Comparative Analysis of Different Connection Schemes for Power balance Machine in Power Plant System

The reduction of auxiliary power is critical for the efficiency improvement of power plants. For coal power plants, the auxiliary power can be reduced by replacing the driving source of auxiliary motors with a small steam turbine driven by the steam with high temperature and pressure. To make sure the power of auxiliary motors is suitable for plant requirements, a power balance machine is required to balance the extra power from steam. In this paper, the connection scheme of the power balance machine is studied for a power plant with two 630°C 1000MW double reheat units. Various electrical connection schemes connecting the power balance machine to the power system are designed. The power flow calculation and system stability analysis are carried out to ensure the system’s reliability.