Impact of PV on the GB Generation and Transmission System

Yutian Zhou*, Lingxi Zhang, Pierluigi Mancarella and Joseph Mutale

*yutian.zhou@manchester.ac.uk

Power and Energy Division

School of Electrical and Electronic Engineering

The University of Manchester

Contents Impact on the GB Generation System 3

- Generation model - Assessment methodology - Findings and impacts

Impact on the GB Transmission System 11 - Transmission model - Assessment methodology - Findings and impacts

Contribution from PV to the Security of Supply 19 - Adequacy assessment model - Assessment methodology - Findings and impacts

Summary 27

WISE-PV Stakeholder Workshop 20 September 2016, London 2

Impact on the GB Gen. Sys.: Model (1/3)

•Nuclear, coal, gas (CCGT) & biomass •Pumped-hydro plants as system operator dispatched storage for providing generation reserve

•Five different scenarios for the mix of different generation technologies (referred to as S1 to S5 later)

Conventional Generation

WISE-PV Stakeholder Workshop 20 September 2016, London 3

2015: 63.6 GW

Conventional Generation Mix in S1 (in % of total conventional capacity)

2035: 68.3 GW

Impact on the GB Gen. Sys.: Model (2/3)

•Wind: aggregated from 39 representative wind farms (on-/off-shore) with different wind speed profiles

•Solar: aggregated from 11 sub-national regions with different solar irradiance profiles

Renewable Generation

WISE-PV Stakeholder Workshop 20 September 2016, London 4

Impact on the GB Gen. Sys.: Model (3/3)

•The National Demand (ND) from National Grid as primary data source

•EHP profiles created by a detailed technical model for 11 sub-national regions

•EV profiles created based on the EV profile from the Future Energy Scenario, National Grid

•Consumer-owned batteries profiles created by a detailed battery model

Demand

WISE-PV Stakeholder Workshop 20 September 2016, London 5

Half-hourly Index

0 4380 8760 13140 17520

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Impact on the GB Gen. Sys.: Method A deterministic unit commitment(UC) model is adopted here, which features Mixed Integer Linear Programming (MILP) algorithm.

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Inputs: characteristics of conventional generators and storage, time series profiles of renewable generation, demand (incl. EV & EHP) and consumer-owned batteries, and requirements of generation reserve

Optimisation: centralised generation scheduling using cluster-technique for different generation technologies with half hourly

resolution

Outputs: schedule of the capacities of conventional generation technologies taking account of the economic cost and technical

constraints, energy production of different generation technologies, and curtailments of wind and PV, etc.

Impact on the GB Gen. Sys.: Findings (1/3) Energy production from different generation technologies

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S1 in 2015 S2 – S5 in 2015

S1 in 2035

S2 in 2035 S3 in 2035

S4 in 2035 S5 in 2035

Impact on the GB Gen. Sys.: Findings (2/3) Demand not supplied

2035 S1 S2 S3 S4 S5

Annual Energy Not Supplied

(% of ATEC*) 0.004 0.042 0.004 0.084 0.018

Maximum Demand Not Supplied

(GW) 3.3 8.2 3.9 10.6 6.8

Total Hours with Demand Not

Supplied (hours) 7 32.5 7.5 103 34.5

*ATEC stands for Annual Total Energy Consumption.

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Impact on the GB Gen. Sys.: Findings (3/3) Curtailment of PV generation

2035 S1 S2 S3 S4 S5

Annual Energy Curtailed

(% of AEA) 0.4 0.4 0.7 1.2 1.6

Maximum Power

Curtailed (GW)

6.4 8.4 11.6 14.5 14.8

Total Hours with

Curtailment (hours)

30 62 89 119 158

*AEA stands for Annual Energy Available.

WISE-PV Stakeholder Workshop 20 September 2016, London 9

Impact on the GB Gen. Sys.: Impacts 50 GW PV Integration

•PV would contribute about 9% of the future energy production in the GB power system.

Infrequent Demand Not Supplied •On condition that all conventional power plants are perfectly reliable, the future GB system will face a challenge of encountering generation capacity deficiency infrequently throughout the year. However, no substantial energy shortage would be expected.

Curtailment of PV Generation •The PV curtailment is attributed to either the minimum stable generation of convention generation, or the insufficiency of conventional generation capacity to provide reserve.

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Impact on the GB Trans. Sys.: Model (1/4)

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A reduced 29-Bus representative GB transmission network

Impact on the GB Trans. Sys.: Model (2/4)

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A reduced 29-Bus representative GB transmission network

2015 2035

Impact on the GB Trans. Sys.: Model (3/4)

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A reduced 29-Bus representative GB

transmission network Representative solar regions

Impact on the GB Trans. Sys.: Model (4/4)

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39 representative wind farms:

- 25 offshore - 14 onshore

A reduced 29-Bus representative GB

transmission network

Impact on the GB Trans. Sys.: Method The classic linear optimal power flow (OPF) is applied in the assessment.

WISE-PV Stakeholder Workshop 20 September 2016, London 15 15

Inputs (from the UC model): generation online/offline schedule, locations of different generation technologies across the network, and

time series of system aggregated load/wind/solar curtailment.

Optimisation: classic linear optimal power flow framework.

Outputs: generation dispatch, network power flow distribution, allocation of wind/load/solar curtailment.

Impact on the GB Trans. Sys.: Findings (1/2)

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Longitude

-6 -5 -4 -3 -2 -1 0 1 2

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582015

Impact on the GB Trans. Sys.: Findings (2/2)

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0%

100%

Maxim

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Pow

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% of

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Longitude

-6 -5 -4 -3 -2 -1 0 1 2

Latit

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Impact on the GB Trans. Sys.: Impacts

No immediate investment needs for transmission network have been identified due to the large-scale integration of PV.

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Contribution from PV to the SoS: Model

Conventional Generation Tech. Average

Unit Capacity (MW)

Average Unit Availability

Nuclear 1781 81%

Coal 1368 88%

Gas (CCGT)

734 87%

Biomass 458 88%

Pumped-hydro

809 97%

Renewable Generation

•33 years of wind speeds at the 39 representative wind farms

Wind

•2 years of solar irradiance for the 11 sub-national regions PV

WISE-PV Stakeholder Workshop 20 September 2016, London 19

Contribution from PV to the SoS: Method

Generation Adequacy Assessment Based on Sequential Monte Carlo Simulation

Maintaining the SoS by Conventional Generation

Maintaining the SoS by Combined PV & Storage

Capacity Value of the Combined PV & Storage

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Contr. from PV to the SoS: Findings (1/4)

WISE-PV Stakeholder Workshop 20 September 2016, London 21

* The LOLF in 2015 is 6.2 occurrences per year

S1 S2 S3 S4 S5

Worst case: S4-2035

Contribution from PV to the SoS: Findings (2/4) Maintaining the SoS with Conventional Capacity

WISE-PV Stakeholder Workshop 20 September 2016, London 22

S4-2035

Only 61 GW of dispatchable generation

capacity

Peak demand of 79 GW due to the EHP integration

The additional 16.5 GW of dispatchable generation capacity is due to the projected capacity portfolio of different generation technologies for S4-2035, and cannot be exclusively attributed to the PV integration

Contribution from PV to the SoS: Findings (3/4) Maintaining the SoS with PV & Storage

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Contribution from PV to the SoS: Findings (3/4) Maintaining the SoS with PV & Storage

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Contribution from PV to the SoS: Findings (4/4) The capacity value of combined PV & Storage

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Contribution from PV to the SoS: Impacts

•For the WISE PV scenarios, the security of supply would improve slightly thanks to the peak reduction that is attributed to the replacement of electric boilers with electric heat pumps. However, the security of supply deteriorates significantly due to the substantial increase of peak demand, which is also attributed to the integration of electric heat pumps.

•In order to maintain the level of security of supply in 2035 at the same level as in 2015, in the worst case scenario for the mix of generation technologies (i.e., S4-2035), an additional dispatchable generation capacity of 16.5 GW is needed.

•For S4-2035, the GB system requires approximately 35 GWh storage to maximise the contribution from the combination of PV & storage to the security of supply.

•The maximum capacity value of the combined PV & storage is equivalent to a dispatchable generator with the capacity of 2.5 GW.

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Summary

GenSys 9% in total

energy production

Curtailments due to reserve

issue

TransSys Mostly

consumed locally

No needs for immediate investment

SoS 16.5 GW more dispatchable

capacity

PV & 35 GWh storage = 2.5

GW dispatchable capacity

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WISE-PV Stakeholder Workshop 20 September 2016, London 28

Impact of PV on the GB Generation and Transmission System

Yutian Zhou*, Lingxi Zhang, Pierluigi Mancarella and Joseph Mutale

*yutian.zhou@manchester.ac.uk

Power and Energy Division

School of Electrical and Electronic Engineering

The University of Manchester