APPROACHES TO CHOOSING A FREQUENCY CONVERTER IN THE STRUCTURE OF FREQUENCY-REGULATED ELECTRICAL DRIVE OF NETWORK PUMP UNITS OF CENTRALIZED HEAT SUPPLY SYSTEMS

Abstract

The necessity of choosing a frequency converter in the structure of the frequency-regulated electric drive of the pumping unit of the centralized heat supply network is substantiated, taking into account the requirements set forth by the technological mode of its operation and economic efficiency. Analytical dependencies related to the parameters of the frequency converter have been determined. The calculation of the frequency control selection parameters was carried out on the basis of technical data related to the operating mode, where the consumption of the coolant changes according to the hydraulic load typical for HVAC applications defined by the European Union Regulation, as well as the technical data of the pump, frequency converter and electric motors provided by the manufacturers. The definition of parameters concerns the operation of pumping units in a typical operating cycle characteristic of district heating networks, which involves operation with a reduced load for a long time. The results related to the range of rotation speed of the electric drive, its power, and torque were obtained. The obtained results provide a basis for the use of frequency converters with a scalar control method in the structure of the electric drive. Using the net present value method, the economic efficiency of using a frequency converter with a scalar control method was determined, compared to the option of using a frequency converter with a vector control method in the structure of an electric drive. The practical significance of the obtained results is that they provide grounds for an objective choice of the type of frequency converter when designing and equipping electric drive systems of network pumping units.