Assisting Communities to Connect to Electric Sustainable Sources (ACCESS) is a new, flexible connection agreement; which SSEPD may offer to community generators in transmission constrained areas. An ACCESS Connection Agreement continues to constrain generators in accordance with SSEPD standard policy for transmission constrained areas. However, the generator would be allowed to produce more than the constraint limit provided it simultaneously brings on sufficient additional demand within the local balancing area.
Objectives
The aim of the PNDC testing was to demonstrate and test the functionalities of the ACCESS demand side management and inter-tripping scheme before trial implementation on the Isle of Mull. The ACCESS system has been tested at PNDC to prove functionality of the system, prove the fail safe operation of the system to communication failure and to evaluate the systems impact on power quality.
Method
The findings from testing at the PNDC have been incorporated into the ACCESS system trial deployment on Mull (November 2015 onward). Specifically the updates relate to the dynamo hardware, the VCharge demand side management system, and the quantum heater hardware. The trial deployment on Mull has started as of November 2015.
- Export constraint target on Mull less than 50kW
- Manage a 400kW community owned hydro generator
- Length of project: will run for two years (April 15-April 17), with installations scheduled to commence in September 2015
- ACCESS is a £2.5m smart grid demonstration project that was one of 6 projects awarded funding by the Scottish Government’s Local Energy Challenge Fund
- The Scottish Government announced the decision to award £1.8m towards the ‘ACCESS’ project, in the first ever round of the Local Energy Challenge Fund
- 9 VCharge dynamos tested
- 2 intertrip schemes tested
- 1 end to end system test completed
Outcome
The ACCESS system testing at the PNDC was completed in three stages. The test stages are listed below:
Power quality testing of the dynamo units (Task 7):
- Task 7.1 Verify the metering and switching functionality of the dynamo hardware
- Task 7.2 Establish the power quality impact of multiple Dynamo units switching behind a single transformer, with specific reference to flicker and harmonics
- Task 7.3 Verify the response of Dynamo units to communication failures
Testing of inter-trip scheme (Tasks 8 and 9)
- Task 8.1 Verify correct operation of the ‘trim’ function, at threshold of 20 Amps, and document the speed of response for Inter-trip B (the Inter-trip variant relying on CTs and VTs for measurement point readings).
- Task 8.2 Verify the response of Intertrip B to communication failures.
- Task 8.3 Verify correct operation of the ‘trip’ and auto re-closing functions should the generator respond incorrectly to a trim command.
- Task 9.1 Verify correct operation of the ‘trim’ function and document the speed of response for MP trim thresholds of 20 and 30 Amps, for Inter-trip A (relying on Tollgrade sensors for measurement point readings).
- Task 9.2 Verify the response of Intertrip A to communication failures.
End to End testing of the DSM system (Task 10)
- Task 10.1 Evaluate the DSM system capability to match load to generation, in a ‘real world’ situation of changing load and generation availability.
- Task 10.2 Verify the DSM system’s response to communications failures at one or more Dynamo units.
- Task 10.3 Verify the DSM system’s response to communications failures at the VSCon.
- Task 10.4 Verify the DSM system’s response to failure of the generator to follow generation/demand set-points as requested.
- Task 10.5 Verify the DSM system’s response to failure of the DSM load to follow generation/demand set-points as requested.
Results
- End to end system functionality, failsafe capability and power quality impactevaluated
- Intertrip scheme A and B functionality and failsafe capability evaluated
- Dynamo hardware functionality, failsafe capability and power quality impact evaluated