Optimization Control In Unit Group Based On Decomposition-Coordination Method Of Large Scale Systems

In the regional power system of our country, each region has a number of fossil fuel power plants containing multiple generating units. In order to achieve maximum economic interest with minimum environment cost, how to determine the distribution of the load among these units rationally is currently a significant problem faced by the power system dispatching center. The load distribution of all fossil fuel power plants in a region is a high-dimensional, multi-objective and highly coupled problem. It encounters great difficulties in digital computing, such as requiring large memory size, costing a lot of time, even facing "curse of dimensionality" when traditional methods are applied to solve this kind of problems. Fortunately, the decomposition-coordination theory of large scale systems is a very effective method to deal with such problems. It can simplify a high-dimensional object, reduce its order, overcome difficulties mentioned above and realize multi-level hierarchical control towards a complex system.In this paper, a group of fossil fuel power plants are taken into account to establish a multi-objective optimization model of load distribution based on economic interest and environment cost. The model is decomposed into a two-tier structure model and an optimal result is achieved using decomposition-coordination method of large scale systems. The method mainly consists of Lagrangian relaxation, sub-gradient algorithm and particle swarm optimization(PSO). And the simulation example tests and verifies the objective that the power plants can obtain the satisfactory economic efficiency with the minimum pollutant emissions.