This paper proposes a power conversion system (PCS) to utilize the differential pressure (DP) energy in district heating systems with reduced DC-link voltage variation. A differential pressure control valve (DPCV) is usually used to regulate pressure for heat transmission to remote areas in district heating systems. However, there is a high probability of malfunctions and failures of the DPCV, due to cavitation, since high-pressure fluids are used in district heating systems. Therefore, a PCS for utilizing DP energy in the district heating system replacing the DPCV is proposed in this paper. In addition, the DC-link voltage of the PCS greatly fluctuates when a sudden change occurs in a hydraulic turbine. It is effectively relieved by using the feed-forward control method. The effectiveness of the PCS for utilizing the DP energy in district heating systems with reduced DC-link voltage variation is verified by simulation and experimental results.
This research was supported by a grant (No. 20172020108970) from the Korea Institute of Energy Technology Evaluation and Planning (KETEP) that was funded by the Ministry of Trade, Industry and Energy (MOTIE) and the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government (MOTIE) (No. 20182410105160).
