Barely a few weeks after the new Minister took over, there was an island-wide power failure for about five hours. There was a hue and cry as if this had never happened previously in Sri Lanka. What hypocrisy! I can understand politicians in the opposition making a major issue of it. But any engineering student will know the technical issues involved. A closer scrutiny of the present situation will reveal that issues that prevailed during the previous governments are no less irrelevant.

However, because of a wrong choice of words probably by the Minister and wrong emphasis by media personnel ignorant of technical issues involved, a stability problem was turned into a monkey business, initially. What the Minister wanted to say perhaps was that the instability was the result of a sudden demand outage or a sudden decrease of supply from the grid at the Panadura substation, and that the outage was caused by monkeys messing around at the substation. But the media stress was on the monkeys, not on the demand outage.

Of course, power demand outage can occur due to several other reasons as well, such as faulty switching system, transmission and distribution power line faults, thunder and lightning. The occurrence of anyone of these events can disconnect consumers from the grid. A stable power system should withstand any power outage or failure, occurring either from the generation-side or from the demand-side, by adjusting the supply connected to the grid.

It is not easy to guarantee power system stability. In a stable grid, power generation and demand must and will be equal. When power-demand varies, the grid control system manages the supply of power by matching that demand by controlling the amount of power generated by generators.

When there is a sudden drop in demand, supply must be reduced immediately, lest the excess supply cause the frequency of the power supply to increase. Frequency of the power supply should normally be at 50 and, by international standards, this should not exceed 50.1. If it surpasses this limit, a lot of equipment and systems depending on the frequency of power supply can malfunction. If generation is not quickly reduced to match the demand, the whole grid system can come to a halt.

The CEB’s official technical statement first talked about the voltage issue. I do not know the reason for mentioning the voltage issue and not the frequency issue. On the other hand, in my view, the recent request by the CEB to switch off solar power from the grid during the New Year period, mentioned correctly the frequency issue.

Similarly, if there is a sudden drop in supply as against the demand, the frequency will drop. Supply can fall short of the demand either due to a failure of the generators/transmission connecting the generators to the grid or due to a sudden increase in demand. If I remember it correctly, the power-demand in England increased suddenly by 400 MW at the end of a particular popular TV Show because most of the viewers powered-on their electric kettle after the TV show.

One of the ways of checking power system stability is to have continuous computer simulation of the power system, subjecting to fault simulation at the real-time operating condition to verify stability and make suitable adjustments if necessary. I am not sure whether the CEB has such a system

The CEB does not have control over demand, but they have control over supply. Usually, thermal/hydro generators that are connected to the grid run below their individual capacity. When demand increases, they can increase fuel supply/water to the diesel engines/turbines connected to the generators. Thus, they can increase power supply. Where demand drops, they can reduce inputs to the power generation system. Increasing or decreasing the inputs to these massive generators is under the control of the CEB grid management system.

Small private solar systems cannot be controlled by CEB grid management system either to vary power supplied to grid by them or shut them down. When power supplied to CEB grid is made up of substantial amounts of power generated by small private solar systems, the CEB grid management system finds it difficult, if not impossible to manage the amount of power supplied to the grid. When demand drops suddenly and if there are insufficient hydro/thermal power being supplied to the grid to reduce supply from to match the decrease in demand, excess power generation cannot be eliminated; the system frequency will increase and will bring about instability. Consequently, a complete island wide shutdown of the grid could take place.

A problem with cheap clean solar energy connected to the grid is the maintenance of stability of the grid. The question is if the country could risk an unstable grid that could cause billions of rupees of loss in industrial and commercial sectors because of an island wide power failure.

There are ways to improve stability of the grid when solar energy is the dominant source of power to the grid. It does not seem that the opposition politicians adopted these measures when they were in power. These measures should have been put in place when solar energy was introduced into the grid. It would have been more meaningful.

A few days after this incident of the island-wide power failure, a politician of the opposition claimed that although the Minister had been briefed about this possibility a week prior to the incident, the Minister did not act on it. However, it is pertinent to observe here that the opposition politicians had been in power for years but had not taken action to remedy the situation. The fact is what happened now could have taken place at any time in the past!

When the Minister or his officials take action to reduce reliance on solar energy, there is virulent criticism hinting at corruption in the form of bribes from the diesel power lobby. The argument adduced is that citizens are being denied cheap clean energy, and that expensive diesel power is instead given preference. However, I do not think the government has banned solar energy. The only thing sought to be done is that such solar energy cannot be connected to the grid especially at the time low demand, in the interest of preserving stability in power supply and consequently in the greater interest of the country. I consider that this is a rational step taken in the right direction to maintain stability of power supply.

With the solar power dominance in the grid, we should have batteries to immediately absorb excess power when there is a drop in demand or release more power when there is a shortage to ensure grid stability. However, ensuring electric batteries of the size required to balance sudden changes in power demand, is not feasible. The government has said they are building a water battery system assured by a hydro power plant with a reservoir and a downstream pool.

A downstream pool will store water when the water from the reservoir is used for power generation. When there is excess power in the grid, water from the downstream pool will be pumped into the reservoir utilizing excess power, and thus the demand and supply will be matched. This excess power will be stored in the reservoir -reservoir acting like a water-battery to store power- to generate power again, when there is excess demand. This should have been done long ago so that the need for diesel power was avoided.

The previous governments should have encouraged domestic solar panels with batteries so that they could store power generated in the daytime when the demand is low and could supply power in the night when the demand is high. By installing smart meters, those people supplying during night peak time could have been paid at a rate higher than the one applicable to power supplied at a time when the demand is low. The difference in the price could have compensated the cost of the batteries of the domestic solar power suppliers. This would have reduced our dependency on the need for diesel power at peak demand time.

Reducing domestic solar purchase prices is not uncommon. I understand that in Australia each household is restricted by the power company to supply not more than a certain amount (3/5 KW) of power to the grid from its domestic solar panel. In 2011, they were offered 66 Australian cents per unit by the single island wide Government electric company, but the purchase price has dropped over the years to 3 Australian cents in certain states after the introduction of the neo liberal economic policy of breaking the Govt. Company into multiple private companies in the power supply business.

I am not a supporter of the NPP government or of the Minister personally. There are other things that the NPP government may not be doing right. But I firmly believe that the power supply issue is a problem created by previous governments whether due to corruption or mismanagement and that the current government is trying to improve things at least in the power system stability arena.

I can understand opposition politicians -some ignorantly and some knowing the real facts- talking about the diesel mafia and the power minister. But I cannot understand some independent political activists shouting ‘diesel mafia’ without properly studying the underlying issues of power system stability.

I believe that probably both the Minister and the CEB can improve their communication capabilities. But it appears that they are doing well in their decision-making process in terms of power system stability.