A Flexible Loss Calculation Method Based on Finite Sampling for MMC HVDC System

During the last decade, an increasing number of Modular Multilevel Converter (MMC) based HVDC projects have been operated, while the overall loss rate increased compared with the Line Commutated Converter (LCC) based HVDC system. Accurate and efficient loss calculation and analysis of HVDC systems are the key steps of studying the loss composition and loss reduction measurements. Since the losses can hardly be accurately measured for the HVDC system, the losses are often obtained by either simulation or analytical calculation, with the disadvantages of time-consuming and low accuracy, respectively. In this work, an efficient and flexible loss calculation method based on finite sampling for the MMC HVDC system is proposed, which can be used for long time-period power loss calculation utilizing the manufacturer's datasheet with device-level characteristics of power electronics switches. This method can flexibly use the finite current samples and switching pulse samples from simulation, field measurement, or calculated from power measurement as the calculation inputs. The accuracy of the algorithm is verified by comparing with the measured data of a practical hybrid HVDC project with both MMC and LCC.