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Changes in the orthogonal signal generator (OSG) configuration of the standard second-order generalized integrator-based phase-locked loop (S-SOGI PLL) have shown to offer an improved low-voltage ride-through capability. However, the resulting PLLs: highpass SOGI (H-SOGI) and lowpass SOGI (L-SOGI) PLLs have no dc-offset estimation capability and lack robustness to disturbances. Therefore, this article focuses on maximizing the merits of H-SOGI and L-SOGI PLLs for grid and industrial applications by incorporating dc-offset estimation and enhancing their disturbance rejection capability. Accordingly, two varieties of SOGI PLLs, namely: extended state highpass SOGI (ES-H-SOGI) and extended state lowpass SOGI (ES-L-SOGI) PLLs are proposed. In the proposed PLLs, states of the OSGs are extended to achieve dc-offset estimation and rejection, while frequency-adaptive implementation of the moving average filter (MAF) is developed to achieve complete harmonic rejection at off-nominal frequencies of the input voltage. To alleviate the undesirable effect of the MAF in terms of the PLL's slow transient response, frequency-adaptive implementation of a phase-lead compensator is introduced. In this article, design guideline that achieves an optimal tradeoff between disturbance rejection and dynamic performance in the ES-H-SOGI and ES-L-SOGI PLLs is presented. Finally, experimental comparison between the proposed ES-H-SOGI and ES-L-SOGI PLLs and their ES-S-SOGI PLL counterpart is carried to show that the proposed PLLs outperform the ES-S-SOGI PLL in terms of dynamic performance while achieving enhanced disturbance rejection capability. [ABSTRACT FROM AUTHOR]

In this research work, deep machine learning-based methods together with a novel data augmentation are developed for predicting flicker, voltage dip, harmonics, and interharmonics originating from highly time-varying electric arc furnace (EAF) currents and voltage. The aim with the prediction is to counteract both the response and reaction time delays of active power filters (APFs) specifically designed for electric arc furnaces (EAF). Multiple synchronous reference frame (MSRF) analysis is used to decompose the frequency components of the EAF current and voltage waveforms into dqo components. Then using low-pass filters and prediction of the future values of these dqo components, reference signals for APFs are generated. Three different methods have been developed. In two of them, a low-pass Butterworth filter is used together with a linear finite impulse response (FIR)-based prediction or long short-term memory network (LSTM) for prediction. In the third method, a deep convolutional neural network (CNN) combined with a LSTM network is used to filter and predict at the same time. For a 40-ms prediction horizon, the proposed methods provide 2.06%, 0.31%, 0.99% prediction errors of the dqo components for the Butterworth and linear prediction, Butterworth and LSTM, and CNN with LSTM, respectively. The error of the predicted reconstructed waveforms of flicker, harmonics, and interharmonics resulted in 8.5%, 1.90%, and 3.2% reconstruction errors for the abovementioned methods. Finally, a Simulink and GPU-based implementation of predictive APF using Butterworth filter + LSTM and a trivial APF resulted 96% and 60% efficiency on compensation of EAF current interharmonics. [ABSTRACT FROM AUTHOR]

Motor drive systems with long feeder cables are widely used in mining and energy sectors, such as offshore oil and gas drilling. In recent decades, to prevent issues with electromagnetic interference, power quality standards have been defined for the 2–150 kHz frequency range. In order to comply with these standards, manufacturers need to design filters to avoid exceeding the thresholds set by the standards. An important aspect that needs to be considered is the accurate modeling of currents circulating through common-mode loops. This article addresses this modeling by using a mathematical approach. The power cable’s common-mode model is extracted from the measurement data using the finite-element method via finding the effective permittivity of the PVC materials. The common-mode noise sources, including the grid side voltage through the front-end diode rectifier and the output voltage through the rear-end inverter, are both modeled by extracting the Fourier series calculations. Consequently, noise emissions circulating through different common-mode loops are analytically modeled. Through the proposed modeling strategy, the harmonic spectrum of resonances can be precisely analyzed. The results are validated through simulation and experimental data. [ABSTRACT FROM AUTHOR]

Increasing awareness for green energy and sustainable energy management has accelerated the popularity for the incorporation of distributed energy resources and distributed energy storage into the distribution network and microgrid. This has proliferated the use of power electronic-based devices giving rise to a serious issue of deteriorating power quality (PQ) in the distribution system. In this context, this article presents a photovoltaic (PV) integrated unified power quality conditioner (UPQC) operating with an adaptive compensating technique based on variable leaky least mean square (VLLMS) algorithm. It is a soft computing-oriented method that offers quicker convergence to the desired condition in an iterative approach keeping the weight of the updating parameters within the specified limit. The VLLMS-based algorithm eliminates the use of low pass or moving average filter for the extraction of fundamental components from polluted source voltage and load current to generate reference signal for the switching of shunt as well as series voltage source converters (VSC) of the UPQC. Due to the involvement of feed-forward component of PV in the compensating technique of shunt VSC, it efficiently and smoothly manages power balance between grid, load, and PV besides resolving the PQ issues of current harmonics and poor power factor at PCC. It also ensures the regulation of dc-link voltage. The series converter maintains pure sinusoidal voltage at the load terminal irrespective of sag/swell and harmonics present in the grid voltage. The effectiveness of the proposed system is verified through simulation as well as hardware implementation under different static and dynamic operating conditions. [ABSTRACT FROM AUTHOR]

In this article, a new saturated amorphous alloy core-based inrush current limiter (ICL) has been designed and built to limit the inrush current of a power transformer. A toroidal core with a middle limb is developed using the Metglas amorphous alloy and the middle limb is excited with a dc current to saturate the amorphous alloy core. Only a very small dc excitation current is required using such a core when compared to that using a similar design with conventional materials. Under normal conditions, the saturated amorphous alloy ICL core steady-state impedance is low and has a negligible effect on the operation of the system. During the energization of a power transformer connected to the ICL, the large inrush current desaturates the amorphous alloy core, resulting in an increase in the ac winding impedance, which limits the peak amplitude of the transformer inrush current and harmonics. To validate the proposed saturated amorphous alloy core-based ICL, a prototype ICL has been built and tested in the laboratory. The experimental results show that the core power loss, core saturation, the fundamentals, and harmonics of the inrush current of the proposed saturated amorphous alloy core-based ICL are significantly better compared with those from the sheet steel core-based ICL. It is expected that the proposed saturated amorphous alloy core will be used in future inrush current limiters that can help to improve the performance of the power transmission and distribution system. [ABSTRACT FROM AUTHOR]

Large-scale deployment of electric vehicles (EVs) is deleterious for distribution system operations. Unplanned installation of EV charging station (EVCS) deteriorates the voltage stability, reliability, and power quality of the distribution system leading to customer discontentment. This article proposes a novel approach for the proper placement of EVCS in a distribution network maintaining the system performance. The design of a test station with vehicle-to-grid (V2G) capability is outlined in this work. The test station is developed with five charging columns taking into consideration the standards and guidelines outlined in the Government of India EV policy. The charging station is connected to the power grid by a dc bus to which numerous EVs are attached. EVCS placement in the IEEE-33 bus radial distribution system is performed by developing six test scenarios. The test case results substantiate the potency of the reliability-index based approach for allocating EVCS both slow and fast chargers in a distribution network. Further, the maximal threshold value for placing the EVCS in various buses in a distribution system is determined using a novel electric vehicle placement index (EVPI). The novelty of the approach lies in the fact that it can include all operational parameters influenced owing to EV deployment, thereby maintaining the overall system performance without any physical restructuring of the network. The efficacy of the approach and the severity level of EVCS placement are validated for a real-time distribution system in Kerala, India. [ABSTRACT FROM AUTHOR]

Addressing power quality issues in shipboard microgrids (SMs), which are mainly attributable to the increased installation of power converters, has received much attention recently. To this end, static VAR compensators, such as thyristor-switched capacitors and fixed capacitors-thyristor controlled reactors (FCs-TCRs), can be effective solutions. Controlling these compensators, however, is not a trivial task as it involves sophisticated operations, especially estimating the firing angle, which should be carried out based on some nonlinear equations. This article aims to propose the application of some simple yet numerically efficient algorithms based on bisection, Newton–Raphson, false position, and secant methods for estimating the firing angle of the FC-TCR. The effectiveness and robustness of these algorithms are demonstrated via modeling of the FC-TCR with the electrical power system of a practical hybrid ferry under MATLAB/Simulink environment, where the results proved that the enhanced power quality issues respect the IEC standards 61000-4-7/30. Furthermore, an experimental setup consists of a digital signal processor and a programmable source is used to demonstrate that these techniques can be effectively applied in real-time applications. [ABSTRACT FROM AUTHOR]

Interharmonic is an emerging issue in photovoltaic (PV) systems. It has been revealed in previous studies that the maximum power point tracking (MPPT) control is one potential source for interharmonics. In cascaded H-bridge (CHB) PV inverters, if the MPPT perturbations of the CHB cells are in-phase, the sum of the voltages of all CHB cells will oscillate with a higher amplitude, leading to an amplification of interharmonics delivered to the grid. To address this issue, a phase-shifting MPPT (PS-MPPT) method for interharmonic mitigation is proposed in this paper. By properly shifting the phase-angle of the MPPT perturbation of each CHB cell, the oscillation of the equivalent total dc voltage can be effectively mitigated, and in turn, the interharmonics can be suppressed to a large extent. The proposed PS-MPPT scheme has been demonstrated on CHB PV inverters through simulations and experimens. The implementation for generalized n-cell CHB PV inverters has further been discussed. Moreover, a hybrid PS-MPPT method is also developed to improve the interharmonic mitigation performance. Simulation and experimental results have validated the effectiveness of the proposed method in terms of interharmonic suppression. [ABSTRACT FROM AUTHOR]

In order to predict the performance of designed electric machines, and also based on which the high efficiency of the drive systems can be obtained, the accurate calculation of the iron loss is necessary. Taking modeling accuracy versus modeling complexity into account, this article proposes a general and accurate iron loss calculation method considering harmonics based on the loss surface (LS) hysteresis model and finite-element method (FEM). Compared with the previous triangular wave excitation, this article uses the data under sinusoidal wave excitation to establish the LS model, which is more convenient for engineering application. A specimen is tested for different flux densities with harmonics, the extensive results verify the modeling method. Due to a powerful hysteresis model, the iron loss calculation can be realized by the direct integration of hysteresis loops. A separated iron loss calculation package is developed, and it is combined with the commercial finite-element software to compute the iron loss distribution. The method that combines the LS model and FEM is proved feasible by comparing the calculated iron loss with the measured one for the Epstein frame. [ABSTRACT FROM AUTHOR]

In glass furnace boosting, particularly in the tin bath and annealing lehr heating systems, an ac–ac power converter is normally employed by the industry. This Triac-based converter driven by integral cycle control (ICC) is employed to provide highly accurate power to the resistive heating elements distributed into the furnace. The advantages of ICC include low inrush current and increased reliability; although its impact on power quality (PQ), due to the subharmonic distortion produced, is significant. While different strategies for energy demand management have been implemented to date, they have not adequately addressed this PQ issue. Thus, the goal of this research is to establish an optimal electrical load scheduling strategy considering criteria about PQ and thermal behavior through a mixed-binary quadratic programming problem which exploits the ICC advantages avoiding PQ degradation. [ABSTRACT FROM AUTHOR]

This article deals with a ride-through strategy for a three-phase grid-tied solar photovoltaic array system. Unlike the conventional control algorithms, this control algorithm does not tradeoff with power quality melioration features while permitting ride-through dynamics of the solar energy conversion system (SECS). As per the revised IEEE-1547 standard, the distributed energy resources have to provide a full range of services even under voltage disturbances caused by faults like existing power plants. In this article, the grid-connected solar power generation system follows the grid code even under ride-through operation with the presence of reactive local load, unlike the traditional algorithms. In order to map future challenges, the low-voltage ride-through features of three-phase SECS at symmetrical/asymmetrical faults, are explored here. This control strategy is capable to operate SECS at various modes. To operate the voltage source converter within a safe limit, a constraint is incorporated on the active power of SECS to avoid overcurrent and energy aggregation in the dc-link capacitor, which reduces the life-time of the dc-link capacitor. Simulated results demonstrate the effectiveness of the control strategy for various operating conditions. The comparative performances of the presented control strategy are analyzed to demonstrate the effectiveness under the presence of distorted grid voltages and non-Gaussian noises in sensed measurements. Test results manifest the dynamics of SECS at various operating conditions. [ABSTRACT FROM AUTHOR]

Harmonics generated by nonlinear critical loads are major anxiety for the industries. A control technique for dynamic voltage restorer (DVR) is described to limit voltage harmonics introduced by adjustable speed drive (ASD) in the utility. Moreover, this control technique maintains constant dc-link voltage of ASD during any disturbances occurring at point of common coupling. Mathematical description to limit ASD voltage harmonics and to generate reference dc-link voltage of ASD is illustrated in the dq0 frame. Transistor clamped H-bridge (TCHB) multilevel inverter (MLI) is used as a voltage source inverter of DVR. An enhanced capacitor voltage balancing (ECVB) method for TCHB MLI for the fast dynamic performance of DVR is also discussed. The proposed control technique of DVR to limit ASD voltage harmonics is simulated using MATLAB software. Furthermore, a simulation for DVR protecting ASD during source harmonics, unbalance, sag, and swell is carried out and results of ASD performances are demonstrated. The working of the proposed controller of DVR with ECVB strategy based TCHB is reverified using experimental results. ASD voltage harmonics mitigation and fast dynamic response of ECVB based TCHB are the highlights of this article. The performance of the proposed strategy shows satisfactory results with a less complex control system. [ABSTRACT FROM AUTHOR]

In this article, a new approach to compensate both the response and reaction times of active power filters (APF) for special cases of highly time-varying harmonics and interharmonics of electric arc furnace (EAF) currents is proposed. Instead of using the classical approach of taking a window of past current samples and analyzing the data, future samples of EAF currents are predetected using a deep learning (DL)-based method and then analyzed, which provides the opportunity to make real-time analysis. This can also serve the needs of other possible APF applications. Two different methods for prediction of future samples of harmonics and interharmonics have been proposed: predetection of harmonics and interharmonics in the time domain (TD) and in the frequency domain (FD). To obtain the best possible accuracy for both methods, grid search has been employed for parameter optimization of the DL structure. Both TD and FD approaches have been tested on field data, which had been obtained from transformer substations supplying EAF plants. It is shown that the response time of the APF algorithms can be compensated using the TD-based approach, while it is possible to compensate both the response and reaction times of APFs using the proposed FD-based approach. The developed method can be considered to be a feasible candidate solution for generating reference signals for the controllers of new generation of compensation devices, which can be referred to as predictive APFs. [ABSTRACT FROM AUTHOR]

A space-shifted wye–delta winding for fractional-slot concentrated winding (FSCW) is proposed that can simultaneously cancel both sub- and super-order harmonics of its stator MMF. The new winding concept proposes two sets of three-phase windings by doubling the number of stator slots connected in the wye–delta configuration. These two winding sets are shifted in space with respect to each other and are connected in series. The wye–delta configuration eliminates subharmonics and enhances the torque-producing component, whereas their relative shifting angle eliminates the dominant higher order harmonics to provide a cleaner and enhanced MMF spectrum. In FSCW motors, dominant space harmonics other than the torque-producing component give rise to undesirable losses in the magnet and rotor core. The efficacy of the proposed method is demonstrated through its stator MMF, harmonic spectrum, and motor performance using finite-element analysis. The application of the proposed winding to a permanent magnet (PM) machine showed dominant sub- and super-order harmonics cancellation, total harmonic distortion reduction, and magnetic loss reduction along with torque density and power factor improvements. A prototype PM machine is built, and the performance of the proposed concept is verified experimentally. [ABSTRACT FROM AUTHOR]

A designer should apportion all loads including nonlinear loads at the design stage such that harmonic distortion levels at the point of common coupling (PCC) fall within the limits set forth in IEEE 519-2014 standard. This article presents one methodology for the analytical determination of the harmonic content at the PCC, thereby enabling possible optimization of load arrangements at the design stage. A side benefit is that the selection of optimize drive topologies for variable speed applications may be identified and thus will reduce the project cost. Distribution transformer loading with various ratios of linear and nonlinear loads and with different drive topologies is compared and is represented in pie chart diagram. [ABSTRACT FROM AUTHOR]

Declining extraction costs and process efficiencies have incented the revival of the oil and gas sector postrecession. The application of drilling rigs has been done more efficiently. These loads are very large, temporary in nature, and mobile. The drilling of each well can be done as quickly as a few hours and typically not more than a few days. These massive loads are complex to own, maintain, and operate, as a result few specialized drillers share the market. Because of the requirements for variable speed and control, drilling rigs are driven by variable frequency drives (VFDs), which are in their clear majority of older technologies such as six-pulse thyristor bridge or SCR-driven motors. These technologies are known to impose steep ramp rates (up and down) as well as rich harmonic content and variable, typically low, power factor. Furthermore, the locations of drilling rigs are typically remote, where distribution systems, if present, are weak, which lead to large background voltage distortions when such loads are present. This paper presents measurements, simulations, and analytical assessments of the characteristics and effects of harmonics and interharmonics (IHs) generated by top-drive and mud-pump VFDs in a large drilling rig operated in Alberta, Canada. Measurement results reveal very high harmonic and IH generation. To further refine the impact assessment of these harmonic emissions, the harmonic attenuation effect of the VFDs is quantified to avoid overestimating the harmonic generation of the loads. The thermal impact of the current harmonics on the coupling transformer is also quantified. [ABSTRACT FROM AUTHOR]

In this paper, a method based on the multiple synchronous reference frame analysis is recommended and implemented to detect time-varying harmonics and interharmonics of rapidly fluctuating asymmetrical industrial loads. The experimental work has been carried out on a typical three-phase alternating current arc furnace installation. In the recommended method, the reference frame is rotated in both directions at speeds corresponding to the positive and negative sequences of all harmonics and all interharmonics 5 Hz apart. To extract the direct current components of the transformed d–q quantities, a low-pass filter is employed. In order to keep the delay of the filter at zero frequency less than a few ms, Kalman estimation technique has been used. Back transformation is then applied for each harmonic and interharmonic component to obtain their positive- and negative-sequences of the associated harmonic and interharmonic in the actual line current waveforms. Parallel computing technique has been applied for the real-time detection of both the phase and the amplitude of all harmonics and interharmonics. This is achieved on NVDIA Jetson TX1 graphics processing unit framework for a sample industrial plant. The developed system is shown to be useful for fast and accurate generation of reference signals for the controllers of the advanced technology power conditioning systems which successfully compensates interharmonics, harmonics, and flicker of the rapidly fluctuating nonlinear industrial loads. [ABSTRACT FROM AUTHOR]

The grid voltage information such as the phase-angle, the frequency, and the amplitude is crucial for the design of synchronization and control of power converters in the micro-grid. The conventional approach to estimate the grid voltage information is accomplished by phase-locked loop (PLL) techniques. Among various existing PLL techniques, filter-based PLLs can provide more accurate estimations even under adverse grid conditions. In this paper, a new single-phase filtering technique based on multiple delayed signal cancellation (MDSC) is proposed for extracting both in-phase and quadrature components of the selected harmonic order of the single-phase grid voltage signal. This MDSC technique can be realized in both the direct-form and the recursive-form. In comparison with existing single-phase cascaded delayed signal cancellation (CDSC) techniques, this MDSC technique utilizes less memory for the extraction of grid voltage fundamental frequency component. The proposed MDSC filter can be applied as a pre-filter to the enhanced PLL (EPLL) for the prompt and accurate estimations of the grid voltage information under adverse grid conditions. Both frequency adaptive and non-adaptive MDSC-based EPLL schemes are proposed in this paper. To validate the effectiveness of the proposed methods, experiments are conducted on the MDSC-based EPLLs and compared with the CDSC-EPLL under various grid voltage disturbances. [ABSTRACT FROM AUTHOR]

This paper presents a novel grid synchronization method with bumpless start that requires minimal computational load and can selectively track the positive sequence of the grid voltage in an unbalanced and distorted three-phase weak grid. Only 12 floating-point operations are required to obtain the in-phase and quadrature components that define a synchronous frame which tracks the positive sequence of the grid voltage. Contrary to a phase-locked loop (PLL), the presented scheme does not require to measure any ac voltages. Therefore, this sensorless method is particularly suited for weak-grid conditions, in which the voltage at the point of common coupling may contain significant noise and can experience larger deviations from the grid voltage (compared to a strong grid) due to the voltage drop in the weak grid impedance. The error in the estimated phase depends on the accuracy of the plant model. If the LCL filter parameters are known, then both the proposal and a PLL-based scheme result in the same steady-state error. Experimental results show the advantages of the proposal compared to a moving average filter PLL. [ABSTRACT FROM AUTHOR]

This paper studies and analyzes the power-quality measurement results due to the special operating characteristics of the wind turbines of a commercial onshore wind farm connected to the power grid of Taiwan Power System when Typhoon Matmo passed through Taiwan. This Kuan-Yuan onshore wind farm of 28.5 MW with 19 1.5-MW wind-turbine generator (WTG) based on doubly fed induction generator is connected to Kuan-Yin primary substation through two of four step-up main transformers of 161/69 kV, 200 MVA. The measured data were recorded from July 22, 2014 to July 29, 2014 for total seven days. During the measurement period, Typhoon Matmo just passed through Taiwan and the 19 WTGs were forced to stop. The power-quality measurement results due to the special operating characteristics of the wind turbines of the studied Kuan-Yuan wind farm subject to Typhoon Matmo were also recorded and studied. According to the measured results, the power quality of the studied Kuan-Yuan onshore wind farm during the measurement period can meet the grid code of Taiwan Power Company except the voltage flicker of ΔV10. The relationships of the recorded times and dates between the measured electrical quantities and power-quality results of the studied onshore wind farm and the Typhoon Matmo passed through Taiwan are also discussed. [ABSTRACT FROM AUTHOR]

In this research work, a multiple synchronous reference frame (MSRF)-based analysis method, used together with exponential smoothing (ES) to accurately obtain the time-varying harmonics and interharmonics of electric arc furnace (EAF) currents, is proposed. The proposed method has been implemented on NVIDIA Geforce GTX 960 graphics card for the parallel processing of all harmonics and interharmonics so that real-time processing of the EAF currents obtained from a measurement point of the electricity transmission system is possible. To obtain the best possible accuracy for the EAF current harmonics and interharmonics estimation, the ES order has been optimized specific to each harmonic and interharmonic frequency component. It has been shown on field data that the implemented system is capable of successfully estimating all harmonics up to the 50th and all interharmonics at 5-Hz resolution in real time. Moreover, active filtering of certain harmonics and interharmonics has been achieved in the simulation environment and it has been shown that successful real-time filtering of any harmonic and interharmonic component is possible with the proposed MSRF+ES method. Hence, it can be concluded that the proposed system can be used to generate reference signals for the controllers of the new technology compensation systems such as active power filters. [ABSTRACT FROM AUTHOR]

This paper presents a system that enables the passive reduction of noise and vibrations in a three-phase induction machine with a stator damper winding connected to capacitors. This is a simple and effective system for reducing the flux density harmonics in an electrical machine. The theoretical study is based on the modeling of a machine equipped with the damper winding obtained from Kron's theory about equivalent circuits of electrical machinery. The analysis of the equivalent circuit allows one to identify possibilities to reduce the flux density harmonics responsible of unwanted noise and vibration components. Finally, an experimental validation is performed. [ABSTRACT FROM AUTHOR]

In order to prevent the power switching devices (e.g., an insulated-gate bipolar transistor, IGBT) from shoot-through in voltage-source converters during a switching period, the dead time is added either in the hardware driver circuits of the IGBTs or implemented in software in pulse width modulation (PWM) schemes. Both solutions will contribute to a degradation of the injected current quality. As a consequence, the harmonics induced by the dead time (referred to as “dead-time harmonics” hereafter) have to be compensated in order to achieve a satisfactory current quality, as required by standards. In this paper, the emission mechanism of dead-time harmonics in single-phase PWM inverters is, thus, presented considering the modulation schemes in detail. More importantly, a repetitive controller has been adopted to eliminate the dead-time effect in single-phase grid-connected PWM converters. The repetitive controller has been plugged into a proportional-resonant-based fundamental-frequency current controller so as to mitigate the dead-time harmonics and also to maintain the control of the fundamental-frequency grid current in terms of dynamics. Simulations and experiments are provided, which confirm that the repetitive controller can effectively compensate the dead-time harmonics and other low-order distortions, and also, it is a simple method without hardware modifications. [ABSTRACT FROM AUTHOR]

Phase-locked loop (PLL) techniques are widely utilized for synchronization and control of grid-connected power electronic systems for estimation of phase angle, frequency, and amplitude of the grid voltage. Recently, an advanced scheme called the three-phase enhanced PLL (3P-EPLL) has been proposed for estimating the grid voltage information. However, recent studies have shown that this 3P-EPLL cannot provide accurate estimations under adverse grid conditions, especially when the grid voltage is polluted with harmonics, dc offsets, and unbalance. This paper proposes an improved scheme of 3P-EPLL. A novel filtering technique called the multiple delayed signal cancelation (MDSC) is integrated into both the phase-angle estimation loop, and the amplitude estimation loop of the 3P-EPLL for eliminating periodic ripples due to harmonics and unbalance in the grid voltage. MDSC filters can indeed provide more flexibility to configure the lowest undesired harmonics, and can have less delay time in the digital implementations when compared with moving average filters and cascaded delayed signal cancelation filters. Thus, the fast response time of the filter is expected. To improve the dynamic performance of the 3P-EPLL, the proportional-integral-derivative controller is used instead of the conventional proportional-integral controller. Comprehensive analysis of the MDSC-based 3P-EPLL is investigated. Both simulations and experimental studies are conducted to validate the prompt dynamic performance of the proposed MDSC-based 3P-EPLL. [ABSTRACT FROM AUTHOR]