- Smart Grid - Home
- Smart Grid Introduction
- What is an Electric Grid?
- Electric Grid Evolution
- What is a Smart Grid?
- Smart Grid - Functions
- Smart Grid - Characteristics
- Smart Grid - Advantages
- Smart Grid - Components
- Smart Grid - Challenges
- Smart Grid Technologies
- Smart Energy Resources
- Power System Automation
- Smart Substations
- Substation Automation
- Smart Grid - Feeder Automation
- Energy Management System
- Smart Grid - FACTS
- HVDC Transmission
- Wide Area Monitoring
- SCADA in Smart Grid
- Smart Grid - DMS
- Smart Grid - OMS
- Volt/VAR Control
- Smart Grid - FMSR
- Smart Grid - HEDT
- Phase Shifting Transformers
- Smart Grid - PHEV
- Advanced Metering Infrastructure
- Smart Meters - Introduction
- Smart Meters - AMI
- Smart Meters - AMIS
- Communication Architecture
- Drivers & Benefits
- Phasor Measurement Unit
- Intelligent Electronic Devices
- Power Quality Management
- Power Quality in Smart Grid
- Power Quality Issues
- Power Quality Monitoring Techniques
- Power Quality Conditioners
- Electromagnetic Compatibility (EMC)
- Power Quality Audit
- Smart Grid Communication
- Smart Grid Communication
- Communication Network
- Communication Technologies
- Broadband Over Power Line
- Internet Protocols
- Web Services in Smart Grid
- Cloud Computing
- Multi Agent System Technology
- IP Based Protocols
- Cyber Security
High Voltage Direct Current (HVDC) Transmission
HVDC is a popular high voltage transmission system used in smart grid for transmitting power in the form of direct current. The need for HVDC system for power transmission arose due to increasing demand and limited efficiency and reliability of the existing power network.
HVDC has several advantages over the traditional AC transmission system such as low losses, very long-distance transmission, higher power transfer capability, and more.
What is High Voltage Direct Current?
High Voltage Direct Current or HVDC system is a modern transmission technology used in smart grid for transmitting high amount of electricity over long distances. This technology involves the conversion of alternating current (AC) into direct current (DC) for transmission of power due to several technical and economical reasons.
The most important thing to note about HVDC is that it is used for high power and long-distance transmission applications. It is very common in smart grid for connecting renewable energy resource to the electric grid.
Main Components of HVDC System
The HVDC system involves the use of AC-DC converters, transmission network and many other components. The block diagram and the function of its components are given below.
The functions of different components of an HVDC system are as follows −
Converting Stations
These are basically grid substations that use AC-DC converters for converting AC into DC and DC into AC. A typical HVDC system consists of two converting stations, one on its sending end and another on the receiving end.
Converters
Converters are the power electronic devices used at converting stations to perform conversion of AC into DC and DC into AC. The converter that converts AC into DC is called rectifier and it is used at the sending end converting station. While the converter that converts DC back into AC is called inverter and is provided at the receiving end converting station.
DC Transmission Lines
These are the high voltage transmission lines used to carry DC power from sending end to receiving end over very long distances. These are mostly overhead lines.
Filters
These are the devices used for removing harmonics from the transmitted power that may introduce during AC to DC conversion.
Control and Protection Systems
These are the systems of components that allow for controlling and managing the flow of electricity and stabilize the voltage and other parameters along with protection from faults and other abnormalities.
Working of HVDC System
Let us now understand the working or operation of an HVDC system by breaking it down in the following stages −
- Stage 1 − Power is generated in the form of AC at the generating stations like thermal power plants, hydroelectric power plants, nuclear power plants, etc. It is stepped up to a very high voltage like 800 kV for transmission using a power transformer.
- Stage 2 − At this stage, the high voltage AC power is converted into high voltage DC power using AC to DC converter or rectifier.
- Stage 3 − The converted high voltage DC power is then transmitted to the receiving end through DC transmission lines that are mostly overhead power lines.
- Stage 4 − At the receiving end, the high voltage DC power is converted back into AC power by using a DC to AC converter called inverter. This AC power can be stepped down to different voltage levels for further transmission or distribution.
This is how a typical HVDC system operates and transmits DC power over long distances.
Importance of HVDC in Smart Grid
In smart grid technology, HVDC systems are very important as they improve the efficiency, reliability and flexibility of the power transmission. It is the most widely used transmission technology in renewable energy and smart grids.
The major reasons behind the use of HVDC in smart grids are listed below −
- Provides seamless integration of renewable energy resources into the grid.
- Reduces power losses and voltage fluctuations during power transmission.
- Improves grid stability through balancing supply and demand, etc.
Advantages of HVDC System
The following are some major advantages of high voltage direct current transmission −
- HVDC transmission system has lower losses during power transmission over long distances.
- HVDC transmission system has high power transfer capability.
- HVDC transmission system provides better control over line parameters like voltage, frequency, power flow, etc. It ensures improved stability.
- HVDC transmission is more economical for power transmission over very long distances.
Disadvantages of HVDC System
HVDC transmission system also has several down sides, some of the majors are listed here −
- The initial cost involved in developing HVDC infrastructure is high due to need of installing converting stations and high-voltage transmission lines.
- As HVDC system required conversion of AC into DC and vice-versa. Hence, it is technically more complex and require advanced technology and skilled personnel for operation and maintenance.
- For short-distance power transmission, HVDC system is not advantageous and economical due to high cost of infrastructure.
- HVDC system can produce harmonics during AC-DC conversion and requires filters to remove.
Conclusion
The HVDC transmission system is one of the most efficient and reliable transmission technologies for long distance power transmission. It is widely used in smart grids because of several advantages like low losses during transmission, high power transfer capability, enhanced stability, better control over power flow, and many more.
HVDC is also important for integrating renewable energy resources to the grid. However, the initial cost involved in setting up the HVDC infrastructure is relatively higher, but it is more advantageous in the development of smart grid technology.
Lets move to the next chapter of smart grid technology and learn about Wide Area Monitoring (WAM) in Smart Grid.