Distributed dispatching for embedded generation
Electrical power systems are currently moving towards distributed generation, using many small generators instead of a few large ones. This can potentially produce great improvements in efficiency, by allowing utilisation of waste heat (cogeneration). However, it also poses new problems of control and co-ordination of large numbers of generators, which may be connected deep within the distribution network. It is well known that existing schemes for planning, dispatching and protection of central generators are not directly applicable to the new technology, and dispatching (scheduling) of small embedded generators is not currently feasible. In this work, a novel dispatching management system which may meet this requirement is proposed. Instead of using a single control centre, it distributes dispatching functions throughout the network. Some functions are performed by controllers and software agents built into the embedded generators themselves, and others handled by dispatcher software associated with a group of generators and loads. The dispatcher operates a small virtual market where energy can be traded between agents representing: generators, loads, network functions (AVR etc), and other dispatchers. This allows multiple dispatchers to be interconnected, so potentially dealing with very large numbers of generators. To test this concept, some prototype agents, a basic dispatcher, and means of communication were created, in the form of programs on a desktop computer. The "REDMan" suite of software achieved successful trading of energy in a simulated environment. This motivated a more advanced trial where REDMan was developed further and used for experimental dispatching of real generating equipment and loads. Construction and assembly of the experimental apparatus, interfacing of hardware to the computer environment, experiments and results are presented and discussed here. The experimental system was dispatched in a satisfactory manner, and much practical experience was gained in the issues relating to dispatching of EG. Several possible avenues for further research were identified.