Hydraulic Power Research Articles

Определение критической частоты вращения ротора высокого давления для двухконтурного турбореактивного двигателя с интегрированным стартером-генератором

Today, the development of aircraft within the electric aircraft concept framework is relevant. In this case, the key technology is the integrated starter-generator, which makes it possible to refuse the mechanical, pneumatic, and hydraulic power take-off from the aircraft engine. In the well-known scientific articles, integrated starter-generators are designed without considering the features due to their location inside the aircraft engines. This study starts a set of projects devoted to the design of integrated starter-generator for a bypass turbojet engine, considering the features of this technical decision. The purpose of this study is to develop approaches to determine critical rotation frequency of high-pressure rotor considering starter-generator integration. Models to determine the critical rotation frequency of a high-pressure rotor with an integrated starter-generator rotor are developed based on non-traditional models of rotor dynamics by mathematical modeling. An area for the integrated starter-generator location has been determined and a constructive method for its implementation is proposed for a bypass turbojet engine. In this study, mathematical expressions are obtained to determine high-pressure rotor critical speed in case of a detailed study of dynamics and in case of an integrated starter-generator preliminary calculations. Based on the value of the critical speed of the high-pressure rotor calculated from the obtained expressions, firstly, it is possible to check the correctness of the choice of the air gap of the integrated starter-generator and strength calculations of the integrated starter-generator in the most difficult operating mode. Secondly, it is possible to determine safe operation area of the bypass turbojet engine with an integrated starter-generator. The results of the study enhance the theoretical foundations of the design of the integrated starter-generators and make it possible to avoid errors in their design and further operation.

Experimental Study of Hydroformed Al6061T4 Elliptical Tube Samples under Different Internal Pressures

In order to achieve crack free elliptical shape under controlled conditions, an experimental set-up was designed and fabricated. This setup consists of three hydraulic cylinders, an intensifier, a hydraulic power pack, storage tanks, forming die, and all parts are controlled by a Programmable Logic Controller (PLC) system. The elliptical samples can be achieved through proper control of internal pressure and axial force with proper sealing. Experimental work has been carried out with different magnitudes of internal pressure and constrained conditions of axial force. Initially die of elliptical shape has been designed and modeled in Abaqus to successfully achieve the particular shape of the Al6061T4 tube under different internal pressure. The fabricated tube hydroforming machine set-up is highly effective for forming 0.5 mm-2 mm thick Al6061T4 alloy tube samples. The Experimental test has been carried out at 12.7 mm outer diameter, 175 mm length and 0.5 mm thick Al6061T4 samples. Bulge height parameters measured at different points of regular distance gap on the axial direction of the tube length and corner radius found at different pressures range of the samples are plotted under different internal pressures. Samples having an 18.7 mm major elliptical bulge were achieved during the experiment. The experimental data was validated by simulation results.

Voltage and frequency regulation in smart grids via a unique Fuzzy PIDD2 controller optimized by Gradient-Based Optimization algorithm

This paper proposes a maiden intelligent controller design that consists of a Fuzzy Proportional–Integral–Derivative–Double Derivative (FPIDD2) controller whose parameters are fine-tuned using the Gradient-Based Optimization algorithm (GBO). The proposed FPIDD2 regulator is employed as a secondary regulator for stabilizing the combined voltage and frequency loops in a two-area interconnected power system. It has been shown that the GBO optimization algorithm outperforms other optimization strategies such as the Chimp Optimization Algorithm (ChOA), the Whale Optimization Algorithm (WOA), and the Gorilla Troops Optimization algorithm (GTO). The proposed FPIDD2 controller is tested in a conventional two-area power system. Then, the investigation is expanded to a two-area hybrid system, with each area comprising a mix of traditional (thermal, gas, and hydraulic power plants) and renewable generation units (wind and solar power). Additionally, the proposed controller takes into account system nonlinearities (such as generation rate limitations, governor deadband, and communication time delays), system uncertainties, and load/renewables fluctuations. In the two tested systems, the dynamic responses of each system demonstrate that FPIDD2 has a superior ability to attenuate the deviations in voltage and frequency in both areas of the system. In the studied conventional system, the proposed FPIDD2 controller is compared with a PID controller tuned by the Multi-Objective Non-Linear Threshold Accepting Algorithm (MONLTA), which has been presented in the literature, and a Fuzzy PID (FPID) controller tuned by GBO. In the investigated hybrid system, the suggested FPIDD2 regulator is compared to a GBO-tuned Integral Derivative-Tilted (ID-T) controller and FPID controller. As a fitness function (FF) for the GBO, the criteria of minimizing the integral time absolute error (ITAE) are applied. The results are presented in the form of MATLAB/SIMULINK time-domain simulations.

Review on Solar Photovoltaic-Powered Pumping Systems

Water and energy are becoming more and more important in agriculture, urban areas and for the growing population worldwide, particularly in developing countries. To provide access to water it is necessary to use appropriate pumping systems and supply them with enough energy for operation. Pumps powered by solar photovoltaic energy are complex electromechanical systems that include hydraulic equipment, electrical machines, sensors, power converters, and control units. Therefore, solar photovoltaic pumping systems are associated with various fields of science and engineering. In remote, less-populated areas without electricity, where it is either challenging to connect to the grid or it is not possible, solar photovoltaic water pumping systems can play a significant role. To see whether solar photovoltaic pumping systems may be a practical, viable, and affordable method of pumping water it is necessary to study different aspects of their operation. The goal of this current article is to evaluate and outline recent research and advancement in the field of solar photovoltaic pumping systems. The major focus is on the standalone photovoltaic pumping system’s components, factors that affect system efficiency, performance evaluation, system optimization, and the potential for integration with modern control techniques. The main objective of this article is to give a broader overview of solar photovoltaic technologies for researchers, engineers, and decision-makers.

A Generalized Hydraulic Model for Propulsion Force Calculations in Radial Jet Drilling

Summary Radial jet drilling (RJD) involves drilling several small-diameter lateral holes from a single vertical wellbore to increase reservoir contact and production. RJD system components (diverter, flexible hose, and jetting bit) are conveyed to the target depth using coiled tubing. A high-pressure flexible hose is used in conjunction with a jetting bit to drill holes laterally. Without a rigid drillstring, no axial force can be transferred to the bit as it penetrates the rock. As a result, the bit is propelled by hydraulic means. Thus, in addition to front-jetting nozzles, RJD bits use back-jetting nozzles. Therefore, the rate of penetration (ROP) and maximum hole length (MHL) must be maximized through proper hydraulic optimization. Existing hydraulic models rely on field-measured parameters (discharge coefficient and flow rate ratio) that vary by the bit design to predict the propulsion force, bit hydraulic power, and the maximum lateral hole length. Hence, this study aims to develop a generalized and accurate hydraulic model that does not require field-measured parameters to make predictions. As a result, the new model can be used for optimizing RJD operations by selecting suitable bit designs and lateral hole geometries. This article presents a new RJD hydraulic model that uses a discharge coefficient that varies with the nozzle aspect ratio. The model predicts the propulsion force, differential pressure across the bit, and MHL based on the design of the bit, nozzle, and lateral hole geometries, and flow rate. To verify the model, extensive experiments were conducted with single-nozzle and multi-nozzle jetting bits. The pump pressure was varied while flow rate and propulsion force were recorded during the tests. Model predictions are compared and validated with experimental data. Measured and model-predicted propulsion forces demonstrate a reasonable agreement with a maximum discrepancy of 25%. Once the model has been validated, it is used to perform a parametric study to investigate the influence of various factors on bit performance. According to the parametric study, nozzle and hole diameters, friction factor, and hose density strongly influence bit performance. Furthermore, the diameter of the nozzle has been found to have a significant effect on bit performance parameters (propulsion force, bit hydraulic power, and MHL).

Fuzzy adaptive trajectory tracking control of work-class ROVs considering thruster dynamics

Work-class remotely operated vehicles (ROVs) are widely used in oceanic observation and underwater operation, which are driven by hydraulic power. A fuzzy adaptive controller considering thruster dynamics is proposed to improve the trajectory tracking performance of work-class ROVs in this paper. The dynamics of the hydraulic motor driven thruster is much higher than the position and orientation tracking ability of work-class ROVs. Thus, the system is divided into two separate subsystems: out-loop position and orientation control system, and inner-loop hydraulic control system. A fuzzy adaptive algorithm is employed in the out-loop position and orientation controller, which estimates the system parameters and disturbances respectively. A disturbance observer is used in the inner-loop hydraulic controller to attenuate the uncertainties and disturbances. A second order filter is adopted to synthesize these two controllers, which generates a smooth hydraulic motor speed command with appropriate bandwidth and range. The stability of the whole control system is proved through Lyapunov theory. Simulation results demonstrate the effectiveness of the proposed trajectory tracking control strategy under parameter uncertainties and disturbances.

Stability Study of Time Lag Disturbance in an Automatic Tractor Steering System Based on Sliding Mode Predictive Control

To improve the working accuracy and anti-interference capability of the steering operation of an automatic tractor, this paper investigates the tractor steering system. In response to the current problems of high steering resistance during tractor field operations and the low service life of the drive shaft of conventional electric steering wheel solutions, an electro-hydraulic coupled power-assisted solution combining EPS and HPS is proposed. The combination of the EPS system’s high control accuracy and sensitive steering operation and the hydraulic power system’s large steering torque greatly reduces the power of the power motor and battery performance requirements, optimizing the power transmission scheme to achieve green and energy-saving purposes. Secondly, the research is focused on the influence of external disturbances on the stability of the steering system during tractor operation, and a combination of model predictive control and sliding mode control is used to study the steering system control strategy. It is finally demonstrated through simulations and experiments that it can compensate for the disturbance of the system control parameters by external disturbances, has the ability of MPC to handle input constraints and maintains the advantages of SMC robustness.

There Is a Science of “Baikal Studies”

ABSTRACT The history, main components, and nonstandard teaching methods of the new scientific discipline “Baikal studies” are provided. An interview with an author of textbooks and scientific and popular scientific publications about Baikal, Deputy Director of the Baikal Museum SB RAS E.N. Kuzevanova, provides a brief historical description of the study of the lake. The ecological and economic problems of Baikal are discussed. An analogy is drawn between environmental laws and economic models. Opportunities for using rent income from the lake’s natural resources to finance improvement of the ecological situation in the Baikal natural area are evaluated. It is concluded that Baikal is already fully capable of “financing itself”; annual rent from the hydraulic power of the Angarа River is estimated at more than 120 billion rubles. There is discussion of the necessity and opportunity for the noncontradictory coexistence of environmental and economic efficiency with respect to the activities of human life on the shores of Lake Baikal.

Technical and Economic Indicators for Operating Irrigation Pump using Natural Gas

This paper presents the experimental for the types of mixers used in mixing natural gas with air to operate the irrigation pump to save energy, many of measurements were carried 2021 year in workshops of Agricultural Engineering Department, Faculty of Agriculture, Ain Shams University, Egypt. Used engine single-cylinder, air-cooled. A new pump with a discharge diameter of 2 inches, which was an Egyptian manufacture. Several types of mixers were manufactured to mix natural gas with air before entering the engine. Using iron pipes of different diameters, three types of mixers were used Mixer with a perforated inner tube of 8, 10. 12cm (L8, L10, L12) . selected determine the four shaft speeds (1750, 2300, 2900 and 3500 rpm) using the engine speed measuring device. The results here dealt with study the analysis of technical indicators for the types of mixers used in mixing natural gas with air to operate the irrigation pump. where the actual power (Braking power) is superior to all types when operating with gasoline was (3.07 kW) A comparison with the use of natural gas, where the mixer type (L10) (2.69 kW) was 10% less than gasoline. the lowest Specific fuel consumption (s. fc) for gasoline was (219.025 gm/Kw.h) at an engine speed of (2900 rpm), The lowest (S.fc) for the types of mixers was the mixer (L10) was (340.144 gm/Kw.h) at an engine speed of (2900 rpm),The highest pump discharge was with the L8 mixer (32.98 m3/h), an increase of 1.8% over gasoline at an engine speed of (3500 rpm), The highest actual hydraulic power with L10 type mixer compared to other type L mixers (0.782 kW) was 12 % lower than that of gasoline. As for the economic indicators the lowest Internal Rate of Return (IRR) was Gasoline ( 0.44), and the highest (IRR) when carrying the mixer type (L8) was (0.60) an increase of 26.6 % over gasoline. the lowest payback period was the type of mixer (L8) was (1.66 year), and the highest payback period When the Gasoline it was (2.27 year).

Grape-like CNTs/BaTiO3 nanocatalyst boosted hydraulic-driven piezo-activation of peroxymonosulfate for carbamazepine removal

• Grape-like CNTs/BT nanocomposite catalyst with Ti − C bond was synthesized. • CNTs/BT boosted hydraulic-driven piezo-activation of PMS for CBZ removal. • CNTs/BT-PMS system generated much more ROS than BT-PMS and CNTs-PMS systems with less energy. • CNTs acted as fast electron lanes for accelerating separation of piezoelectric carriers. • Piezoelectric field effectively suppressed destruction of CNTs in PMS system. Both carbon nanotubes (CNTs) and piezoelectric materials can activate peroxymonosulfate (PMS). However, the activation of PMS by CNTs suffers from poor reusability while hydraulic-driven piezo-activation of PMS faces the problem of limited charge separation. To solve the above problems, grape-like CNTs/BaTiO 3 (CNTs/BT) nanocatalyst with a Ti − C bond was prepared. Results indicated that hydraulic-driven CNTs/BT-PMS system offered remarkable carbamazepine removal efficiency (91.93%, 120 min) with satisfactory reusability. The energy consumption of PMS activation by CNTs/BT was only 39.33% and 26.59% of those by CNTs and BT, respectively. Piezoresponse force microscopy and finite element simulation further suggested that these superior performances were mainly responsible for the synergistic effects of CNTs and BT, leading to stronger piezoelectric response with efficient piezo-generated charge separation, which in turn improved the efficiency for producing reactive species. Notably, the built-in piezoelectric field of BT constantly replenished electrons to CNTs and effectively suppressed the destruction of CNTs caused by chemical oxidation. This durable composite might be a promising catalyst for PMS activation with potential utilization of residual hydraulic power during water treatment.

Downsizing the electric machines of energy-efficient electro-hydraulic drives for mobile hydraulics

The poor energy efficiency of state-of-the-art mobile hydraulics affects the carbon dioxide released into the atmosphere and the operating costs. These crucial factors require urgent improvements that can be addressed by the electrification of fluid power. This approach has already generated electro-hydraulic drives that remove flow throttling and enable energy recovery. However, the entire power managed by the actuators of conventional systems must pass through the electric machines. This characteristic is unfeasible for medium-to-high power applications since they need electric motors and electronics with high power ratings and large onboard generation of electricity. Thus, this paper applies to a hydraulic excavator’s boom the idea of splitting the power being transferred to/from the actuator between the hydraulic and electric domains (i.e., a centralized hydraulic power supply is involved). The objective is downsizing the power rating of the boom’s electric components while maintaining the high-power output of the hydraulic actuator. The results show the expected behavior of the hybrid excavator in terms of motion control, but only 57% of the boom’s peak power is now exchanged electrically. The resulting electric machine with 61% downsizing favors the system’s cost and compactness supporting the electrification process that is aligned with the low-carbon economy.

Lightweight Electrohydrostatic Actuator Drive Solution for Exoskeleton Robots

The practical long-term application of power-assisted exoskeleton robots requires lightweight, high-efficient, and high-control precision actuators. Based on the improvement of hardware design and control method, this article proposes a complete drive solution for the joint drive of exoskeleton robots and promotes the research of robot joint drive based on the pump-controlled hydraulic system. Specifically, a compact, backdrivable, and energy-efficient drive unit, lightweight electrohydrostatic actuator (LEHA) with a weight of 2.5 kg and a rated power of 340 W is designed first. Then, by combining the fifth-order high-precision dynamics model of LEHA and virtual decomposition control method, a high-performance controller with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L_{2}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L_{\infty }$</tex-math></inline-formula> stability is developed to realize the precise position trajectory tracking control of LEHA. Experimental results based on actual exoskeleton robot knee joints show that the proposed solution has high trajectory tracking performance over the frequency range of human body swing phase motion (0.5–1.5 Hz) and different loads (0–20 kg). Moreover, compared with the valve-controlled hydraulic power system with the same exoskeleton robot knee joint and wearer, test results show that the average efficiency increased by 18.13% after using LEHA under the swing phase test.

Research on Hydraulic Power System Operation Status Diagnosis Technology Based on Hybrid CNN Model

Aiming at the problems that the features extracted from the traditional system operation state are not adaptive and the specific system operation state is difficult to match, a gearbox system operation state diagnosis method based on continuous wavelet transform (CWT) and two-dimensional convolutional neural network (CNN) is proposed. The method uses the continuous wavelet transform to construct the time-frequency map of the hydrodynamic system operating state signal, and uses it as the input to construct a convolutional neural network model, and forms a deep distributed system operating state feature expression through a multilayer convolutional pool. The structural parameters of each layer of the network are adjusted by the back propagation algorithm to establish an accurate mapping from the signal characteristics to the system operating state. In the experiments under different working conditions and different system operation states, the accuracy of system operation state recognition reaches 99.2%, which verifies the effectiveness of the method. Using this method of adaptively learning rich information in the signal can provide a basis for intelligent system operation state diagnosis.

Research on Design and Analysis Method of the Double Planetary HMCVT Based on High Efficiency Transmission

The hydro-mechanical continuously variable transmission (HMCVT) is the critical component in the transmission system of the high-horsepower tractor. However, different structural layouts have a significant influence on transmission efficiency, especially for the HMCVT with multiple planetary rows. Therefore, the double planetary HMCVT, which, based on efficiency characteristics, was designed in this study, as well as the efficiency distribution area under different loads, were analysed. First, the method of the single planetary row in structure layout is constructed and redefined, revealing the transformation law of transmission in different layouts. Moreover, the different layout efficiencies and output transmission ratios were derived as the theoretical basis for selection. Then, the obtained transmission and efficiency characteristics were selected as the best combination to design the double planetary HMCVT. The theoretical efficiency and hydraulic power shunt characteristics were analysed with the circulating power, and the influence of circulating power on operational efficiency was determined. Finally, the hardware-in-the-loop system of HMCVT was designed. Herein, a new type of variable load efficiency characteristic analysis method is proposed, which treats the engine and transmission as an efficient whole. The variational performance of the efficiency field in hydro-mechanical stages are discussed under full load and variable load. This research provides theoretical support for efficiency improvements in design and analysis of the multi-planetary HMCVT tractor.

Flow control in a small Francis turbine by system identification and fuzzy adaptation of PID and deadband controllers

The ever-escalating power-demand together with depletion of fossil-fuel reserve and increasing-thrust on using climate-friendly system drive the transition to higher use of sustainable-green-energy. There is an immense need of harnessing hydraulic power from runaway-streams in hill-areas from small-hydropower-installations. A laboratory-scale system with Francis-turbine has been set-up with low-cost easily-maintainable electrohydraulic-actuation system for controlling the opening of the inlet-guide-vanes. The actuation system has a proportional-valve and cylinder. Deadband-nonlinearities due to the valve-overlap and cylinder-friction in this system along with large-disturbances in both the connected-load and the upstream-water head have been tackled by appropriate system-modelling supplemented by identification of the model-parameters. These parameters have been estimated by carrying-out steady-state-performance test at a rated-speed of the turbine combined with simulation of the model. A real-coded-genetic-algorithm has been used for parameter-updating the aiming minimum deviation between the experimental-variation of the turbine-efficiency against discharge and the evolving simulation-prediction. This model has been utilized for extracting the demand of the guide-vane-actuation-system in the face of head and power-disturbances. A controller with fuzzy-tuned PI-gains and a nonlinear deadband function has been proposed. Experimental-results demonstrate successful-tackling of large-power disturbances by the containment of the maximum-departure of the turbine speed in the open-loop from the rated-value to only 0.156%.

Redesign of a Hydraulic Manifold in Additive Manufacturing for Application in a Cleaning and Inspection Robot

A flexible joint riser inspection and cleaning robot must be small and powerful to perform its mission. Hydraulic units are commonly used in submerged operations for power. We designed a custom hydraulic unit as a robot. As the hydraulic manifold is complex, we developed it to be fabricated by additive manufacturing. The objective was to reduce the volume and mass of the hydraulic power unit. We achieved several computational analyzes and analytical methods to validate the designed concept. As a result, we obtained a more compact and lighter structure at the end of the process.

FEATURES OF THE DYNAMICS OF HYDRAULIC FLUID POWER DEPENDING ON THE MODES OF EXTERNAL LOADING

An aim is a scientific search of possibility of replacement of mechanical drive of rotation of rotor thrower of earthmover on hydraulic fluid power and determination of his dynamic descriptions on the basis of mathematical model, that examines the modes of starting, set motion, and his sudden stopping for an insuperable obstacle from the side of the poured out soil. Method. Static calculation of by hydraulic fluid power on the basis of researches descriptions of loading of working organs of earthmovers and dynamic calculation with the use of package applied programs of VisSim. The mathematical model of hydraulic fluid power includes the imitation modules adjusting of serve of axial piston pump and change of moment of resistance on the modes of starting of hydromotor at idling motion, normal ladening of rotor thrower and sudden stop. Results. For by hydraulic fluid power of rotation of thrower of earthmovers machine can be applied gerotor hydromotors with the swept volume to 200 cm3, and also high-speed axial piston hydromotor with reducing gears. Necessary on the displacement gerotor hydromotors are mass-produced by the row of foreign firms. The calculation of dynamics of hydraulic fluid power showed that at the critical mode of sudden stop of rotor thrower at his hit on an insuperable obstacle from the side of soil, there are attenuation pressure fluctuations. The worked out program of design can be substantially used for the use of other values of loading and frequency of rotation of hydromotor. Conclusion. Results undertaken studies can be drawn on at development of earthmovers of new generation at substituting of mechanical drive of rotor thrower by hydraulic fluid power.

Sustainable cooling cycles by algorithmically supported design of decentral pump systems

Accounting for up to 25% of electricity consumption in industry, pump systems are significant electricity consumers. Designing pump systems is a complex process because of the multitude of parameters and their combinations (pump types, interconnection variants, various load scenarios). Moreover, decentral pumps can be integrated to reduce the required hydraulic power, which further increases the complexity. This complexity can no longer be mastered with conventional planning methods. The aim of this paper is to tackle the complexity of pump systems design using algorithm-based design methods. The design problem is formulated as a mixed-integer nonlinear optimisation program with the objective of minimising the life cycle costs. The solution involves three steps: (i) the placement of decentral pump stations to reduce the hydraulic power, (ii) the preselection of suitable pump types, and (iii) the optimisation of the selection and operation of pumps. To solve the optimisation problem, an exact off-the-shelf solver and a problem-specific heuristic solution method are used. These are compared with conventional design methods. Both the algorithm-based and the conventional design methods are applied to an industrial cooling cycle operated by BASF SE. The results show that due to decentralisation, up to 38% (248 kW) of hydraulic power can be saved. With the help of the algorithm-based design methods, savings can also be achieved with regard to the efficiency and costs: up to 21% of the life-cycle costs can be saved while increasing the net efficiency from 47.2% to 57.8%. Furthermore, the algorithm-based design methods are superior, leading to 15% (approx. 770 000 €) lower life-cycle costs compared to conventional methods. Conventional methods based on the best efficiency point or mean efficiency show the lowest level of performance. The advantages are particularly evident in system variants with a high complexity. The trade-off between investment costs and energy demand is presented transparently using a Pareto front.

Optimal pump scheduling in multi-phase distribution networks using Benders decomposition

With the growing adoption of renewable energy resources in the power grid, co-optimizing the operation of water and power distribution networks (WDNs and PDNs) increases the flexibility of both systems. The optimal water power flow problem (OWPF) is formulated to manage resource utilization across the WDNs and multi-phase PDNs. The nonlinear WDN hydraulic constraints and PDN ac power flow equations render the OWPF problem nonconvex. This paper formulates a convex optimal water power flow (C-OWPF) problem adopting successive approximations in WDNs and branch-flow relaxations in PDNs. The C-OWPF problem is a mixed-integer semidefinite program, which is computationally challenging even for small instances. Additionally, privacy considerations of WDN and PDN operators motivate the need for solving the C-OWPF in a distributed fashion. This paper develops a C-OWPF solver based on Benders decomposition that overcomes computational complexity challenges and preserve the privacy of the respective operators. The merits of the Benders decomposition-based solver are demonstrated on the IEEE 4-bus PDN coupled with a 3-node WDN and the IEEE 123-bus PDN coupled with the 36-node WDN.

Efficiency of a Twin-Two-Pump Hydraulic Power Pack with Pumps Equipped in Constant Pressure Regulators with Different Linear Performance Characteristics

The efficiency problem of hydraulic pump units with advanced double structures with constant pressure regulators with different linear characteristics in the case of work in an open supply system is presented in the paper. The main parts of the hydraulic power pack structure and pressure controller functions are described. The equation is given for the calculation of energy losses in particular pumps and the whole multi-pump power pack unit. The difference between the efficiency of particular pumps and the hydraulic pump unit was discussed.