A Linear Regression Model for THD Sensitivity in PV Based Microgrid with Varying Insolation Levels

Solar PV systems can be used for powering small microgrids in rural area of developing countries. Generally, a solar power microgrid consists of a PV array, an MPPT, a dc-dc converter and an inverter, particularly as the general loads are A.C in nature. In a PV system, reactive current, unbalancing in currents, and harmonics are generated due to the power electronics-based converters as well as nonlinear loads (computers induction motors etc). Thus, estimation of the harmonics levels measured by the Total Harmonic Distortion (THD) is an essential aspect of performance assessment of a solar powered microgrid. A major issue that needs to be examined is the impact of PV system control parameters on the THD. In this paper, we take up this assessment for a small PV based rural microgrid with varying levels of solar irradiance. A Simulink model has been developed for the study from which the THD at equilibrium conditions is estimated. This data is in turn used to design a generalized Linear Regression Model, which can be used to observe the sensitivity of three control variables on the magnitude of the THD. These variables are: Solar Irradiance levels, Power Factor (PF) of connected load magnitude of the connected load (in kVA) The results obtained show that the greatest sensitivity is obtained for load kVA variation.

Sensorless Speed Contorl of Doubly-Fed Induction Machine Using Reactive Power Based MRAS

A sensorless speed control method for doubly-fed induction machine (DFIM) operating with constant frequency but in variable speed mode is presented in this project work. The control method is based on rotor speed estimation technique by a reactive power model reference adaptive system (MRAS) observer. The presented technique does not depend on any kind of flux evaluation and also independent to the resistance variation of either stator or rotor. The MRAS observer has a capacity for speed catching operation. PI controller is designed and also optimized using algorithm for better dynamic behaviour of the machine. MATLAB Simulink model and the simulation results are shown to check the effectiveness of the observer and also of the controller.

Thermal integration of PEM Fuel Cells and metal hydrides storage system for Zero Emission Ultimate Ship (ZEUS)

The ZEUS (Zero Emission Ultimate Ship), developed in the framework of the national research project TecBia conducted by Fincantieri and co-founded by Italian Ministry of Economic Development, is a 25m length vessel characterized by a zero-emissions propulsion system. The on-board power generation is provided by 4 PEM Fuel Cell modules (140 kW power installation) fed by hydrogen stored into 48 Metal Hydride tanks (MH). PEMFC and MH thermal systems are coupled to recover the heat produced by PEMFC and to feed the endothermic dissociation reactions of hydrogen from MHs. This paper provides a Matlab-Simulink model to simulate the dynamic behaviour of the PEMFC power generation system and the thermal coupling with MH racks installed onboard. Three typical operative profiles are simulated to verify the thermal management control system and the impact of transient conditions on the propulsion plant. Furthermore, the effects of the major exogenous parameters are investigated. Results verify that thermal coupling between the two systems is guaranteed; however, an excessive load increase can lead the stacks to operate under non-optimal conditions for significant periods of time. The effect of exogenous parameters has been verified to be negligible and does not significantly affect the control system.

Different computational technique for solution of variation issue

Issue of large demand of electricity by customers in all countries becomes a big challenge to all. In this paper the issue of frequency and corresponding power in the generating station has been focused and three generating units taken as a source of electricity generation. Computational technique like; PI, PID, Fuzzy and GA Technique has been applied for the solution of such issues, when the generating unit is operating normal and also even in disturbing condition. The Simulink model has been simulated and comparative result of response has been tabulated for best effectiveness. Comparative results show that the GA techniques gives good results with respect to the other techniques by satisfying the all system parameters in all the conditions.

Modelling, analysis and experimental verification of air disc brake used in heavy duty vehicles

This paper proposes a reliable mathematical model that can be used for design stage of new air disc brake (ADB) development projects. All three phases of braking mechanism (brake apply, brake release and automatic adjustment) are modelled by Matlab Simulink in consideration of hysteresis and adjuster performance experiments. Firstly, mathematical relations of each friction interfaces of air disc brake components are derived and mathematical equations adapted to the Simulink model. To ensure the accuracy of ADB system model, hysteresis and adjuster performance experiments are conducted on a prototype disc brake mechanism supported by a test fixture. This prototype single piston disc brake mechanism is fitted to wheel size in 17.5″ used in heavy commercial vehicles. The predicted clamping force, mechanical ratio, brake efficiency and adjuster rate results are verified by using experimental data. The maximum deviation in hysteresis results is 3.08%. Besides, the maximum deviation in adjuster performance results is 7.15%. The numerically and experimentally obtained hysteresis and adjuster performance results show good agreement. The proposed model is modified in consideration of mechanism supported by a brake calliper for predicting actual performance of single piston brake mechanism on the brake level. The hysteresis and the adjuster performance analyses are conducted by using modified ADB model to calculate the hysteresis based brake efficiency and the adjuster rate. The brake efficiency of new single piston brake design provides similar efficiency as the twin piston disc brake used in heavy commercial vehicles.

A grid interconnected nested neutral point clamped inverter with voltage synchronization using synchronous reference frame controller

<p><span lang="EN-US">Nested neutral point clamped multi level inverter with inter connection to grid through the synchronous reference frame (SRF) controller for synchronization of voltage to the grid is demonstrated. The system's main feature is that voltage stress in each inverter switching device is kept to a minimum, and redundant inverter switching states are utilised for neutral point and flying capacitor voltage balancing with sinusoidal pulse-width modulation (PWM) technique, synchronisation to grid voltages, and power injection with low harmonic generation. The inverter receives its input from a photovoltaic (PV) source that is coupled to DC-DC booster converters that are regulated by the maximum power point tracking (MPPT) incremental conductance algorithm to maintain a constant dc voltage. The system is examined under various load conditions with MATLAB Simulink model.</span></p>

Performance Analysis of Commercial Passive Balancing Battery Management System Operation Using a Hardware-in-the-Loop Testbed

With increased usage, individual batteries within the battery pack will begin to show disparate voltage and State of Charge (SOC) profiles, which will impact the time at which batteries become balanced. Commercial battery management systems (BMSs), used in electric vehicles (EVs) and microgrids, typically send out signals suggesting removal of individual batteries or entire packs to prevent thermal runaway scenarios. To reuse these batteries, this paper presents an analysis of an off-the-shelf Orion BMS with a constrained cycling approach to assess the voltage and SOC balancing and thermal performances of such near-to-second life batteries. A scaled-down pack of series-connected batteries in 6s1p and 6s2p topologies are cycled through a combination of US06 drive and constant charge (CC) profiles using an OPAL-RT real-time Hardware-in-the-loop (HIL) simulator. These results are compared with those obtained from the Matlab/Simulink model to present the error incurred in the simulation environment. Results suggest that the close-to-second life batteries can be reused if operated in a constrained manner and that a scaled-up battery pack topology reduces incurred error.

A grid interconnected nested neutral-point clamped inverter with voltage synchronization using synchronous reference frame controller

<p><span lang="EN-US">Nested neutral-point clamped multi level inverter with inter connection to grid through the synchronous reference frame (SRF) controller for synchronization of voltage to the grid is demonstrated. The system's main feature is that voltage stress in each inverter switching device is kept to a minimum, and redundant inverter switching states are utilised for neutral point and flying capacitor voltage balancing with sinusoidal pulse-width modulation (PWM) technique, synchronisation to grid voltages, and power injection with low harmonic generation. The inverter receives its input from a photovoltaic (PV) source that is coupled to DC-DC booster converters that are regulated by the maximum power point <span lang="EN-US">(MPP)</span> tracking incremental conductance algorithm to maintain a constant dc voltage. The system is examined under various load conditions with MATLAB/Simulink model.</span></p>

Power Bus Management Techniques for Space Missions in Low Earth Orbit

In space vehicles, the typical configurations for the Solar Array Power Regulators in charge of managing power transfer from the solar array to the power bus are quite different from the corresponding devices in use for terrestrial applications. A thorough analysis is reported for the most popular approaches, namely Sequential Switching Shunt Regulation and parallel-input Pulse Width Modulated converters with Maximum Power Point Tracking. Their performance is compared with reference to a typical mission in low Earth orbit, highlighting the respective strengths and weaknesses. A novel solar array managing technique, the Sequential Maximum Power Tracking, is also introduced in the trade-off and was demonstrated able to boost energy harvesting, especially in the presence of mismatching in the solar array. It also can achieve top levels of reliability using a rather simple control hardware. Its operation was verified both by a Matlab–Simulink model and by an experimental breadboard.

Modeling The Sport Differential Mechanism

The study is devoted to the issues of mathematical modeling and simulating the sport differential mechanism (DM) with controllable torque redistribution. The issue is caused by the elaboration of ADAS systems with the automated torque vectoring for transmissions of all-wheel-drive (AWD) vehicles and the inclusion of such devices in the combined autonomous vehicle trajectory control scheme. At the article's beginning, the use of devices for redistributing traction forces is reasoned by analyzing the curvilinear vehicle motion, where they could ensure the accuracy of vehicle steerability. The literature review highlights modern developments in the field of modeling and researching such DMs. Considering the vehicle turn with a minimum radius, the conditions corresponding to passing greater torque over the outrunning rear axle are determined. All the mechanism's components and loads acting between them are described in detail. To form an original method of mathematical description of the mechanism functioning, the system of differential equations, systems of kinematic and force connections are considered separately. The article details the mathematical approach to generalize the way for automating the equation compilation for rotational mechanical systems such as vehicle transmissions. In the simulation section, a Simulink model reflecting the functional components and calculation procedures is presented. A series of testing and simulations on the DM operation with forcible torque distribution is carried out. Modeling data are presented, and the analysis of simulation results is performed. In the completion, conclusions are made regarding the scope and use of this model and the prospects for further developing the method proposed to automate the formation of equation systems.