Balancing the power grid. Technological challenges and innovative solutions.

Starting from 1991 to 1997, electricity consumption dropped significantly to 160 billion kWh, which may be an indirect indicator of a long-term economic crisis.

The period from 1998 to 2013 can be conditionally defined as a period of recovery of the economy, which was characterized by an increase in electricity consumption to 180 billion kWh, but this process was associated with deindustrialization of the economy, which affected the modes of electricity consumption during the day.

During this period, demand is saturated with the load of the commercial and household sector, which is uneven during the day, due to which the range of daily changes in load increased from 5,000 MW in 2001 to maximum 7000-8000 MW during the winter periods of 2012.

At the same time, the pace of introduction of flexible capacities did not correspond to the speed of growth of variable load range, which led to an increase in the relevance of the problem of covering loads in the evening and balancing the development of renewable energy.

Is there a balance?

If we pay attention to the typical schedule of electric loading of the Ukraine power grid in the winter months, one can distinguish, for example, when passing the maximum loads in the evening hours of winter periods at the level of 21.6 GW at an average daily temperature in Ukraine -6.1? C, coverage of energy consumption in Ob ' Unified energy system Ukraine provides NPPs, TPPs, CHPPs, hydroelectric power stations, and even renewables.

At the same time there can be up to 41 coal-pulverized coal-fired power generating units of TPP  with a total capacity of 6.8 GW. Nuclear power plants operate at a load of 10.8 GW. Already the next day in the morning, in the coverage of the Ukraine grid load, 23.7 GW, 45 PG coal-fired power generating units with a capacity of 8.7 GW participated. Simply put, it was necessary to include an additional 4 coal-fired power units.

Such an increase to cover the morning fast-growing peak load is characterized by additional payments to TPP owners from the energy market for "maneuverability" and "working capacity". According to the rules of functioning of the energy market of Ukraine, such payments sharply increase the single wholesale price of electricity, which is later laid in the tariff for industrial and domestic consumers. Thus, in the structure of the average tariff of the generating companies of the TPP, the charges for maneuverability, block start up, working capacity and deviation from dispatching graphics make up almost 40% of the cost of each produced kilowatt-hour.

The balance between consumption and generation is achieved by changing the load on the Hydro Power Plants and TPP, but the load of the TPP varies in a limited range, which usually does not exceed 30% of the installed power unit. Depending on the season, this range in total in the UES of Ukraine ranges from 1.5 to 2 GW.

Another about 3 GW of the regulatory range is given by the hydroelectric power station and the hydroelectric power station at the availability of water and the availability of hydro units in the work.

But there remains about 1.5 GW unregulated difference between peak and night consumption. The problem has to be solved at the expense of stops for the night with the subsequent launch of the pulverized coal-fired TPP in the morning. In some periods, the number of such operations reaches 15 launches / stops per day.

This situation leads to an additional cost of gas (fuel oil) and coal (to provide these launches), a significant deterioration of technical and economic performance of equipment, as well as to accelerate the wear of equipment units and increase the number of emergency repairs.

Due to the loss of powerful electric power consumers in the territories of Ukraine temporarily occupied by the Russian Federation, recently the power system operator has to maneuver (to stop at night and let it in the morning) to balance the consumption, including 300 MW coal units, which are designed for operation in the basic mode and are very limited resource for launches.

But even these measures are not enough to fully balance consumption and generation, and have to unload the NPP, through the introduction of so-called "dispatching constraints." Due to the impossibility of providing an unloading to a night-time consumption failure that lasts about 6 hours, NPPs often carry a load below the set value of 1500 MW.

Since the beginning of hostilities in the Donbass, from the autumn of 2014, Ukraine's thermal energy has a significant shortage of coal "A" (anthracite), which is used as fuel for TPP power units involved in the load following modes.

Import, even conditional, of coal leads to a significant increase in the cost price of electricity produced, due to the fact that the cost of coal in the TPP tariff is indexed at the prices of the international energy exchange on the so-called Rotterdam + formula.

The attraction of TPP power plants to cover variable loads in cyclic mode is now characteristic of many power systems in the world. Figure 1 shows the output load for British coal-fired power plants, which illustrates the use of TPPs to cover morning, day and evening peak loads, and deep discharge overnight, while reducing demand for electricity.

However, such modes of operation are characterized by a negative impact on the residual life of the main equipment due to the growth of small-scale fatigue.

The consequences of prolonged periods of operation of the TPPs in cyclic mode are due to an increase in the number of pipe damage and steam pipes, wear and tear, corrosion, and other equipment failures, which means an increase in accident rates, loss of reliability, rising repair costs, and the search for additional investment in equipment renewal.

Estimated for the US energy market, the cost of a single start-stop cycle for TPP Pawnee is between 114 and 121 thousand US dollars.

Such daily expenses of the system operator for compensation of cyclic modes of thermal power stations significantly affect market prices and affect the final accounts of consumers.

As for the Ukrainian TPP, most of the power units already exceeded the park's resource lifetime and require deep modernization. Certain economic expediency for the owners of generating capacities operating today in load following exists, so, instantly, it is financially advantageous and non-alternative, in terms of increased profitability, but as they say on Wall Street, this is the same as picking coins in front of an asphalt roller . The collision is inevitable.

Therefore, in the long run, the operation of the TPP in the grid of Ukraine in a maneuverable regime with regular deep discharge below the technical minimum to cover variable loads is not appropriate in terms of long-term development and maintenance of energy supply reliability.

And in this article we will try to consider alternative methods of solving problems of the balance of generation / consumption using the innovative technologies that are often discussed by the world expert community.

How much space do we need to maneuver?

But first, let's try to determine how many of these innovative technologies we need to implement, to ensure the stability and reliability of our  power grid?

After all, in addition to the daily uneven loading schedule, there are challenges associated with the need to balance production from renewable energy sources. The National Renewable Energy Action Plan for the period up to 2020 and the Action Plan for the implementation of the National Renewable Plan for for the period up to 2020 are approved. The main objective of the Plan is to bring the share of energy received from RES in the final energy consumption of the country up to 11% by 2020, which will reduce the use of primary energy resources by the year 2020 by 8.6 million tonnes in the year. or 9.2 bcm of natural gas. At the same time, such large-scale implementation of renewable sources does not correspond to the structure of generating capacities and potential of transmission lines.

With regard to future demand ratings for maneuvering power, such studies were carried out in NAS works, but the most recent data were presented by NPC Ukrenergo during the presentation of their research on the impact of renewable energy on the stability of the grid. The Company's experts determined that, while maintaining the current trend, the implementation of renewable energy facilities, which will be accompanied by non-relevant plans for the introduction of maneuvering capacities, will be 2,500 megawatts of high-flexible capacity. And experts of the system operator were invited to fill it with high-maneuverable gas-piston power plants, with the addition of Li-ion-dispatchable batteries. We, in this article, try to focus, albeit at a glance, on all existing and promising technologies and solutions for balancing loads in the grid.

Electricity markets.

In order to unify the mechanisms of functioning of the electricity markets with the EU approaches and the fight against large vertically integrated monopolies in Ukraine, the energy market reform is being implemented based on the principle of the creation of the market of bilateral agreements, the market for the day ahead and the balancing market. It is the balancing market to be used by the system operator to balance the demand and supply in the grid during peak hours, as well as to fill the night load failure. One of the promising areas is load management, or Demand Response. Such a motivational tool for attracting production capacities to regulatory needs has long been known and was used in the 1930s. The first document in the USSR for regulating the loading schedule was the Circular of the USSR Supreme Economic Council of November 26, 1930, No. 85 "On the regulation of load schedules". From the collection of papers ed. prof. Kukel-Krajewski, a well-known example, as in 1931, Mosenergo concluded agreements with 25 enterprises to reduce their load in peak hours with payment of compensation for each unloaded kilowatt. The total load of 22 enterprises was reduced by a total of 12 MW. If consumers were simply disconnected, Mosenergo would suffer losses from lack of electricity, as well as a consumer would be damaged due to a lack of output. However, in today's realities, when the introduction of large volumes of renewable energy in the grid causes regular frequency and power fluctuations, such payments for balancing power grow from year to year and create additional load on the wholesale price of electricity and tariffs of consumers. An example is the situation in the Spanish energy system, when system operator payments for capacity and demand response in 2015 amounted to more than 1 billion euros and is a factor in the growth of electricity prices.

Innovative technologies of electric energy storage.

The main technology for the accumulation of electric energy in the energy system is the Pumped Hydro Power Plants. Hydro-accumulating power stations today account for 99% of the capacity of electricity accumulation in Europe. However, further development of large capacities of the hydroelectric power station and the HPS is inextricably linked with the change of the ecosystems of the regions, which will greatly slow down the development of hydropower in the future.

According to the information of the Energy Storage Database, which concentrates all information on current and implemented projects of innovative load management systems, the total volume of regulatory capacity in the world is 1708 units with a total capacity of 196 301 MW, including large hydroelectric power plants.


Of course, such storage technologies have different applications. Most of these technologies are used to maintain the stability of the grid, as well as to shift the consumption time from peak hours to hours of failure of the boot, due to the high cost, as well as the replacement of the power units in cyclic modes.

In the USA, the share of the Pumped Hydro in the structure of flexible capacity reaches 95% (23.4 GW). The remaining 5% are:

- Thermal storage.

- Battery electrochemical storages.

- Compressed air storages.

- The flywheel energy storage.

This is a very illustrative example, in spite of the significant support from the state, only 5% of the installed capacity for regulatory purposes is innovative. The European Energy Storage Association has developed the structure of existing energy storage technologies, which includes physical, thermal, electrical, chemical, electrical and mechanical effects on the physical properties of the energy storage. Next, we will consider the typical technologies of these categories.

Compressed air power plants

Excessive electric energy produced by renewable sources is used to supply powerful compressors that pump air under pressure into the reservoir. Traditional stations of this type use natural underground cavities (salt caverns, gas fields) as a reservoir, as it is a huge amount of compressed air. The technological scheme of the "regulator" using compressed air is presented in Fig. 2. During the failure of the load, compressed air accumulates, and air is released under pressure into the gas turbine unit (GTU) at peak hours. This technology involves the use of GTU to cover peak loads. Thanks to this technology, the efficiency of the gas turbine increases and the start and end time to the nominal power decreases. The application of this technology for controlling variable loads will be effective in areas where the landscape does not allow for the construction of a pumped hydro power plants. From open sources, it is known about the commercial exploitation of the German air storage unit at the Huntorf, where an installation with a capacity of 28 MW with a 4-hour charging-discharging cycle. In Ukraine, the promising potential location of such an object may be the district of Kalush, where it is possible to organize injection and daily storage of compressed air in the produced salt mines.

Electrochemical (battery) energy accumulation technologies.

One of the most common types of innovative load management technologies is battery-operated electrochemical storage. Most of them are designed to balance the operating modes of RES. There are different types of batteries based on chemical compounds: NaS, NaNiCl2, Ni-Cd, Li-ion, etc. For example, a single electrochemical battery installation (NaS) with a load capacity of 34 MW operates in Rokkasho, Japan, since 2008, where it is used to stabilize wind power. In the whole world about 1000 projects more than 4 GW of electrochemical storages of different type are installed. The most relevant is the introduction of battery technology in conjunction with renewable energy sources (RES). At the end of the article, we will look at a business case where the world's most popular lithium-ion storage have found application in Australia and what results it has achieved.

Mechanical drives based on flywheels.

The flywheel system  stores energy  by converting the electric energy from the network to the kinetic energy of the rotating element, which can move up to 4 hours without additional charge. During periods of high demand for electric power, the flywheel swith on a generator - automatically or with the help of a control system. Kinetic energy is transformed again into electricity and enters the electric power system.

The main advantages of this technology are the speed and ability to dynamically react to the frequency change in the power system. The main drawback is danger to human. This technology was criticized after the United States in 2011, when two flywheels were dismantled at the regulating power unit. In Germany in 2011 during the operation of such a storage engineer died. An essential disadvantage of technology is self-discharge throughout the day. According to general conclusions, the implementation of mechanical storage technologies will focus on the implementation of auxiliary services, such as frequency and voltage regulation in local networks.

There are also innovative suggestions that use gravity, such as Gravity Power. These technologies allow to dispose, according to the developers, the concrete of biological protection of reactors of the NPP. It can be used for the construction of a mine with a piston, which in the hours of night failure of the load rises up under the pressure of water pumped by the pump, and in hours of peak loads the piston under the action of gravity is released, pushing the water into the hydro turbine and producing peak electricity.

Use of the system of charging-discharging of electric cars

One of the promising directions is the so-called Vehicle-to-grid (V2G) concept, the two-way use of electric vehicles and hybrids, which involves connecting the machine to a common grid for charging a car and reposing extra power to the backhaul when there is an urgent need to balance power. The idea is relevant because, according to research by scientists at the University of California, the battery of the average electric car is not used 95% of the time. Owners of cars with technology V2G will be able to sell power to power at hours when the car is not used, and to charge the car in the hours when the electricity is cheaper,

And indeed, the statistics convinces that the growth of sales of electric cars for 2017 indicates the enormous potential of such a concept. Let's understand:

China showed sales growth of 72% - 600 thousand sold electric cars.

The European Union has shown an increase of 37% - 300 thousand sold electric cars.

Ukraine showed an increase of 2.3 times - 2,600 sold electric cars.

The US showed an increase of 27% - 200 thousand sold electric cars

Russia, finally, caught up with the United States, the gain also amounted to 27% - sold 95 electrocars.

In the first half of 2018, the pace of sales of electric cars grew by more than 40 percent. In the first half of 2018, around 195,000 electrified vehicles were sold in Europe, up 42 percent over the same period in 2017. These include both fully electric cars (BEVs) and hybrid cars (PHEV cars and light cars, according to this trend, the total number of European electrified vehicles is expected to reach 1.35 million. However, if you estimate this power of Ukrainian electric cars as a potential for regulation of the power system - the whole fleet of electric cars will not allow to balance no more than 50 MW.

In addition, for the implementation of such technology in the scale of the need to balance the energy system, there is a lack of the most important, namely, business models. For example, in the UK already there are almost 110,000 electric cars, which is equivalent to approximately 2 GWh of power of the required storage batteries or other storage devices. And now all the British community is concentrating on solving three key issues that need to be resolved to launch such a system: charging stations equipped with the ability to both receive and provide electricity to the network, develop software for process management and create a business- models of monetization of participation in balancing for owners of electric cars.

Tesla Business Case in Australia.

Lithium-ion batteries are developing the most intensively lately, finding more and more applications in electric transport, portable power supplies, space and aircraft. The most striking example of such a large-scale energy project is the Tesla PowerPack in Australia.

So, we analyze this project:

1. The storage consists of Powerpack batteries with a installed capacity of 100 MW and peak of 129 MWh. This is enough to provide electricity for 30,000 households (within an hour) at peak times and interruptions. The cost of the system is estimated at $ 50 million.

2. The storage system has been built up for 100 days and connected to wind turbines at Hornsdale Wind Farm near Jamestown, owned by the international energy company Neoen Energy, for balancing their production. Currently, 70 MW and 39 MWh are reserved by the state in case of an unforeseen situation. The remaining 30 MW and 90 MWh Neon battery company can uset as it like - for example, to sell on the market. What the company succesfully did.

3. The energy operator AEMO (Australian Energy Market Operator) in January 2018 appealed to energy companies to provide electricity to the general energy grid at moments of planned maintenance of the system. As a rule, at such moments the cost of energy increases significantly. According to calculations, in this particular case, the cost of energy should have risen to 9,000 Australian dollars (about $ 6942) per 1 MWh. But due to the use of Tesla's energy storage and adjacent wind farm plants, it managed to keep the cost of energy at 270 Australian dollars (about $ 208) per 1 MWh. Thus, managed to save millions of dollars in the energy market. In two days, while the battery worked at full capacity, the company managed to sell energy at 1 million.

Evaluations and conclusions

If you design the implementation of such a system in Ukraine, then you need to turn to the current values of the cost of electricity. According to Energy Regulator, the average wholesale market price of electroenergy in 2018 is UAH 1,587 / MWh (approximately $ 60). For comparison, the cheapest innovative technology of regulation has the cost of generated electricity at the level of 100 $ / MWh.

Thus, we can conclude that the current market price for electricity is not attractive under the current regulatory system for investments in innovative load balancing systems in Ukraine. However, if we study the experience of the countries where electricity market reform has already taken place, in particular Poland, one can find the difference between the value of "base" and "peak" (when it is expected to use our technologies) of electricity, which reaches double the level during the periods of active growth of peak demand power. However, for most of the time, the difference does not exceed 20% of the cost of the package "basic". This gives grounds to predict the lack of market mechanisms for creating attractive business models that will provide economically viable introduction of innovative regulatory technologies.

Recently, the system of "contracts for price differences" is actively used to attract low carbon investments in Britain, when the investor of the project guarantees the purchase of electricity at the margin price set in the format - market price + surcharge for the difference to the cost price.

An example of such an approach to creating guaranteed returns is the contract for the British Hinckley Point, in which the UK government guarantees the purchase of all generated electricity from nuclear power plants for 35 years at a price of 92 pounds per MWh. While at the spot market now the base electricity is traded at a price of about 40-45 pounds per MWh. Similar elements of subsidization could be used in the domestic energy market to provide multiple synergies - solutions to the technological problem of regulating variable loads and attracting investment in such projects.

The future is not a continuation of the present. Power systems undergo evolutionary processes, rejecting outdated forms of existence, in search of the most effective model. And, it seems,  evolution moves with a jumps. Outdated power systems need the next stage of development - this is the infusion of new investments and technologies. And states for technology and investment in the 21st century compete with their jurisdictions and legislative systems. And here the same case - the very high quality legislative driver will allow us to ensure the economic attractiveness of projects that are vital to us to provide light, warm, family evenings.


Subscribe for Updates

Find Us in Social Media

Contact Us