Probabilistic Security Assessment in Practice

Transcription

1 Workshop : Increased utilisation of the Nordic Power Transmission System Probabilistic Security Assessment in Practice Idar Gimmestad Kjetil Uhlen STATNETT SINTEF Energiforskning AS 1

2 Background and objective: Development of prototype tools for handling and determination of flexible power transfer limits Results from 2001 Handling congestions between price areas in Elspot (The Flexlast -prototype) Module for calculation of congestion cost Module for calculating Risk Index Results from 2002 Handling internal bottlenecks within price areas Module for estimation of Expected Interruption Cost (EIC) Module for handling of regulating power market (RPM)-costs Objective 2003/2004: Implement a practical tool for Statnett s NCC 2

3 Reliability based operation N-1 criterion (deterministic) Little flexibility, uncertain if the power system capacity is fully utilised The alternative: Reliability based criterion which opens for flexible power transfer corridor (PTC) limits. Weighing between cost and risk Risk = probability x consequence 3

4 Motivation for using flexible reliability based PTC limits Increase utilising of the existing network Allowing increased risk for short interruptions at some places, while Keeping the consequences under control Why: Reduce costs 4

5 Flexible reliability based PTC limits Risk level Increased capacity increased risk level Today Today's situation Today Increased capacity Accept increased risk Increased capacity equal risk level Capacity 5

6 Flexlast - Prototype structure PSS/E-file Nordpool Uploading Data format Congestion cost Assembly of results Contingency analysis 6

7 Summary of project activities in 2002 The project has implemented methods for risk based socio-economic evaluation of power transfer limits as an alternative to deterministic criteria. Prototype software modules has been established. The results have demonstrated that it is possible to implement a practical tool for handling of internal bottlenecks (congestions within price areas) Testing of the prototypes: A few cases are tested as part of the project. Need to carry out more realistic case studies in order to gain experiences. Further development and implementation should be done in close cooperation with control centre staff and the new control centre/ems project. 7

8 Resulting modules from project activities Flexible PTC flow limits Congestion cost between price areas Risk index calculation Assembly of results Decision aid Regulating Power Market costs Expected interruption cost estimation 8

9 Network areas of interest 132 kv 300 kv 420 kv SVELGEN GROV GYLTHALSEN STAKALDEFOSS DALE KOLLSNES FANA STORD FARDAL HOVE MODAL EVANGER HØYANGER REFSDAL LEIR- DØLA SIMA JOSTEDAL FORTUN AURLAND KR.SUND TROLLHEIM ISTAD BRANDHOL DRIVA GRYTTEN AURA ORKDAL GRANA KLÆBU VERDAL STRINDA HÅVIK HUSNES SAMNANGER MAURANGER GISKEMO TAFJORD ØRSKOG SYKKYLVEN BRATTSET NEA BLÅFALLI OKSLA DAGALI HAUGEN HÅHEIM LEIVDAL LITJFOSSEN SAUDA ÅSEN RØLDAL ÅSKÅRA BRYGGJA ULSET NESFLATEN VÅGÅMO SAVALEN HYLEN KVILDAL SONGA VEMORK RJUKAN Ø.VINSTRA RENDALEN SAURDAL VINJE HOLEN TOKKE 9

10 Model for decision-making Decision on operating startegy involves: Transfer limit (Amount of corrective re-dispatch) If and where to split the network Generation & Consumption Deficit network area Security criteria Congestion cost Expected interruption costs System protection Operating strategy 10

11 Operating strategies N-1 Meshed network N-0 Radial network without UFLS?? zero? Congestion cost Interruption cost?? N-1/2 Radial network with UFLS where? Split network where? 11

12 Illustrating example S Consumption forecast P GC = 300 MW P LC = 500 MW PL=min load + (max load -min load)*factor = 1700 MW Local Generation PG = PL PINT = 700 MW Import demand PINT = PL PG = 1000 MW Main Transmission Network λ 4 C limit 600 MW (N-1) interface flow B λ 3 P LB = 400 MW Bids on RPM A B C Thermal limit 600 MW A λ 2 Power [MW] λ 1 Price [NOK/MWh] Last (actual) RPM price 320 NOK/MWh PTC P GA = 400 MW P LA = 800 MW BFK = 500 MW 12

13 Object function Min Cost = Min (Cost corrective redispatch + Cost interruption) Cost corrective redispatch = (RPM local bid RPM current hour) * Ρ Cost interruption = Σ (λn * Pn+1 ) * Rline * KILE * Fv + Σ (λn * Pn UFLS ) * RUFLS * KILE * Fv 13

14 Corrective re-dispatch and flow Operating strategy Regulated power [MW] Interface flow [MW] Meshed network N Split between B and C Split between B and C Split between A and B Split between A and B N-1/2 with UFLS N-0 without UFLS N-1/2 with UFLS N-0 without UFLS

15 Total cost and elements Operating strategy Congestion cost [NOK] Interruption cost [NOK] Total [NOK] Meshed network N Split between B and C N-1/2 with UFLS Split between B and C N-0 without UFLS Split between A and B N-1/2 with UFLS Split between A and B N-0 without UFLS

16 Costs with different strategies N-1/2, w/ufls Split B-C N-0, wo/ufls N-0, 500 Costs [NOK] Joint network N-1 Special regulation cost Interruption cost wo/ufls Split A-B N-1/2, w/ufsl Regulation [MW] Sum cost Regulated power Interface flow 16

17 Total strategy costs Expected Interruption Interruption costs costs Congestion Corrective cost redispatch Costs [NOK/hour] N-1 N-1/2,split B-C, w/ufls N-0,split B-C, wo/ufls N-0,split A-B, wo/ufls N-1/2,split A-B, w/ufls 17