Intelligent Controller Based Improved Fault Ride-through Capability of Hvdc System Connected to Weak Ac Grid

In the paper, a novel HVDC transmission system operating with weak ac system has been modeled with speed and precision & analyses the control strategy & performance of system, which is controlled using fuzzy. The system can feed a weak or even dead network under fluctuations and big variations of the input power. The fuzzy logic-based control of the system helps to optimize the efficiency of the link under various disturbances. This model provides the basic building blocks found in a typical HVDC system that can be used to build models for individual users own models. The specific contributions, in this paper are that a DQtype of phase-locked-loop for synchronizing the firing pulses to the HVDC converter has been presented. This gate-firing unit is capable of a providing a clean sinusoidal synchronizing voltage from a polluted and harmonic distorted commutation voltage. The simulations based on PSCAD/EMTDC show that proposed fuzzy logic based HVDC system can operate steadily, has the capability to restore steadily when short circuit fault occurs, and obvious in advantages.