Vijayan SR, Asst Vice President - Grid Automation, Power Grids Division, ABB India
India has witnessed a massive power grid failure in July-August 2012 due to overdrawing by some states. What are the steps that could have been taken to improve Grid Discipline?
In analysing the grid failure of 2012, it was observed that overloading and consequent tripping of 220 kV system had pushed the system to the edge. As is the case with most system failures, no single factor was responsible for the grid disturbance. The various factors that led to the grid collapse could have been outages of some transmission lines or overdraw attributable to frequency control. Other factors could also have been related to control of power flow within permissible limits, co-ordination between Load Dispatch Centers (LDCs) and non-compliance to instructions from the central and regional LDCs by the state LDCs.
There are different schemes/methods which are now implemented to maintain the grid discipline. The Availability Based Tariff (ABT) is one of these, where penalties are imposed if the grid frequencies are not maintained due to over/under draw of power. However, the maximum penalty in such cases that can be imposed by regulatory commissions in accordance with the Electricity Act, 2003 is meagre in the face of the damage such non-compliance can cause to the grid.
Further, as any major disturbances in the transmission system are also linked to power generators which are connected to the transmission system, implementation of Automatic Generation Control (AGC) is another step taken toward improving grid discipline. AGC will automatically restrict line flows to scheduled limits and also maintain the frequency at the nominal value. However, for some reasons this is not implemented yet, although it has been part of our grid code for several years.
So, effective implementation and enforcement of such schemes become key to maintain optimal grid discipline.
Being a technology leader in the power sector, what are the latest technologies you would have recommended as a solution for ensuring the reliability of the national power grid in India?
The evolving grid has new complexities to consider. Globally countries face the challenge of reducing their carbon footprint while maintaining and enhancing economic growth, hence power is one area that is in focus for national change. The result is that power generation is becoming distributed with increased penetration of renewable energy. The nature of harnessing renewable sources implies intermittent and unpredictable energy flow. Consumption trends are also changing with the new demands of industry, smart cities and urbanisation, and we see multi-directional power flow. All these influences call for new technologies to shape the grid of the future. To meet the challenges of renewable generation and the dynamics it brings into network operations, technologies that not only deal with integration, but also stability are required. Here solutions such as microgrids with energy storage are available today, making the grid more reliable and resilient with both off-grid and grid-connected solutions.
In the context of grid disturbance, there are various technologies available in the transmission segment today which strengthen the transmission network. There are also solutions that offer data on real time network status and behaviour to increase situational awareness to the system operators at the LDCs.
Some of these technologies and functions include:
- High Voltage Direct Current (HVDC) transmission system
- Flexible AC Transmission Systems (FACTS)
- Digital Substations
- State Estimation and Dynamic Stability/Security Assessment along with SCADA/EMS systems for power flow monitoring and contingency analysis
- Phasor Measurement Unit (PMU) and Wide Area Monitoring System (WAMS)
- Asset Management, Condition Monitoring / Condition Based Maintenance, Predictive and prescriptive analytic solutions
- PowerStore - ABB's containerized plug-and-play microgrid solutio
- Distributed Energy Management Systems (DERMS)
The government's focus on Grid Reliability has thrown up several opportunities at the national and state levels. To what extent you have been able to participate in these opportunities and what kind of modern technologies you have offered?
The government's focus to improve grid reliability, provide 24x7, quality power to all, and push towards distributed renewable generation has underpinned the need for technology implementations in the power system. In today's parlance the implementation of such technologies are termed as 'Smart Grid' technology. Smart grid technology is not a single technology, rather a collection of existing and emerging technologies working together. A smart grid is a combination of intelligent devices in the field like the transformers, circuit breakers etc., with sensors and powerful control systems with the convergence of OT (Operational Technology) and IT (Information Technology) for centralised monitoring and control.
ABB is a technology leader in electrification products, robotics and motion, industrial automation and power grids, serving customers in utilities, industry and transport & infrastructure globally.
The following are a few examples of ABB's smart grid technology :
- Supervisory control and data acquisition systems (SCADA)
- Energy Management System (EMS) for transmission systems
- Distribution Management System (DMS/ADMS) and Distribution Automation
- Digital Substations
- Microgrids & Renewable Integration
- PMU & WAMS
Enterprise Asset Management and Asset Performance Management and Condition Based Maintenance systems
Communications systems - wired and wireless
Building control for optimal performance
Some of the recent orders won in this technology space in India are:
1) ABB will deliver a 110 kilovolt (kV) digital substation to Technopark, one of the largest Information Technology (IT) parks in India, located in Kerala and spanning an area of 930,000 square meters. Due to the nature of the industry, the campus is highly dependent on reliable, round the clock power to serve the 350 companies employing more than 50,000 people.
2) ABB has teamed up with India's national electricity grid operator Power Grid Corporation of India Limited in a mega project to deliver a transmission link that will have the capacity to bring reliable electricity to more than 80 million people. The Raigarh-Pugalur 800 kV ultrahigh-voltage direct current (UHVDC) system will connect Raigarh in Central India to Pugalur in the southern state of Tamil Nadu. The 1,830-km link will be among the longest in the world. With a capacity of 6,000 MW - the equivalent of more than six large power plants.
How do you think the present level of grid reliability in India compares with global benchmarks? Do you think there are any more measures that are called for to take it closer to the global benchmarks?
It is important to mention that India is one of the largest unified grids in the world, implying immense complexities in operation, and efficient management of the grid. It was a great achievement for everyone associated with India's power system when the southern grid was synchronised and connected to form one single national grid. ABB commissioning this project, and was fortunate to play a role in India's milestone in achieving 'One nation - One grid - One Frequency' Talking about benchmarks, there are various parameters like T&D losses, 24x7 power availability, and power quality which are the key indices. As the grid evolves, there is room for improvement, with the help of technology that will bring our national grid closer to the global benchmarks.
While we implement more automation solutions and bring intelligence to grid operations, cyber security is an important aspect that we need to address both in terms of system implementations and organisational policies to mitigate the various threats and vulnerabilities of such an automated system.
-BS Srinivasalu Reddy