Optimal Compensation of Voltage Drop Across Long Power Cable in Motor Drive Systems: A Vector Controlled Approach

This paper proposes an optimal voltage compensation method for the drop across long power cable in a motor drive system. In the proposed method the drive is utilised to compensate the voltage drop and no additional voltage regulation device is required. The method is optimised by means of vector control-based approach introduced in this paper. The independent control of voltage vectors in the d-axis and q-axis allow compensation of the amplitude drop and the phase shift. The analysis in this paper proves the minimum voltage compensation can be achieved by the independent control of the d-axis and the q-axis voltages. A dqn model of the long power cable is used in this paper which decouple the mutual coupling between the three phases. The paper starts with analysing the dependency of the voltage drop on the cable parameters and the operating power factor. Then, a brief background of the dqn power cable model is introduced. Detailed analysis of the proposed method is presented. The MATLAB simulation results show the operation from standstill slip to synchronous speed slip to verify the validity of the method in that slip range. The experimental verification is carried out by using a lumped long cable model with two different sets of inductance and resistance. It is seen that the proposed algorithm can reduce the voltage requirement by 15%–18% compared to the commonly used scalar compensation method.