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Copyright of Przeglad Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper attempts to provide a clear explanation of how the concept of double frequency complex plane is applied to the calculation of complex electrical power. This is a step to remove the confusion associated with the calculation of complex electrical power that has persisted in the scientific community to this day. It starts with a discussion on the conventional method of calculation of complex power and its relation with the Steinmetz’s original method of power calculation in steady state AC circuit. An excerpt from the writing of Steinmetz is then included in which he enumerated mathematical equations that were used to make adjustments while calculating two times the supply frequency complex electrical power from the supply frequency complex voltage and current. Since the equations appear to contradict the laws of conventional complex algebra, considerable confusion arose soon after the Steinmetz’s publication. This confusion persists even today. Usual text books do not touch upon this issue and merely describe the mathematical equation required for calculation of complex power. This paper tries to provide a justification behind the adjustment equations involving double frequency complex plane used for complex power calculation through a simple R-L circuit and provide analytical explanation of the equations enumerated by Steinmetz. [ABSTRACT FROM AUTHOR]

This paper deals with the quasi-instantaneous determination (in a single-step response time) of apparent, active, and reactive (i.e., blind and distortion) power mean values including the total power factor, total harmonic distortion, and phase shift of fundamentals of a power electronic and electrical system (PEES) using the ip-iq method, which is the main contribution of the paper. The power components' mean values are investigated during the transient and steady states. The power components' mean values can be determined directly from phase current and voltage quantities, using an integral calculus over one period within the next calculation step and using moving average and moving rms techniques (or digital filtering). Consequently, the power factor can be evaluated with known values of a phase shift of fundamentals (using a Fourier analysis). The results of this study show how a distortion power component during transients is generated even under a harmonic supply and linear resistive–inductive load. The paper contains a theoretical base, modeling, and simulation for the three and single phases of the transients in power electronic systems. The worked-out results can be used to determine and size any PES. The presented approach brings a detailed time waveform verified by simulations in Matlab/Simulink 2022a and the Real-time HW Simulator Plecs RT Box 1. [ABSTRACT FROM AUTHOR]

Titanium alloys belong to the group of difficult-to-cut materials, machining of which leads to a number of challenges including large thermal loads on the cutting inserts and difficulties in obtaining a high quality machined surface. Great cutting forces, in turn, result in increased energy consumption. Therefore, it becomes important to attempt to reduce the amount of power consumed during machining, which can be achieved, among other things, by reducing the value of the coefficient of friction in the cutting zone. This paper presents a study on the influence of the size as well as the Cu nanoparticle concentration added to cutting fluid in MQL method on the power grid parameters while turning of Ti6Al4V titanium alloy. In this research, nanoparticles of 22 nm and 65 nm at concentrations of 0.5 wt% and 0.75 wt% were used. Turning process was carried out with constant cutting parameters and variable aerosol formation parameters, i.e. mass flow rate of nanofluid and volumetric flow rate of air. Based on the study, the use of 22 nm nanoparticles at 0.5 wt% concentration is recommended to achieve the smallest monitored values of the power grid parameters. The statistical analysis revealed that, out of the aerosol formation parameters considered, both the air flow rate and nanofluid flow rate do not significantly affect the values of the analysed power network parameters. However, the most significant factor is the variable nanoparticle size. [ABSTRACT FROM AUTHOR]

Featured Application: The study in the paper is focused on how to calculate the mean value of each power component in steady- and transient states of PES. Worked-out results can be used to determine and size of, e.g., the auxiliary power train of HEV vehicles with oscillating torque compensation, also for photovoltaic systems, PFC topologies, and similar. This paper deals with the quasi-instantaneous determination of an apparent-, active-, and reactive (i.e., blind and distortion) power mean values, including total power factor, total harmonic distortion, and phase shift of fundamentals of power electronic system (PES) using the p-q method. The power components' mean values are investigated both during transients and steady states. Using an integral calculus over one period and the moving average method (or digital filtering), the power components' mean values can be determined within the next calculation step directly from phase current and voltage quantities. Consequently, with known values of a phase shift of fundamentals (using Fourier analysis), the power factor can be evaluated. The results of this study show how a distortion power component during transients is generated even under harmonic supplying and linear resistive-inductive load. The paper contains a theoretical base, modeling, and simulation for the 5-, 3-, and 2-phases of PES transients. A system compensated by switched capacitors as well as an active power filter shows a possibility to compensate for distortion and reactive power components in the next calculation step. Worked-out results can be used for the right determination and sizing of any PES. The presented approach brings the detailed time-waveform and improved quality of electrical quantities (time-waveforms), and through quasi-instantaneous (single step) response time of compensation, minimizes nascent overvoltage of the system. [ABSTRACT FROM AUTHOR]

This paper describes a speed control device for generating electrical energy on an electricity network based on the doubly fed induction generator (DFIG) used for wind power conversion systems. At first, a double-fed induction generator model was constructed. A control law is formulated to govern the flow of energy between the stator of a DFIG and the energy network using three types of controllers: proportional integral (PI), sliding mode controller (SMC) and second order sliding mode controller (SOSMC). Their different results in terms of power reference tracking, reaction to unexpected speed fluctuations, sensitivity to perturbations, and resilience against machine parameter alterations are compared. MATLAB/Simulink was used to conduct the simulations for the preceding study. Multiple simulations have shown very satisfying results, and the investigations demonstrate the efficacy and power-enhancing capabilities of the suggested control system. [ABSTRACT FROM AUTHOR]

Copyright of Electric Power Engineering Technology is the property of Editorial Department of Electric Power Engineering Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, a control model based on hybrid algorithm is proposed to improve LVRT capability of the DFIG system. The proposed hybrid system is joined performance of fertile field algorithm (FFA) and momentum search algorithm (MSA) with adaptive neuro-fuzzy inference system (ANFIS). The searching behavior of FFA is enhanced by the updating behavior of MSA. Hence, commonly the proposed system is known FAMSANFIS technique. The purpose of the proposed control system makes sure LVRT capacity on DFIG-based wind energy conversion system under fault and voltage dip conditions. Here, the FFA–MSA methodology is used as the offline way to recognize the optimal solutions as obtainable search space. The FFA–MSA system, multiple parameters are measured to be related with LVRT, as voltage, real and reactive power, and current, correspondingly. The objective function solved using the FFA–MSA system is characterized. In light of the achieved data set, ANFIS performs and forecasts the better probable control signals from machine-side and network-side converter. Through fault conditions, the proposed system regulates system and voltage instability problem, respectively. The LVRT capability of the DFIG system is enhanced and, in addition, the power quality is improved through the aid of proposed system. The proposed control procedure is implemented on MATLAB/Simulink framework, and performances are assessed using the comparison analysis with existing techniques. [ABSTRACT FROM AUTHOR]

This paper introduces an innovative approach for achieving optimal energy management (OEM) in renewable-based hybrid microgrids (HMGs). The HMGs exhibit enhanced efficiency, minimizing power loss while maximizing generated power, making them advantageous over traditional MGs. This new approach consists of a modified model predictive control based improved Firefly1to3 algorithm (MMPC-IFA1to3). Here, MMPC adeptly regulates converter switching phenomena, ensuring stability during uncertain conditions in HMG. On the other hand, FA1to3 states that for each member movement of a firefly population, occurs towards three members. Here, the improved nature of FA1to3 is achieved by using the chaotic function to fine-tune the regulation parameter. This unified method generates the best power references for both active and reactive powers, making switching operations in voltage source converters simpler. This paper mainly emphasizes active and reactive power management through objective function minimization. The proposed IFA1to3 approach effectively incorporates constraints to minimize costs, ensure power availability, and mitigate voltage deviations in renewable-based HMGs. Moreover, charging/discharging of energy storage devices and power exchange between the utility grid and DC MG are carried out through the MMPC-IFA1to3 algorithm by monitoring active and reactive loads simultaneously. The corresponding converters are modeled based on the bidirectional power flow to cope with active and reactive power management. Further, the robustness of the proposed approach is verified under different operating conditions, and outcomes are compared with benchmark techniques in a MATLAB/Simulink environment to evidence its superior EM in HMG. Finally, the proposed MMPC-IFA1to3 approach is validated in a real-time environment through the dSPACE DS 1104 embedded processor to evidence its industrial applications through its robustness and OEM during various case studies. • In the hybrid MG, MPC regulates converter of the connected sources, while MMPC controls the VSC converter. • A novel FA, combining FA1to3 with chaotic logistic function, optimizes power references generation in this study. • Proposed MMPC-IFA1to3 approach ensures voltage stability and effectively manages ARP during uncertainties in MG. • The proposed IFA1to3 is more effective for multi-objective functions optimization. • Real-time validation of the proposed approach in dSPACE DS1104 evidences its practical applicability. [ABSTRACT FROM AUTHOR]

This paper contributes to narrowing the long-standing theoretical gap with power theory (or “power definitions”) for nonlinear ac switching circuits. The true instantaneous energy transformation and storage components of ac circuits are identified from the Poynting Theorem. This paper tackles the problem of power identification from the most general form of energy conservation. Therefore, it is no longer necessary to mathematically “define” powers to fit the engineering solution of a problem. The identification technique does not present problems with physical meaning since it is in full agreement with Maxwell's Equations. In this paper, the method is applied to the identification of the power components of single-phase switched circuits. Instantaneous energy is decomposed only into energy transformed (related to active power) and energy stored (related to reactive power). Examples that have caused physical interpretation problems with other power theories are presented for illustration and validation. [ABSTRACT FROM PUBLISHER]

Microgrids have been widely adopted in many countries because they provide more reliable electricity service to those users connected to the power grid. These systems comprise various power sources, energy storage devices, and loads. However, detailed studies require considering linear and nonlinear loads, which are now used in this type of network. In addition, experimental tests require devices that emulate loads, represent different topologies, and construct assemblies for better identification, validation, and theoretical approximations of the power grid. Therefore, this paper presents a programmable electronic load to emulate linear and nonlinear loads of a microgrid, based on the control of a single-phase voltage source converter that considers rectification and power dissipation stages. Furthermore, a control stage allows power consumption variations, controlling the current demanded by the load, according to the reference current waveform programmed through a user interface. A synchronous reference frame phase-locked loop is implemented on a microcontroller. Thus, the programmable electronic load enables studying power quality in microgrids. Finally, the operation of the programmable electronic load is validated through experimental and simulation tests, considering different case studies. [ABSTRACT FROM AUTHOR]

In this paper the use of active power filter to improve voltage and current distortion caused by the presence of dispersed generation in the distribution system is investigated. The harmonics produced by photovoltaic distributed generation sources is studied and the unified power quality conditioner is introduced as a technique of minimizing these harmonics generated by the presence of distributed generation. The network is modeled and simulated in ETAP 16.0 software environment and harmonic load flow results show an increase in harmonic level when DG is introduced into the network which is subsequently reduced by the introduction of UPQC into the network. [ABSTRACT FROM AUTHOR]

Featured Application: The presented parameters estimation method of an induction motor can be implemented in the applications of electric vehicles, traction systems and safety-critical drive systems. The method is based on signals which are easy to measure in the scalar and vector controlled drives. In this paper an induction motor parameters estimator, based on the Model Reference Adaptive System (MRAS), is presented and described. A comprehensive literature study on MRAS type parameters estimators for induction motors is also provided. The authors propose a novel PQ-MRAS estimator concept which enables the simultaneous calculation of stator and rotor resistances in the induction machine, which is its major advantage over previous investigations. The estimator employs the active (P) and reactive (Q) power of the machine which is calculated by the only measurable signals, such as stator voltage and current. The paper includes a detailed description of the proposed estimator. The PQ-MRAS was tested for various operating conditions of a drive system with the induction motor. The results obtained from computer simulation tests were verified on the laboratory set up with a DS1202 card. [ABSTRACT FROM AUTHOR]

The paper deals with an efficient approach to determine complex power generated by a thin wire antenna above a lossy ground. Once the current distribution along a thin wire is obtained by numerically solving the Pocklington integrodifferential equation the complex power of the antenna can be obtained by solving the integral over the inner product of tangential component of the electric field and current distribution along the wire stemming from Poynting theorem. Numerical calculation procedure uses the vectors and matrices already constructed within the calculation procedure for the current distribution. Some illustrative numerical results for the active power, reactive power and apparent power of the dipole antenna radiating over a lossy half-space are presented in the paper for different values of input parameters. [ABSTRACT FROM AUTHOR]

The traditional approach to calculate the active and reactive power in AC power systems requires the measurement of the phase shift between the voltage and current for the evaluation of the power factor. To do this, power analyzers can implement several methods. In principle, it is always necessary to identify specific points of waveforms (e.g., using a zero-crossing detection technique) and get their time shift. In a similar way, the frequency value must be evaluated in order to calculate the angular frequency. Unfortunately, this kind of common method exhibits some issues, such as the large sensitivity to noise. Moreover, inaccuracies in the evaluation of the power factor have a big impact on the final estimation of the electric power. This paper presents a simple but effective way to calculate the electric power, overcoming the need for a direct measurement of the phase shift and frequency. In particular, it is shown that the active power can be easily calculated as the difference between the peak value of the instantaneous power and apparent power. The reactive power and power factor are evaluated by exploiting the same quantities. The practical implementation of the proposed formulation in power analyzers guarantees several benefits without reducing accuracy. [ABSTRACT FROM AUTHOR]

In this paper, a power compensator using supercapacitors in parallel to protect grid-connected devices connected to the distributed power supply in the case of a low-voltage ride-through (LVRT) situation in designed, and a grid-connected device control method with improved responsiveness is proposed. In the LVRT situation, the distributed generation power may boost the DC_link voltage, increasing the risk of destroying grid-connected devices. To prevent this, the power compensator designed in this study absorbs active power in a fault situation and stores it in the supercapacitor to suppress the DC_link voltage rise and efficiently use the power. In addition, we propose methods to improve the response of the grid reactive power through the reactive power compensation of the power compensator in LVRT situation. To this end, the power angle (θPW) was extracted through the formula, and the reactive power command, to be compensated by the power compensator, and the reactive power command, compensated by the grid-connected devices, were calculated according to the active power value. In this way, the grid power controlled by the power compensation device and the grid-connected devices was controlled by the active/reactive power of the same power angle and analyzed mathematically. Active power control and static grid support were performed in the normal state where the reduction rate of the normal value of the grid voltage was around 10%. However, when the grid voltage dropped by 10% to 100%, the reactive power control was appropriately performed with dynamic grid support by increasing the voltage from 10% to 20% or more. We conducted a simulation of the new and renewable energy grid-connected devices using the OPAL-RT-based Hardware-in-the Loop Simulation (HILS) system to control the proposed active/reactive power. [ABSTRACT FROM AUTHOR]

This paper presents a new active power loss allocation (LA) scheme for fair allocation of losses among the end-user with due consideration to deregulation in power supply. In this deregulated environment, the developed technique assigns losses judiciously because it has simplified the difficulties lying with the division of cross-term power loss equation analytically without any assumptions and approximations. Further, it establishes a direct relationship between two end-voltages of a branch and its subsequent load currents, in terms of node-injected complex powers. This LA scheme assigns losses to the network participants with due consideration to their demands, power factors, and geographical locations in the network. Again, the strategy followed for remuneration of distributed generators (DGs) awards all benefits of network loss reduction (NLR) to the DG owners in terms of incentives/penalties after analyzing their actual impact towards system loss reduction. The effectiveness of the proposed method is not only investigated at different load levels but also with various types of DG power injection using a 33-bus radial distribution network (RDN) with/without DGs. The comparison results obtained signify the novelty of the present technique in contrast to other discussed established methods. [ABSTRACT FROM AUTHOR]

A decentralized intelligent droop-based control strategy is proposed in this paper for the enhancement of equal active and reactive power sharing in an islanded inverter-based microgrid. Droop control is mostly preferred because it does not need communication facilities for its implementation. However, the presence of different feeder impedances for the different distributed generators (DGs) in a microgrid make reactive power sharing inaccurate. Furthermore, as a result of considerable load changes and different droop characteristics for the DGs, the inverter's output voltage and frequency are altered and these in turn alter the reactive and active power sharing respectively. With these conditions, the generalized droop control (GDC) strategy fails to effectively share load reactive and active power among the DGs. In order to extenuate these challenges, this paper presents a nonlinear autoregressive exogenous neural network droop-based control (NARX-NN DBC) strategy which does not depend on the varying line impedances, droop gains for the different DGs and is less affected by fluctuating loads in the grid. A microgrid, made up of two DGs and a load is modelled in MATLAB/Simulink environment and validation of the proposed control strategy is done through many simulations. Within the simulation runtime, NARX-NN DBC yielded a maximum frequency percentage deviation of 0.46% from the nominal value of 50 Hz whereas GDC yielded 0.62%. Regarding the voltage, NARX-NN DBC gave maximum deviation of 0.026% meanwhile GDC gave 0.079% from the nominal value for 380 V. In addition, during 0.57–0.64 s with load active power demand of 4.6 kW, NARX-NN DBC registered 0.43% power sharing error whereas GDC registered 6.5%. On the other hand, during 0.57–0.64 s, with 5kVAr load power demand, NARX-NN DBC registered 0.2% whereas, GDC registered 2%. These obtained results clearly show that NARX-NN DBC strategy has a better performance compared to GDC strategy with respect to power sharing in an autonomous microgrid.

The objective of this paper is to investigate the contribution and effectiveness of the use of a Neural Network (NN) Multi-Layer Perceptron (MLP) of feed-forward type technique to discriminate between the Supply Voltage Unbalance (SVU) and the stator Inter Turn Short-Circuit (ITSC) of an induction motor. The proposed approach in this paper is based on the exploitation of any useful information existing in both the current and the voltage quantities simultaneously provided by the various instantaneous powers such as the active and the reactive powers as well as the power factor. The merits of the proposed approach using the NN technique as an effective solution to the problem of discrimination is assessed by a simulation work and then validated by an experimental work conducted by the Diagnosis Group of the LDEE Laboratory. [ABSTRACT FROM AUTHOR]

This paper proposes a control strategy for a three-phase three-wire thyristor-controlled LC -coupling hybrid active power filter (TCLC-HAPF), which can balance active power and compensate reactive power and harmonic currents under unbalanced loading. Compared with TCLC-HAPF with conventional control strategy, active power filters and hybrid active power filters which either fail to perform satisfactory compensation or require high-rating active inverter part for unbalanced compensation, a control strategy was proposed for TCLC-HAPF to operate with a small rating active inverter part for a variety of loads with satisfactory performance. The control idea is to provide different firing angles for each phase of the thyristor-controlled LC-coupling part (TCLC) to balance active power and compensate reactive power, while the active inverter part aims to compensate harmonic currents. First, the required different TCLC impedances are deduced. Then, independent firing angles referenced to the phase angle of voltage across TCLC are calculated. After angle transformations, final firing angles referenced to phase angle of load voltages are obtained. In this paper, a novel controller for TCLC-HAPF under unbalanced loading is proposed. Simulation and experimental results are provided to verify the effectiveness of the proposed controller in comparison with a state-of-the-art controller. [ABSTRACT FROM PUBLISHER]

The active power loss allocation of a radial distribution system faces numerous challenges due to deregulation of power supply. The huge penetrations of distributed generators (DGs) result reverse current in the network, which leads to complexity in cross-term decomposition and power loss allocation. Further, the system loss may decrease/increase due to penetration of DGs into the system. The distribution of this reduced/enhanced portion of losses among the end-users again brings complications in the radial distribution network (RDN) loss allocation. In light of above issues, this paper formulates a circuit theory based branch oriented LA algorithm which removes the impact of mutual terms analytically from the loss equation without any assumptions and approximations. This method allocates losses to the load points in the presence/absence of DG units with due respect to their load demands, power factors and positions in the power network. Moreover, a new DG remuneration scheme has been developed from the power loss equation which provides all the benefits of network loss reduction only to the DG owners in terms of incentives/penalties after analyzing their real impact towards RDN loss reduction. This technique is further extended to investigate the response as regard to energy loss allocation and load power factor variation keeping in view to practical field of application. The performance with respect to different load factors and DG power injections are also investigated using two test distribution systems i.e., IEEE-28 and 30 bus test systems. The comparative result obtained highlights effectiveness of the developed procedure against other existing procedures. [ABSTRACT FROM AUTHOR]

This paper deals with the quasi-instantaneous determination (in a single-step response time) of apparent, active, and reactive (i.e., blind and distortion) power mean values including the total power factor, total harmonic distortion, and phase shift of fundamentals of a power electronic and electrical system (PEES) using the ip-iq method, which is the main contribution of the paper. The power components’ mean values are investigated during the transient and steady states. The power components’ mean values can be determined directly from phase current and voltage quantities, using an integral calculus over one period within the next calculation step and using moving average and moving rms techniques (or digital filtering). Consequently, the power factor can be evaluated with known values of a phase shift of fundamentals (using a Fourier analysis). The results of this study show how a distortion power component during transients is generated even under a harmonic supply and linear resistive–inductive load. The paper contains a theoretical base, modeling, and simulation for the three and single phases of the transients in power electronic systems. The worked-out results can be used to determine and size any PES. The presented approach brings a detailed time waveform verified by simulations in Matlab/Simulink 2022a and the Real-time HW Simulator Plecs RT Box 1.

In this paper, the regulation control problem of the active and reactive power at the common connection point between a doubly fed induction generator and the grid is approached. The proposed controller is developed exploiting the passivity properties of the considered model for the control system. It is considered the existence of a wind turbine that delivers a time-varying torque to the generation unit which exhibits a highly nonlinear structure due to the variations of the wind speed. From a theoretical perspective, the main feature of the contribution lies in the fact that it is formally proved that the equilibrium point of the closed-loop system that corresponds to the desired power exhibits practical global asymptotic stability properties. This characteristic is obtained applying well-known theory from the perturbed nonlinear dynamical systems theory. However, in the numerical evaluation of the proposed controller, it is illustrated how these properties are indeed stronger since asymptotic stability is achieved. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of a self-excited reluctance generating system by using active and reactive power balances. The FEA simulation results are employed to account for both saturation and cross magnetizing effect of $d$ - and $q$ -axis inductances. The procedure to determine the operating point with this method is proposed, and the influence of generator parameters, including stator resistance and inductances, are also investigated. Experiments are carried out at no-load and resistive load conditions separately, verifying the predicted values. In addition, the active and reactive power balance curves are also used to determine whether the generating system works at certain conditions. If there are no crossing points between the two curves, the generator is not able to generate. At last, it is shown that the capacitors and load resistors can be selected based on the power and reactive balances, achieving both high output power and high power factor. [ABSTRACT FROM AUTHOR]

DC grid has a prospect of application in collecting and transmitting large-scale renewable energy over long distance. However, the randomness and fluctuation of the renewable power may hamper the stable operation of DC grid. Energy storage device is able to actively absorb or supplement active power, which can be used to smooth the power fluctuation. The paper investigates a DC grid topology with energy storage and proposes a coordinated control strategy. The proposed strategy enables coordinated control of the renewable energy output power, pumped storage power and the grid consuming power. During the steady state, the control strategy enables the system DC voltage stable and power flow of the grid under zero-error control. During the faulted time, the coordinate control strategy enables the converter fast response and maintains the system DC voltage within safety margin. The effectiveness of the coordinated control strategy is verified by simulation in PSCAD/EMTDC. [ABSTRACT FROM AUTHOR]

SUMMARY This paper discusses power flow analysis and DC capacitor voltage regulation of a modular multilevel cascaded converter (MMCC) based on double-star chopper cells (DSCC). This analysis reveals the relationship between the circulating current through the DC link and the average power flowing out of or into each chopper cell. The DC component of the circulating current supplies half the active output power to the upper and lower strings of the chopper cells, while in contrast the fundamental frequency component transfers an amount of power between the upper and lower strings. Thus, the MDCC-DSCC can balance the capacitor voltages among the cells by controlling the amplitude of the fundamental frequency component of the circulating current. A new control method based on power flow analysis is employed, and its effectiveness is verified by circuit simulation. [ABSTRACT FROM AUTHOR]

Finite control set-model predictive control (FCS-MPC) is employed in this paper to control the operation of a three-phase grid-connected string inverter based on a direct PQ control scheme. The main objective is to achieve high-performance decoupled control of the active and reactive powers injected to the grid from distributed energy resources (DER). The FCS-MPC scheme instantaneously searches for and applies the optimum inverter switching state that can achieve certain goals, such as minimum deviation between reference and actual power; so that both power components (P and Q) are well controlled to their reference values. In addition, an effective method to attenuate undesired cross coupling between the P and Q control loops, which occurs only during transient operation, is investigated. The proposed method is based on the variation of the weight factors of the terms of the FCS-MPC cost function, so a higher weight factor is assigned to the cost function term that is exposed to greater disturbance. Empirical formulae of optimum weight factors as functions of the reference active and reactive power signals are proposed and mathematically derived. The investigated FCS-MPC control scheme is incorporated with the LVRT function to support the grid voltage in fulfilling and accomplishing the up-to-date grid codes. The LVRT algorithm is based on a modification of the references of active and reactive powers as functions of the instantaneous grid voltage such that suitable values of P and Q are injected to the grid during voltage sag. The performance of the elaborated FCS-MPC PQ scheme is studied under various operating scenarios, including steady-state and transient conditions. Results demonstrate the validity and effectiveness of the proposed scheme with regard to the achievement of high-performance operation and quick response of grid-tied inverters during normal and fault modes. [ABSTRACT FROM AUTHOR]

Copyright of Revista Vínculos is the property of Revista Vinculos and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposes a new type dc/ac inverter named: hybrid-coupling grid-connected inverter (HGCI) for photovoltaic active power generation with power quality conditioning, which consists of a full-bridge three-phase dc/ac inverter coupling to the power grid in series with a thyristor-controlled LC filter. Compared with the conventional inductive-coupling grid-connected inverter (IGCI) and capacitive-coupling grid-connected inverter (CGCI), the proposed HGCI has distinct characteristics of wide operational range and low dc-link operating voltage. Based on these prominent characteristics, the system cost and operational cost can be reduced. Moreover, it can transfer the active power and compensate reactive power, unbalanced power, and harmonic power simultaneously. In this paper, the analysis of the structure, parameter design, and control method of the HGCI is proposed and presented. Finally, simulation and experimental results are provided to verify the effectiveness and performance of the proposed HGCI in comparison with the IGCI and CGCI. [ABSTRACT FROM AUTHOR]

Summary: Crosstalk noise is one of the serious reliability concerns in nanoscale integrated circuits. Repeater insertion together with shielding wires is a typical method to suppress crosstalk noise associated with global data bus. A new crosstalk‐noise‐aware bus coding scheme with ground‐gated repeaters is proposed in this paper to minimize the routing overhead as well as power consumption of data bus systems. A subset of 4‐to‐6 crosstalk‐noise‐aware codes is selected to minimize the number of simultaneous data transitions. The routing overhead is reduced by 12.31% with the new bus coding scheme compared with the conventional data bus with shielding wires. Furthermore, the leakage power and worst‐case active power consumptions are reduced by 12.5% and 18.26%, respectively, with the new crosstalk‐noise‐aware data bus system as compared with the previously published bus coding system in an industrial 40‐nm CMOS technology. [ABSTRACT FROM AUTHOR]

A cascaded control structure is proposed in this paper for injecting active and reactive power in a three-phase grid-connected solar photovoltaic (PV) system by considering external disturbances. In the proposed cascaded control structure, there are two control loops—the outer loop voltage controller is used to ensure a continuous balance in power flow between the PV arrays and electrical power grid whereas the inner loop current controller controls the output current of the inverter. Moreover, the DC-DC boost converter is controlled to achieve a constant voltage at the input of the inverter. In order to obtain the power balance and extract maximum power, an incremental conductance (IC) based maximum power point tracking (MPPT) method is used in this paper. The current controller is designed using a nonlinear adaptive backstepping technique to regulate the active and reactive components of the grid current. The regulation of these currents towards desired values which in turn control the active and reactive power delivered into the grid. The overall stability analysis of the system is performed based on the formulation of control Lyapunov functions (CLFs). Finally, the performance of the designed controller is tested on three-phase grid-connected PV systems with single as well as multiple PV units under different environmental conditions and compared with an existing sliding mode controller. Simulation results confirm the effectiveness of the proposed adaptive backstepping control scheme and demonstrate the superior performance over the sliding mode controller. [ABSTRACT FROM AUTHOR]

Single-phase inverters are widely used in different renewable energy applications. Although the full-bridge inverter is typically used, dual-buck inverters provide an important advantage, since they eliminate the shoot-through problems. However, solutions proposed in the literature require additional inductors, use linear controllers designed around an operation point, or cannot be used in grid-connected applications. This paper presents a hysteresis current control of a single-phase dual-buck full-bridge inverter for grid-connected active power injection. Includes the dynamical model in state variables, as well as analytical conditions to guarantee the evolution of the error dynamics in a set with boundaries defined by the designer. Moreover, the paper provides guidelines for the design of the dead band required for the transitions between the positive and negative semi-cycles (and vice-versa) of the grid voltage. Finally, simulation results validate the main features of the controller as well as the design of the dead band. [ABSTRACT FROM AUTHOR]

Motor current signature analysis (MCSA) based detection of rotor cage faults (RFs) in medium-high voltage induction motors has become common in the field due to its low-cost remote monitoring capability. However, low-frequency load oscillations (LOs) in applications that employ speed reduction couplings can induce frequency components in the vicinity of that of RFs. It has been reported that false-positive or -negative RF indications can be produced with the MCSA, if the frequency components produced by RF and LO overlap. There, recently, have been studies on discriminating RF and LO; however, the case where two harmonic components overlap at the same frequency, which is the most difficult and serious case, has not been investigated. In this paper, a spectrum analysis of instantaneous active and reactive power is applied, and it is shown that RF and LO can be separated for the case where the MCSA fails due to the overlap in the two spectral components. An experimental study performed on a 380 V motor with a speed reduction gear shows that RF and LO can be reliably detected and separated for avoiding false RF indications. [ABSTRACT FROM PUBLISHER]

When wind speed changes, the slip of Doubly-Fed Induction Generator (DFIG) changes first, then it causes changes to the state of the DFIG. When the DFIG runs on hyper-synchronous power generating state, rotor and stator generate active power to outside. When the DFIG runs on sub-synchronous power generating state, the rotor absorbs active power and stator generates active power to outside. When the real-time requirement is high, the process needs to be calculated in real time. This paper uses the real time calculation formula about slip, stator current vector and rotor active power to analyze change laws of rotor active power under changes of slip. The results show that the formula can calculate the active power of rotor in real time, and with increasing of slip, the active power absorbed by DFIG rotor gradually decreases, the active power generated by DFIG rotor gradually increases. [ABSTRACT FROM AUTHOR]

• The new Half Cyclic Operation (HCO) method is based on Bang-Bang control of PVPP active and reactive power which performs damping operations in just half of cycles. • The proposed control method does not need any power curtailment in steady state, so, is economically viable. • Improving transient stability margin in successive faults without becoming saturated, loosing capability of oscillation mitigation or causing frequency excursion. • Fast response to faults and quick retorn to pre-fault operation point which is crucial in grids with high level of renewable penetration. • IEEE 9-bus and IEEE 39-bus test systems are used for representing new control method performances. This paper utilizes the fast response capability of the photovoltaic power plants (PVPPs) in providing active and reactive power to increase transient stability margin and oscillation damping in the power system along with improving energy conversion efficiency. The new half cyclic operation (HCO) method is based on the Bang-Bang control of active and reactive power in PVPPs, which does not need any power curtailment. While oscillation is detected, the control system starts to sequentially half-cyclic switch the control system between stability mode and maximum power point tracking (MPPT) mode. Switching between MPPT and stability modes helps with energy conversion efficiency increment, rotor oscillation damping, and transient stability improvement. This strategy automatically leads the operation point to MPPT as oscillation gets mitigated. IEEE 9-bus and IEEE 39-bus test systems are used for representing new control method performances. The obtained results prove the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

This review article presents an overview of the Static Synchronous Compensator (STATCOM) device, its working principle, and its application for improving the stability of wind farms. The article also highlights the importance of STATCOMs in enhancing the power quality of wind farms by improving voltage stability, reducing power fluctuations, and mitigating grid faults. Due to continuously fluctuating wind speeds and faults, the active power, reactive power, and terminal voltage are susceptible to continuous change, which applies to terminal voltage as well. When a STATCOM is connected to the grid, the active power, reactive power, and terminal voltage are maintained at the same level during the connection. This also contributes to an increase in the system's transient stability, which is an important consideration. The review further describes the modeling and control of STATCOMs, including the selection of appropriate control strategies for specific wind farm applications. Finally, the article concludes with a summary of the future research directions for the STATCOM device and its potential for integration into the smart grid. [ABSTRACT FROM AUTHOR]

In this paper, an improved load sharing control scheme is presented, which is able to improve the transient response and power sharing accuracy of parallel-connected inverters used in microgrid. It also shows how the improved droop method can be easily adapted to account for the operation of parallel-connected inverters, providing good performance under the variation and disturbance of loads, as well as achieving good steady-state objectives and transient performance. Two DSP-based single-phase Microgrid inverters are designed and implemented. Simulation and experimental results are all reported, confirming the validity of the proposed control technique. [ABSTRACT FROM AUTHOR]

Summary: The inflation of clean, efficient, sustainable, effective, secure, and reliable electricity demand have been triggered much interest for Microgrid (MG) at a miraculous and quickened pace. The necessity of reliability enhancement, diversity of fuel, cutback of greenhouse gases, severe weather fluctuation etc. has stimulated the inclusion of MG concept not only in utility level but also in customer and community level. Incorporation of solar photovoltaic (SPV) and thermoelectric (TE), termed as Solar photovoltaic‐thermoelectric (SPV‐TE) hybrid system is found be a very promising technique to broadening the utilization of solar spectrum and enhancing the power output effectively‐cum‐efficiently. This hybrid architecture caters electrical energy with additional thermal energy that signifies upon harnessing of solar insolation in an exceptional way. But in order to retain the voltage profile in the permissible level, MG needs storage mechanism for smoothening of renewable based power inconstancy, catering high active power significantly and dodging the long term reactive power rising. This paper illustrates the comparative analysis of three systems such as Conventional MG;TE coupled Conventional MG, and only TE coupled solar PV based MG defining the necessity of employment of energy storage system (ESS). The superiority of third system has been outlined in terms of lesser complexity in source integration, mitigating the detriment of Wind energy system (WES) and Fuel Cell Systems (FCT) integration in real life application, delivery of higher active power, and lesser reactive power absorbance over the two other systems. The studied system is modeled in MATLAB/Simulink environment and the results are presented to support, verify, and validate the analysis. [ABSTRACT FROM AUTHOR]

Summary: Solar photovoltaic system (SPV) has gained tremendous popularity among researchers as well as in industrialists. Although SPV is a transparent way of electricity generation; still, it suffers from lower quantum efficiency. During the conversion process, solar insolation received by the SPV array turns the system intensely heated at the back side of the modules giving rise to high temperature. This heat is further utilized by the process of thermoelectric effect for electricity generation by thermoelectric generators (TEGs). The combined photoelectric‐thermoelectric effect generates a significant amount of power for the system. This paper portrays on implementation of the aforementioned SPV‐TEG system in hybrid nonconventional distribution generator (h‐NDG) in order to retrieve enough power from SPV array giving rise to higher active power delivery to the system and lower the reactive power absorbance by the system. The comparative analysis is done under two subsystems such as solar PV‐TEG‐wind energy system (WES) over solar PV‐WES and solar PV‐TEG‐fuel cell technology (FCT) over SPV‐FCT. Several constraints like active power, reactive power, and solar power are studied for every subsystem under healthy and faulty conditions. The entire system is modeled, studied, and validated in the MATLAB‐Simulink environment. [ABSTRACT FROM AUTHOR]

A well‐designed scheme is essential for assessment and protection of the stability of power system after an unanticipated event. This paper proposes a strategy for regulating three‐phase faults and other events that endanger frequency or voltage stability of the system. The aim is to promptly identify such events utilizing supervised learning‐based classification modules, and initiate suitable emergency control. The imbalances of active and reactive power after an event have been utilized to predict the stability of system. A new optimization‐based formulation has been presented for estimation of reactive power imbalance. An event predicted as unstable is counteracted by prompt load shedding. Conventionally, load shedding is based on frequency or voltage information independently which reduces the effect of load shedding. This work proposes a new load shedding procedure considering both active and reactive power. The proposed scheme is tested on New England (NE) 39‐bus system and Northern Regional Power Grid (NRPG) 246‐bus system, and results of load shedding have been compared with two existing load shedding schemes. The results indicate the accuracy of classification modules in identifying faults and unstable events, and the proposed load shedding restores stability of the system with less amount of load shed and better voltage profile. [ABSTRACT FROM AUTHOR]

In this paper it is shown that it is not possible to generalize the classical concepts of apparent power and power factor to the general polyphase nonsinusoidal case by unique concepts if one wants to retain the meaning with respect to efficiency of the electrical energy transfer as well as with respect to power oscillations. Separate generalizations are proposed and discussed. [ABSTRACT FROM AUTHOR]

The paper deals with an efficient approach to determine complex power generated by a thin wire antenna above a lossy ground. Once the current distribution along a thin wire is obtained by numerically solving the Pocklington integro-differential equation the complex power of the antenna can be obtained by solving the integral over the inner product of tangential component of the electric field and current distribution along the wire stemming from Poynting theorem. Numerical calculation procedure uses the vectors and matrices already constructed within the calculation procedure for the current distribution. Some illustrative numerical results for the active power, reactive power and apparent power of the dipole antenna radiating over a lossy half-space are presented in the paper for different values of input parameters.