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Chapter 1 Introduction

5.2 Numerical Results

5.2.2 Power Dispatch

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Regional Solar curtailment 2050

(a)Solar generation and curtailment

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(b)Wind generation and curtailment Figure 5.6Yearly variation of solar and wind generation and curtailment in various regions

5.2 Numerical Results 85

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Power Dispatch in Base Case

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Power Dispatch in High RE Case

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Power Dispatch in Base Case in June

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Figure 5.7Overall generator dispatch pattern and activity profile of energy storage and inter-regional transmission lines in 2050 in base, and indicative high RE penetration scenarios

penetration increases substantially in May-August. In both cases, RE curtailment is observed in high RE penetrated time slices. It is mainly reported when the system cannot accept additional RE, despite lowering/ stopping generation of other generators and/ or store it. In the base case, highest solar energy curtailment (5%) is observed in April and March in H12 and H13 time slices respectively. In high RE penetrated case, highest solar curtailment is in April-H12 time slice, and in June-H13 for wind. Curtailment for wind and solar energy in these two time slices are 88% and 22% respectively. Highest total RE curtailment of 37%

is observed at April-H12 time-slice. Storage mainly works as daily energy arbitrage device as it is charged by available excess RE power (mainly solar) and is discharged when RE generation is not available. Compared to base case, storage activity is much higher than power exchange in the high RE scenario. Impact of seasonal variation of RE production is prominent on seasonal variation of storage charging/ discharging and energy export/ import pattern.

Regional daily and seasonal power dispatch

Regional picture of dispatch pattern is different from the overall one and worthy of inspection.

Dispatch patterns of four regions RJ, UU, HR, and PB are illustrated in Figure 5.8. In UU, base case dispatch is heavily dominated by coal. Due to the absence of other firm generators, heavy cycling of coal-based power plants is seen. UU is a net power exporter in the base case.

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Power Dispatch in Base Case in Uttar Pradesh

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Power Dispatch in Base Case in Rajasthan

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Power Dispatch in Base Case in Haryana

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Power Dispatch in Base Case in Punjab

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Biomass Coal Curt−Solar

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Figure 5.8Regional generator dispatch pattern and activity profile of energy storage and inter-regional transmission lines in 2050 in various RE penetration scenarios

5.2 Numerical Results 87 All solar generation is absorbed without any storage or curtailment activity. In high RE case, coal-based generation reduces drastically. Solar generation gradually increases from January to April, and then reduces to its lowest in July. Afterward, it again increases till December.

High solar penetrated time slices are involved with higher generation curtailment. Highest solar curtailment (26%) is observed in the 13thhour of February. Wind dispatch is higher in rainy season, but interestingly curtailment is low in these seasons. Rather wind energy curtailment is as high as 100% in some time slices, like May 12. From this it is evident that wind generators are backed down to accommodate cheaper solar power. In high RE case, quantum activity of storage is observed compared to base case when storage is absent.

Clearly, storage follows solar seasonal as well as daily dispatch pattern and acts as a daily arbitrage device.

In RJ, renewable play a major role in power dispatch, both in the base and high RE case. Coal, gas, and lignite are the firm resources supporting the balancing operation in base case. Nuclear power also supplies a significant portion of energy demand. In both cases, a decline in solar energy production is seen in monsoon, along with considerable wind generation increase. In the base case, solar energy curtailment is negligible; rather 100% wind curtailment is seen in some time slices. In high RE scenario, the highest solar curtailment percentage is around 23%, during June H13. In this case, wind curtailment is as high as 100% in some time slices. In the months of February-June, wind energy curtailment is prominent. Wind energy curtailment occurs mainly in the daytime to accommodate solar energy penetration. In the base case, daily as well as seasonal variation of storage charge- discharge follows solar dispatch pattern. Most of the generation is consumed within the region with very little export in the base case. In high RE penetration case, export increases substantially.

In HR, coal and nuclear power plants are main firm generating options in the base case.

HR is a net power exporter in base case, but in high RE case, it is a net power importing region. Inter-regional power trading contributes significantly to daily system balancing. In high RE case, solar curtailment is prominent in almost all months. Solar curtailment level as high as 57% is seen in some time slices.

PB is heavily dependent on energy import in the base case. Energy import provides as high as 50% energy requirement in some time slices. Considerable storage activity is also seen to support solar penetration. Though solar PV curtailment is seen only in some seasons in the base case, all seasons in high RE case are associated with solar curtailment. Highest solar energy curtailment in the base case and high RE case are around 19% in APR-H12 and 26% in APR-H13 respectively. Dependency on energy import decreases in high RE scenario, with an increase in storage activity.