Research on the technology of ultra-long power supply in low voltage for tunnel construction

Voltage drop in the cable line is a significant problem in today´s ultra-long low voltage power supply system. It caused the problem that electricity demands of the system and the requirement of transmission distance cannot be fulfilled. The technique that imports 10 kV or 35 kV class Voltage into the tunnel has been used as the solution. But it extends the project cycle, largely increases the budget and brings security concerns. The paper analyses the 400 V long distance power supply problem and compares reactive power compensation devices through Matlab/Simulink simulations, such as the shunt capacitor, SVC (Static Var Compensator), STATCOM (Static Synchronous Compensator) and OCC-STATCOM. The OCC-STATCOM demonstrates better capacity of real-time power load tracking and shows higher transmission power in the construction. The paper also does OCC-STATCOM correction based on real projects.