1. Load Management System with Intermittent Power on the Grid Ruth Kemsley CEng MIMechE MIEE ruth.kemsley@econnect.com Econnect Ventures Ltd

2. Econnects long experience with demand-side management –distributed load control devices –providing system (frequency) control on small islanded networks with intermittent and limited generation sources Desire to develop these devices and associated system design techniques to assist grid integration of renewables using DSM Need to evaluate potential markets and target technology development accordingly Project background

3. Identify contractual requirements and commercial benefits of different load management systems –under the Renewables Obligation and electricity trading arrangements Model economic benefits of load management to customers with intermittent generation on site Develop low cost load management system –incorporating communication technologies and switching devices –to maximise renewable energy use on a demonstration site Identify associated social and psychological aspects Project objectives

4. Project tasks Identified and evaluated four potential control strategies for a load management system on the distribution network –A solution to voltage rise problems caused by distributed generation –Ensuring zero export from a site with renewable generation –Avoiding load demand discrepancies –Creating an additional market for renewable energy Selected one strategy suitable for application at the test site Demonstrated technical aspects of load management equipment Investigated the social aspects of the load management strategy

5. Project partners Econnect –analysed potential DSM strategies –carried out computer modelling work –designed, developed, installed and tested load management equipment Findhorn Foundation Community –provided a test site and assisted with implementation De Montfort University –carried out social impact studies

6. Mitigating voltage rise from embedded generation –technically achievable –benefits of avoiding voltage-related constraints ~ 4 x implementation cost in case study Maximising on-site usage of renewables on a site with embedded generation and loads –technically possible to ensure close to zero power export to the grid –quick payback of implementation cost possible Avoiding demand discrepancies between actual and contractual volumes of load –possible only to reduce, rather than avoid, demand discrepancies –savings ~ 5 x installation cost over 20 years in case study Creation of additional demand for renewable energy –complex system with high capital cost of duplicated heating equipment –possible to reduce energy bills and increase generation / supply companies revenues –benefits less marked Conclusions from preliminary evaluation

7. Technique selected for demonstration at Findhorn Foundation Community 75kW wind turbine with plans for ~600kW more wind capacity (at time of project inception) Extensive low voltage distribution network, administered by FFC Power export from site rare, but will increase significantly when new wind turbines added Installation aimed to demonstrate load management technology Minimising energy export from embedded generation

8. System tasks DECIDE WHETHER TO INCREASE SITE LOAD MEASURE POWER EXPORT SEND SIGNAL TO LOAD CONTROLLERS SWITCH LOAD ON OR OFF SWITCH LOAD ON OR OFF SWITCH LOAD ON OR OFF

9. System components POWER MEASUREMENT UNIT COMMUNICATIONS UNIT LC ADD LOAD OR REMOVE LOAD 1 2 3 SEND ON OR OFF SIGNAL GRID SUPPLY POWER IMPORT OR EXPORT FINDHORN DISTRIBUTION NETWORK CURRENT AND VOLTAGE MEASUREMENT IMMERSION HEATER SPACE HEATER SPACE HEATER TRAFFIC LIGHT LC CONTROL UNIT LOAD CONTROLLERS AND CONTROLLABLE LOADS (SMALL PERCENTAGE OF TOTAL SITE LOAD) POWER IMPORT OR EXPORT, kW 4

10. Engineering challenges Measurement of imported / exported power Signal communications – needs to be robust –powerline carrier demonstrated here via overhead line and underground cable –low power radio –communications cables –internet Control algorithm for deciding when to switch devices –need to avoid increasing import from grid! –need to avoid switching large blocks of load simultaneously

11. Social challenges Selecting suitable loads for automatic management Identifying and communicating benefits to consumers of surrendering control over their loads –traffic light idea popular with the community – voluntary load switching –test loads were mostly in central community buildings Ensuring no loss of quality or reliability of supply Integrating system with tariff structure to incentivise take-up

12. System design Prototype equipment GRID SUPPLY POWER IMPORT OR EXPORT POWER MEASUREMENT UNIT COMMUNICATIONS UNIT LOAD CONTROLLER LOAD CONTROLLER SUBSTATION – CENTRAL CONTROLLERLOAD CONTROLLER / TRAFFIC LIGHT

13. Simulation results Key to developing control algorithms and identifying benefits Example results: –assume 72kWh per day provided by 40kW of deferrable load –without control – timeswitch controls 40kW just before midnight –with control – 40kW switched on and off throughout the day depending on wind availability –saving in this instance = 19kWh – depends on wind profile and switching speed

14. Test results Demonstrated: –low-cost power measurement system –simple PIC-based control algorithm –powerline carrier communications over three phase low voltage network around test site (including cable and overhead lines)

15. Conclusions Identified several beneficial applications of load management in context of renewable energy Extended application of Econnects load controllers from off-grid systems to grid-connected operation Developed a load management system for implementation Demonstrated successful technical operation of component parts Identified issues which will make a system practicable and successful