Volume 20, Issue 6 -

Mitigation of commutation current ripple (CCR) in the brushless direct current (BLDC) motor drive using DC-DC converter based topologies are achieving widespread popularity. However, undesired alternating current (AC) components are presented in the DC-link voltage across the capacitor of the DC-DC converter which leads to a destabilization of the power supply during the commutation interval. In addition, undesired speed regulation and audible noise occur which deteriorates the motor performance. In order to encounter this problem, different conventional compensation techniques based on the low-pass filter (LPF) has been proposed. However, LPF requires a close relation between dynamic coupling and active compensation. In view of the limitation, this paper proposes a proportional-resonant (PR) compensator to stabilize the DC-link voltage. Performance of the PR compensator is tested on a combination of modified single-ended primary inductor converter (MSEPIC), DC-link voltage selector circuit is used in the proposed current ripple mitigation technique for BLDC motor drive. The PR compensator is utilized to stabilize the DC-link voltage whereas the DC-link voltage selector circuit is employed to achieve a regulated DC voltage from the MSEPIC converter for efficient current ripple suppression during the commutation interval. Simulation and experimental results verify the effectiveness of the proposed compensation scheme for current ripple mitigation technique of BLDC motor drive. The simulation and experimental results clearly reveal that the PR compensator effectively stabilized the DC-link voltage, which alleviates the CCR.

Fault detection in induction motors has drawn growing attention due to importance of these motors in different industries. Analysis of motor currents is a common method for the fault detection. This method is preferred compared with other approaches because of its economic and technical superiorities. In this paper, a modified model of an induction motor including stator fault and a new technique are proposed for detection of stator winding faults. Firstly, Walsh-Hadamard transform is applied to stator currents. Then, variation of Walsh-Hadamard transform is used as the criterion for the detection. Plenty of simulation cases are utilized to evaluate the method. To enhance accuracy of the model, isolation layer resistance (R f ) is also taken into account. For further evaluation, a large number of experimental data were recorded from different experiments to assess the method in practice.

Abnormal Voltages in electrical distribution system is a threat to power system security and may cause equipment damages. Reconfiguration aids in the proper distribution of load and thus improving the voltage profile. The multi objective framework including node voltage deviation as primary objective and power loss and reliability as secondary objectives is formulated. The novel meta heuristic method based on binary particle swarm optimization (BPSO) is employed to find the optimal radial distribution network configuration for an assortment of objective function. The effect of inertia weight, position and population of swarm is deeply investigated. The proposed method has been verified on IEEE 33 and 69 bus radial distribution systems and found to be effective in minimizing node voltage deviation. The impact of the reconfigured system on voltage deviation, power loss and reliability has been studied extensively. BPSO calculations are found to be simple and has good Convergence characteristics in comparison with other meta heuristic techniques.

The increasing demand in transmitting electrical energy at very high voltages with low transmission losses and improved efficiency has led to the development of compact metal enclosed gas insulated substation. There are various advantages of gas insulated substations over conventional substations yet there are a few problems associated with the switching operation in gas insulated substation. The fast transient voltages arising due to the switching operation of disconnectors or circuit breakers may impair the service reliability. The fast transient currents are associated with these fast transient voltages. The main aim of this paper is to characterize the fast transient currents generated due to the switching operations in a gas insulated substation. The dominant frequency content has been identified for different rise times of the fast transient currents and the percentage attenuation in amplitude is determined at different distances from the source. The variation in the peak value of current with distance from the source is also analysed. The experimental work is carried out on 145 kV gas insulated substation models of different configurations and comparison of the results for different case studies are reported.

Power Quality has always been a major concern ever since the increase in the usage of many power electronic loads such as Personal Computers (PCs), TVs, variable frequency drives in nearly every household. These loads are a major source of harmonics into the distribution system. Unbalanced Three-phase loads or different single-phase loads result in unbalance in the three-phase voltages and currents in the grid. Equipment damage, Loss of data, nuisance tripping, overheating of wires, relay tripping are few of the major issues caused due to power quality. Also, there is an increase in the awareness about the various power quality issues as well as its ill-effects amongst the consumers. Hence, it is essential to improve the quality of the power supplied. Active and Passive filters play a huge role in the mitigation of power quality issues. In recent years, usage of active filters has increased because tuning is possible for various harmonic elimination and active filters when combined with a storage system can provide active as well as reactive power compensation. The fast depletion of non-renewable sources of energy and its effect on the environment has shifted the focus on the usage of non-renewable energy sources such as solar energy, wind energy, etc for the production of electricity. In this research work, solar energy is combined with shunt active filter for the mitigation of various power quality issues occurring in a grid-connected non-linear and unbalanced three-phase load. The active power filter will provide reactive power compensation to the non-linear load and active power delivery for unbalanced loads such the grid current and voltage will remain balanced and the stress on the grid is reduced while meeting the load demand. A battery system is also integrated to store the excess energy that may be generated by the Photo-Voltaic(PV) array and acts as a source of energy when PV array output is low or nil. Conservative Power Theory is used for controlling the power injection into the system by the Voltage Source Converter(VSC). The proposed system is verified using MATLAB/SIMULINK.

In this paper, a modern two stage frequency control approach for two area interconnected power system with doubly fed induction generator (DFIG) based wind turbine is proposed. For first stage, a proportional integral derivative (PID) controller is designed for every conventional thermal area to control frequency and tie line power. In the second stage, a PID controller is implemented in DFIG to regulate its speed and accordingly control system frequency particle swarm optimization is used to tune the controllers of conventional thermal units and DFIG. The effectiveness and robustness of the proposed control scheme are investigated under different operating conditions using MATLAB/Simulink.

This paper presents a new architecture of energy hubs for animal farms considering the availability of energy resources in the farm such as biogas, solar, etc. It is proposed to combine three energy carriers: biogas, heat and electricity into an aggregate system to improve the energy efficiency of the farm. The problem is to determine the optimal allocation of distributed energy resources such as biogas generators, photovoltaics, battery and electric grid, etc. with the objective function is minimizing the total cost of energy hubs, i. e. life cycle cost while subjected to the constraint of heat, electricity and gas demands. The uncertainty of renewable energy is taken into account not only with the daily and monthly variation of the resource but the forecasting error as well. In addition, the sensitivity of the life cycle cost with respect to the price of electricity is analysed in different scenarios. The problem is examined in a case study of a typical pig farm in Northern Vietnam in both cases: with and without the ability to sell the surplus electricity to the grid. The simulation result shows the effectiveness of the proposed energy hub compared to other approaches.

This paper presents a new approach based on the application of a bit-shift operator based multi-objective seeker-optimization-algorithm (BS-MOSOA) for designing of combined primary and secondary power distribution system (CPDS) considering both system cost and reliability. In number of researches works the planning of secondary power distribution system (PDS) has not been considered for planning strategy. However, it is observed that the total investment and operational cost components of secondary PDS plays an important role in the overall system cost. Thus, in this proposed research a CPDS has been considered for comprehensive planning of complex PDS. Furthermore, a reliability index called Contingency-load-loss-index is used for the reliability assessment of the network. The algorithm uses a modified version of seeker-optimization-algorithm (SOA), which is based on the status of changing switches and shift operator to generate a group of non-dominated solutions. Also, fuzzy theory approach is used for selection of most suitable solution among the non-dominated solutions from the obtained Pareto-front. The proposed method is illustrated on a real test case consist of a residential primary and secondary network of 75 electrical nodes. Furthermore, a qualitative comparison is made with existing traditional and classical methodologies, to show the efficacy of the proposed planning approach.

Compulsators are AC generators which are specifically designed to maximize the current they can deliver for a given duration of time. A passive compulsator is being designed and developed as a source for a railgun which had been designed, fabricated and tested with a capacitor bank in the author’s laboratory. To minimize the internal impedance of compulsators, slotless armature windings are used instead of conventional slotted armature windings . For a constant mass of rotor, performance analysis of compulsator driving a railgun has been done for both slotted and slotless armature windings and the comparison is made between the projectile velocities, peak current, delivered energy density (DED) and stress on the conductor (in the case of slotless armature) between the two designs using flux-linkage or coupled circuit modeling of the system in this paper. From the analysis done using circuit modeling, two designs from both, slotted and slotless compulsators have been selected, such that both result in the same projectile velocity, and modeled and simulated in finite element method (FEM) based software to compute the tangential and radial stresses on the armature conductors as well the flux densities experienced by the conductors and the slots.

This paper presents a battery control and monitoring strategy for a DC microgrid feed by a public utility (PU) photovoltaic (PV) including with multi-battery bank (BB). The BBs respond to the changes in a power imbalance between generation and demand within a DC micro-grid, to maintain the micro-grid voltage and reliability enhancement. The fuzzy model reference learning control (FMRLC) controller has been designed to power control of the battery bank. The proposed battery control and monitoring system (BCMS) strategy keep the battery charging and discharging power as per standard charging/discharging characteristics of the battery. The BCMS allows continuous monitoring and intelligent control of distribution system operations such as battery bank energy storage (BBES), the PV system and the electric load of the consumer. A power sharing between the sources has been controlled for smooth supply. A graphical user interface (GUI) in the MATLAB environment has been configured to demonstrate the control and monitoring of the DC micro-grid and the operation performance of the BCMS algorithm for various scenarios (i.   e modes). The proposed BCMS shows better operational performance for various operating conditions in terms of monitoring and control of the batteries power in the grid-connected DC micro-grid.

The evolution of high performance power electronic converters makes a feasible way to integrate the Renewable Energy System (RES) to the grid. High performance in terms of stability, good transient and steady state response, load variations is achieved in this work using Current Controlled Voltage Source Inverters (CCVSI) by deriving the control law using Lyapunov function at the expense of a time varying reference current. In this work, a single phase equivalent circuit is represented for the three phase grid connected renewable energy system, and mathematical modeling is developed to design the controller. Analysis using Lyapunov based controller is carried out to ensure the real and reactive power flow from the renewable energy system to the grid connected with the non linear load. The reference current for the controller is generated using the Symmetrical Component theory. This theory requires no transformation and desired source power factor can be achieved. To exhibit the efficacy of the Lyapunov controller, the simulation is carried out using MATLAB/Simulink environment. It is observed that the desired power factor is obtained and Total Harmonic Distortion (THD) is within the IEEE limits in the grid side. The performance of the system is validated experimentally and the results are compared with the conventional hysteresis controller for the same application.