Variable Speed Diesel Generator Research Articles

Technical and economical comparison of optimized diesel-electric propulsion systems for a pleasure craft

The article compares between them three diesel-electric propulsion and power generation systems, characterized by a similar overall power but with diesel-generator sets very different in number and power; these systems are developed for the needs of an existing pleasure craft. In addition, each system configuration includes two versions, with diesel-generators operating at constant speed and other at variable one. Once defined the used diesel engines type, the characteristics of the six diesel-electric systems have been defined and optimized, by a genetic algorithm, in both design and off design ship speeds. The main performance, weight and cost of the generated systems, with both constant and variable speed diesel-generators, are compared between them and with the pleasure craft current mechanical propulsion system, for different vessel speeds. The comparison results are presented in graphical and tabular form and extensively commented.

Speed Control and Optimization of Variable Speed Diesel Generator Set

Speed Control and Optimization of Variable Speed Diesel Generator Set

Research into the operating modes of a stand-alone dual-channel hybrid power system

<abstract> <p>The article describes the development and simulation of a stand-alone hybrid power system based on a variable-speed diesel generator and a hydrogen fuel cell generation system. The goal of the research was to investigate the electromagnetic processes of this power system, which supplies power to autonomous energy consumers with varying load demand. MATLAB Simulink was used to simulate the proposed hybrid power system and check its operating capacity. The results of the simulation include the dependencies of current and voltage changes in the critical components of the hybrid system at stepwise load rate changes. In the future, the developed models and simulation results will allow researchers to select semiconductor devices and create microprocessor-based control systems for electric power installations that meet specific requirements. The dual-channel power system can provide a required power output of 3 kW when powered by a diesel generator and 1 kW when powered by a hydrogen fuel cell. At the same time, the total harmonic distortion (THD) at a load between 100 W and 3 kW varies within acceptable limits between 3.6% and 4.4%. It is worth noting that these higher power complexes can be incorporated into stand-alone electrical grids as well as centralized distribution systems for power deficit compensation during peak loads.</p> </abstract>

Research on Speed Optimization and Adjusting Strategy of Variable Speed Diesel Generator Base on Sliding Interval

A marine variable speed generator can dynamically adjust the set speed of a diesel engine according to the actual power load level by the grading method, so the goal of energy conservation is achieved. However, the grading method relies on engineering experience. The actual range of power load fluctuation is uncertain, which leads to a decrease in fuel efficiency. Therefore, a method based on load sliding interval is put forward. In this method, a fixed width load interval is set at first, and then the interval slides on the diesel engine load at a step of 1%. The minimum fuel consumption rate speed for the interval is optimized during the sliding process. Finally, a minimum fuel consumption rate speed curve corresponding to the sliding interval position is obtained. The optimization objective is to have the minimum weighted average fuel consumption rate at the integer load points within each interval. The actual power load is monitored and used to determine the current load interval during the calculation of the set speed. The minimum fuel consumption rate speed curve optimized was applied to query the setting value of the diesel speed. The mean value engine model was applied for simulation under three load conditions. The results show that the sliding interval method could achieve the best fuel saving effect under any power load; the set value of the diesel engine speed changed smoothly under the fluctuating power load conditions, and the fuel saving ability was better according to the actual power load conditions on the ship.

Modeling and design optimization of a hybrid power generator for full-electric naval propulsion

The purpose of this work is to build a model of diesel engine useful for studying new hybrid solutions for power generation. This kind of study is of significant interest particularly for the marine sector, due to recent limitations on fuel consumption and constraints imposed on the minimum powertrain efficiency. In this paper a variable-speed diesel generator model is presented. The model simulates both the dynamic behavior of the engine and the fuel consumption during the operating cycle. This model was developed using experimental results of bench tests conducted on the VL1716C2-MLL engine by Isotta Fraschini Motori (IFM) SpA. Diesel engine dynamics is based on the formulation found in the technical literature on mean value models and then adjusted through experimental data. Special attention was paid to developing the procedure to find the minimum specific fuel consumption for a given load. Initially, the presented resutls concern the correct response of the model under different load conditions. Then, the improvement in specific fuel consumption (obtained by adjusting the engine speed according to the load), in comparison with fixed speed operation, is shown.

Power Control Strategy for Hybrid System Using Three-Level Converters for an Insulated Micro-Grid System Application

This paper presents a simulation of an insulated micro-grid system based on the three-level converters control for energy management. Different renewable power sources (wind turbine and Photovoltaic (PV) energy systems) are used to energize the micro-grid. However, a battery energy storage system (BESS) and a variable diesel generator are also used to improve the reliability of the system. The contribution of this research is focused on the power control method based on improving the quality of energy transfer, mastering dynamic interactions and maximum energy production from renewable energies to reduce the fuel consumption by the diesel. Firstly, the proposed control model for each renewable energy was carried out through simulation in the environments of Matlab and Simulink to test the robustness and performance. The second part of this research is dedicated to managing the sharing of power between load, generators, and storage systems by extracting the references of power. The three-level PWM rectifiers for variable speed diesel generators was used to maintain and control the DC bus voltage of the isolated micro-grid. The results obtained from simulations show a good correlation between static and dynamic systems even for fluctuating sun power and wind speed.

Coordinated Control Strategy for Hybrid off-Grid System Based on Variable Speed Diesel Generator

In this article, the control of hybrid <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> -grid configuration based on a variable-speed diesel generator and solar photovoltaic array, is implemented. To ensure a stable operation with the ac voltages and system frequency regulation, back-to-back connected converters are controlled using vector-based control, and stator flux-oriented frame-based control. To adjust the speed of diesel engine according to specific fuel consumption, an effective control strategy is developed. In addition, to compensate for the slow dynamics of variable speed operation and to balance the power in the system the dc-link voltage and battery current are controlled using a double-loop control strategy. Furthermore, the dynamic model of the dc–dc boost converter is integrated with the perturbation and observation method for obtaining smooth and efficient maximum power point tracking (MPPT). To prevent overshoots during the sudden transition, all proportional-integral controllers are reinforced with a back-calculation antiwindup scheme. The performance is obtained using MATLAB/Simulink and validated on real-time hardware to demonstrate the effectiveness of coordinated control under variations of loading and weather conditions.

Сравнительный анализ энергетических показателей судовой электростанции на базе классических дизель-генераторных установок и электростанции с дизель-генераторной установкой переменной частоты вращения

The article highlights an important scientific and technical problem: increasing the operation efficiency of the diesel generator power plants. One of the possible solutions of the problem is developing the diesel generators that operate in a variable speed mode with shared loads on the power plant. Introducing such diesel power plants into practice in recent decades has become possible due to the necessary converting semiconductor equipment, as well as a significant increase in prices for hydrocarbon fuels and objectively formulated requirements to improve the environmental performance of technical complexes. There is presented a comparative analysis of the energy efficiency of two power plants: with classic diesel generators and with a variable speed diesel generator. It has been proposed to compare the energy efficiency of the power plants by calculating the specific and absolute fuel consumption. The method of determining parameters of fuel consumption is considered. The method is based on using a multi-parameter characteristic of a diesel engine and the values of the efficiency ratios of the elements of the power equipment of plants. The results of calculating the specific fuel consumption of the power plants when changing the load power subject to the operating mode of the generators are presented. The results confirm the energy efficiency of the power plant with a variable speed diesel generator. Efficiency is increased due to saving the hydrocarbon fuels. The maximal savings correspond to the power plant operation under the load 20% less than the nominal.

Variable Speed Diesel Generators: Performance and Characteristic Comparison

Diesel generators (DGs) are set to work as a backup during power outages or support the load in remote areas not connected to the national grid. These DGs are working at a constant speed to produce reliable AC power, while electrical energy demand fluctuates according to instantaneous needs. High electric loads occur only for a few hours a day in remote areas, resulting in oversizing DGs. During a low load operation, DGs face poor fuel efficiency and condensation of fuel residues on the walls of engine cylinders that increase friction and premature wear. One solution to increase combustion efficiency at low electric loads is to reduce diesel engine (DE) speed to its ideal regime according to the mechanical torque required by the electrical generator. Therefore, Variable Speed Diesel Generators (VSDGs) allow the operation of the diesel engine at an optimal speed according to the electrical load but require additional electrical equipment and control to maintain the power output to electrical standards. Variable speed technology has shown a significant reduction of up to 40% fuel consumption, resulting in low GHG emissions and operating costs compared to a conventional diesel generator. This technology also eliminates engine idle time during a low load regime to have a longer engine lifetime. The main objective of this survey paper is to present the state of the art of the VSDG technologies and compare their performance in terms of fuel savings, increased engine lifetime, and reduced greenhouse gases (GHG) emissions. Various concepts and the latest VSDG technologies have been evaluated in this paper based on their performance appraisal and degree of innovation.

Rural area electrification with variable speed diesel generator and lithium-ion battery hybrid system

Rural area electrification with variable speed diesel generator and lithium-ion battery hybrid system

Rural area electrification with variable speed diesel generator and lithium-ion battery hybrid system

Rural area electrification with variable speed diesel generator and lithium-ion battery hybrid system

Study on the Variable Speed Diesel Generator and Effects on Structure Vibration Behavior in the DC Grid

Global warming and air pollutants are in general major worldwide concerns including for the marine shipping industry. Equipped with new technologies, the onboard DC grid has proven several advantages, including up to 27% reduction in specific fuel consumption with reduced emissions. That can be achieved by installing an optimized variable speed diesel generator. The engine speed is adjusted according to the required power, which allows to always keep the best efficiency of the combustion process. However, it also exposes some changes in the behavior of the structure vibrations. Measurements on an experimental variable speed diesel generator show that vibration increases when trying to slow down the engine for the same load. This behavior is closely related to the resonance in low rev range that usually occurs with general gensets. In other words, we can conclude that the DC grid’s variable speed generator may be beneficial for fuel efficiency, but not for mechanical life and safety. Several measures had been given, of which the alternation of the natural frequency is presented as an economical and efficient solution. The ultimate goal is to maintain operational safety while respecting reduced fuel consumption.

Судовая электроэнергетическая система с обратимой валогенераторной установкой по схеме машины двойного питания и дизель-генератором переменной частоты вращения

The article presents the analysis of the operating modes of small displacement vessels, which states that most of the working time the vessels are in standby mode, or move at low speed. The main ship diesel engines operate at a load of 10-15% (maximum 20%), which impacts the operational performance: the oil and water jacket of the engine do not have time to warm up, fuel and oil consumption increases. There takes place coking of piston rings, intercoolers and other components, which leads to a sharp decrease in the service life of the engine. In order to eliminate the disadvantages happening in the main engines operation in shared load modes, it is considered to use the shaft generator unit as a propeller shaft unit in the prolonged operation of the vessel at passing with a low speed and maneuvering. Such a variant of the shaft generator can be called a reversible shaft generator unit (RSGU) capable of operating in both generator and motor modes. At the same time, it is advisable to power the reversible shaft generator and general ship consumers from a diesel generator, which, in order to save fuel, can be applied as a variable speed diesel generator unit. There is presented a RSGU variant based on an asynchronous machine with a phase rotor and a frequency converter in the rotor (a double power supply machine). The functional and structural schemes of the ship’s electric power system using the variable speed diesel generator and the propulsive system based on the reversible shaft generator are presented. In the Matlab software there are developed the simulation models and presented the results of simulation modeling of the operating modes of the above systems.

Increasing the Efficiency of a Diesel-Generator Power Plant

A variant of a diesel generator power plant consisting of a conventional diesel-generator set and a variable-speed diesel-generator set is considered. A transformer-free topology of the power circuit of the variable-speed diesel-generator set is proposed on the basis of an active voltage rectifier, a mains inverter, and a buffer energy storage device. The block diagram for controlling a diesel-generator power plant is developed. The autonomous and parallel operation modes of the diesel-generator sets are considered. A block diagram of the speed controller on the basis of intelligent controls is proposed for the variable-speed diesel generator set. The simulation model of the diesel-generator power plant is implemented in the MATLAB/Simulink suite. Results of simulation modeling of the power plant’s dynamic operational modes under load switching are presented. The variable-speed diesel-generator set is shown to provide energy-efficient operation of the power plant and compliance with the requirements for the quality of generated electricity when the internal combustion engine runs at low energy efficient rotation speeds in the shared load mode.

Дизель-генераторная электростанция с вентильным генератором по схеме машины двойного питания

The article considers the problem of improving power efficiency of the diesel generator power plants as one of the priority objectives for development of low power generation in Russia. Improving energy efficiency for autonomous facilities is directly related to the optimization of hydrocarbon fuel consumption by marine diesel engines. It is possible to optimize the fuel consumption of internal combustion engines by creating variable-speed diesel generators (VSDG), which are diesel-generator units with semiconductor converters, i.e. systems with valved generators. Optimization of specific fuel consumption by VSDG is provided by the forced regulation of the rotational speed of the shaft of the internal combustion engine in accordance with its multi-parameter characteristic in the shared load conditions of the power plant. The synchronous electric machine is used as a generator as part of a ship power station. Its use in the classic constant-speed diesel generators is more preferable than an asynchronous electric machine. In the development of VSDG - valved power plant - the use of an electric machine with a phase rotor as a generator is technically justified, because the installed capacity of the frequency converter in the rotor circuit of an asynchronous generator with a phase rotor is determined by the sliding power and, with a limited range of speed control, SDGV significantly reduces the installed capacity of the electrical equipment. Such power topology of a ship’s power plant is called VSDG based on a dual-power machine. There has been proposed to consider a variant of a ship power plant based on VSDG with a dual-power machine. Its functional diagram and mathematical model are developed. A structural diagram is presented and dynamic modes of the amplitude and frequency of the generated voltage are modeled during electrical load switching.

Электростанция на базе дизель-генераторной установки переменной частоты вращения и буферного накопителя энергии

The article describes the diesel generator complex which consists of two diesel generators. In order to save fuel, it is advisable to choose one diesel generator of inverter type, i.e. to switch it to a variable speed mode. The buffer storage device is used as a part of the power plant in order to ensure the required parameters of the generated electricity under peak loads, as well as when the generator is operating at the limit of rated power. There has been given the control algorithm and transient processes of the charge / discharge of the buffer storage device in a diesel generator power plant. The power plant that consists of a classic diesel generator and a variable speed diesel generator unit (valved generator) has been chosen as an object research. A block diagram of the power plant conducting is proposed, as well as a power transformer topology of a variable-speed diesel generator based on a step-down pulse-width converter. There has been presented an algorithm for controlling the connection of a buffer storage device depending on its charge and the load power value both in stand-alone mode and in parallel operation of generator sets. In the MatLab Simulink computer environment a simulation model of a power plant was developed and transient processes of load switching, as well as charge / discharge of a buffer energy storage device were studied. An electrical circuit diagram of an experimental bench of a variable-speed diesel generator set is illustrated. The results of experimental studies of dynamic modes of operation on a prototype variable speed diesel generator with a power of 3.2 kW are also presented.

Advanced Control of a Compensator Motor Driving a Variable Speed Diesel Generator with Rotating Stator

Variable speed generators can improve overall genset performance by allowing the diesel engine to reduce its speed at lower loads. In this project, a variable speed diesel generator (VSDG) uses a rotating stator driven by a compensator motor. At lower loads, the stator turns in the opposite direction of the rotor, a process that can be used for purposes like maintaining a fixed relative speed between the two components of a generator. This allows the diesel engine to turn at a lower speed (same as the rotor) and to increase its efficiency. The present research addresses the control of the compensator motor driving the generator’s stator using a variable-frequency drive that adapts the speed to its optimal value according to the load. The performance of the proposed control strategy was tested using a Freescale microcontroller card programmed in C-code to determine the appropriate voltage for the variable-frequency drive. The control algorithm uses a real-time application implemented on an FDRM-KL25Z signal processor board. The control performance of a 2 kW asynchronous motor (LabVolt EMS 8503-00/208 V/3 ϕ/60(50) Hz) was demonstrated experimentally at different operating conditions.

Combined Electric Power Plant Simulation Model

The article is dedicated to a simulation model of a wind/solar power plant. A variable speed diesel generator set is used as a backup energy source. A matrix frequency converter is used to control frequency of the gene­rated voltage. The simulation model is implemented in the MATLAB Simulink environment. Oscillograms of currents and voltages are obtained when the model operates with an active inductive electrical load with the variable load value in the 1000–4000 VA range. During operation with a rated power load, the deviation of the line voltage parameters lies within the normal range (load voltage drop does not exceed 4% of the nominal value, total harmonic distortion does not exceed 2% in the 0–2000 Hz range). The constructed model can be used in the design of energy facilities, as well as in the development and testing of algorithms for control and monitoring systems.

Coordinated Power Management for Variable Speed Diesel Generator and Lithium-ion Battery Hybrid System

This paper presents coordinated operation of power management strategies for a hybrid system. This hybrid system is modeled based on dynamic variation of load power and its effective distribution strategy. The proposed hybrid system consists of variable speed diesel generator (VSDG) and lithium-ion battery which is able to supply electric power for Power, Water and Communication (PWC) economically and efficiently in rural areas. The variation of power demand in PWC load is highlighted in load profile. The total PWC load is effectively shared by two VSDGs and one Lithium-Ion battery bank. The use of advanced VSDG helps hybrid system to reduce fuel consumption as its speed varies with load demand. The proposed segmentation of high frequency and low frequency components of load currents and their assignation to suitable source helps to reduce the transients during load variations. Also, one of the generators will be switched off when the total power demand goes below specified level and hence significant fuel savings can be achieved. The execution of proposed system is assessed through MATLAB/Simulink model and its validation by experimental test bench.

МОДЕЛИРОВАНИЕ ПЕРЕХОДНЫХ ПРОЦЕССОВ ДИЗЕЛЬ-ГЕНЕРАТОРНОЙ УСТАНОВКИ ПЕРЕМЕННОЙ ЧАСТОТЫ ВРАЩЕНИЯ НА БАЗЕ АКТИВНОГО ВЫПРЯМИТЕЛЯ НАПРЯЖЕНИЯ

The variants of transformerless power topologies of ship diesel generator sets of variable rotational speed are considered. A power circuit of a diesel generator set of variable rotational speed on the basis of an active voltage rectifier and a buffer energy store, which has the highest efficiency in terms of weight and size and performance, is proposed. A block diagram of a control system for semiconductor converters as part of a diesel generator set of variable rotational speed is presented. The control system of the active voltage rectifier is implemented upon the principle of regulation according to the position of the generalized voltage vector of the network. In order to increase the energy efficiency of the inverter diesel generator set there has been developed the algorithm for smooth control of the rotational speed of the internal combustion engine using setting mechanism of suspend mode. The proposed algorithm (gradient descent method) is borrowed from the neural network technologies and allows calculating the rotation frequency of the internal combustion engine shaft corresponding to the minimum specific fuel consumption when operating at the current fractional load. In MatLab Simulink computer environment a simulation model of a variable-frequency diesel generator set based on active voltage rectifier was developed and transients were studied. The results of simulation modeling of the dynamic modes of the load switching have been presented, taking into account its size and nature; the indicators of the specific fuel consumption of the internal combustion engine as part of a diesel generator set of variable rotational speed are presented, as well. Using a variable-speed diesel generator set based on an active voltage rectifier has been proved to allow ensuring the required quality indicators of the generated electricity when the internal combustion engine is operating at lower energy-efficient rotation frequencies in the fractional load mode.