Kruhol M. Energy efficiency improvement of thermal power plant auxiliary systems

The dissertation is devoted to solving a pressing scientific and engineering problem of improving energy efficiency of thermal power plant auxiliary systems through implementation of group frequency regulation for induction motors that drive auxiliary mechanisms. The thesis presents a detailed analysis of auxiliary power consumption structure at thermal power plants. Approach to classification of auxiliary mechanisms has been advanced to take into account similarity of the operating modes and performance. Regulation methods for centrifugal mechanisms that are applied in Ukrainian thermal power plants have been analyzed, their advantages and disadvantages shown. Application of group control for auxiliary mechanisms with close optimal supply voltage frequencies has been suggested. Mathematical models of centrifugal mechanisms considered as load on electric drive have been developed. Optimal control parameter problems for auxiliary mechanisms have been formulated and solved under various techniques of the mechanism operation regulation. Auxiliary power consumption at a combined heat and power plant has been simulated for a typical summer month under the plant operation according to the heat schedule. Comparison of the simulation results with the actual auxiliary consumption data proved high accuracy of the developed mathematical models of the auxiliary mechanisms. Feasibility of group control application to the auxiliaries in Kharkiv CHPP-3 has been studied. It is revealed that group control should be used for centrifugal mechanisms operating in the air-gas flow duct of the boiler, while feed pumps are best regulated by individual variable frequency drives and network pumps – by classical regulation techniques. Practical recommendations for implementation of group frequency regulation for auxiliary mechanism electric drives under operating conditions of Kharkiv CHPP-3 are given.