Over the course of the 20th century, electricity made a transition from a novelty, to a convenience, to an advantage and finally to an absolute necessity. This conventional electricity grid is transforming into an intelligent network. The future network features diverse generation systems scattered all over the network including at distribution and even consumption levels. Also, there are new loads such as Electric Vehicles (EV) along with technological innovations including energy storage and lower voltage power flow control devices affecting the grid stability and thereby the quality of power supply. But with this transformation, there emerges a question ‘Can electricity be intelligently delivered without power quality?’
As a result of electricity revolution, it’s infrastructure is getting more and more inter-linked with ICT forming an ‘intelligent’ network. Further, with increasing Internet of Things (IoT) enabled devices, rapid increase in electronics white goods at user level, use of power electronics in integration of renewable energy with the grid, power quality issues will increase manifold. To undo these PQ issues, efficient power quality monitoring and mitigation by key stakeholders will be vital.
This blog focuses on the importance of power quality (PQ) in future intelligent electricity networks and is an attempt to draw attention on necessary steps to be undertaken by different stakeholders to maintain PQ in the new, evolving ‘grid of things’.
IMPLICATIONS OF PQ ISSUES IN AN INTELLIGENT NETWORK
An intelligent electricity network has a myriad of technologies (like sensors, robotics, advanced data analytics, automation, etc.) that forms an interconnected system capable of analysing large amounts of data, including various IoT applications. These systems are like sensory organs, capable of giving the electric system the flexibility and agility necessary to enable ideas like a self-healing grid and plug-and-play generation. Moreover, it is about weaving together energy, automation, communication & software analytics to deliver greater intelligence, predictability, and safety in everything around us. In digital era the sensitive electronic devices not only give greater control over the electrical system but also are vulnerable to poor power quality environment. In an intelligent electrical power system, non-linear loads are the main cause of power quality (PQ) degradation. The PQ issues like harmonics generated by these non-linear loads are complex and diversified in nature. The power system which is not capable of handling non-linear loads faces the problem of voltage unbalance, sag, swell, momentary or temporary interruption and ultimately complete outage of the system. This has led to losses estimated to the tune of over $9.60 billion (as per the study by Manufacturers Association of Information Technology & Emerson Network Power (India) in 2009).
The PQ issues arising in an intelligent network affects both Utilities and End Consumers as follows:
-Indian utilities experience extensive voltage variations, frequency variations on the grid leading to breakdown of network elements and at odd times leading to severe downtime.
-Harmonic currents drawn from upstream voltage sources by non-linear loads, through the impedance of cables and transformers create harmonic voltage distortion.
- End-Consumer – Voltage dip, long interruptions, etc. cause large inconveniences and have significant financial impacts to various industrial process equipment. Consumers also suffer due to under-voltage, light-flickering, etc. resulting in equipment damage or data loss followed by business down time. Harmonics generated at non-linear load utilisation point further impacts their demand and energy efficiency.
Gaps in PQ Regulations
Another clog for Power Quality in an intelligent network is the regulatory standards. When analysing the PQ Regulations and its prescribed limits, it is observed that the regulatory requirements are not consistent among States in India. Also, the central regulations framed by CEA and CERC remain silent on the applicability of Regulations for distribution system voltage levels.
For instance, at 11kV voltage level, there are inconsistencies in standards across voltage variation, voltage unbalance and harmonics.
- Voltage Variation: Tamil Nadu specifies voltage variation limit as +6% and -10% whereas other states specify limits as +6% and -9%.
- Voltage Unbalance: CEA does not specify any standard below 33kV and further there is a difference in standards between different states.
- Harmonics: Tamil Nadu, Gujarat, and Maharashtra specifies THDv as 5% with individual harmonics content not exceeding 3% whereas Karnataka specifies THDv as 3.5% with individual harmonics content not exceeding 2.5%.
The poorer the Power Quality, the more would be the initiatives required from concerned stakeholders and regulatory bodies to adopt corrective measures to ensure and enforce better Power Quality.
WHAT WILL CHANGE THE SCENARIO?
Intelligent electricity network is about intelligent management of electricity in the energy value chain from source to socket. The demand of continuous availability of quality supply has made monitoring & management of PQ data immensely important. In this environment, fast methods for measuring and estimating PQ disturbances through techniques like Artificial Intelligence, Fuzzy Logic, etc. are more efficient and reliable solution in distribution networks. It detects most (and almost all) of the power quality events and disturbances. Key benefits of PQ monitoring in the intelligent network are as follows:
- Ensures power system reliability
- Identify the source and frequency of events
- Helps in the preventive and predictive maintenance
- Evaluation of incoming electrical supply and distribution to determine if power quality disturbances are impacting
- Determine the need for mitigation equipment
- Reduction of energy expenses and risk avoidances
- Process improvements – monitoring systems allow to identify the most sensitive equipment and install power conditioning systems where necessary
Also, one should recognize that responsibility for maintaining power quality lies with different stakeholders including Utilities, Utility Workforce, Regulators, End consumers and OEMs. What role could these different stakeholders play in maintaining power quality in the intelligent grid?
- Utilities: Power utilities can play a vital role in maintaining PQ as they aim at controlling & modifying the pattern of demands of various consumers. Utilities must focus on monitoring and troubleshooting of all those PQ issues which enable them to provide continuous power supply to their customers without any interruption. The refined data from PQ monitoring will help to critically analyse the power system behaviour and important decision making points in the network. Thus, utility can also save their capital cost by avoiding malfunctioning or premature failure of the equipment due to undesired PQ disturbances in the electrical power systems.
- Utility Workforce: For technology to be useful, utility needs employees that understands the implications of IoT technology and has the mindset to create, absorb, and adapt to the resulting augmented intelligence/behaviors. A workforce that is comfortable with the pace, magnitude, and risk of IoT-driven changes is the need of intelligent network. Next-generation utility staff need to know not only the physics of the grid but also the operation of sophisticated monitoring, control, and analytical systems. Hence, utilities must develop skills or compete strongly for the skills required to support ever-more complex core utility systems.
- Regulators: Regulatory policy is a key factor that influences the PQ-Intelligent grid equation. Regulators must issue regulations on acceptable limits for PQ issues setting clear rules of the game. This is to be followed with tariff incentive/penalty mechanisms for entities which inject harmonics into the network. By strategically configuring the level of the incentive (being the penalty or reward), incentives can be given to provide an optimal level of quality. This can be realized by identifying gap in performance which is defined as the difference between actual & targeted performance. All this will eventually help in providing the consumer clean power supply from utility within the specified limits.
- End Consumers: Across various PQ disturbances, it is observed that customers are responsible for roughly 70% of the PQ issues, while the remaining 30% comes from the network. Customers must be aware of the PQ issues affecting the system from their end as at the end they are the one who pay for these in-efficiencies. Moreover, high-end industrial customers must take certain precautionary measures like
– Maintaining true power factor within prescribed limits to reduce reactive power demand
– Reduce harmonic currents while using more energy efficient equipment at their premise
– Keep a log of faced power disturbances at premises, which may come handy in finding effective solutions
- OEMs: They should be aware of PQ norms and consider the same in design of their equipment. OEMs must clearly understand the customer’s loads and design the equipment with more tolerable limits.
(Read more in our earlier blog: “Key barriers to resolve and scale-up PQ awareness and implementation” to understand more best practices to eliminate PQ barriers in India)
Such a collaborative approach by all stakeholders for maintaining Power Quality in the IoT-enabled intelligent grid will unlock greater efficiencies as well as offer desired win-win opportunities for all.
Quality of supply is an inherent part of intelligent electricity network. In this smart environment, the barriers to the adoption of these new intelligent tools can be high, but the risk and cost of not pursuing them is greater in the form of PQ issues. Therefore, a collaborative effort by different stakeholder will serve well the purpose of maintaining reliability and quality of the grid.
The effective mitigation of power quality issues will not only safeguard the network but it will also be the foundation for creating a more sustained and reliable intelligent electricity network.
Monitoring intelligent distribution power systems: a power quality plan by Neil R. Browne, Timothy J. Browne and Sean T. Elphick, University of Wollongong, 2010.
Design and Development Of Intelligent Computational Techniques for Power Quality Data Monitoring and Management by Zahed Javed Paracha, Victoria University Australia, 2011.
Report on Power Quality Monitoring by Khemraj
The power is on: How IoT technology is driving energy innovation by Rob Young, John McCue and Christian Grant, January 21, 2016.
Intelligent Electricity Network, University of Sydney.
Intelligence in Electricity Networks for Embedding Renewables and Distributed Generation by J.K. Kok, M.J.J. Scheepers and I.G. Kamphuis,2009