A high-voltage direct current (HVDC) electrical transmission system is termed as the electrical super highway. For transmitting very high voltages over longer distances this super highway has become a highly efficient option. Also, the need for HVDC transmission is thereby increasing the need for renewable sources of energy. Thus shaping the grid future to a reliable one.
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| Fig 1. HVDC power transmission |
CHARACTERISTICS OF HVDC
DC supply is a constant current, zero-frequency system. Unlike AC, its current and voltage do not change periodically with respect to time. Long distance AC transmission suffers from energy losses and high expenses. These drawbacks in this long distance energy transmission can be alleviated by employing HVDC transmission. This system requires only lesser expenses and also has lesser losses when compared to that of AC systems.
HVDC links are used to interconnect systems with different frequencies or voltages. The Rio Madeira link in Brazil is the longest dc link in the world. The power through the links can be controlled independently of the frequency between the systems. Synchronization of AC systems to be interconnected is such a complex process. After synchronization, interconnected systems should have same voltage and frequency. This is not easy to achieve. This synchronizing problem can be solved by adopting HVDC for power transmission due to its asynchronous nature.
Nowadays HVDC has unlimited power controlling facilities due to technological advancements. It can provide controlled and constant power supply. Also, it can increase the transmission capacity and the stability of the system. The need of the power generated from the non-renewable sources can also be enhanced.
Since most of our electrical networks are AC appliances; the need and availability of AC systems are more than dc systems. Otherwise, DC systems with a number of conversion equipment have to employed. This is one of the drawbacks of HVDC systems. Expensive filters are required to be installed on the HVDC power lines to eliminate the noises in the communication lines.
HVDC links are used to interconnect systems with different frequencies or voltages. The Rio Madeira link in Brazil is the longest dc link in the world. The power through the links can be controlled independently of the frequency between the systems. Synchronization of AC systems to be interconnected is such a complex process. After synchronization, interconnected systems should have same voltage and frequency. This is not easy to achieve. This synchronizing problem can be solved by adopting HVDC for power transmission due to its asynchronous nature.
Nowadays HVDC has unlimited power controlling facilities due to technological advancements. It can provide controlled and constant power supply. Also, it can increase the transmission capacity and the stability of the system. The need of the power generated from the non-renewable sources can also be enhanced.
Since most of our electrical networks are AC appliances; the need and availability of AC systems are more than dc systems. Otherwise, DC systems with a number of conversion equipment have to employed. This is one of the drawbacks of HVDC systems. Expensive filters are required to be installed on the HVDC power lines to eliminate the noises in the communication lines.
