Optimised district heating systems using remote heat meter communication and control
Description of the project
The objective of this project is to develop and test methods and algorithms which will enable district heating operators to implement Demand Side Management (DSM) in consumer heating systems.
The methods will involve the efficient use of remotely read heat meter data as a tool to implement DSM to optimise district heating system operation. This will improve utilisation of the system in general and reduce costs, leading to a better total economy to the benefit of all the involved parties.
Consumer heating systems, as the heat load source of a district heating system, determine the operation of the total district heating system. Yet it is unusual that the operation of consumer heating systems can be monitored or controlled by the district heating operator. The optimal operation of the district heating system is therefore limited to providing sufficiently high temperature and pressure to all customers, without any possibility of optimising the system as a whole.
Remote reading systems are becoming more commonplace, developments are leading to other meter related applications. Two-way communication systems are beginning to emerge allowing the supplier to send messages and data to the consumer and vice versa. Two-way communication systems are currently at a relatively early stage of development, but technology is developing quickly and there is a wide range of transmission media available. In the slightly longer term, it is expected that it will be possible to not only communicate with the meter, but to also use it as the central control element in the heating installation.
Summary of the final report of the project
State of the art - information study about meter communication systems
An information study on the application of remote reading to district heating meters has been carried out, including information about meters and meter communication and using meters for diagnostic purposes. Information directly relevant to DSM and district heating is scarce. The study includes information about legal demands for remote reading, tariff structures and an outline of ownership details about typical consumer substations.
Results indicate that some remote reading systems are so well established that they are readily available as standard solutions, i.e. telephone modem communication. However, technologies are constantly being improved and upgraded, new developments are taking place and technical barriers are being overcome.
Conclusions are that:
- For DSM purposes current technology can provide communication systems capable of providing sufficient amounts of stable, good quality data cheaply.
- For communication with district heating meters data transfer speeds are sufficient with the currently available systems and DSM requirements do not need to push for greater data transfer speeds. Higher speed is also expensive.
- Focus should be on how to use the data/information and how to achieve savings.
Analysis and implementation activities
Methods of reducing heat load at peak hours Theoretical analysis has been carried out and promising strategies have been tested in a simulation model. Main contributors to peak load have been identified; end of night set back, hot tap water consumption and, in some cases, ventilation start. For some building categories it is possible to reduce heat load during peak hours. In buildings where night set back is not used it may be possible to reduce heating during peak periods without any detrimental effects.
Detection of inefficient consumer substations
During the heating season of 2000/01data was collected from 3 substations at the University of Trondheim. Due to poor data quality with insufficient resolution no conclusions could be drawn from the results. Alterations were made and measurements were repeated during the heating season 2001/02. Measurements show that for meters with good resolution it is possible to use several methods to detect inefficient substations. Combined with meter communication this means that useful information can be forwarded to the district heating company and/or the building caretaker or building services provider. It is concluded that advanced meter technology combined with meter communications can improve the operation of district heating networks.
Adaptive control of secondary supply temperature
An algorithm has been written to obtain a secondary flow temperature that will minimise the primary return temperature. Data for testing the algorithm has been obtained from the same substations as mentioned above. Tests on the algorithm have shown that, within the limits that it has been possible to change the secondary flow temperature, it is possible to detect an optimum secondary flow temperature which gives a maximum primary return temperature. The optimum characteristic is flat, in accordance with investigations that have been carried out in a previous IEA district heating and cooling annex.
Heat meter surveillance
Methods of detecting faulty meters using a suitable method of long term meter surveillance has several advantages over traditional calibration methods. Measurement equipment has been installed in a consumer substation, which has an in-built flow resistance. Initial results show that there is no significant change in the flowmeter, from which can be concluded that there is no significant drift of the flowmeter during the first year after installation.
Danish Technological Institute, Energy Division / Centre for District Heating Technology , Denmark
SINTEF Energy Research, Refrigeration and Air Conditioning Division, Norway
Viken Energinett AS, Norway