Zoran Božović, the Director of the Head Office of EPS for the production of energy

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In the next two year, many difficulties are expected to appear in the course of providing enough coal from “Kolubara”. – The plans for electricity production are going to be fulfilled by redirecting of available coal quantities to more efficient thermal blocks and by greater involvement of “Thermal Power Plant –Heating Plant Kostolac”.

The electricity balance for the year 2013 envisages the production of 35.1 billion kilowatt hours in the Thermal Power Plants. Out of this, nine billion KWh is envisaged to be obtained from hydro energy, which might not happen if the third year in raw average inflows of the Danube River and the Drina River basin are lower. Whether EPS is going to have to buy or not electricity on the market during this summer will depend on hydrological conditions, because then is going to be obvious whether “Kolubara” could provide enough quantities of coal for the operations of TPP Nikola Tesla A and B. With the envisaged hydrology, the production plan is planned in a way that out of balance electricity purchase most probably is not going to be necessary.

Zoran Božović, the Director in the Head Office of EPS for the production of energy, said for our paper that the thermal sector is the “backbone“ of the electric power system of EPS and that many activities are underway with the aim of affirming “Kolubara’s“ authority further.

While preparing electricity balance for the year 2013 many issues have been discussed in detail and much more than before to come to the answer on how to harmonize given insufficient quantities of coal with possible and necessary Thermal Power Plant production balance.

Maximum efficiency

The most important is that for the upcoming winter, and the winter thereafter we will have enough quantities of coal for the operation of TPP NT. I am talking about the coal for TPP NT because MB “Kolubara” has great difficulties because of the delay with land expropriation for the timely preparation of the coal production. In TPP Kostolac the situation is stable. They succeeded to prepare the mine “Drmno” for production of nine million tons of coal that is necessary for the operation of two TPPs with the commissioning of the fifth ECS system. Moreover, regarding the fact that the second phase of the revitalization of the first block in TPP “Kostolac” was postponed for the year 2014, and that would enable us to use coal from the OPM “Drmno” maximally during the next year i.e. to utilize the full capacity of Kostolac power plants – said Božović.

Unlike” Kostolac”, TPPs “Nikola Tesla” are going to operate in accordance with the available quantities of coal they receive from “Kolubara”. Our interviewee mentioned that because of the lack of coal, longer planned downtimes of the specific blocks are scheduled, which is however going to be useful to finish the started revitalizations.

If it happens that we have limited delivery of coal in some periods, we would regulate it  by the “cold” reserve in the system, which means that some capacities in Obrenovac would not operate for some time – said Božović and explained that in that case part of the electricity quantities would have to be bought on the market. Regarding this, he mentioned that in the system of EPS, there is no corresponding cold reserves actually, because the power of the units in the “Panonic TPPs- HPs” that are waiting to be put into the operation”, do not correspond to the power of some larger power unit of TPP NT, and the gas usage costs are much higher than that of using coal.

Our interviewee pointed out that an alternate solution was made up for the more efficient usage of the basic fuel, and that is redirection of available coal to the more efficient power units. All available coal would be directed in accordance with the efficiency and power of the power units, starting from the largest to the smallest. In that way it would be possible to get maximum possible amount of electricity from the given quantities of coal. During the summer period, the operation of TPP would be organized by applying the method of load decrease i.e. units would be operating with less power than that rated, and that would be used for testing of secondary regulation in the electric power system.

-The next two years are going to be extremely tough, until the two new open pit mines are opened in “Kolubara” and until the delay in preparation for coal production i.e. preparation of ground and removal of overburden is eliminated. In order to achieve this, large financial funds are needed, above all for the purchase of equipment and machinery, because most of the machinery used in Kolubara is approaching the end of its lifetime, and it is not profitable to invest in its repair- said Božović.

Funds were invested equally

To our question whether the present state in MB “Kolubara” is partly the consequence of insufficient investing in mining capacities, so that at the moment production capacities of revitalized TPPs are surpassing that of the mines, he said that the revitalization of the TPPs is not completed yet, and the investments were financially almost equal.

We can hear the opinions that we increased the power of TPPs, and that we neglected OPMs. At that, we forget that the revitalization of TPPs were forced, because the main equipment was old and we needed to extend its lifetime. During the revitalization we could not stick to the old obsolete technology, for which we did not have neither respective equipment nor spare parts. We had to modernize the equipment, and then we introduced new control technologies and in that way we got the power units with greater capacities than we had before. It contributed to the fact that delays in the OPMs became more visible. That led to the unfounded impression that less was invested in mining capacities than in the thermal capacities – said Božović.

He pointed out that during such observation, main differences between the TPP and the OPM are lost, and explained:

–       Power Plant is a unique facility, independent unit with synchronized technology. During the works on the equipment there are no large additional costs neither on the object itself nor on the location surrounding the Power Plant as it is the case with the OPM. Excavation of coal is extremely complicated. The operations are performed in two phases, the first phase is preparation of land and removal of overburden, the second one is the very coal exploitation. Thereby, the working areas are huge, which additionally increases costs. If you add to it the fact that expenditures grow also because of the delay in the expropriation process, and because of all these facts and relocation of the settlements, river beds and roads, that we experience in “Kolubara”, it becomes clearer why it seems to have been more invested in the Power Plants than in OPMs.

The depths chose excavators

Božović said that there is an additional factor because of which “Kolubara” came into the very specific situation – and that is deep formation of the coal seams. That means, the seams of coal are now much deeper than we used to have in the past decades. That is the reason why short-term and long-term solutions for the consolidation of “Kolubara” are more complicated now.

Stating that the elaborates are prepared, on which the Expert board of EPS is going to decide upon, and according to which it should be decided what kind of equipment should treat the increasing dipping of the coal seams, Božović said that also the new depths out of which the coal should be excavated are the reason that in the following years “Kolubara” is going to be in the center of attention. He did not say that, but we heard among the miners that excavators the mine possesses are incapable to operate in such depths.

We asked whether the improvement of secondary regulation, that is going to be performed if the power units are active with less power than rated, are to increase the stability of the constant frequency of 50 Hz of the transfer network or operative stability of TPPs of EPS.

Primary regulation helps us maintain the given frequency as much as possible. Each, even the minimum deviation from the set frequency, has to be compensated by an action in the system. For that purpose the HPPs are the most suitable, especially reversible HPPs. They can jump in anytime to compensate the production of the TPPs if the increase in consumption occurs or if one of the power units gets out of the grid. Because of it, it is said that our HPPs provide high flexibility of EPS’ electric power system. The secondary regulation relates more to the correlation among different power sources, thermal, hydro or some other potential. The inclusion of thermal sector into the secondary regulation is something completely new for us, but it is possible. Four power units in TPP NT are already tested and they should be harmonized now with the EMS. Our aim is, however, to enable all power units to perform this function, because the needs for the services of secondary regulation are going to increase along with the construction of wind parks and incorporation of other similar large producers of renewable electricity sources – said Božović.

In the electricity market

Opening of the electricity market in Serbia is going to demand from EPS to increase the business rather than technical – technological performances. However, it is important that we significantly raise the level of the operational readiness and availability of our PPs, and especially their flexibility, were the secondary regulation I talked about also belongs. The service of secondary regulation is being additionally paid for and it brings extra profit to those who provide it.  It is estimated that secondary regulation increases the costs of equipment maintenance in the PP, that is valorized by certain price in the EU countries. It is also going to be the case in our country.  Beside the electricity and system services, we could offer also thermal energy, technological steam and certain finished goods from the side products of coal combustion, such as ashes or gas, to the market. Regarding coal, EPS is not going to be dealing with the coal retail, but there is still need that EPS supplies the public sector in general consumption- said Božović.

Source: Kwh/Serbia Energy