Showing papers on "Power factor published in 2020"

A 300-kHz 6.6-kW SiC Bidirectional LLC Onboard Charger

Abstract: The reverse LLC voltage gain is lower than unity. The dc-link voltage is then lower than the peak grid voltage so that the buck type dc–ac converters cannot be grid-tied directly, which causes the LLC reverse operation difficult in bidirectional application. This paper proposes a silicon carbide (SiC) bidirectional LLC charger architecture to achieve high efficiency and high power density. The first stage is an interleaved bridgeless totem pole power factor correction (PFC) to achieve unity power factor. The second stage is a 300-kHz LLC taking advantage of wide zero voltage switching (ZVS) range and magnetic integration. Thanks to extra control freedom of high dc-link voltage, the dc–dc voltage gain regulation is shared by the dc–ac stage taking advantage of high voltage SiC MOSFETs. A reverse LLC voltage gain compensation control by regulating dc-link voltage is proposed to enable the LLC bidirectional operation. A digital adaptive synchronous rectification driving scheme is proposed based on the LLC primary driver signals, which immunes to the circuit oscillation caused by high dv/dt and parasitic elements. A 6.6 kW SiC bidirectional LLC charger is build. The power density is 3.42 kW/L with 3 kW/kg and increases 55.6% over the reference design. The charging efficiency is above 96% through the battery voltage from 240 to 420 V, and 2% higher than the state-of-the-art products. The peak discharging efficiency under 6.6 kW is 96%, and 1% higher than the state-of-the-art efficiency.

Grasshopper optimization algorithm based two stage fuzzy multiobjective approach for optimum sizing and placement of distributed generations, shunt capacitors and electric vehicle charging stations

Abstract: In this paper a two stage Grasshopper Optimization Algorithm (GOA) based Fuzzy multiobjective approach is proposed for optimum sizing and placement of Distributed Generations (DGs), Shunt Capacitors (SCs) and Electric Vehicle (EV) charging stations for distribution systems. In the first stage Fuzzy GOA approach is used for optimum sizing and allocation of DGs and SCs for improving the substation power factor, real power loss reduction and voltage profile improvement of the distribution system. In the second stage distribution system integrated with DGs and SCs is considered and fuzzy GOA approach is used for identifying optimum locations for EV charging stations and number of vehicles at the charging stations. EV battery charging load models are developed from the Lithium ion battery charging characteristic curves for load flow analysis. Simulation results are shown to show the advantages of fast converging properties of GOA over GA and PSO techniques. Simulation results are demonstrated on 51 bus and 69 bus distribution networks to show the advantages of proposed methodology compared to conventional objective based simultaneous optimization approach. The effect of EV load growth and the effect of uncertainties in DGs and distribution system load are shown on the distribution system performance.

Ultrahigh Performance of n-Type Ag2Se Films for Flexible Thermoelectric Power Generators

Abstract: Due to the limited thermoelectric (TE) performance of conducting polymers and rigidity of inorganic materials, it is still a huge challenge to prepare low-cost, highly flexible, and high-performance TE materials. Herein, we fabricated n-type Ag2Se films using a porous nylon membrane as a flexible substrate by vacuum-assisted filtration, followed by hot pressing. A very high power factor of ∼1882 μW m-1 K-2 at room temperature is obtained. The high power factor is mainly the result of the high density of the Ag2Se film and the tuned grain orientation, which is realized by the synthesis of multisized Ag2Se nanostructures. The film also exhibits excellent flexibility with 90.7% retention of the power factor after bending around a rod of 4 mm radius for 1000 times. A four-leg TE generator is assembled with the Ag2Se film, and its maximum output power is up to 3.2 μW at a temperature difference of 30 K, corresponding to the maximum power density of 22.0 W m-2 and a normalized maximum power density of 408 μW m-1 K-2. This work provides an effective route to achieve high-power-factor, high-flexibility, and low-cost TE films.

PSO-GWO Optimized Fractional Order PID Based Hybrid Shunt Active Power Filter for Power Quality Improvements

Abstract: This paper presents a Hybrid Shunt Active Power Filter (HSAPF) optimized by hybrid Particle Swarm Optimization-Grey Wolf Optimization (PSO-GWO) and Fractional Order Proportional-Integral-Derivative Controller (FOPIDC) for reactive power and harmonic compensation under balance and unbalance loading conditions. Here, the parameters of FOPID controller are tuned by PSO-GWO technique to mitigate the harmonics. Comparing Passive with Active Filters, the former is tested to be bulky and design is complex and the later is not cost effective for high rating. Hence, a hybrid structure of shunt active and passive filter is designed using MATLAB/Simulink and in real time experimental set up. The compensation process for shunt active filter is different from predictable methods such as (p-q) or (i d -i q ) theory, in which only the source current is to be sensed. The performance of the proposed controller is tested under different operating conditions such as steady and transient states and indices like Total Harmonic Distortion (THD), Input Power Factor (IPF), Real Power (P) and Reactive Power (Q) are estimated and compared with that of other controllers. The parameters of FOPIDC and Conventional PID Controller (CPIDC) are optimized by the techniques such as PSO, GWO and hybrid PSO-GWO. The comparative simulation/experiment results reflect the better performance of PSO-GWO optimized FOPIDC based HSAPF with respect to PSO/GWO optimized FOPIDC/CPIDC based HSAPF under different operating conditions.

A Model Predictive Power Control Method for PV and Energy Storage Systems With Voltage Support Capability

Abstract: The cascaded control method with an outer voltage loop and an inner current loop has been traditionally employed for the voltage and power control of photovoltaic (PV) inverters. This method, however, has very limited power regulation capability. With the fast increasing penetration of PV power generation systems in the distribution network, the voltage rise/drop has become a serious problem impacting negatively on the power quality and grid stability. Therefore, flexible power regulation is highly desired for PV inverters to provide ancillary services. This paper proposes a novel model predictive power control (MPPC) scheme to control and coordinate the dc–dc converter and inverter for grid-connected PV systems with energy storage systems (ESS). By regulating the dc-bus voltage and controlling the active and reactive power flows, MPPC can support the power grid to maintain stable voltage and frequency and improve the power factor. Numerical simulation and controller hardware-in-the-loop (CHIL) testing have been conducted on a PV-ESS system to verify the capability and effectiveness of the proposed control strategy.

Topology and Control of a Four-Level ANPC Inverter

Abstract: Four-level hybrid-clamped inverter is a newly proposed topology that can operate under a wide voltage range without switches connected in series. However, when it is applied in medium voltage high power conversions, the flying capacitors in each phase will occupy a huge volume and a high switching frequency is required to restrain the voltage ripples. In order to overcome this drawback, a four-level active neutral-point clamped inverter is discussed in this paper, which consists of only six switches and no diodes or flying capacitors are required. In order to balance the neutral-point voltages under the full power factor and modulation index range, a capacitor voltage balance method based on carrier-overlapped pulsewidth modulation is proposed in this paper. The upper and lower dc-link capacitor voltages are balanced by zero-sequence voltage injection and the central dc-link capacitor voltage is balanced by adjusting the duty cycles of switching signals slightly. Simulation and experimental results are presented to confirm the validity of this method.

99% Efficient Isolated Three-Phase Matrix-Type DAB Buck–Boost PFC Rectifier

Abstract: Three-phase power factor correction rectifiers are an essential area of power electronics, supplying a direct current load with tens of kilowatts, or more, from the public three-phase mains and achieving sinusoidal input currents. In many applications, isolation is required between the mains and the load, for example, due to safety reasons or different grounding schemes. This paper describes the modulation, design, and realization of a buck–boost-type, unity-power-factor, isolated matrix-type, dual-active-bridge, three-phase rectifier. It uses a circuit similar to a conventional dual-active-bridge converter, but employs a direct matrix converter to connect the high-frequency transformer's primary winding to the mains. A soft-switching modulation scheme is proposed and comprehensively analyzed, deriving closed-form solutions and numerical optimization problems to calculate switching times that achieve minimal conduction losses. Based on this analysis, the design of an 8-kW 400-V rms three-phase ac to 400-V dc prototype is discussed, striving for the highest possible efficiency. Using 900-V SiC mosfet s and a transformer with an integrated inductor, a power density of ${\text{4}}\; {\text{kW}\cdot \text{dm}^{-3}}$ ( ${\text{66}}\; {\text{W}\cdot \text{in}^{-3}}$ ) is achieved. Measurement results confirm an ultrahigh full-power efficiency of 99.0% at nominal operating conditions and 98.7% at 10% lower input voltage.

LLMLF-Based Control Approach and LPO MPPT Technique for Improving Performance of a Multifunctional Three-Phase Two-Stage Grid Integrated PV System

Abstract: This study presents a novel leaky least mean logarithmic fourth (LLMLF) based control technique and learning based perturb and observe (LPO) maximum power point tracking (MPPT) algorithm, for optimal control of grid-tied solar photovoltaic (PV) system. Here, a novel LLMLF algorithm is developed for active component extraction from load current, and a novel LPO MPPT algorithm is developed for optimal MPPT operation. The proposed LPO is the improved form of perturb and observe (P&O) algorithm, where inherent problems of traditional P&O algorithm like steady-state oscillation, slow dynamic responses, and fixed step size issues are successfully mitigated. The prime objective of proposed LLMLF control is to fulfill the active power requirement of the loads from generated solar PV power, and excess power is fed to the grid. However, when generated PV power is less than the required load power, then LLMLF fulfills the load by taking extra required power from the grid. During this process, power quality is improved at the grid. The controller action provides reactive power compensation, power factor correction, harmonics filtering, and mitigation of other power quality issues. Moreover, when the solar irradiation is zero, then the dc link capacitor and voltage source converter act as distribution static compensator, which enhances the utilization factor of the system. The proposed techniques are modeled and their performances are verified experimentally on a developed prototype, in solar insolation variation condition, imbalance loading condition for linear/nonlinear loads, as well as in different grid disturbances such as over-voltage, under-voltage, phase imbalance, harmonics distortion in the grid voltage etc., where it has shown a very good performance.

Design of a High-Efficiency, High Specific-Power Three-Level T-Type Power Electronics Building Block for Aircraft Electric-Propulsion Drives

Abstract: The electric propulsion drives for the more-electric aircraft need lightweight and high-efficiency power converters. Moreover, a modular approach to the construction of the drive ensures reduced costs, reliability, and ease of maintenance. In this article, the design and fabrication procedure of a modular dc–ac three-level t-type single phase-leg power electronics building block (PEBB) rated for 100-kW, 1-kV dc-link is reported for the first time. A hybrid switch (HyS) consisting of a silicon insulated-gate bipolar junction transistor (IGBT) and silicon carbide metal–oxide–semiconductor field-effect transistor (MOSFET) was used as an active device to enable high switching frequencies at high power. The topology and semiconductor selection were based on a model-based design tool for achieving high conversion efficiency and lightweight. Due to the unavailability of commercial three-level t-type power modules, a printed circuit board (PCB) and off-the-shelf discrete semiconductor-based high-power switch was designed for the neutral-point clamping. Also, a nontrivial aluminum-based multilayer laminated bus bar was designed to facilitate the low-inductance interconnection of the selected active devices and the capacitor bank. The measured inductance indicated symmetry of both current commutation loops in the bus bar and value in the range of 28–29 nH. The specific power and volumetric power density of the block were estimated to be 27.7 kW/kg and 308.61 W/in3, respectively. The continuous operation of the block was demonstrated at 48 kVA. The efficiency of the block was measured to be 98.2%.

An Adaptive D-FACTS for Power Quality Enhancement in an Isolated Microgrid

Abstract: Technologies of microgrids (MGs) help power grid evolve into one that is more efficient, less polluting, reduced losses, and more flexible to provide energy consumers’ want and need. Because of the nature of various renewable energy sources (RESs) integrated into the MGs such as variability and inability to accurately predict and control, different technical problems are created. Power quality is one of the most important issues to be addressed, especially harmonic distortion and voltage stabilization. Many devices have been proposed to improve these two aspects that may result from loads nonlinearity and sources uncertainty. In this study, an adaptive switched filter compensator (ASFC) with developed proportional-integral-derivative (PID) controller is proposed to improve the overall dynamic performance of the MGs. The PID’s controller gains are optimally tuned via the application of grasshopper’s optimization algorithm (GOA) to act adaptively with self-tuning as the operating conditions may subject to change during MG operation. Different case studies are proposed to reveal the robustness of the presented ASFC on harmonic mitigation, dynamic voltage stabilization, reactive power compensation and power factor improvement considering the features of RESs such as variations of wind speed, solar PV irradiation and temporary fault conditions. A distribution synchronous static compensator (D-STATCOM), as one of the most popular D-FACTS, with optimal tuned PID controller by using the GOA is also proposed. To validate both the proposed ASFC topology and the modified D-STATCOM, comparative studies including what has been published in literature are examined by using MATLAB/Simulink platform. The results advocate the effectiveness, robustness and latency of the proposed devices.

Compact Three Phase Multilevel Inverter for Low and Medium Power Photovoltaic Systems

Abstract: A new three phase multilevel inverter with reduced number of components count is proposed in this paper. This inverter is designed using a single DC source per phase to generate multiple level output voltage which makes it suitable for low and medium voltage applications, including ac-coupled renewables or energy storages. A generalized circuit configuration is shown in this paper following which the number of output voltage level can be increased as per expectation. Although, each element endures the voltage stress equivalent to the input DC voltage, the value of total standing voltage (TSV) is reduced by the utilization of minimized number of components with respect to the number of series connected capacitors. Further, staircase modulation scheme is used to generate the switching signals. Hence, the proposed inverter can be operated at low switching frequency with optimal output current harmonic distortion which decreases switching losses and suppresses power factor falling. In order to validate the theoretical explanations and practical performances of the proposed inverter, the hypothesis is simulated for 9, 13 and 39 output voltage level inverters for three phase with a line voltage total harmonic distortion (THD) of 6.06%, 4.16% and 2.10% respectively in MATLAB/Simulink and a 5-level single phase laboratory prototype is implemented in the laboratory.

A Magnetically Controlled Single-Stage AC–DC Converter

Abstract: In this letter, a magnetically controlled single-stage ac–dc converter is proposed for low-power application which has the following features. First, single-stage operation is achieved by sharing switches between LLC resonant converter and totem-pole bridgeless power factor corrector (PFC) converter. Second, the power factor correction function is inherently achieved by designing the PFC converter to operate in discontinuous conduction mode. Third, the dc-link voltage is almost constant. Fourth, fixed switching frequency and duty cycle can be implemented for the switches, which simplifies the magnetic component and driver circuit design. Fifth, the LLC resonant converter is designed to operate at series resonant frequency, the highest efficiency operating point, so the converter can always achieve the maximum efficiency operation. Meanwhile, at this operating point, the converter output voltage is independent of the load so that it is functioning as a dc transformer; and finally, soft switching for all semiconductors is achieved. A 75-W experimental prototype is built to validate the proposed magnetically controlled single-stage ac–dc converter

A Comprehensive Review on Optimal Location and Sizing of Reactive Power Compensation Using Hybrid-Based Approaches for Power Loss Reduction, Voltage Stability Improvement, Voltage Profile Enhancement and Loadability Enhancement

Abstract: With the modernization of power grids, the network optimal utilization is essential to ensure that voltage profile at each bus is maintained within an acceptable range, voltage stability of the system is enhanced, power losses in lines are minimized, reliability and security of system are improved and etc. These can be achieved by introducing reactive power compensation devices such as Flexible Alternating Current Transmission System (FACTS) devices, Custom Power (CP) devices, synchronous condenser, capacitor bank and etc in distribution or transmission networks. Optimal location and sizing of the reactive power compensation devices are significantly important to ensure sufficient investment onto this device. Recently, most of conducted studies had focused on the techniques for determining the optimal location and sizing of various reactive power compensation devices in the power system using various indices proposed in the literature to access the power loss, voltage stability, voltage profile and line loadability. However, no review paper had discussed on the application of the existing indices adopted in the available techniques for solving the optimal location and sizing problems for all types of reactive power compensation devices. In this paper, current literature survey on optimal location and sizing of reactive power compensations had been discussed which includes analytical, conventional, metaheuristic and hybrid based approaches. The main objectives are to reduce power losses, to mitigate voltage deviations, to increase voltage stability and to improve reliability and security of the system.

On-Board Single-Phase Integrated Electric Vehicle Charger With V2G Functionality

Abstract: Mass adoption of electric vehicles (EVs) is contingent on the availability of charging infrastructure. One solution to this issue is the introduction of on-board fast chargers, but such solutions typically require the installation of additional magnetic components that increase EV mass. An alternative approach is the dynamic redeployment of drivetrain components for charging when the vehicle is stationary. This article proposes an on-board single-phase charger that reuses the traction inverter and motor. The system consists of a dual-inverter drivetrain, which affords higher voltage charging compared to conventional systems. In addition, the system is able to operate bidirectionally and operate at any power factor for grid support services with real and reactive power exchange without subjecting the motor to low frequency harmonic currents. Experimental tests demonstrated operation at 19.2 kW using a 110-kW EV motor and a full-scale, state-of-the-art, dual-inverter drive prototype. Measured peak efficiencies of over 97% demonstrate the viability of integrated charging in a real-world scenario.

Rooftop Solar PV Penetration Impacts on Distribution Network and Further Growth Factors—A Comprehensive Review

Abstract: In order to meet the electricity needs of domestic or commercial buildings, solar energy is more attractive than other renewable energy sources in terms of its simplicity of installation, less dependence on the field and its economy. It is possible to extract solar energy from photovoltaic (PV) including rooftop, ground-mounted, and building integrated PV systems. Interest in rooftop PV system applications has increased in recent years due to simple installation and not occupying an external area. However, the negative effects of increased PV penetration on the distribution system are troublesome. The power loss, reverse power flow (RPF), voltage fluctuations, voltage unbalance, are causing voltage quality problems in the power network. On the other hand, variations in system frequency, power factor, and harmonics are affecting the power quality. The excessive PV penetration also the root cause of voltage stability and has an adverse effect on protection system. The aim of this article is to extensively examines the impacts of rooftop PV on distribution network and evaluate possible solution methods in terms of the voltage quality, power quality, system protection and system stability. Moreover, it is to present a comparison of the advantages/disadvantages of the solution methods discussed, and an examination of the solution methods in which artificial intelligence, deep learning and machine learning based optimization and techniques are discussed with common methods.

AC-DC Converters for Electrolyzer Applications: State of the Art and Future Challenges

Abstract: The main objective of the article is to provide a thorough review of currently used AC-DC converters for alkaline and proton exchange membrane (PEM) electrolyzers in power grid or wind energy conversion systems. Based on the current literature, this article aims at emphasizing the advantages and drawbacks of AC-DC converters mainly based on thyristor rectifier bridges and chopper-rectifiers. The analysis is mainly focused on the current issues for these converters in terms of specific energy consumption, current ripple, reliability, efficiency, and power quality. From this analysis, it is shown that thyristors-based rectifiers are particularly fit for high-power applications but require the use of active and passive filters to enhance the power quality. By comparison, the association combination of the chopper-rectifier can avoid the use of bulky active and passive filters since it can improve power quality. However, the use of a basic chopper (i.e., buck converter) presents several disadvantages from the reliability, energy efficiency, voltage ratio, and current ripple point of view. For this reason, new emerging DC-DC converters must be employed to meet these important issues according to the availability of new power switching devices. Finally, based on the authors’ experience in power conversion for PEM electrolyzers, a discussion is provided regarding the future challenges that must face power electronics for green hydrogen production based on renewable energy sources.

A Three-Phase Single-Stage AC–DC Wireless-Power-Transfer Converter With Power Factor Correction and Bus Voltage Control

Abstract: Wireless power transfer (WPT) technology has been a research and industrial hotspot with applications in many areas, such as wireless electric vehicle charging system that requires high power, high efficiency, and high power factor (PF). Usually, the power is drawn from a 50/60 Hz single-phase or three-phase ac power source. For a high power application, a three-phase ac source is commonly used. In this paper, a three-phase single-stage WPT resonant converter with PF correction (PFC) and bus voltage control is proposed to improve efficiency and power quality of three-phase input and reduce production cost and complexity for a high power WPT system. A T-type topology is applied as the common part to perform both the PFC and dc–dc WPT functionalities simultaneously. The proposed converter is much more advantageous than a conventional three-phase two-stage WPT converter with individual PF corrector. In addition, three-phase single-stage topologies have better power quality than single-phase single-stage topologies because zero-sequence components can be naturally eliminated.

A PFC Based EV Battery Charger Using a Bridgeless Isolated SEPIC Converter

Abstract: Conventional power factor correction (PFC) circuits in electric vehicle (EV) battery chargers have the efficiency limitation due to high conduction loss associated with a diode bridge rectifier (DBR) at the input. To mitigate this issue, a bridgeless (BL) single ended primary inductance converter (SEPIC) with improved power quality, is presented in this article. The input current shows a unity power factor operation over the entire charging duration. Due to elimination of DBR and the current conduction through relatively less number of devices, conduction losses are significantly reduced. This, in turn, improvises the charger efficiency as compared to conventional BL SEPIC converter. The overall performance of proposed charger is illustrated with the help of various operating modes, design equations, simulation-based performance and experimental validation under steady state as well as over wide fluctuations in ac mains voltage. The EV battery is charged at constant current/ constant voltage control mode, which provides satisfactory results for improved efficiency and inherent PFC, thus, improving overall performance of the charger.

Enhanced SOGI Controller for Weak Grid Integrated Solar PV System

Abstract: This paper presents a two-stage three-phase solar photovoltaic (PV) system, which is controlled through a novel enhanced second order generalized integrator (ESOGI) based control technique. The proposed ESOGI is used for fundamental component extraction from nonlinear load current and distorted grid voltages. This integrator effectively and simultaneously manages to address the DC offset, inter-harmonic and integrator delay problems of the traditional SOGI. In addition, this control technique provides power factor correction, harmonic elimination, and load balancing functionalities. The ESOGI controller is used to generate reference grid currents for controlling the voltage source converter (VSC), interfacing the PV panel with the grid. Extensive experimental results on a developed prototype in the laboratory, depict that the total harmonic distortion (THD) of the grid injected currents and voltages are found well under IEEE-519 standard.

Development of cascaded multilevel inverter based active power filter with reduced transformers

Abstract: Active power filter is a power electronic converter used for improving the quality of supply by eliminating the effect of harmonics due to non-linear loads. This paper recommends a concept for shunt active power filter (SAPF) using a single power source fed to a cascaded multilevel inverter (CMI) with 3-φ transformers. Apart from traditional transformer based topologies, the required number of transformers are substantially reduced, resulting in less space requirement, which leads to low cost and simple control system. The proposed CMI based SAPF has a capacity to compensate for contaminated load with high harmonic and a low power factor. The effective i d -i q theory is used to calculate compensation currents. DC link voltage regulator analyzed through delay time and controller gain. The tasks of the controller in the SAPF can perform all necessary actions for correct operation in SAPF. A wide range of computer simulation results demonstrated and validated the results with the prototype experimental setup.

A Novel Scalar PWM Method to Reduce Leakage Current in Three-Phase Two-Level Transformerless Grid-Connected VSIs

Abstract: The advancement in modulation strategies brings emergent solutions to suppress the leakage current in three-phase two-level transformerless grid-connected voltage source inverters (VSIs). However, most of the techniques are analyzed based on reduced common-mode voltage pulsewidth modulation (PWM) in motor drivers but fail to satisfy the specific requirement of grid-connected applications, such as wider power factor operation and lesser current distortion. To overcome such substantial drawbacks, this paper proposes a novel scalar PWM method for transformerless grid-connected VSIs. First, presented through a generalized scalar approach with unified zero-sequence voltage generation, the method is simple to implement and favored in practice. Besides, systematic and comprehensive mathematical analysis is illustrated to exhibit the validity of implemented method in reducing leakage current and shows its advantages over whole power factor range in terms of dc-link current harmonic, output current quality, and switching losses. Finally, simulations and experimental results are carried out to verify the effectiveness and superiority of the proposed method.

Optimal Placement and Sizing of DGs in Distribution Networks Using MLPSO Algorithm

Abstract: In today’s world, distributed generation (DG) is an outstanding solution to tackle the challenges in power grids such as the power loss of the system that is intensified by the exponential increase in demand for electricity. Numerous optimization algorithms have been used by several researchers to establish the optimal placement and sizing of DGs to alleviate this power loss of the system. However, in terms of the reduction of active power loss, the performance of these algorithms is weaker. Furthermore, the premature convergence, the precision of the output, and the complexity are a few major drawbacks of these optimization techniques. Thus, this paper proposes the multileader particle swarm optimization (MLPSO) for the determination of the optimal locations and sizes of DGs with the objective of active power loss minimization while surmounting the drawbacks in previous algorithms. A comprehensive performance analysis is carried out utilizing the suggested approach on the standard IEEE 33 bus system and a real radial bus system in the Malaysian context. The findings reveal a 67.40% and an 80.32% reduction of losses in the two systems by integrating three DGs with a unity power factor, respectively. The comparison of the results with other optimization techniques demonstrated the effectiveness of the proposed MLPSO algorithm in optimal placement and sizing of DGs.