What are all the power quality issues and what among them are critical?
The major power quality issues are those resulting from the unpredictability and variability of the grid-tied Renewable Energy generators. With rising number of RE connections accessing the grid, power quality issues are compounded by the burgeoning growth of non-linear loads, variable speed drives, switching capacitors, power conditioning devices and power electronic devices. They cause harmonic distortions, reactive power disturbances, rampant voltage fluctuations, oscillatory transients and load imbalance. Total harmonic distortion (THD) is a critical power quality parameter which often gets less attention but which needs to be monitored closely in an increasing complex grid with a heterogeneous power mix.
How does power quality impact large and small consumers of electricity, particularly the economic impact?
Power quality adversely impacts the grid in many ways. Foremost is that the deterioration in power quality is directly related to technical losses. Moreover, issues like harmonic disturbances create imbalance and grid instability. Total harmonic distortions in voltage and current reduces the grid capacity to evacuate electricity and causes stress on the power distribution network, which might lead to the triggering of electrical protection systems and network failure. The economic impact of network breakdown and system restoration is huge, which the electricity companies cannot afford. In a network affected by poor power quality, corrective measures like conductor replacements, reconfigurations and line balancing invite avoidable capital expenditure. Technical losses in distribution systems due to poor power quality impacts utility’s revenue stream. Increase in expenditure on regulatory compliance is another concern for the utility, as the reliability indices get impacted due to poor power quality.
How does the injection of RE power enhance or deteriorate grid stability and quality?
Injection of renewable energy into the grid is a complex operation because it is dependent on the changing meteorological conditions. Power conversion equipments, reactive loads and capacitive switching in grid-connected renewable energy systems tend to generate harmonics and oscillatory transients. However, this can be tackled using appropriate harmonic filters, transient suppression and using efficient inverters and other electronic devices. Changing weather conditions affect RE generation and cause system balancing issues. The problems can be overcome to a large extent through load forecasting and planning, advance weather information and availability of supporting battery energy storage system to cut in during emergencies.
While the RE injection impacts the generation side, the impact of EV revolution -on the demand side is not receiving much attention now. What are the consequences of having large variations both on the generation and load side and how to manage them?
There is always inertia before market forces combined with government policies and regulations try to change it. This is particularly true in the case of the EV revolution. Thanks to the concessions offered to the EV industry by the government in the latest Union Budget, the interest in the development of EV infrastructure has received a positive thrust. However, much more needs to be done in developing robust and reliable EV charging infrastructure – one which intelligently communicates with the smart grid and helps in balancing supply vs demand. EV infrastructure has to communicate with the distribution network during bidirectional flow of electricity. Typically, when a large number of EVs are drawing power from or supplying power to the grid, the charging control systems and the grid demand response must work in unison to ensure grid stability.
Will DC grid with Storage be a good alternative and will DC Smart Grid will be the future?
DG grid with storage system is a good alternative for community microgrids, and this is already being put to use effectively in an islanded mode of operation. However, for bulk power evacuation, AC distribution system will still remain the mainstay infrastructure. Therefore, both AC and DC grid systems must co-exist. Migrating completely to DC grid for bulk power transmission means huge capital investments, and it does not make economic sense. However, smart DC grid can usefully serve its purpose of supplying power to the local community, in a microgrid setup, energized by renewable sources of generation.
As a senior professional associated with the power sector for more than three decades, how do you envision the Indian Grid and the Utility market emerging in the next five years?
In the next five years, bolstered by policy initiatives, I foresee a major thrust in the EV infrastructure development. There are already many advances made in battery energy storage systems. The battery energy storage systems are packing more capacity in a smaller footprint. This means more backup power available for renewable energy systems.
Automated demand response or demand side management is another area which will have play a significant role in regulating energy consumption based on real-time pricing or load signals. Consumers will be empowered to choose the time of use and the tariff that they pay for the electricity, interacting with an intelligent grid in real-time
Distribution asset analytics is another area which I foresee will undergo a rapid digital transformation, with the use of artificial intelligence (AI) and machine learning (ML). Real-time network visualization and asset condition analytics will allow proactive maintenance of the network. Internet of Things (IoT) will form the backbone of remote grid monitoring system with AI-based analytics, on a cloud platform. With a highly interactive grid monitored and controlled by sensors, Big Data will come into play for network data mining and analytics. Digital twins is another concept which will find a much wider application in automating the grid, making fault detection quicker through predictive maintenance and network restoration faster in case of breakdowns.
Mr Jayant Sinha is the CEO of Ensource Consulting and provides consulting services to utilities and industries on energy and cost saving solutions. He has 32 years' experience working on clean energy projects in India, UK, Spain and Middle East. He has worked on power sector transformation programs, R-APDRP and IPDS, of the Ministry of Power, Govt of India. He is an Engineer from BITS, Pilani, with specialization in Energy Sustainability Management from Cambridge University. He has published several papers in reputed energy journals, some of which can be accessed at: https://jayantsinha.wordpress.com.
Mr. Jayant Sinha would be one of the expert speakers in the Conference Session "Smart Grids - The Mother of all Solutions- Ensuring a Continued RE Development and Integration" scheduled on 29th November 2019 at the Intersolar India Conference.