPTCL shall maintain a minimum of 98% availability for recovery of full transmission charges. Recovery of fixed charges below the level of target availability shall be on pro-rata basis. At zero availability, no transmission charges shall be payable.

7 PROCEDURE FOR CALCULATION OF AVAILABILITY Availability shall be calculated and declared separately for each voltage level. The transmission elements shall be grouped into following categories. a) AC transmission lines: Each circuit of AC transmission line shall be considered as one element. b) Inter-Connecting Transformers: Each 3ph transformer or bank of three Sph transformer shall form one element.

8 PROCEDURE FOR CALCULATION OF AVAILABILITY c) Static VAR Compensator: SVC along with SVC transformer if any shall form one element. d) Switched Bus Reactor: Each switched Bus Reactor shall be considered as one element. Weightage factor for each category of transmission elements shall be as under: a) For each circuit of AC line- Surge Impedance loading (SIL) multiplied by Circuit Km. ( SIL rating for various voltage level and conductor configuration shall be as per the procedure adopted for power system analysis)

9 PROCEDURE FOR CALCULATION OF TRANSMISSION SYSTEM AVAILABILITY (TSA) b) For each ICT- The rated MVA capacity c) For SVC- The rated MVAR capacity d) For switched Bus Reactor: The rated MVAR capacity. The availability for each category of transmission elements shall be calculated based on the weightage factor, total hours under consideration and non-available hours for each element of that category.

10 The transmission elements under outage due to following reasons not attributable to KPTCL shall be deemed to be available: 1) Shut down of transmission elements availed by other agencies for maintenance or construction of their transmission system. 2) Manual tripping of the line due to over voltage and manual tripping of elements as per the directions of the RLDC/SLDC.

11 Outage time of elements due to acts of God and force majeure events beyond control of KPTCL shall be excluded. Outage time caused by grid disturbance not attributable to KPTCL shall also be excluded. Eg. Faults in substations or bays owned by other agencies causing outage of KPTCL elements. However, if the elements are not restored on receipt of directions from SLDC while normalizing the system following a grid disturbance within reasonable time, then the element will be considered not available for whole period of outage and outage time shall be attributable to KPTCL.

12 The % availability is calculated for each transmission element as follows: 1 st calculate Availability index= Total time under consideration-outage hours due to unscheduled interruptions/total time under consideration. Next calculate availability= Availability index*weightage factor % availability= availability/weightage factor Then, % availability of category of elements= Sum of availability of all elements/sum of weightage factor of all elements. Then, % System Availability is calculated as the average of all category availabilities.

13 FORMULA FOR CALCULATION % TSA = o*av₀ + p*avp + q*avq + r*avr X 100 o+p+q+r Where, AV = Availability o = No. of AC lines p = No. of ICTs q = Capacitor Bank r = Bus Reactors

14 Zone: Bangalore Element: AC lines Sl. No. Name of the line Voltage kv Conductor Ckt.kM SIL Weightage factor Un- Total time of Scheduled considerationhours Interrupti ons- hours Availability Index Availability (Avi) % Availability A B C=A*B D E F=(D-E)/D G=C*F H=G/C*100 1 Nelamangala - Peenya I 220 Drake % Total

15 Sl.No. Zone No. of AC lines Wf Availability No. of ICT's Wf Availability No. of SVAR's Wf Availability %TSA of Zones 1 Bagalkote Bangalore Gulbarga Hassan Mysore Tumkur KPTCL TOTAL KPTCL TOTAL AVO AVP AVQ %TSA=

16 INCENTIVE KPTCL shall be entitled to incentive on achieving annual availability beyond the target availability of 98% as per the following formula. Incentive= ATC* (TSA achieved-target availability)/target availability No incentive shall be payable above the availability of 99.75%. 50% of the incentive shall be shared by the long time customers in the ratio of their average allotted transmission capacity for the year.

17 SURGE IMPEDANCE LOADING Surge Impedance Loading (SIL) in MW s of a long transmission line is defined as ratio of (kvre)²/si where VRE is the receiving end voltage in KV and SI is surge impedance of the line. SIL is typically the limit of the maximum power that can be transmitted through the line at the voltage level considered. SIL can be increased by reducing the SI of the line.

18 SIL VALUES AS PER KEGC 2005 Typical values of SIL are as follows: a) 400 kv lines Quad conductor MW b) 400 kv lines Twin conductor-515 MW c) 220kV lines Single conductor-132 MW d) 110kV lines SC 50 MW e) 66kV lines SC 35 MW

19 SURGE IMPEDANCE SI is defined as the (L/C), where L and C are Inductance and Capacitance of the line. SI can be reduced by bundling. Bundling is the use of two or more conductors per phase, which reduces L and increases C. Hence twin/quad conductors are used in 400/765kV lines.

20 Transmission lines produce reactive power due to their natural capacitance. Mvar produced = ½ CV² Transmission lines also utilize reactive power to maintain their magnetic fields. Mvar used = ½ LI² SIL is the loading of the line when Mvar produced = Mvar used i.e., when ½ LI² = ½ CV² Which gives V/I = sqare root of L/C, which is nothing but the SI of the line.

21 THANK YOU