Abstract: Linear analysis, simulation, and experimental results are used to verify the stability of the control algorithm across a range of operating conditions. Finally, expressions for the harmonic impedance of the system are derived to study the effects of supply voltage distortion on the harmonic performance of the system. Many grid-connected power electronic systems use a voltage source inverter (VSI) connected to the supply network through a filter. This filter, typically a series inductance (smoothing reactor), acts to reduce the switching harmonics entering the distribution network. An alternative filter is a Resistor Capacitor Inductor (RCL) network, which can achieve reduced levels of harmonic distortion at lower switching frequencies and with less inductance, and therefore has potential benefits for higher power applications. For the schematic simulated diagram which is forwarded in this paper, it is likely possible to transmitted high power very close to their limit with negligible reactance and susceptance. The systematic diagram consists of a 12 pulse bridge rectifier, dc links, pulse width modulated (PWM), voltage source inverter (VSI) and converter transformers. This paper gives the feasibility converting a double circuit AC line into composite AC-DC transmission line given the advantage of stability improvement, damping oscillation and reactive power compensation for AC weak buses. Simulation and experimental studies using MATLAB Simulink model are carried out for the coordinated control as well as independent control of AC and DC power transmissions.
Keywords: HVDC, HVAC, Converter transformer, Harmonics, Smoothing reactor, Filter