This project will demonstrate if flexible reactive power is possible, assess whether it is a solution to voltage problems, loss minimisation and thermal network constraints, and understand if participants are willing to provide reactive power as a service.
It will carry out engagement and literature review to document which technologies are able to provide reactive power flexibility and, undertake studies to demonstrate if optimised reactive power dispatch has the ability to defer network reinforcements and minimise losses. It will then carry out Cost Benefit Analysis to determine the financial and environmental costs/benefits achieved from the use of flexible reactive power, and carry out a market assessment to determine asset owners’ interest in providing flexible reactive power as a service, before developing an initial market design.
Benefits
The Q-Flex project has a strong benefits cased based on two main factors. The first links to the benefits of the reactive power flexibility market the project is looking to develop. This will provide licensees with a new method of meeting constraints and minimising losses whilst reducing the need for reinforcement. This will provide a cost saving to customers.
The second is the benefit to the general flexibility market in GB. As the project will be delivering a new form of flexibility market which makes use of assets already available on the distribution network, it will help create a more nascent and liquid flexibility market.
Learnings
Outcomes
The project has produced the following outcomes to date:
- A set of reports containing learning on the potential for flexible reactive power support to reduce losses and resolve thermal and voltage constraints in distribution networks. This involves the use of power factor correction for assets connected at 11 & 33kV and may improve network operation at 33 & 66kV.
- Solar PV and Wind have been identified as being good candidates for flexible reactive power support in cases where they have very low capital and opportunity costs for market participation.
- Solar PV with grid-forming inverters could be particularly useful in the Winter Demand scenario.
- Reasoned assumptions have been generated for the impact of these opportunities on NGED’s network, in a manner which is replicable for other DNO/DSOs.
- The Distributed Future Energy Scenarios and the Distribution Network Options Assessment are both used, as well as Engineering Justification Papers to indicate the costs of potential reinforcements.
- The net present financial value of the potential reactive power flexibility has been calculated for various network areas. The calculation method should be applicable to all DNO/DSOs as it is based on the ENA’s Common Evaluation Methodology.
- Several different market designs have been considered: based on the outcome of a liquidity test analogous to NGED’s process for active power flexibility procurement, potential providers could be offered a fixed-price in the case of non-liquidity. Alternatively, if market liquidity was found to be sufficient, a pay-as-clear market could be set up.
- It is expected that the majority of Constraint Management Zones are likely to require fixed pricing at the present time.
- A better understanding of the requirements for a live reactive power flexibility trial has been obtained and some cost estimates generated.
- These concern monitoring, modelling and dispatching reactive power flows on NGED’s network.
- Learning from Q-Flex has been shared with potential flexible reactive power providers through dissemination.
- 132kV reinforcement deferral modelling will be conducted in the future and included within the project’s outputs.
We have highlighted the further research and development that needs to be addressed before this capability is mature for roll out.
Lessons Learnt
Project Reports
1. The Reactive Power Catalogue, summarising the technical potential of reactive power support for various technology classes.
2. A Market Interest Summary Report, summarising the learnings from engagement with potential providers of flexible reactive power
3. A Power System Modelling Report, outlining the PSSE studies performed to investigate the ability to resolve constraints and/or minimise losses on NGED’s network through the use of reactive power flexibility.
4. A Cost-Benefit Analysis Report, showing the work done to determine whether any of the technically possible scenarios covered in the Power System Modelling Report are financially advantageous.
5. A Market Design Report, outlining several potential market designs based on input from potential market participants.
Those not hyperlinked here will be added to the Q-Flex page of the NGED website once completed.
Summary of learnings
- Likely potential providers of flexible reactive power are: Solar PV, Wind and Battery Energy Storage Systems.
- Solar PV is most economic at night and Wind most economic when no wind is blowing, due to the negligible opportunity costs in these scenarios.
- Spare incumbent inverter capacity means that some generators can provide reactive power with no opportunity cost, even when providing full active power. Furthermore, many generators would have negligible CAPEX costs incurred in developing the provision for flexible reactive power support.
- The costs of procuring reactive power from these providers is therefore assumed to be low.
- Power factor correction has been shown to have the theoretical capability to reduce losses and resolve both thermal and voltage constraints on 33 & 66kV networks.
- Increases in thermal headroom of up to 5% have been demonstrated.
- However, reactive power providers' interchangeability has been found to be poor for both reinforcement deferral and loss minimisation, meaning that certain generators are placed very strategically for certain constraints. Any future flexible reactive power market must address this.
- Increasing range of allowance power factors from 0.95-0.95 to 0.75-0.75 has not shown a significant improvement in reinforcement deferral due to the 3% limits on voltage swings for generators. This means that the limitations for reactive power support may be due to the requirements of the network more than the technical capability of reactive power providers.
- There are potentially large net benefits to deferring reinforcement, but there is still a lot of uncertainty that needs to be addressed before these benefits can be recovered.
