How to deal with low power factor (PF) in DG sets? - Part 2

Robust Power Factor correction systems have been designed by expert power electronics developers as per the given limitations and system boundaries (in Part 1). The newly designed systems deploy the principles of the conventional Automatic Power Factor Corrector (APFC) but they differ significantly on aspects like the control logics and subsequently the controller hardware that are cutting-edge and sophisticated. In common language, this corrective mechanism is known as reactive power consumption whereby a mirror image of the tracked power factor is formed to correct it in real time.

To put this into effect you would need the below things:

1.      Thyristors with solid state relays - As the name itself suggests and unlike the conventional magnetic induction relays, these are made up of solid state electronics (semiconductors) that are helpful in eliminating transient currents and reducing the time lag between the consecutive switchovers of capacitors.

2.      Multiple current sensors-A current transformer should be available for every electrical phase of the layout. It will virtually balance the load and correct the power factor on every phase line.

3.      Microprocessor-based controllers - The additional phase-wise data parameters and the calculation of power for correction determination have rendered micro controller based controllers slow and sluggish. That is why hardcoded PLCs or faster microprocessors work better than them.

Advantages of correcting the Power Factor with the above advanced methods:

1.      More alternator efficiency- The copper losses that are associated with an alternator are directly proportional to the square of the current that it delivers. Thus, the correction of power factorwill lead to lesser current per unit power and reduce the associated copper loss.

2.      Reduced overheating and voltage fluctuations - There’ll be reduction in the currents in the total system. Due to this, overheating and voltage fluctuations in the windings and the transmission network due to the shuttling of loads is greatly reduced. This further saves T&D losses.

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Low power factor in dg sets – Part 1

The state of power supply has been erratic for a long time and many areas in the country are still struggling for a reliable source of electricity. Especially the industries that need uninterrupted power supply for economic sustainability have shown a tremendous rise in moving to diesel generators as an important source of electricity and not just a temporary arrangement. With the increase in usage and desirability of diesel generators the need to find ways to improve their efficiency and power factor (PF) is also on the rise.

What are the causes of low power factor?

Different load sizes that come with different power factor effects is the primary cause for the overall reduction in the power factor of an electrical layout. But various other reasons contribute to power factor output being low and in a significant way. The reasons are primarily connected to the fundamental limitations of a power generator.

A diesel power generator is a source of power that doesn’t have a network of sources and loads to load it. Thus, it has a limited capacity to fulfill sudden and large demands of reactive power. To build more on this limitation, the below can be associated as reasons why there is lower power factor in dg sets:

1.      Over sized dg sets

Designers of a plant usually tend to oversize a dg set or limit its loading owing to a largely existent myth that 0.8 is the ‘designed’ PF for dg sets. This essentially leads to liberally sized diesel guzzlers that do not deliver the full version of their economic capability. The alternator of a dg set is same as its larger variants connected to utility power turbines with scaled down proportions. Which means that it by design has the capability to deliver the exact amount rated as its KVA (kilovolt-ampere). So, 0.8 is not a design variable but it’s more like a thumb rule inferred from the average power factor in any industrial electrical layout with a general set of inductive - PF values .8 to .85, non-linear – Power Factor values .5 to .65 and linear (unity PF) - 0.80.

2.      Phase loading that’s unbalanced

Most of the industrial electrical layouts have loads that are liberally connected on various power phase lines because physical limitations of the process layouts are simpler to visualize when compared to the electrical balancing on every line. This doesn’t seem to be a problem when it comes to the grid connected situation where the primary connection of a phase maintains the sync in the remaining from the utility side owing to a grid’s macro effect. But in the case of a dg set that’s’ captive, syncing the phases is not even a function built into its power electronics.

3.      The load of compensation

From various reports on the effect of different power factors on dg sets and detecting safe zones it has become evident that close to unity Power Factor is achievable and safer but low Power Factor for greater periods has more negative impact.

This is part one of a two-part series. In the second part, learn how to correct dg sets with low Power Factor.

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Emission norms for Diesel Generators.

With all due respect to how much technology has advanced in the past few decades itself, pollution and harm to the environment has grown to an alarming state. If it weren’t for certain norms, rules and regulations that monitor the number of factors polluting the environment, the world would have been in shambles.

In India, the Ministry of Environment has been working tirelessly to ensure that the ratio for pollutants is balanced well with nature. The latest amendment from Ministry of Environment (Central Pollution Control Board) was rolled out in July 2014 which calls for substantial reduction in emissions from diesel generator sets.

These norms put a limit on how much volume of pollutants a certain diesel generator must emit. And the only thing better than damage control is preventing the harm. Most diesel generators produce harmful gases like Sulphur Dioxide, Carbon Mono Oxide, and Non-Methane Hydro Carbons among others.

What makes Mahindra Powerol Diesel Generators a whole lot better than most generators is the minimal amounts of hazardous gasses in parts per million units of volume that are emitted from their highly efficient diesel generator sets. 

From plants located in the municipality boundaries of a city or town to those located in distant areas, the standards set by the State Pollution Control Board are always met by these diesel generators.

To know more about diesel generators, visit http://www.mahindrapowerol.com/