Hybrid inverter for HVDC/weak AC system interconnection
The concept of the hybrid converter is introduced. By independently controlling a naturally commutated converter (NCC) and an artificially commutated converter (ACC), real power and reactive power can be controlled independently. Alternatively, the ac bus voltage can be regulated without affecting the real power transfer. Independent control is feasible only within certain operating boundaries. Twelve pulse operation, sequential control, and complementary circuits may be viewed as variations of the hybrid converter. The concept of the hybrid converter is demonstrated by digital simulation. At the current state of technology, the NCC is best implemented by a 6-pulse bridge using thyristors as the switching elements. A survey of power electronics applicable to HVDC applications reveals that the capacitively commutated current-sourced converters are either technically or economically better than the other alternatives for the implementation of the ACC. The digital simulation results show that the problems of operating an HVDC system into a weak ac system can be solved by using a hybrid inverter. A new control scheme, the zero Q control, is developed. With no reactive power interaction between the dc system and the ac system, the stability of the HVDC/weak ac system operation is significantly improved. System start-up and fault recovery is fast and stable.
- Research Organization:
- Stanford Univ., CA (USA)
- OSTI ID:
- 5157286
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
24 POWER TRANSMISSION AND DISTRIBUTION
AC SYSTEMS
COMPUTERIZED SIMULATION
CONTROL SYSTEMS
DC SYSTEMS
ELECTRICAL EQUIPMENT
ELECTRONIC CIRCUITS
ENERGY SYSTEMS
EQUIPMENT
HVAC SYSTEMS
HVDC SYSTEMS
HYBRID SYSTEMS
INVERTERS
POWER SYSTEMS
PULSE CIRCUITS
SIMULATION
STABILITY