To show that the new power electronic reactive compensation unit can be deployed across a range of locations and to deal with a range of potential voltage problems.To show over a period of between 18 months and 2 years of on site operation that the new units reliably improve the voltage profile seen by our customers both in terms of absolute voltage, and the magnitude of apparent voltage changes.The device will be tested at the Power Networks Demonstration Centre (PNDC) in Cumbernauld. This will ensure that it can operate over the full voltage, and frequency envelope it is designed for. This testing is important as these extreme events are unlikely to occur very often, if at all, on our normal network. However the capability of the electronic reactive compensation unit to operate under these unusual conditions to maintain voltage is very important. The equipment supplier has developed the device and will own all the associated Intellectual Property. Scottish and Southern Energy plc will develop installation methods and the communications required to allow the device to be integrated into our overall voltage control system. All development carried out by SSEPD will be shared with other DNOs
Power quality monitoring will be carried out at each site before and after installation, to ensure that harmonic emissions are within acceptable limits. We will also check that the device does not result in noticeable flicker due to rapid voltage changes.
We will deploy three units on different network types to tackle different problems.
1. A network with a large wind turbine and several smaller wind turbines where there are problems with the voltage rising too high at times of low load and high wind output.2. A network where the existing voltage control methods, result in a large range of voltages presented to customers. For the particular circuit where a trial unit is to be installed, these are automatic tap changers on 132/33kV transformers, fixed tap 33/11kV transformer, and an 11kV voltage regulator several miles away from the fixed tap transformer. The overall source impedance of the network is so high that step changes in load result in large changes in voltage. The high speed operation of the device should result in smaller apparent voltage changes to customers.3. A network with a large PV farm and several smaller PV installations where there are potential problems with the voltage rising too high at times of low load and high PV output.
Benefits
This project will be successful if we are able to determine the ability of the devices to maintain the voltage within statutory limits and to reduce apparent step changes in voltage.
Learnings
Outcomes
A summary report has been produced detailing real time field performance of the 11kV DVAR VVO device. The dissemination event shared the learning outcomes for the Isle of Lewis trial, more details can be found on the SSEN Innovation Website. As a result of the trail the Technical Readiness Level (TRL) of the device increased from TRL6 to TRL8 and with the correct processes and procedures in place it would be suitable for business as usual operation, without the requirement of further investigative work.
The summary report highlights improved levels of voltage and reactive power compensation on the network. The business will look to explore other opportunities thought the Active Network Team and their interaction with new renewable generation connections to use the devices specifically targeted at either wind or PV farm installations.
Lessons Learnt
In projects where the method involves products developed abroad, the procurement process can be long drawn out due to the need for harmonisation of different rules and approaches. There is no simple way to predict how much time it can take to complete the necessary formalities; a significant slack period should be included to cover procurement. In hindsight, a full year for procurement should have been considered at the start.
Also, if supplier experts are essential for some of the site acceptance activities, additional time contingency ought to be considered to allow for the proper coordination of the availability timings of all stakeholders.
Identifying suitable ground mounted arrangements for the installations of the current devices has proven very difficult given the challenges around maintaining electrical clearances and safety from the system.
This device solves a very specific electrical system power quality issue, the trial positively highlighted the device’s ability to satisfactorily mitigate and address the localised power quality challenge. There has been a significant interest in the dissemination events and received very positive feedback. However, there are limited opportunities on the distribution network presently to deploy the device. One of the qualities of the device is its ability to increase the power flow onto the network from a renewable generator in a remote location. There would be a significant number of existing and future renewable generators which could benefit from acquiring, owning and operating this device.
