Once we have understood the issues and where they are occurring on the network, it will be vital to have the appropriate tools to support them in the most cost effective way. TVV will be trialling a number of technologies and solutions to determine the most efficient way to achieve this.
Automated Demand Response, or ADR, is a mechanism that electricity providers can use to reduce the load on a network by regulating usage at peak times, typically between 15:00 and 20:00.
Honeywell Building Services’ has developed a solution for Automated Demand Response which is being trialled on this project. This comprises a central server and automation controllers connected to commercial customers’ Building Management Systems, and will be integrated with the Distribution Management System provided by GE.
The image below shows the setup of the Honeywell ADR solution:
A Distribution Control Engineer will request a ‘load shed’ on a portion of the electrical network, if he/she spots an overload condition emerging later in the day. Commercial customers on that portion of the network that are integrated with the ADR scheme will be contacted by the Honeywell central server to shed electrical load at a certain time. This might involve their BMS turning off an escalator, pre-cooling and then turning off air conditioning, and many other possibilities. The Control Engineer will hope to realise the target load shed value.
The graph below sows the peak load reduction from an ADR trial:
The Honeywell controller receives a signal from the Honeywell DRAS (Demand Response Application Server) and is able to schedule various shutdown events on the BMS for later in the day.
The building supervisor also receives a communication via email and can ‘opt out’ if the timing of the load shed is inconvenient. A load shed request will typically be issued with a few hours’ notice.
The DMS is fully integrated and receives messages back from the Honeywell DRAS, using industry standard XML via HTTPS, with SOAP authentication headers. These messages confirm how many ADR-enabled customers are in scope for the load shed and what proportion of the target load shed value can be reached. The Control Engineer may have to repeat the process to achieve his/her target load shed value, to ensure stability on the LV network.
The project will be recording details of a Telecoms evaluation based upon a) Using a dedicated SIM card versus b) Using Building Manager’s own internet connection to communicate with the Honeywell JACE controller.
Cold Thermal Storage
The project is deploying three “Ice Bear” units into commercial buildings within Bracknell; working with California based Ice Energy these systems are at their most basic a large thermal storage tank, but with one significant twist.
The Ice Bears principle function is to shift energy usage away from the peaks of the daytime to the night, when energy is cleaner, greener and less costly! The way it does this however is unique. The Ice Bear has two basic modes: ice charging and ice cooling.
Ice charge mode happens throughout the night when a self-contained charging system freezes water in the Ice Bear’s insulated tank by pumping refrigerant through a configuration of copper coils within it. The condensing unit then turns off, storing energy until cooling is needed. It is literally a battery in the form of a huge block of frozen water.
As daytime temperatures rise the Ice Bear unit replaces the energy intensive compressor of the building’s air conditioning unit. The Ice Bear, fully charged from the night before, switches to Ice Cooling mode. The Ice Bear uses the ice, rather than the AC unit’s compressor, to cool the hot refrigerant, slowing melting the ice as it travels through a series of copper coils.
Once the 6 hours of ice cooling is used, programmed to cover midday peak loads, the Ice Bear transfers the job of cooling back to the building’s AC unit to provide cooling as needed. During the cool of the night, the Ice Charge mode is again activated and the entire cycle begins again.
Energy storage doesn’t get much cooler than this!
Hot Thermal Storage
The project is deploying Energy and Micro-generator Management Appliances (EMMAs) from Coolpower Ltd to learn about how customers with PV, and other sources of electrical micro-generation can maximise the use of the energy they generate themselves while at the same time restricting the maximum export of energy to the DNOs network.
EMMA diverts surplus power from your generator to one or more thermal stores, typically as part of the Thames Valley Vision project these will be immersion heaters as these provide a useful energy store even in hot weather when heating is not required. While doing this EMMA holds electricity export below a set threshold which will ensure that the safe peak export for a street is not exceeded.
The cost of these units can in some cases be less than the cost of a upgrading the DNOs cable network. SSEPD are exploring the potential benefits to a DNO in the TVV project.
Note: EMMA units can be configured to divert all excess electricity to a thermal store until it is full and then allow further excess energy to be exported to the grid. However this mode of operation is already understood, does not have the same level of benefit to a DNO, and is not being studied as part of this project. If you wish to do this then you can purchase an EMMA unit directly from Coolpower at the following address.
Energy Storage and Management on low voltage networks
The project will be installing 25 Energy Storage and Management Units (or ESMU’s as we affectionately call them).
These novel devices will be formed of power electronics and energy storage in chemical batteries.
The ESMU’s will help us understand the role of energy storage in managing issues associated with overloading and excess solar generation but also how the power electronics can be used to improve power quality on the network.
The ESMU’s will be controlled by a new suite of Smart Control algorithms being developed by the University of Reading to see if there are better ways of managing energy storage than just simply charging and discharging the batteries.
The TVV project is also looking to evaluate how various new commercial models can help customers and businesses take up new services and offerings such as Automated Demand Response. The new commercial arrangements will trial different payment incentives to perform load shed events. These trials will help us understand the rate at which businesses are likely to take the technology and reduce the load on their building not just for the planet but for their wallet as well!