The Power Quality and Reactive Power scenario in the country is constantly changing for the better for last more than a decade, thanks mainly to changing tariff structures providing power factor incentives and imposing harmonic penalties. Tamil Nadu Electricity Board was the first to take the pioneering initiative of imposing harmonic penalties. Maharashtra State Utility was also the first to have started incentivizing maintenance of good power factor. The move of rationalizing tariff structures is now followed by most Indian utilities by implementing measures like KVAH tariff structures, penalizing overcompensation of power factor and imposing penalties for excessive harmonic levels.
The rationalized tariff structures have led to rapid changes in the sphere of Power Quality and Reactive Power Solutions. The solution basket has become large and there are solutions available to suit the specific needs of individual customers.
There was a time more than a decade ago when it was considered good enough to maintain a power factor of 0.9 Lag just to avoid low PF penalty. The solutions were simple enough in the form of mainly fixed capacitor banks. Very few consumers used automation to control power factor and most consumers overcompensated to be on the safe side as overcompensation was not penalized. The PF incentives encouraged automation, however a major part of consumers continued with overcompensation with fixed capacitor banks. The Detuned reactors got popular and essential with the increased use of PF automation.
The reactors served three major functions:
- Reduction of Capacitor Inrush Current.
- Avoidance of Harmonic Resonance.
- Harmonic Mitigation.
Harmonic regulations did not get support from utilities and regulators barring an exception of Tamil Nadu Utility. Harmonics remained mainly an ignored area unless they caused failures and maintenance issues.
Harmonic regulations in Tamil Nadu boosted popularity of static solution AHF.
KVAH Tariff, now in force in most states, has popularized low voltage static reactive compensation solution SVG also known as STATCOM. This LV SVG initially came in as a fine correction solution for
Power Factor maintenance but its usage kept
increasing and went beyond fine correction to larger correction reactive power support. Increasing popularity of SVG adversely affected the Power Factor capacitor market.
Trending Now Medium Voltage SVG/STATCOM
Now Comes the biggest and the most significant change – Medium Voltage SVG up to 33 kV Voltage Level.
Medium Voltage SVG got foothold in India with CEA mandating its use for having Dynamic Voltage Support for renewable power generating units. The steady state reactive power support being provided by capacitor banks was found ineffective during occurrence of grid faults which triggered LVRT and HVRT requirements.
Capacitor banks with response time of more than a minute could not save large scale isolation of renewable power during grid faults. The renewable plants mostly coming in remote locations are not backed by strong grid. The grid inertia is low, and SCR values are also low.
In such a scenario Medium Voltage SVG fills the gap and strengthens and stabilizes the grid. Medium Voltage SVG further takes a large part of harmonic mitigation burden on itself. MV SVGs have the capability of mitigating Harmonics generated by renewable Solar and Wind plants up to 13th level and in some cases up to 23rd level. Conventional High Pass Passive Filters can be used to mitigate higher level harmonics up to 49th level.
MV SVG/STATCOM for Industrial Applications
Now with the availability of MV SVG at affordable prices its use is fast expanding in conventional industrial plants also.
MV SVG for industrial units has come as a boon for resolving multiple issues being faced by industry like voltage dips and load unbalance. The industry has been living through both these issues in the absence of an affordable and reliable solution.
However, the major use of MV SVG/STATCOM in industrial plants remains confined to Reactive Power support and harmonic mitigation.
Additionally, the MV SVG solution has following positives:
- It can be used directly at incoming voltage level without the use of an intermediate transformer.
- Water cooling of IGBTs makes the system robust, compact and maintenance free.
- It is ideal for KVAH tariff as it controls the PF in both directions by providing needed inductive or capacitive KVAR.
- It stabilizes the grid parameters.
- Harmonic mitigation at incoming voltage level is economical.
- Low footprint.
- Minimizes or even eliminates use of MV capacitor banks.
- Attractive ROI
- Load balancing
- Voltage dip mitigation
The industry has been suffering enormously due to frequent voltage dips in the absence of any workable and affordable solution. The voltage dips are caused by grid faults. Stabilizing the plant after a voltage dip is time consuming, labour intensive and generates substandard production till the plant stabilizes. These interruptions impact plant performance, cause machinery breakdowns etc.
The voltage dip issues have become more acute with large scale induction of renewable power generating plants in the grid which are normally installed at remote locations where grid inertia is weak and short circuit ratio is low. Every grid fault leads to a voltage dip condition in a weak grid environment. As explained earlier MV SVG/STATCOM support for renewable power generating units can minimize voltage dip occurrences.
Further a medium Voltage SVG support for industries has emerged as an affordable solution to mitigate voltage dips to avoid interruptions in industrial plants. Continuous process plants stand to gain maximum from voltage dip mitigation by MV SVG/STATCOM.
The PF capacitor market is shrinking with
increased use of SVG/ STATCOM. The MV SVGs/ STATCOMSs come with type tests as per IEC Norms, PSSE/ PSCAD modeling, CEA Benchmarking etc. for reliability of operations. The MV SVG/STATCOM is fast capturing the Power Quality and Reactive Power solutions market as it appears to be the most affordable and comprehensive power quality solution.
Baldev Raj Narang is an Electrical Engineering Graduate from Delhi College of Engineering, and is currently the CEO of Pune-based Clariant Power System Ltd. He is also the Chairman of Capacitors and Power Quality Division of IEEMA, Member of ETD 01 of BIS and Member of Working Group 11 of IEC TC08. He had previously worked for Indian Oil Corporation and Century Enka Ltd, among others.
