Ukrainian Grid Research Articles

Modelling the efficiencyof power system with reserve capacity fromvariable renewable sources of energy

The paper considers modeling the efficiency of power system with integration large share of variable renewable sources of en-ergy with the account ofclimate conditions ofUkraine. The proposed methodology with its position between system planning and dispatch simulation contributes to the field of hybrid energy system models.The idea behind the methodallowshigh spatial and temporal resolution as well as the inclusion of the technical details of the power system and its dispatch.The novelty of this method is the usage ofa parametric approach is chosen to analyze different variable renewable sources of energyscenarios, precisely every possible its share and mix. This provides insights on the systematic effects of different resource mixes and may serve as a new ap-proach to the analysis of future power system development.The additional novelty aspect allows theoptimization of the design of the technical details of the power system with large variable renewable sourcessharesto have continuous improvementof its energy efficiency.The energy balance model generatoris well suited for the analysis of large share of variable renewable sources integration in the power system. The design of technical details of the power system with large variable renewable sourcesshares wasoptimized with the energy balancemodel.The results of numerical modelling demonstratedthat at 80% variable renewable sources of energy share, the overproductionis reduced to 20%, down from over 100 % without grid extensions.With it, the necessary wind and solar capacity decreases. Consequently, the possible achievable variable renewable sources of energy share areincreased, assuming the same technical potential. According to the results, a Ukrainian grid would allow to increase the possible variable renewable sources of energy share from 50% to 75%.

ВОДЕНЬ В ЕЛЕКТРО- ТА ТРАНСПОРТНІЙ ЕНЕРГЕТИЦІ

It is shown that more energy is consumed in hydrogen production than can be obtained from its use. We are talking about the production of green hydrogen. The production of 1 m3 of hydrogen consumes 4 to 5 kWh of electricity, although it contains 2.9 kWh of chemical energy. The calorific value of hydrogen is 3.3 times less than that of methane. Hydrogen as a substance is characterized by a high penetration capacity, its transportation in ordinary pipes causes their corrosion and embrittlement. The implementation of this process requires the use of special materials for pipelines, as well as special design, compressors, sensors. Hydrogen has wide explosive limits, high torch propagation rate, and its use is associated with the application of special safety measures. The use of hydrogen as a fuel to drive the gas maneuvering capacity in the grid or to replace liquid motor fuels requires generating capacity for its production commensurate with the installed capacity of the entire Ukrainian grid, significant volumes of water and solving the problem of using excess oxygen. The energy costs of producing hydrogen for fuel cells are quite significant, so converting it back to electricity is clearly inappropriate. Thus, given the cost of electricity from renewable sources and the economy of hydrogen production, its continued use is disadvantageous. A similar conclusion can be drawn regarding the transport of hydrogen in the compressed or liquefied state. The driver of hydrogen energy is the desire to prevent anthropogenic impacts on climate change. The large number of hydrogen energy projects that are being launched today in Europe and in the world can be explained by the considerable funds allocated to research this problem. Powerful companies and scientists - hydrogen acts - are interested in implementing such projects. References 9, figure 1.

VOLTAGE ASYMMETRY INFLUENCE ON RESOURCE CON-SUMPTION AT POWER GENERATING PLANTS

The objective of this paper is to provide new research on the linkages between voltage asymmetry, energy efficiency, and resource efficiency to inform policymaking in this area about the possibilities of electricity saving potential. Asymmetry voltage coefficients value in Ukrainian grid were experimentally identified based on assessments of 23 Ukrainian companies during 2016-2018. It was estimated, that 26 % of transformers have asymmetry voltage coefficient of reverse sequence lower than 2 % and 12 % of transformers have asymmetry voltage coefficient of zero sequence lower than 2 %. The estimated resource saving potential for Ukrainian power generating plants is up to 1’978 GWhel/a, which is up to 1.5 % of total electricity produced. Equivalent reducing electricity generation at coal power plants could prevent emissions up to 292.79 t/a of ash emissions; 733 kt/a of CO2 emissions; 5.9 kt/a of SOx emissions; 2.9 kt/a of NOx emissions; 9.03 m3/a of nuclear waste.

VOLTAGE ASYMMETRY INFLUENCE ON RESOURCE CON-SUMPTION AT POWER GENERATING PLANTS

The objective of this paper is to provide new research on the linkages between voltage asymmetry, energy efficiency, and resource efficiency to inform policymaking in this area about the possibilities of electricity saving potential. Asymmetry voltage coefficients value in Ukrainian grid were experimentally identified based on assessments of 23 Ukrainian companies during 2016-2018. It was estimated, that 26 % of transformers have asymmetry voltage coefficient of reverse sequence lower than 2 % and 12 % of transformers have asymmetry voltage coefficient of zero sequence lower than 2 %. The estimated resource saving potential for Ukrainian power generating plants is up to 1’978 GWhel/a, which is up to 1.5 % of total electricity produced. Equivalent reducing electricity generation at coal power plants could prevent emissions up to 292.79 t/a of ash emissions; 733 kt/a of CO2 emissions; 5.9 kt/a of SOx emissions; 2.9 kt/a of NOx emissions; 9.03 m3/a of nuclear waste.

Usage of biomass CHP for balancing of power grid in Ukraine

The article contains the first considerations of the problematic of Ukrainian grid balancing issues raised by a rapid increase of RES share in total electricity supply. The provision of balancing electricity with accent on biomass combined heat and power plants (CHP) usage is considered. Three technical concepts are proposed for engaging of existing and planned biomass CHP into balancing operation primary operating in baseload regimes, namely – greenfield biomass thermal power plant (TPP) and CHP working primary in baseload regimes and provide balancing electricity when needed (with and without steam accumulation). It is shown that there are no principle technical limitations for biomass CHP/TPP usage for grid balancing. The levelized cost of electricity (LCOE) of balancing electricity for proposed concepts are calculated and compared with the reference technology proposed by the national grid operator (gas-piston engines and/or gas turbine). According to the calculations performed the LCOE (EUR/MWh) of balancing electricity could be 77-88 EUR/MWh for biomass CHP primary operating in baseload and 216 EUR/MWh for greenfield biomass TPP against 206 EUR/MWh for gas-piston/gas-turbine for applied assumptions, prices and tariffs.

Research of key aspects of load-following mode implementation at NPPs of Ukraine

In the grid system of Ukraine HPPs are operated in the load-following mode (hereinafter referred to as LFM) and TPPs are operated to meet the power demand which HPPs cannot satisfy. The TPPs are characterized by high-cost electricity generation, high level of deterioration of equipment and of environmental stress. The paper analyzes the international experience of NPP operation in the LFM, as well as the possibility of Ukraine’s NPPs operation in this mode, and researches the influence of different features and key aspects of the possible operation in the mode. The results of the research show that NPPs of Ukraine can be operated in the LFM, the implementation of the mode could improve economic performance of the NPPs on account of selling "maneuvering" electricity at a higher price, could give more maneuvering abilities to the Ukrainian grid, and decrease dependence on organic sources of energy. (fossil fuels)The research of the key aspects and possibility of the LFM implementation at Ukrainian NPPs is urgent and actual in the current political situation. Ukraine is faced with the power shortage in the Ukrainian grid system, especially shortage of “maneuvering” power and short supply of organic sources of energy.

Broker hybrid algorithm for NordugridARC 2.0 for Ukrainian grid segment

With the development of science one can observe an increase in the volume of experimental data to be analyzed to obtain new knowledge. The current volume of such computations often exceeds the capacity of a single cluster to compute in a satisfactory amount of time. Therefore, there is a necessity in a distributed computation of such amounts of data using the GRID-systems. For the load balancing in such systems one uses special mechanisms – brokers, which implement a certain policy, under which such system distributes tasks among computing resources according to utilization of computational resources in the system or according to the properties of the task. To implement the algorithm of balancing a broker should take into account enough number of factors to find the most appropriate task that can perform it with the lowest possible load or in minimum amount of time. One can use regular information sources of software that maintain the GRID-system, as well as additional ones that are not included in the standard package of this software. The article is dedicated to the problems of a broker construction using heterogeneous information sources. The proposed method is implemented on the basis of the Ukrainian segment GRID using the software package NordugridARC 2.0. Also, this technique can be implemented on other similar software packages for the GRID.