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In order to solve the problem that the long cable variable voltage and variable frequency (VVVF) system does not adopt an effective capacitor voltage sharing control method, resulting in a poor effect of resonance overvoltage control, the resonance overvoltage control algorithm of the long cable VVVF system based on discrete mathematics is studied. First, the long cable frequency conversion drive system is established. In order to ensure voltage loss in the range of motor requirements, a frequency converter–cable–motor (ICM) system connection mode is used to maintain the system operation. Based on the research of the capacitor voltage balance control strategy of a long cable frequency conversion drive system, the discrete mathematical model of the AC side of the ICM system is established by using this control strategy. The improved constant active power controller is obtained by establishing the mathematical model, and the resonant overvoltage in a long cable frequency conversion drive is realized by using the constant active power controller. The experimental results show that the algorithm can effectively control the resonance overvoltage phenomenon in the long cable frequency control system, and the control accuracy is over 97%. It has good performance and can be applied in practice.

The paper designed a new drive and control system of 4-quadrant converter for traction shearer according to index requirements of 4-quadrant converter of shearer, and introduced design of hardware circuit and software implementation of the system. The field experiment results show that the system realizes fast braking of shearer, provides continuous braking force for shearer, and improves control performance and reliability of traction operation for shearer, which has good popularization value for engineering applications.

Electrical submersible pump (ESP) require remote operation of inverter via a long cable. The conventional control algorithm of inverter does not operate effectively. In this paper, a new power supply scheme is proposed, namely: Inverter - Motor - Generator - Transformer – Long Cable - ESP power supply program, referred to as IMGEESP power supply system. Based on the analysis of the IMGEESP, the model of the long cable was established, the functional relationship between inverter and smart power of the IMGEESP was deduced, so that the voltage model is constructed. The frequency converter and the intelligent power supply of IMGEESP are coordinated and controlled according to the speed command of the ESP and the cable length. Simulation results verifies the correctness and effectiveness of the proposed IMGEESP.