1. Impact of Wind Farms Aggregation on Large System Scheduling Cost Under Frequency Linked Deviation Settlement Mechanism
Presented by
Anoop Singh
Authored by
Parul Mathuria, Anoop Singh
Department of Industrial and Management Engineering, Indian Institute of Technology Kanpur, U.P., India.

2. All India Electricity Generation Capacity (As on 31 Dec 2016 )

3. Growing role of RE in Grid
Thermal dominated and large wind penetrated system of India. (~70%)
RE capacity share ~ 15%
India targets 175 GW of renewable power capacity (75 GW Wind) by 2022.
Growing share of RE impinges on grid stability
Need for flexible generation
Storage
Forecasting load and RE generation
Demand response

4. Managing Grid stability in the Indian power system - ABT
Demand supply mismatch causes system frequency to deviate
Frequency linked pricing for Availability Based Tariff (ABT)
Three components of ABT,
(i) Capacity Charge – for the plant availability
(ii) Energy Charge – for scheduled energy exchange and
(iii) Unscheduled Interchange Charge – for deviating from the schedule, linked top prevailing frequency.

5. Research Questions
What is the cost of intermittent wind to the system?
What should be the optimal scheduling (commitment and dispatch) of generators connected into the grid?
How geographically diversified wind sites supports system operation?

6. Description
This work
Determine the production levels of thermal units to deal with the uncertain wind power production.
Quantum of wind curtailment and load shedding
Considers operational characteristics unique to the Indian power system such as frequency linked pricing (UI mechanism)
Wind uncertainty is modelled by Monte Carlo Simulations (MCS) using Choleskey decomposition
Correlation between generation outputs of geographically diversified wind sites
Objective: Minimizing cost => Total system operation cost (Cost of thermal generation + UI cost + Load shedding cost)

7. 24 hour scheduling problem considering hourly load profiles and inter-temporal constraints that bind each of the 24 hourly solutions.
Net interchange between considered area and rest of the grid is responsible for frequency deviations
Case Study of real utility system of the Indian state of Tamil Nadu.

8. Mathematical Modeling
Scheduling (advanced planning with forecasted wind) and Rescheduling (real time dispatch with uncertain wind realization)
Cost of Thermal Generation
Operational Constraints
Start-up, shutdown costs
Minimum, maximum capacity
Ramp up, Ramp down
Minimum Up time, down time
Cost due to Unscheduled Interchange
Frequency Linked Price curve
Cost of Load Shedding
Network Constraints
Rescheduling does not desynchronize previously committed units, though real time commitments of additional generators are allowed

9. Case Study – Tamil Nadu Tamil Nadu 62-bus transmission test network
16 thermal generators (3190 MW total), 3 wind farms at buses 2, 25, 58 (30% penetration in terms of energy in 24 hours)
Forecasted load profiles (max MW total)

10. Case Study - system

11. Wind Generation Profile
Wind generation output (at bus 2, 25, 58) for 24 hours for two different sets of locations
Case 1 Distinct Located wind farms Case 1I Closely Located wind farms W1 W2 W3 1 W1 W2 W3 1
0.2973

12. Results
Total system operation cost (Cost of thermal generation + UI cost + Load shedding cost)
Significantly high cost in Case 2 with correlated wind sites

13. Results (3 components of total cost)
High cost of thermal generation with correlated wind (Case 2)
Earning from UI in Case 2 due to bulk wind generation during certain hours.
Load shedding is affected by network constraints

14. Results (Frequency Deviations and NI)
Large frequency deviations with Case 2 when system needs to manage bulk wind with area interchange

15. Results (Wind Curtailments)
High wind curtailments in Case 2 due to bulk availability of wind at same time instant

16. Conclusions & further work….
Geographically diversified wind sites may contribute to lower operation cost by offering better grid management.
Imbalances can be managed, perhaps, in a better way for a large integrated system.  more transmission capacity; better regional inter-connection
Higher thermal cost and system operation cost due to high stress on thermal generation in case of correlated wind generation output. Wear of machines not accounted for.
Wind+ solar variability…….need to be studied

17. www.iitk.ac.in/ime/anoops anoops@iitk.ac.in
Thank You