Line Voltage Variations Research Articles

PID-Based control of sepic power stage with QS bacterial-based search algorithm for renewable energy applications

In response to the growing need for efficient power conversion in renewable energy applications, this study addresses the issue of harmonic distortion and low Power Factor (PF) values caused by non-linear loads, such as electronic devices. Low PF results in reduced efficiency, increased energy consumption, and higher costs for both consumers and utilities. Active correction, typically involving an active circuit implemented using a power converter, provides an optimal solution by offering high performance, precise regulation, and low harmonic distortion. This research proposes a Power Factor Correction (PFC) solution utilizing an Interleaved DC-DC Single Ended Primary Inductance Converter (SEPIC) for the power stage and a Proportional Integral Derivative (PID) controller for the control block, tuned by a Quorum Sensing (QS) bacterial-based search algorithm. The PID controller parameters are derived using a frequency-domain approach, which presents advantages such as reduced design complexity, improved stability margins, and enhanced SEPIC performance. Simulation results indicate reduced overshoot, settling time, rise time, and Total Harmonic Distortion (THD) percentage, as well as increased efficiency and power factor nearing unity. The proposed scheme also demonstrates improved dynamic performance for variations in load, line, and reference voltage. Owing to its high efficiency, precise voltage regulation, and minimized impact on the electrical grid, this solution is well-suited for renewable energy applications, where optimizing energy conversion and ensuring stable operation are crucial for the overall performance of renewable energy systems.

Phasor measurement unit application-based fault allocation and fault classification

<span>This paper makes a contribution to the field of fault location finding in a new way that helps in the improvement of grid reliability. This paper proposes a study-based approach for fault allocation and fault type classification that uses the study of voltage and current frequency during the abnormal condition. Although, ideally frequency of voltage and current are the same in the abnormal condition they may differ from each other. This difference in frequency is separately measured by the phasor measurement unit (PMU) block at MATLAB/Simulink platform. The PMU (PLL-based, positive-sequence) block is inspired by the IEEE Std C37.118.1-2011. In this approach, we measure the line voltage and current frequency variation with the help of installed PMU after this we present this measurement in characteristics form with the help of the scoping tool in MATLAB/Simulink and study them one by one, and proposed a conclusion for fault location identification and fault type classification. The proposed approach is able to identify the source side and load side fault location and also able to classify faults into two categories namely symmetrical and asymmetrical. The proposed approach is tested on two MATLAB/Simulink models and observed satisfactory.</span>

High step-up DC-DC converter based on double self-lift switched-coupled-inductor

ABSTRACT This paper presents a novel switched-inductor based DC-DC converter with high step-up capability for interfacing the low voltage input from renewable energy sources to a high voltage DC bus. In the proposed converter, coupled inductors (CIs) are employed in lieu of discrete switched inductors to enhance the voltage gain and reduce the voltage stress on the switches. The number of turns in the CI windings is properly designed and one diode-capacitor multiplier cell (DCM) is connected at each of the two secondary windings to obtain the desired high voltage gain value. Since the required voltage conversion ratio value of 15.833 is obtained by employing CIs, the switches experience only lower voltage stress levels of about 5.79% and 26.3% of output voltage under practical conditions. Experimental results obtained from 24 V-380 V, 175 W prototype converter confirm that it operates at 93.6% full-load efficiency. Further, the supply current drawn by the converter is continuous with 15.4% ripple. Simple closed-loop control is implemented to regulate the converter’s output voltage against variations in line voltage and load current.

Discrete controller with state and disturbance estimation for robust performance of DC/DC Buck converter

This paper presents discrete robust control of DC/DC buck converter. Regulating the output voltage of the DC/DC converter digitally, irrespective of line voltage and load variation has been driving motivation for investigation of discrete sliding mode control. Average model is used to design discrete sliding mode controller. Extended state observer is designed to estimate state and disturbance of the discrete model. Switch-free controller is designed, estimated value of disturbance is used in controller to compensate its effect. The significant contribution of this paper includes assurance of robust performance by compensating disturbance contributed by load, parameter and supply variations. Proof of existence of sliding modes and stability also has been contribution. It is shown that the proposed method provides robust voltage regulation both in simulation and experiment.

All–MOS self-powered subthreshold voltage reference with enhanced line regulation

A nano-watt self-powered voltage reference configuration has been developed for the integrated microsystems in standard CMOS technology. The circuit is highly immune to temperature variations, and can be made very insensitive to the power supply glitches originating from the simple regulation mechanisms used to harvest energy from the environment. The proposed reference is an all-MOS topology without operational amplifier or on-chip resistors, generating a stable output with excellent line regulation owing to the modifications proposed to suppress the line voltage variations. All the MOS devices are working in weak inversion to ensure operation at nano-ampere current levels. Simulated in 0.18-µm standard CMOS process, a prototype of the proposed reference consumes an overall power of 14 nW at 0.7 V minimum supply. The average voltage reference is 255 mV with an average temperature coefficient of 17.05 ppm/°C across −40 °C to +125 °C. The line regulation is 0.00797%/V and 0.00456%/V, respectively, when the reference is subjected to a line voltage of 0.9–2.0 V and 1.0–2.0 V. The power supply rejection ratio is −110 dB, −91 dB and −68 dB for 0.1 Hz, 10 Hz, and 1 MHz at room temperature, respectively.

A Modified Luo Converter-Based Electric Vehicle Battery Charger With Power Quality Improvement

Most of the single-stage single switch power factor correction (PFC) solutions have limited applications in high power ac–dc converters as an increased voltage across and current through the semiconductor devices are seen, which, in turn, results into lower efficiency. This article deals with a modified isolated Luo PFC converter-based electric vehicle (EV) charger with two switches and input clamping diodes at the primary of an isolation high frequency transformer (HFT). This configuration facilitates the advantage of comparatively low switch voltage stress, which is clamped at the input voltage. The proposed converter is selected to operate in discontinuous conduction mode (DCM) to obtain built-in PF correction capability at ac mains. The operation of the converter in DCM, considerably reduces the control complexity due to reduced number of sensors. A prototype is implemented to verify the improved power quality (PQ) performance of the proposed modified Luo converter. An improved low ripple-based charging is provided in constant current-constant voltage modes, which improve the long-term battery service life. The performance of the converter is found robust enough to validate the efficacy of charging at steady state and at varying line voltage variation range. The improved PQ indices are observed to meet the international standards of IEC 61000-3-2.

Design and Stability Analysis of a Discrete-time Sliding Mode Control for a Synchronous DC-DC Buck Converter

This paper presents the design, analysis, and verification of a new scheme of digital sliding mode control (DSMC) for output voltage control of synchronous dc-dc buck converter to achieve fast transient response and high robustness under wide parameters variations. In this article, two different control laws are proposed for controlling the switches. First, a control law, without considering the disturbance item in the dynamic equation of the synchronous buck converter system, is obtained in the state space model and its stability analysis is presented. Then, in order to improve the dynamic performance of the buck converter, in the case of load and line changes, another control law, with considering the disturbance item is obtained and analyzed. In fact, we designed a control law that closed-loop system has strong robustness against matched or unmatched uncertainties as it reduced chattering, steady state error, overshoot and undershoot of output voltage. Its implementation only needs output error voltage measurement and doesn’t need current measurement. The simulation results are obtained using the MAT-LAB/SIMULINK software. Simulation results show that the proposed DSMC in the presence of a disturbances model is superior to proposed DSMC without disturbances consideration during immediate load and line voltage variations. In other words, it exhibits considerable reduction in terms of the overshoot and undershoot of output voltage response through an optimal control law during load changes. The proposed method almost overcomes the steady-state error and reduces the chattering to about 0.8%. Also, the overshoot and undershoot values are 4.8% and 3.9%, respectively.

A Normalized Output Error-Based Sliding-Mode Controller for the DC–DC Cascade Boost Converter

A normalized output error-based sliding-mode (SM) controller for the dc–dc cascade boost converter is proposed. In this controller, the reference inductor current trajectory used in the sliding surface is computed using the bounded normalized voltage error. As compared to the traditional hysteresis-based SM controller, the proposed controller provides more room for tuning the controller gains and thus significantly improves the transient responses in the presence of load, line, and reference voltage variations. The stability analysis of the proposed SM controlled system is provided. Also, a comparative study of the traditional and proposed SM controllers for the regulation of the cascade boost converter is presented. The experimental results show the superiority of the proposed controller in handling load, line, and reference voltage variations.

Cost implication of Line Voltage variation on Three Phase Induction Motor operation

Globally, there is a drive toward ensuring energy efficiency in all aspect of production operations and power supply systems. Industries are the backbone of our modern word, and a significant percentage of industrial operations are motor driven. Three Phase Induction Motor is massively deployed in industries due to its ruggedness, reasonable cost and ease of maintenance. The energy efficiency of the induction motor is affected by the internal configurations of the motor and the nature of the supply. Power supply fluctuations result in power quality issues and its attendant negative effects on equipment operation. This research, studies the cost and performance implication of the effects of balanced over voltage, balanced voltage, balanced under voltage and unbalance voltage on the operation of the three phase induction motor using the peculiarities of Nigeria. The result shows that, there is an increase in operational cost due to increased energy loss in the windings as a result of voltage variations from the balanced state, with balanced over voltage operation showing more cost severity among the voltage variations considered.

Investigation of a Voltage-Mode Controller for a dc-dc Multilevel Boost Converter

The multilevel dc-dc boost converter (MBC) is well known for its simple circuit structure and high voltage gain. Several controllers have been previously employed for their output voltage regulation. However, due to the non-minimum phase nature of the MBC, these controllers use both the inductor current and output voltage as feedback variables. This increases the complexity of the controller design and cost of implementation. In order to overcome these drawbacks, a voltage-mode controller for the regulation of the MBC is proposed in this brief. By using the generalized reduced-order state-space model of the converter and frequency-domain techniques, the stability of the voltage-controlled converter system is analyzed. In addition, some simulation and experimental results illustrating the ability of the proposed controller to regulate a $3{x}$ dc-dc multilevel boost converter in the presence of load and line voltage variations are provided.

Design and Implementation of Single Phase AC-DC Buck-Boost Converter for Power Factor Correction and Harmonic Elimination

<p class="Abstract"><span>This paper discusses the Power Factor Correction (PFC) for single phase ACDC Buck-Boost Converter (BBC) operated in Continuous Conduction Mode (CCM) using inductor average current mode control. The proposed control technique employs Proportional-Integral (PI) controller in the outer voltage loop and the Inductor Average Current Mode Control (IACMC) in the inner current loop for PFC BBC. The IACMC has advantages such as robustness when there are large variations in line voltage and output load. The PI controller is developed by using state space average model of BBC. The simulation of the proposed system with its control circuit is implemented in MatLab/Simulink. The simulation results show a nearly unity power factor can be attained and there is almost no change in power factor when the line frequency is at various ranges. Experimental results are provided to show its validity and feasibility. <br />Keyword</span></p>

Improvements in performance and reliability for segmented linear LED drivers**Project supported by the National Natural Science Foundation of China (No. 61106026).

Several improvements have been made to the conventional segmented linear light-emitting diode (LED) driver topology to enhance the performance and reliability of the system. A compensation technology is proposed to adaptively adjust the impedance of the sensing circuit to keep the output luminance constant in case of line voltage variations. Based on the proposed technology, an active over temperature protection technique is presented to constrain the averaged LED current according to the junction temperature to prevent the driving IC from overheating. Otherwise, a pulse width modulation dimming circuitry which is compatible with input logic level ranging from 1.8 to 20 V is proposed. The proposed technologies are implemented in a 1.0 μm 5/20/500 V BCD technology with three high voltage MOSFETs integrated on chip. The experimental results show that within 220±15% V, 50 Hz AC line-voltage variation, the output luminance is restrained to 4% in total. The output luminance can also be effectively controlled by the PWM dimming circuitry, and a dimming range of 95% is achieved with good linearity.

순환최소자승법을 이용한 직류도시철도 변전소의 가선전압변동 모델링

The DC overhead line voltage of an electric railway substation swings depending on the accelerating and regenerative-braking energy of trains, and it deteriorates the energy quality of the electric facility in the DC railway substation and restricts the powering and braking performance of subway trains. Recently, an energy storage system or a regenerative inverter has been introduced into railway traction substations to diminish both the variance of the overhead line voltage and the peak power consumption. In this study, the variance of the overhead line voltage in a DC railway substation is modelled by RC parallel circuits in each feeder, and the RC parameters are estimated using the recursive least mean square (RLMS) scheme. The forgetting factor values for the RLMS are selected using simulated annealing optimization, and the modelling scheme of the overhead line voltage variation is evaluated through raw data measured in a downtown railway substation.

Single stage single phase active power factor corrected Ĉuk Topology Based AC-DC Converter

This paper focuses on the analysis of a power factor correction (PFC) converter using close loop Ĉuk topology. Regardless of the input line voltage and output load variations, input current drawn by the buck or buck-boost converter is always discontinuous. The Boost converter suffers from high voltage stresses across the power electronic devices. The input current in Ĉuk converter is comparable to boost converter’s input current. In this paper output voltage is controlled by inner current and outer voltage control loop along with power factor correction (PFC). It shows less input current THD, nearly unity power factor and better output voltage regulation of AC-DC converter under variable input voltage and output load. In this paper the relative performance between normal diode rectifier, open loop Ĉuk rectifier and close loop Ĉuk rectifier is presented. An algorithm for implementing close loop Ĉuk rectifier in digital domain is developed and simulated. DOI: http://dx.doi.org/10.11591/ijpeds.v4i2.5574

OLTC Voltage and Reactive Power Control in Area Transmission System for Improvement Line Loss and Voltage Variation

Coordination on load tap changers (OLTCs) voltage and reactive power compensators in area transmission power system is presented to improve efficiency and voltage variation using a novel optimum procedure technique. The novel optimum technique procedure used hybrid differential evolution (HDE) to coordinate the OLTCs setting and reactive power compensation for reducing line losses and voltage change rate. The objection function is selected total line loss under the limited range of OLTCs setting and reactive power compensation. The proposal design method is used to IEEE-30BUS power system to demonstrate the useful method. The result exhibits to less line losses and a little voltage variation.

Power electronics converter control based on rule based algorithm

The exact modeling of power converter circuit that includes several semiconductor switching devices is not easy due to the non-linear and time varying characteristics of the switching devices. Thus, controlling the system effectively without exact mathematical model is very important. The rule based controller RBC can easily be used in the control of any systems when an exact mathematical model of the system cannot be obtained. In this paper, a RBC for DC-DC converter is proposed for output voltage control of DC-DC converter. As compared to conventional fuzzy logic control FLC, it provides improved performances in terms of overshoot limitation and sensitivity to load and line voltage variations. Simulation and experimental results of buck converter confirm the validity of proposed control technique.

Static VAR compensation of a fixed speed stall control wind turbine during start-up

An installed 900 kW fixed speed stall controlled soft-started wind turbine connected to a weak distribution grid was modeled under start-up conditions. Generator and soft-start control and design parameters were not available, so a modeling process independent of this information was developed. Field measured transients were closely reproduced in simulation using a full-order generator model with generic parameters and a thyristor-based graduated interconnection to the grid. A Static VAR Compensator model was then added to the wind turbine model to explore a method of reducing start-up transients. It was found that for the specific transients modeled, a 300 kVAR SVC supplied sufficient reactive power to limit line voltage variations to within 3% of steady state values. Model details and simulation output are presented in this paper.

Dynamical analysis of a novel zero‐voltage‐switching‐PWM DC‐DC half‐bridge converter

In this work, based on the duty‐cycle‐shifted‐PWM half‐bridge converter, a zero‐voltage‐switching‐PWM (ZVS‐PWM) half‐bridge converter is proposed. Both main switches of the proposed converter achieve zero‐voltage‐switching and the converter uses constant‐frequency operation. The small‐signal mathematical model for the ZVS‐PWM half‐bridge converter is derived. Notably, it is verified that the dynamical behavior of the ZVS‐PWM half‐bridge converter is better than that of the conventional PWM half‐bridge converter from a system point of view. The accuracy of theoretical results is verified by simulation and experimental results. A classical controller is then designed to achieve fast output voltage regulation despite variations in line voltage and load resistance.

High-Voltage Closed-Loop Power Supply for Ozone Generators

In this paper the design, implementation and experimental results of a high-voltage power supply for ozone generation are presented. The power stage arrangement is formed by a buck converter plus a current-fed parallel-resonant push-pull inverter. The buck converter is used to both regulate the output power against the line voltage variation, and to control the power delivered to the ozone generator (OG). The push-pull inverter assures safe operation of the OG by working at the parallel resonant frequency given by the high-voltage transformer plus OG characteristic. The closed-loop operation of the proposed converter is analyzed and implemented as a method to compensate variations in the line voltage and in the OG. A low cost commercial UC3872 integrated circuit is used to control both the push-pull inverter and the buck converter, providing OG power control and regulation via buck converter duty cycle. Protections against short circuit and no load operation are also implemented. Experimental results for a 100 W prototype are shown and discussed.

Compensation Strategy of Autotransformers and Parallel Lines Performance, Assisted by the UPFC

In this paper, reactive power compensation through the tertiary winding of an autotransformer, is proposed. Such an approach emerges as an alternative to support the significant voltage variation present over two parallel connected autotransformers, in the South Eastern Brazilian system. The above proposal will also help in controlling the line voltage variation due to the UPFC series converter action. A detailed steady-state analysis of the series voltage and the shunt reactive current when supporting line voltage, is realized. Such analysis is based upon the d-q coordinates. The UPFC effect over an uncompensated parallel line, is also studied. The waveform simulations performed to control each transformer terminal voltage, were obtained utilising the ATP/EMTP program. Results concerning the effectiveness of the autotransformer tertiary winding reactive power injection by the UPFC shunt converter, as well as the load flow control over the referred transformers, are also presented.