Power Performance Indicators Research Articles

Analysis of the Thermal–Mechanical–Hydraulic Coordination Mechanism of a Constrained Piston Hydraulic Engine

By effectively integrating traditional engines with reciprocating plunger pumps, the constrained piston hydraulic engine can simultaneously output hydraulic energy and rotational mechanical energy, which effectively solves the problems of the complex structure, long power transmission chain, and low energy conversion efficiency of traditional power sources. Based on a certain single-cylinder diesel engine, a single-cylinder axial constrained piston hydraulic engine was designed, and its thermal–mechanical–liquid coordination mechanism was studied and analyzed in-depth. A mathematical model of the thermal–mechanical–liquid coupling working process of the single-cylinder axial hydraulic engine was established, and the conversion mechanism and output of the three types of energy, thermal, mechanical, and liquid, were simulated and analyzed. The results show that under the premise of improving the overall efficiency, the constrained piston hydraulic engine can effectively output mechanical–hydraulic dual-element power, and its combustion characteristics and output power performance indicators meet the expected design requirements. The maximum amplitude difference of the output hydraulic oil flow rate reaches 248 L/min, and the flow rate fluctuates greatly, so it is necessary to adopt methods to suppress the flow rate pulsation to ensure the reliability of the output flow rate.

A Review of Design Solutions for Wind Power Plant Equipment

The aim of the study is to find efficient solutions in wind energy engineering with a view to develop new designs of wind power plants featuring the best power performance indicators. The aim that had been set forth was achieved by selecting and analyzing the results reported in the relevant publications. The most promising technologies were incorporated into united designs and modeled in the Solid Works and Ansys software environments. The study results are described, and the development trends in the wind power plant construction technologies and ways of improving their performance indicators are formulated. They include: application of Magnus cylinders, alteration of blade design, addition of supplementary assemblies and components, application of transverse-axial wind turbines and air flow concentrators, use of measures to ensure a constant wind power plant power output regardless of the incident air flow velocity, and multirotor designs. New technical solutions in the field of windwheel designs for wind power plants are proposed: a counter rotor transverse-axial wind turbine with an air flow concentrator, a Magnus wind turbine with supplementary adjustable blades, and a transverse-axial wind turbine with adjustable diameter and height. The obtained results can be used in studies in the field of wind energy engineering, for analyzing the publication activity on topics relating to renewable energy sources and wind power plants, in particular, for studying the state of the art in the field in writing research papers and dissertations related to wind power plant performance efficiency. The problems that may be faced during the subsequent use of the study results to combine individual trends that improve the efficiency in a single wind power plant to achieve its maximal possible efficiency are pointed out.

Modern State of Hydropower and Construction of Hydro Turbines in Russia and Abroad

The role that hydropower plays in the world’s energy balance is considered, and a comparative analysis of using hydropower resources in Russia and abroad is presented. It is shown that Russia occupies the world’s second place in its hydropower potential after China; however, no more than 20% of the country’s hydraulic power resources have presently been harnessed. This is significantly lower than in Germany, France, Sweden, and Japan, countries in which 65–90% of their available hydraulic power resources are used. In view of a great variety of natural conditions, turbines of different types are used in the hydraulic power industry. It has been determined that the power performance indicators (efficiency and capacity) of the hydraulic machines that are presently produced in Russia correspond, as in the years of the former Soviet Union, to world-class standards. Trends in the development of hydropower and construction of hydraulic turbines are analyzed. It is shown that, given insignificant scales of constructing new hydroelectric power plants in Russia, replacement of the equipment at the existing hydroelectric power plants that had worked out its standard service life long ago is the industry’s main development line for the nearest (10–15 years) future. The need to replace the operating hydraulic machines mainly stems from inefficient utilization of water stream at the existing hydroelectric power plants. It is pointed out that, despite the emerged tendency toward decreasing the reliability of hydraulic power units that have been in operation for a long period of time, its catastrophic drop is not observed at any of the examined hydroelectric power plants even though their machines have been in operation for twice as much as their standard service life (30 years) or even more. Refurbishment of the machines makes it possible and shall mandatorily improve the power performance characteristics of the machines, resulting in an increased power capacity or improved efficiency (of energy generation). An improvement in the power performance characteristics of new hydraulic turbines is achieved almost solely due to the use of more advanced runners while keeping the other flow path elements unchanged.

Уменьшение магнитных потоков рассеяния в линейных генераторах Вернье с помощью высокотемпературных сверхпроводящих элементов

The article presents the results of studies aimed at improving the power performance indicators of linear electric generators for wave power plants by reducing the flux leakages using high-temperature superconducting (HTS) inserts placed in between the teeth. The generator design involving application of the Vernier principle for magnetic flux modulation with a translator in the form of a hollow cylinder is considered. Generators of this type are used in float wave power plants driven directly by a reciprocating float, which transmits large forces at a low motion speed. The calculations were carried out using the HTS properties modeling procedure based on representing the currents induced in a superconductor in the form of magnetic moments of these currents, which made it possible to simplify the analysis of the electromagnetic field in the generator without significant additional errors. As a result, the characteristics of the electromagnetic force longitudinal components and phase winding flux linkages versus the translator displacement have been obtained. The use of HTS inserts and a distributed winding in the stator made it possible to reduce the electromagnetic leakage losses and increase the interaction force between the stator and translator. However, since the additional outlays for the cooling system and thermal insulation of the HTS elements are commensurable with the generator cost, the obtained results on improving the power performance parameters do not allow an unambiguous statement to be made about the effectiveness of the considered technical solutions.

Mathematical model and simulated power performance of a novel O-type engine

Reciprocating engines such as V-type, L-type and W-type engines are used widely in our daily life. However, there is still some room for the improvement of power performance if the configuration of the cylinder and connecting rod system is changed. In this paper, a novel O-type engine is put forward firstly. The structural features of the O-type cylinder sets are described briefly, and then the relevant mathematical model with hypotheses is established to conduct the performance analysis. Secondly, the O-type engine is compared with the general range of power performance of gasoline engine to demonstrate its merits. Then, the power performance indicators, namely the mean indicated pressure (PMI), space occupation efficiency (SOE) and heat efficiency (HE) of the novel engine are analysed and discussed in detail through MATLAB with the verification and validation which are conducted to ensure the reliability of results. And the results show that the power performance of the O-type engine is better than most of gasoline engines; the power performance indicators in the research are not monotonous at different volumes with the bore stroke ratio increasing; the proper range of the volume and the bore stroke ratio is obtained to make the engine achieve a high power performance. All in all, the research is helpful for the development and application of the O-type engine.

К оценке состояния гидротехнических сооружений гидроузлов в современных условиях

The effect the limitations imposed on the water storage reservoir’s headrace level (HRL) variation rate have on the hydroelectric power plant (HPP) power performance indicators is studied taking the cascade of Yenisei HPPs as an example. For quantitatively determining the effect the limitations imposed on the Sayano-Shushenskaya HPP’s HRL variation rate (depending on the air temperature in the preceding period) have on the HPP power performance indicators, water energy calculations were carried out for the following Yenisei cascade operation scenarios: operation of the Sayano-Shushenskaya HPP with variable limitations imposed on the HRL variation rate depending on the air temperature in the previous period; operation of the Sayano-Shushenskaya and Krasnoyarsk HPPs with variable limitations imposed on the HRL variation rate depending on the air temperature in the previous period. The mean energy capability (E0) and the guaranteed power output in winter (Nguar) were taken as the HPP performance indicators from which the effect of limitations was estimated. As a result of the accomplished computations, the guaranteed winter power output in the Sayano-Shushenskaya hydropower system decreased by 17.37%, and its mean energy capability decreased by 3.29%. Based on the accomplished water-energy calculations, a new (corrected) operating mode of the Sayano-Shushenskaya HPP was obtained, in which the regime of levels did not escape beyond the temperature-related limitations. The changes in the Sayano-Shushenskaya HPP operation mode led to a change in the HPP tail race flows. As a result, the Krashoyarsk HPP operation mode was also changed due to the new inflow regime to its site. The study results show very clearly that application of environment temperature-related limitations on the Sayano-Shushenskaya HPP hydraulic structures directly affects the power performance indicators of the Krasnoyarsk HPP. The strongest effect on the Krasnoyarsk HPP parameters takes place at the average temperature in the Karlov site from –17 °С to –11.8 °С in winter and from +8.5 °С to +11 °С in summer. This is connected with the Sayano-Shushenskaya HPP HRL variation rate limitation curve pattern, which in its turn entails a decrease in the HPP tail race flow and, as a consequence, a decrease in the total inflow to the Krasnoyarsk HPP site. As regards the temperature range at the Krasnoyarskaya HPP site, it is from –20 °C to –11 °C for the winter period and from +5 °C to +8 °C for the summer period. The difference in the mean energy capability and guaranteed power output of the Krasnoyarsk HPP during operation under the above-mentioned conditions is 12.9% for mean energy capability and 13.7% for guaranteed winter power output. Key words: limitation of water level variation rate in a water storage reservoir, change of power performance parameters, cascade of Yenisei HPPs.

К оценке состояния гидротехнических сооружений гидроузлов в современных условиях

The effect the limitations imposed on the water storage reservoir’s headrace level (HRL) variation rate have on the hydroelectric power plant (HPP) power performance indicators is studied taking the cascade of Yenisei HPPs as an example. For quantitatively determining the effect the limitations imposed on the Sayano-Shushenskaya HPP’s HRL variation rate (depending on the air temperature in the preceding period) have on the HPP power performance indicators, water energy calculations were carried out for the following Yenisei cascade operation scenarios: operation of the Sayano-Shushenskaya HPP with variable limitations imposed on the HRL variation rate depending on the air temperature in the previous period; operation of the Sayano-Shushenskaya and Krasnoyarsk HPPs with variable limitations imposed on the HRL variation rate depending on the air temperature in the previous period. The mean energy capability (E0) and the guaranteed power output in winter (Nguar) were taken as the HPP performance indicators from which the effect of limitations was estimated. As a result of the accomplished computations, the guaranteed winter power output in the Sayano-Shushenskaya hydropower system decreased by 17.37%, and its mean energy capability decreased by 3.29%. Based on the accomplished water-energy calculations, a new (corrected) operating mode of the Sayano-Shushenskaya HPP was obtained, in which the regime of levels did not escape beyond the temperature-related limitations. The changes in the Sayano-Shushenskaya HPP operation mode led to a change in the HPP tail race flows. As a result, the Krashoyarsk HPP operation mode was also changed due to the new inflow regime to its site. The study results show very clearly that application of environment temperature-related limitations on the Sayano-Shushenskaya HPP hydraulic structures directly affects the power performance indicators of the Krasnoyarsk HPP. The strongest effect on the Krasnoyarsk HPP parameters takes place at the average temperature in the Karlov site from –17 °С to –11.8 °С in winter and from +8.5 °С to +11 °С in summer. This is connected with the Sayano-Shushenskaya HPP HRL variation rate limitation curve pattern, which in its turn entails a decrease in the HPP tail race flow and, as a consequence, a decrease in the total inflow to the Krasnoyarsk HPP site. As regards the temperature range at the Krasnoyarskaya HPP site, it is from –20 °C to –11 °C for the winter period and from +5 °C to +8 °C for the summer period. The difference in the mean energy capability and guaranteed power output of the Krasnoyarsk HPP during operation under the above-mentioned conditions is 12.9% for mean energy capability and 13.7% for guaranteed winter power output. Key words: limitation of water level variation rate in a water storage reservoir, change of power performance parameters, cascade of Yenisei HPPs.

Оценка эффективности классических законов управления частотно-регулируемых асинхронных двигателей

Adjustable-frequency induction motor-based drives occupy the dominating place among adjustable electric drives. Therefore, it is important to consider rational methods for controlling induction motors (IMs) from the viewpoint of decreasing their energy consumption. There are two such control methods: using the proportional law of controlling the motor power supply frequency and voltage and using the law that maintains constant stator and rotor flux linkages and the main flux linkage in the air gap. A procedure for calculating the power performance indicators of an adjustable-frequency IM for these control laws is proposed, using which they can be calculated and compared in a relatively simple manner without iterations. The calculation formulas used in the procedure are based on the system of vector equations for a steady-state operation mode and on the equivalent circuit drawn from these equations. An example of calculating the indicators of induction motors with the capacity P2 = 15 kW during their operation with a constant torque in the specified range of rotation frequencies is given. The results from calculating the motor power performance indicators during motor operation with a constant torque and with decreasing the power supply voltage have shown that the control law maintaining a constant rotor flux linkage yields higher values of the efficiency and power factor. It is exactly this law that is more preferable for use in the adjustable-frequency drive control systems.

Evaluating the Effect from Constructing Binary Geothermal Power Units Based on Spent Petroleum and Gas Boreholes in the South Regions of Russia

The article substantiates the possibility of efficiently harnessing the geothermal resources available in the North Caucasian region through constructing binary geothermal power plants (GeoTPPs) using idle petroleum and gas wells. The power capacities of GeoTPPs are evaluated, and the basic characteristics of these power plants in case of constructing them in the promising areas are determined. The overall useful GeoTPP capacity equal to approximately 330 MW can be obtained from using the entire fleet of idle wells available in these areas. Diagrams confirming the possibility of reaching the optimal flowrate of geothermal heat carrier circulating in the geothermal circulation system loop are presented. This flowrate corresponds to a binary GeoTPP’s maximal useful power output. The article shows, taking the Ternair geothermal field as an example, that it is inefficient to use medium-enthalpy thermal waters for generating energy at a binary GeoTPP involving reinjection of a spent heat carrier. It is shown that good prospects can be expected from applying a hybrid geothermal and combined-cycle technology, by means of which it is possible to use lowenthalpy (80–100°С) thermal waters for generating electricity in a highly efficient manner. In accordance with such technology, geothermal heat is used in the binary GeoTPP cycle for heating low-boiling working fluid to its evaporation temperature. The working fluid is evaporated and superheated by using the heat of exhaust gases from a gas turbine power unit. Owing to combined use of the thermal water heat potential and the heat of exhaust gases from a gas turbine power plant in a hybrid process system, it becomes possible to obtain high power performance indicators of hybrid geothermal and combined-cycle power plants. This conclusion is confirmed by the results from numerical evaluations carried out as applied to the Ternair geothermal field. With the fully harnessed resource potential of the Ternair field, the total capacity of hybrid geothermal and combined-cycle power plants may reach 60 MW, a level that would make it possible to relieve a significant part of energy, environmental, economic, and social problems faced by the city of Makhachkala.

Тенденции развития совмещенных магнито-электроиндукционных электромеханических преобразователей энергии

The modern state of the electromechanical science is reviewed. State of the art in combined inductive-capacitive electromechanics is considered, and the fields of its possible practical applications and prospects for its further development are analyzed. A new approach for mathematical description of transients in dually conjugated dynamic systems is proposed, and the differential equations for combined inductive-capacitive electromechanical energy converters are derived proceeding from the proposed approach. The generalized Lagrangian theory of combined inductive-capacitive electric machines is developed as uniting the generalized Lagrangian models of inductive and capacitive electro-mechanical energy converters developed proceeding from the fundamental principles of binary-conjugate electrophysics. The possibility of optimizing an inductive generator’s operating mode using a capacitive generator with setting up a parallel or a series resonant circuit (with the interaction matrix serving as the controlling parameter) has been determined. The combined device is essentially a resonant machine, which has the best power performance indicators. The electrodynamic and electromechanical equations of combined inductive-capacitive electrical machines are given for the case when the structure of their excitation system contains ferroelectromagnets serving as dual-purpose active electrotechnical materials. The necessary Lagrangian for combined inductive-capacitive energy converters has been constructed by introducing a new matrix describing the interaction (mutual influence) between the inductive and capacitive subsystems. Simultaneous solution of these equations fully determines the dynamic behavior and power performance characteristics of the generalized model of combined machines of different designs and in any modes of interaction between their functional elements. It is shown that combined inductive-capacitive electromechanical converters have great prospects for use in microsystem electromechanics (for example, in microdrives at the level of nanotechnologies).

Research on the Parameter Matching of Power Device of Hybrid Sanitation Vehicle

In this paper, I introduced the working principle and drive type of hybrid cars, and parallel hybrid system was the driver type of hybrid sanitation vehicle. Combined with vehicle parameters and power performance indicators of the original model, I matched the appropriate engine, electric motor, battery and design the corresponding transmission.

Prospects for using hybrid power installations on the basis of solid-oxide fuel cells integrated with intracycle coal gasification

Results from calculation of a hybrid power installation operating on synthesis gas are presented. The process circuit of a combined-cycle plant with coal gasification and solid-oxide fuel cells is given together with its power performance indicators. Prospects for using hybrid power installations on the basis of solid-oxide fuel cells that use coal as primary fuel are estimated.

An analysis of the operation of a solar adsorption periodic-duty refrigerating plant

We present estimates of the limiting power performance indicators of solar absorption refrigerating plants that were carried out using the constraints of the first and second laws of thermodynamics, as well as a method for determining the optimal adsorbent regeneration temperature, at which the maximum coefficient for conversion of solar energy into the energy of cold can be obtained. The effect of different parameters on the adsorbent regeneration temperature is analyzed, and the maximum attainable integral coefficient of the conversion of solar energy into the energy of cold is presented.