The Research Of Marine Diesel Power Station’s Power Electrical Load

The load capacity of marine diesel power station needed to be tested carefully in order to ensure the safety of the sailing. On behalf of the static load, water resistance is widely used. This kind of mock load costs less and can be easily applied, but it cannot reflect the dynamic condition. On the contrary the power electronic load (PEL) which consists of the dual PWM converters can fit these requests. PEL can mock load in different levels and different characters with the outstanding performance by the control of the power devices. At the same time, it can reduce the energy wasting by the energy feed-back to the grid.This thesis will introduce the trend and the condition of using dual PWM converters as mock load nowadays in the beginning. And then the mathematic model of it is built, in order to analyze the power flow in the system. Based on the instantaneous power theory, the switch table and the model of the direct power control are built on the Simulink software platform. In order to alleviate the difficulty in hardware design, space vector modulation (SVM) is adopted in this system. By this change, those drawbacks are eliminated, forming the SVM-DPC. To achieve the direct power control without ac-voltage sensor, the concept of flux which exists in motor is introduced. In this way, the virtual flux-linkage oriented direct power control without line voltage sensors (VF-DPC) model is built.The distortion of ac current and the fierce fluctuation of dc voltage which appear with the abrupt change of load are not wanted. So the integrated control of dual PWM converters is needed. The feed-forward control method is added to the system, besides the existing of balancing the input and load power. To the coordinate control strategy of this system, coefficient modified load power feed-forward is proposed. The simulation testifies the correctness of this strategy.