Band 22, Heft 3

Emerging technologies in an electric vehicle (EV) had greater advancement in the control, batteries and electric motors design. But safety and reliability are the major concerns when the consumer is dealing with a high voltage conductor for charging. The recurring of plugging in the switch for charging is an undeniable disadvantage. Therefore, to eliminate the human intervention in charging of a battery, wireless power transfer (WPT) will be the most effective methodology to charge the EV. This paper aims at building the prototype of 1 kW inductive WPT with high frequency supply with power converters. To design this system, standards of EV charging systems are incorporated; also, a suitable coil structure is identified for the given EV model as per the standards. The mismatch or misalignment of the receiver coil, air gap between receiver–transmitter (i.e., proximity) and compensation techniques are considered in this work. Efficient design of power electronic converter is implemented for both transmitter and receiver side. Both coil design model and the power electronic system are integrated to test the performance of proposed WPT technology.

Sensors of any kind contribute to extra space and electronics when they are used in any application. Besides, the sensor noise also has the effect of altering the overall gain of the system. This is more prevalent in non-linear systems like motor control. In applications which have strict space constraints like Electric vehicles, the use of sensors must be optimized, which, in turn, gave rise to many sensorless state estimation strategies. This paper proposes a novel sensorless control technique for brushless direct current (BLDC) motor used in electric vehicle applications. The concept of sensorless control in BLDC Motor drive eliminates the hall-effect position sensor, thereby giving better performance and improves the robustness of the overall drive system. The main objective of this work is to estimate the position of the motor at standstill condition using stator saturation effect concerning the rotor, accelerate the motor from standstill so that enough back EMF is generated. This acceleration technique speeds up the motor to a stage where a self-actuating control mechanism is used to generate control signals with back EMF or line voltages. The motor can be started with a load, which is a significant constraint for electric vehicle application. The proposed method will avoid the reverse rotation of the motor. The proposed work is simulated in Matlab/Simulink software, and results obtained show that it works well under dynamic conditions of starting, acceleration and load switching. The hardware setup of the proposed work is developed using the TMS320F2812 DSP processor. Simulation and experimental results validate the effectiveness of the proposed work for electric vehicle application.

Thyristor Controlled Series Capacitor (TCSC) is employed as actuator in an interconnected power system using Supplementary Damping Controller (SDC) to enhance the power transfer capabilities between areas as well as damp out the Inter-Area Low-Frequency (IALF) oscillations by varying the impedance of transmission lines. The time-varying delays in the feedback loop and asymmetric saturation limits at the output of TCSC may reduce the performance of the designed controller and lead to closed-loop instability if these are not considered in the process of controller design. Usually, a Minimum Absolute Saturation Bound technique (MASB) is used to convert asymmetric saturation limits into symmetric one. However, such consideration provides an apparent conservative and degrades the performance of the control system. To reduce the conservative in the control design process, a Normalized Saturation Bound (NSB) technique is used in this paper to convert asymmetric saturation limits of TCSC of time-delayed power system. The L-K functional and generalized sector conditions are utilized in the proposed controller design process to compensate the effect of time-varying delay and converted symmetric saturation limits. Sufficient conditions required for controller design are formulated in LMI form. 2-area 4-machine power model is used to verify the performance of the designed controller. From the simulation results, it is observed that the designed controller is giving superior performance in the present of time-varying delays and asymmetric saturation as compared to the designed controller using MASB technique.

In this work, a new maximum power point tracking algorithm (MPPT) for photovoltaic systems is proposed. The considered system is composed of a photovoltaic panel charging a battery using a buck-type DC–DC converter. Computational simulations are carried out to compare the performances of the MPPT algorithms, therein analyzing the output voltage and output power behavior at the photovoltaic panel. Three evaluation scenarios are considered: with constant irradiance and temperature, randomly chosen conditions and using real data. The results of the simulations show that the proposed algorithm applied to the photovoltaic system achieves a better performance than the main MPPT algorithms in the literature.

This research work proposes a planning strategy pertaining to the techno-economic operation of Indian power systems. The proposed strategy focused on the reactive power (VAr) planning (RPP) subject to the system operating cost minimization ensuring system security. To mitigate the RPP issue, unique meta-heuristic hybridized techniques are adopted to size the optimal parameter settings such as alternator’s reactive power, tap settings of transformers etc. instigated by power flow analysis satisfying all equality and inequality constraints. The controlling variables are optimally determined to solve this non-linear RPP problem. The bottleneck for the installation of static VAr compensators at weak buses is also wiped out by different analytical techniques viz. loss sensitivity, power flow and modal analysis. Two different inter-regional transmission networks prevailing in India are considered to measure the adaptability, efficacy and efficiency of the proposed approach. The results obtained by applying the proposed approach have confirmed that network loss-minimization procedures produce an acceptable solution and reduce the operating cost which is especially important in RPP. The responses of bench mark functions and statistical analysis of the outcomes from both systems allow us to assess the overall efficiency and efficacy of the proposed techno-economic planning approach.

Recently, distributed generators (DGs) are being largely amalgamated with radial distribution systems because of their positive impacts on these systems such as voltage profile improvement and power loss minimization. However, if this integration is not well-planned, it can lead to serious problems in the protection devices. One of these problems is the recloser-fuse miscoordination. This paper presents an effective solution to the recloser-fuse miscoordination due to DGs integration with RDS. The proposed approach is based on suppressing the DG current during fault period so that the contribution of DG to the fault current becomes minimal. Two types of superconducting fault current limiters (SFCLs) namely, saturated iron-core and shielded iron-core SFCLs are studied and a comparison between their performance is presented. The proposed solution was implemented on IEEE 33-bus RDS. All simulation studies are performed on MATLAB script. The simulation results illustrated that saturated iron-core SFCL could not recover recloser-fuse coordination in some of the studied cases. However, shielded iron-core SFCL could successfully restore the recloser-fuse coordination in all the studied cases. This shows that shielded iron-core SFCL is preferred in solving recloser-fuse miscoordination.

In active distribution networks, it is a challenging task for the utility and system operators to identify and analyze the power quality (PQ) disturbance and its cause. Likewise, the consumers are curious about the quality of power supply being provided and the economic impacts of low PQ. Thus, continuous monitoring of the overall quality of the power at the consumer end has become a significant concern in distribution networks. This paper presents a new composite power quality index (CPQI) for low-voltage distribution networks. The CPQI is formulated as a weighted average of five basic parameters, namely voltage level, current harmonic quality, voltage harmonic quality, power factor, and system frequency. The main emphasis is on quantifying the overall quality of the power supply under different PQ disturbance conditions. The CPQI estimate helps in a preliminary investigation of tracking the low PQ location and its source. The proposed CPQI is evaluated on a variety of simulated signals obtained from a CIGRE low-voltage microgrid network. Furthermore, the formulated CPQI is investigated on a LabVIEW-based virtual instrumentation platform with LED loads. It is interpreted from the results that the proposed CPQI is able to evaluate the overall PQ at a load terminal with diverse load conditions subjected to different power quality disturbances.

Modular multilevel converter for high voltage DC system has great potential as the key role in global energy interconnection . Adaptive reclosing or restarting after suffering from short-circuit faults is a critical segment to realize safe and stable operation. An adaptive restart scheme for the half-bridge sub-module transmission system is proposed, which is based on the active current injection of the auxiliary fault discriminate module. Combined with the engineering experience, the transient characteristics of the line current during the fault restart stage are analyzed. The ratio of the current peaks at both ends of the fault point is used as the criterion. Moreover, the restart current suppression strategy is introduced into the adaptive restart scheme. It provides a decision-making basis for discriminate the property of the fault and improves the success rate of fault restart. The simulation results show that after the external auxiliary module is introduced into the adaptive restart stage, the restart current does not exceed the rated value. Finally, The permanent fault and the transient fault can be successfully distinguished, providing a reliable guarantee for the subsequent action decision of the protection devices.

The rapid suppression of fault current flowing through overhead transmission lines and safe restart of the system are critical problems to be solved urgently to improve the stability of the DC grid. A novel adaptive restart strategy combined with fault current suppression is proposed, which suitable for full-bridge modular multilevel converter high voltage direct current system. The resistance-capacitance energy transfer branch is used to achieve a large reduction and rapid attenuation of the fault current amplitude at restart time. The transient fault and permanent fault can be discriminated in a short interval after restarting based on the frequency domain amplitude characteristics. The proposed scheme has both restart-current protection and fault property identification functions, overcoming the high cost and low component reusability of traditional single-function fault current limiting schemes. The simulation results show that the scheme has a significant fault current suppression effect and accurately discriminates the fault property to realize rapid recovery.