Power Quality Aspect of Smart Grid

INTRODUCTION

The prime objective of the electric power industry in this era is to meet growing demand cleanly, reliably, sustainably, and at low cost. The Smart Grid vision is aiming for new products, processes & services, improving industrial efficiency and use of cleaner energy resources. As per National Smart Grid Mission (NSGM), the total estimated cost for all the projects and NSGM activities for 12th Plan is Rs.980 Crore including a budgetary support of Rs.338 Crores. Initiatives like microgrids, EVs, solar rooftop system are directed towards improving Quality and reliability of Power and will be partly-funded under NSGM.

With this investment, the vision promises to transform the existing grid into an intelligent & efficient grid with the help of smart technologies. But with the increasing smartness of the grid, are we really thinking about power quality? If not, then we need to! Because quality focussed grid, capable of delivering power quality; free of sags, spikes, disturbances, and interruption will be one of the crucial characteristics of smart grid.

Power quality is one of the key aspect of smart grid’s functionality. Implementation of smart grid requires the balance between two main aspects: efficiency and reliability. Often reliability is given priority however, it is not always guaranteed.

"Power Quality is an important aspect for successful and efficient operation of existing as well as future grid"

Power quality guarantees the necessary compatibility between the sensitive electrical and electronics components to assure an uninterrupted and high-quality supply of electricity in future. PQ is therefore, an important aspect of the successful and efficient operation of existing as well as future grids.

This blog draws attention to the kind-of subsided but an important aspect of smart grid- ‘Power Quality’.

POWER QUALITY ISSUES RELATED TO SMART GRID

The concept of smart grid lies in the integration of information and communication technologies into the existing power system infrastructure to give maximum benefit to the end-user. This blend of technologies and sources of energy can be expected to have an impact on power quality, likely negative, with PQ problems becoming more rather than less troublesome. Some of the prominent PQ issues in the smart grid are mentioned below:

  • Emission by new devices
    With implementation of smart grid, we envisage growth both in distributed generation (production at lower voltage levels) and in new types of consumption (for example, charging stations for electric vehicles, expanded high-speed railways, etc.). Some of these new consumption devices emit power quality disturbances, for example, harmonic emission. Harmonics and interharmonics will be high, below the frequency 2 kHz. Above 2 kHz, the emission is low over the whole spectrum which is generated by other equipment like energy efficient drives, micro-generators, and photovoltaic installations. The measurement of these low levels of harmonics at higher frequencies will be more difficult than for the existing situation with higher levels and lower frequencies.

  • Interference between devices and power line communication
    Smart grids will facilitate communication between devices, customers, distributed generators, and the grid operator. Power-line communication might seem an obvious choice due to its easy availability, but choosing power-line communication could introduce new disturbances in the power system, resulting in further reduction in power quality. Depending on the frequency chosen for power-line communication, it may also result in diverged disturbances, interfering with radio broadcasting and communication. It is also true that modern devices can interfere with power-line-communication, either by creating a high disturbance level at the frequency chosen for power-line communication or by creating a low-impedance path, effectively shorting out the power-line communication signal.

  • Increased harmonic voltage distortion
    With smart grids, the amount of consumption will increase with similar growth in production. This continued growth in both production and consumption could lead to the harmonic voltage distortion becoming unacceptably high. Also, the number of switching actions will keep on increasing and might reach unacceptable values. One may say that production and consumption are in balance at the power-system frequency, but not at harmonic frequencies.

POWER QUALITY IMPROVEMENT WITH SMART GRID

It might be tempting to think with the above-mentioned PQ issues that the spread of smart grid technology will increase PQ problems. But there is other side to the coin! Smart grid technology will help in reducing the PQ challenges. We can manage PQ only if we can measure it and smart grid gives us an opportunity to measure PQ. Smart Grid includes several components that help utilities deliver better quality power to your home. Equipment like smart meters on the distribution grid helps manage voltage and power factor. Smart meters, a key component of smart grid are advanced electric meters that provide both you and your utility with more information about the power delivered to your home. Like other digital devices, they include a transformer to step down the voltage for the digital electronics. They are engineered to meet strict FCC (Federal Communication Commission) requirements to keep from interfering with other electronic or communications equipment.

Smart Grid also ensures switching and protection of the devices connected to it for maintaining unprecedented reliability of the network. But this can be severely impacted due to poor PQ, leading to mal-operation and/or failure of the devices. To cater to this, smart grid provides advanced Distributed Management System (DMS) application like Power Quality analysis.

“Utilities can use Smart Grid technology to optimize the quality of supply for every customer they serve which enables a more efficient and accurate supply of power”

Smart Grid further gives opportunity to improve the performance of the existing power system (or to prevent deterioration) without the need for large investments in lines, cables, transformers, etc. From a customer viewpoint, the improvements can be in terms of reliability, voltage quality or price.

Voltage quality improvement, expected to be made by smart grid in the near future would be a reduction in long-term voltage-magnitude variation. Therefore, with real-time information, utilities can use Smart Grid technology to optimize the quality of supply for every customer they serve which enables a more efficient and accurate supply of power.

CONCLUSION

In the situation where integrated generation, as well as consumption decreases the quality of power in the smart grid, it is essential to analyse both generation and consumption in a very thorough way. Smart grid gives opportunities to leverage its resources and monitor PQ, improving the quality of supply to end-user. The new technology associated with smart grid offers the opportunity to improve the quality and reliability as experienced by the customers. The smart grid will be at the heart of tomorrow’s connected world underlining the ‘Quality’ of life for each one of us. Thus, Power Quality is and will be an important aspect of smart grid for its efficient operation that needs attention from the industry. It concludes that higher the quality of power, more efficient will be the Smart Grid.