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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]

• 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 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]

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]

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]

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]

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]

Since the established wind farms (WFs) have a strong demand for reducing maintenance costs, the fatigue load suppression of wind turbines (WTs) has become more important in WFs. To suppress the fatigue load during operation, the traditional schemes are tried by allocating the optimized power setting value to each WT, which does not directly point to the key operating parameters that affect fatigue. In response to this, an advanced WT control model with two-degree-of-freedom (2Dof) is applied in this paper to ensure that the generator torque and pitch angle (two key parameters affecting fatigue load) of each WT are directly controlled. In order to achieve effective control of the above two parameters in multiple WTs, a hierarchical distributed control architecture with dynamic-local-reference is proposed to jointly optimize the above two configurable parameters at both the WT and WF levels. Several cases are compared to verify the proposed method, and simulation results show that the proposed 2Dof control model for WT and distributed control framework for WF can significantly reduce the fatigue load of each WT while completing the active power command of the whole WF. • Two-degree-of-freedom wind turbine control model is applied in wind farms. • Distributed model predictive control (DMPC) framework is adopted. • Dynamic WT reference power algorithm is proposed based on DMPC. • Fatigue load of all wind turbines in the wind farm are significantly reduced. [ABSTRACT FROM AUTHOR]

This paper amis to show the detail of the Standard IEEE 1459-2010 for single phase systems. This Standard aims to quantify the power of electrical systems; however, it does not detail of the deduction of the equations from the circuit diagram. So the contribution of this document is the step-by-step deduction of the equations from the system's voltages and currents. The deduction is made for both linear and non-linear singlephase systems. The detail of the calculation for the active, reactive and apparent power and also the calculation of the power factor and harmonic distortion are presented. [ABSTRACT FROM AUTHOR]

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]

Non-Intrusive Load Monitoring (NILM) is the task of determining the appliances individual contributions to the aggregate power consumption by using a set of electrical parameters measured at a single metering point. NILM allows to provide detailed consumption information to the users, that induces them to modify their habits towards a wiser use of the electrical energy. This paper proposes a NILM algorithm based on the Deep Neural Networks. In particular, the NILM task is treated as a noise reduction problem addressed by using denoising autoencoder (dAE) architecture, i.e., a neural network trained to reconstruct a signal from its noisy version. This architecture has been initially proposed by Kelly and Knottenbelt (2015), and here is extended and improved by conducting a detailed study on the topology of the network, and by intelligently recombining the disaggregated output with a median filter. An additional contribution of this paper is an exhaustive comparative evaluation conducted with respect to one of the reference work in the field of Hidden Markov Models (HMM) for NILM, i.e., the Additive Factorial Approximate Maximum a Posteriori (AFAMAP) algorithm. The experiments have been conducted on the AMPds, UK-DALE, and REDD datasets in seen and unseen scenarios both in presence and in absence of noise. In order to be able to evaluate AFAMAP in presence of noise, an HMM model representing the noise contribution has been introduced. The results showed that the dAE approach outperforms the AFAMAP algorithm both in seen and unseen condition, and that it exhibits a significant robustness in presence of noise. [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]

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]

Voltage and frequency are both significant index of city grid. Electric vehicles (EVs) have the potential to provide ancillary services for power grid since they are in stop state at most time during a day. This paper proposes a novel unified EV charging and discharging strategy by controlling active power to provide voltage and frequency regulation in city power grid. The objective of the strategy is to solve the voltage drop/rise and frequency fluctuation in city power grid with minimum influence on EV owners travelling demand. The available V2G regulation power is obtained according to the EV owners' transportation demand, initial and real‐time battery SOC and departure time. In case of voltage and frequency deviation out of the limitation, the EVs can participate in correspondence regulation by fast adjustment of charging or discharging power within the limitation. Simulations on an urban distribution network and an urban power grid are presented for voltage regulation and frequency regulation, respectively. The results have demonstrated the effectiveness of the proposed strategy. It can be concluded from the results that EV can be scheduled to solve the city grid voltage drop/rise and frequency fluctuation with the proposed strategy. [ABSTRACT FROM AUTHOR]

This paper proposes an active power based model reference adaptive system for sensorless speed estimation of primary field oriented brushless doubly-fed reluctance generator (BDFRG). In this regard, the active power associated with secondary winding of BDFRG is used for the process of speed estimation. BDFRG is more reliable and requires less maintenance. Its structural advantages demonstrate higher working efficiency and lower losses as compared to equivalent doubly-fed induction machines. Moreover, active power of BDFRG can be controlled by suitable speed regulation, which in turn can be achieved by a low rating bidirectional converter connected to the stator secondary (i.e., control) winding. These inherent features make BDFRG as a prospective candidate in the applications like wind and tidal power generation. The efficacy of the proposed control technique is established by a 1.6 kW BDFRG in Matlab/Simulink. A dSPACE-1103 based laboratory prototype is used for the hardware validation. [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]

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]

As large‐scale integration of wind systems into the power grid is on the rise, advanced control techniques for wind power generators are highly desired. This paper proposes a simple but effective control technique for doubly fed induction generators (DFIGs) based on the multi‐objective model predictive control (MOMPC) scheme. The future behaviors of the DFIGs are predicted by using the system model and the possible converter switching states. The most appropriate vector is then determined by a cost function. By properly modifying the cost function with active and reactive powers as the control objectives, fast grid synchronisation, smooth grid connection, flexible power regulation and maximum power point tracking (MPPT) can be achieved, respectively. In order to reduce the switching frequency for switching loss reduction, a nonlinear constraint is integrated into the cost function. The controller is simple without using any Proportion Integration (PI) regulators, current loops, and switching tables. A numerical simulation of a 2MW system based on MATLAB/Simulink is built to verify the effectiveness of the proposed method. The results show that the proposed method can achieve quicker transient response, better steady‐state performance, and lower switching frequency compared to the conventional switching table based direct power control (DPC). [ABSTRACT FROM AUTHOR]

Abstract This paper focuses on the direct optimal power generation control for a horizontal-axis tidal turbine system by using fuzzy power tuning. The dynamics of this tidal turbine system is first described and modelled based on the modelling of individual components. The generator power is also be described from the power converter and DC-bus side. A fuzzy logic tuning method is then proposed to derive the optimal generator power by using the power converter current and its variations as input variables. The derived optimal generator power is used as the reference for direct power control by using cascaded control loops. The effectiveness of the proposed control has been verified based on a 50 kW tidal turbine system with gear ratio of 2 in MATLAB/Simulink simulations. The test results validate the proposed fuzzy tuning method is reasonable and the active generator power can be readily maximized while the reactive power is minimized by using the proposed direct optimal power control method. Highlights • The direct optimal power generation control for a horizontal-axis tidal turbine system. • Fuzzy logic tuning method is then proposed to derive the optimal generator power. • Direct power control by using cascaded control loops. [ABSTRACT FROM AUTHOR]

Electric energy transport theories are still a debatable subject regarding their validity and applicability in various aspects. This paper includes a comparative study of the group of theories which are categorized as instantaneous theories as opposed to periodic-averaged ones. As a preliminary review this paper presents first the three apparent power definitions in order to emphasize the difference between them. A discussion regarding their accuracy for energy metering of various conditions such as multiphase and non-sinusoidal environments is presented. Instantaneous theories are then reviewed and compared with periodic averaged theories. The review focuses mainly on p-q theory ( PQT ) and its derivative, instantaneous multi-phase theory. The legacy application of this theory for active filtering is briefly presented and the new idea of using the theory for multi-load and multi-source theory is presented as well. The comparison identifies the similarities and differences between the instantaneous and periodic averaging theories, and their inter-relations. [ABSTRACT FROM AUTHOR]

Electric energy transport theory is one of the key factors in smart grid development. Electric energy and power transport theories enable the development of advanced energy metering, improve fault-location algorithms, electric network diagnostics algorithms, power conditioning of active filters and of smart grids, energy storage management at energy reservoirs, and new energy forecasting analytical algorithms. In this paper, the periodic averaged theories, including the periodic averaged formulation of Poynting vector theory, are presented. The presentation is conducted in a unique comparative formalism and approach, enabling the demonstration of equivalence between the various theories in general and the equivalence of some elements in the decomposition of the electrical expressions for the powers in particular. The paper shows the equivalence of the modern theory of Currents׳ Physical Components to the Conservative Power Theory, and its formulation, for being applicable to various grid monitoring and energy control applications. A corrected computation for the reactive power by means of time-domain Conservative Power Theory is proposed as well. Moreover, equivalence in single phase systems between Buchholz apparent power and geometric apparent power is shown, which indicate the suitability of using apparent power definitions to grid manufacturing and modern distribution systems design. [ABSTRACT FROM AUTHOR]

This paper proposes a novel direct power control (DPC) strategy for neutral-point-clamped (NPC) three-level rectifiers, to directly control the active power, the reactive power and the neutral point potential of the rectifiers by referring to three pre-calculated vector influence tables and minimizing an objective function. In the three vector influence tables, the influences of different voltage vectors on the active power, the reactive power and the neutral-point potential are shown explicitly. A conceptual description and control algorithm of the proposed controller are presented in this paper. Then, numerical simulations and experiments are carried out to validate the proposed method. Both the simulation and experimental results show that good performances during both the steady-state and transient operating conditions are achieved. As a result, the proposed strategy has been proven to be effective for NPC three-level rectifiers. [ABSTRACT FROM AUTHOR]

SUMMARY This paper presents detail assessment of the impact of renewable energy type distributed generation operation modes on the voltage stability indices. Most of renewable distributed energy sources are capable of operating in two modes, which are constant voltage and constant power modes. Different simulation results were obtained for voltage stability index (VSI), which serves as indicator of stability. Furthermore, this study has also considered charging station (CS) as a load, that is, gradually increased at the selected bus until the system attains instability state. The persistence of the instability can lead to voltage collapse, and VSI value can give an indication of the collapse as well. In this paper, the concept of active power voltage stability index (P-VSI) is introduced with the aim of predicting the voltage collapse as a result of incremental CS loading in the network. Based on the analysis conducted in radial networks with multiple distributed generation units, the P-VSI gave better indication for the voltage collapse much more than reactive power voltage stability index. The analysis was conducted on 33 bus distribution system. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Three-phase rectifier is typically realized by six power switches. However, this rectifier is fault sensitive in power switches. To enable continued controllable operation, the grid phase with fault rectifier leg can be connected to center tap of the dc-link capacitors, known as the four-switch three-phase rectifier (FSTPR), using hardware reconfiguration. However, the symmetry of three-phase currents and reliable operation of the FSTPR cannot be retained due to the offset of the two-capacitor voltages. This paper proposes a finite control set model predictive control (FCS-MPC) to obtain the balanced three-phase current with the offset of two-capacitor voltages suppressed. The PI-Controller-free FCS-MPC with a second-order Luenberger observer is adopted to improve the dynamic performance of FSTPR. The performance of the proposed control scheme is illustrated by extensive simulation and experimental results. The comparison with the conventional voltage-oriented-control, which is based on PI controller and pulse width modulation (PWM), is also presented to show the superiority of the proposed FCS-MPC. [ABSTRACT FROM AUTHOR]

Purpose This paper aims to propose a new sleep signal controlled footless domino circuit for reducing the subthreshold and gate oxide leakage currents.Design/methodology/approach In the proposed circuit, a P channel MOSFET (PMOS) sleep switch transistor is inserted between the power supply and the output node. The sleep transistor, the source of the pull-down network, and the source of the N channel MOSFET (NMOS) transistor of the output inverter are controlled by this additional sleep signal to place the footless domino circuit in a low leakage state.Findings The authors simulate the proposed circuit by using HSPICE in 45-nm CMOS technology for OR and AND logic gates such as OR2, OR4, OR8, AND2 and AND4 at 25°C and 110°C. The proposed circuit reduces leakage power consumption as compared to the existing circuits.Originality/value The proposed circuit significantly reduces the total leakage power consumption up to 99.41 and 99.51 per cent as compared to the standard dual-threshold voltage footless domino circuits at 25°C and 110°C, respectively, and up to 93.79 and 97.98 per cent as compared to the sleep control techniques at 25°C and 110°C, respectively. Similarly, the proposed circuit reduces the active power consumption up to 26.76 and 86.25 per cent as compared to the standard dual-threshold voltage and sleep control techniques footless domino circuits at 25°C and 110°C, respectively. [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]

This paper presents an improved performance of coordinated control scheme for exchanging power between a single phase electrical grid and battery energy storage system (BESS) using adaptive neuro-fuzzy inference system (ANFIS). The grid connected BESS has several practical applications in respect of storage of excess energy, reduction of maximum demand and reduction of power fluctuation on local grid/micro-grid. In these scenarios, the coordinated closed loop control strategy facilitates charging and discharging operation of the battery via dc-ac bidirectional converter. During charging mode of operation, the grid supplies active power to the battery for restoring back its energy. On the other hand, the closed loop action is also capable to control active and reactive power in decoupled way by discharging battery and the required electrical powers can be injected into the nearby grid conveniently. At first, the required closed loop control schemes are implemented using proportional-integral (PI) controller and the performance of the BESS using PI based control schemes is investigated. Then, the ANFIS based control strategy is used for improving overall control capability and it provides superior dynamic performance in comparison to the PI based control scheme under charging and discharging operation cycle of the battery. Various simulation studies are performed on 230 V, 50 Hz single phase ac grid connected 100 Ah, 120 V battery using MATLAB-SIMULINK 2014b software to validate the improved control concept. [ABSTRACT FROM AUTHOR]

In this paper, neuronal direct power control (DPC) strategy is applied for a doubly fed induction generator (DFIG) based wind energy generation system. Used in three level neutral point clamped (NPC) rectifiers, to directly control the active and reactive power, switching vectors for rotor side converter were selected from the optimal switching table using the estimated stator flux position and the errors of the active and reactive power, also the grid side is controlled by direct power control based a grid voltage position to ensure a constant DC- link voltage. This approach is validated by using MATLAB/SIMULINK software and simulation results can prove the excellent performance of this control as improving power quality and stability of wind turbine. [ABSTRACT FROM AUTHOR]

With the increasing capacity of distributed generation (DG) connected to the power grid, the future generation of photovoltaic (PV) systems are expected to provide a full range of voltage regulation during grid faults in order to enhance the low-voltage ride-through (LVRT) capability of a PV system. In such a condition, the DG should remain connected to the grid for reactive power support, thereby improving voltage profile. This paper aims to propose a control strategy of active and reactive power for a single-stage three-phase grid-connected PV system to enhance the LVRT. The dynamic behaviours of the system were investigated by considering various scenarios such as varying irradiance, local load disconnection, and short circuits, at different locations during the multi-DG operation. Results confirm that the grid-connected PV system is able to remain connected to the power grid during steady-state and transient-state conditions without violating the grid code requirements. The established dynamic behaviour analysis model of the proposed control for grid-connected PV systems can be used in planning an operational strategy for a practical system. [ABSTRACT FROM AUTHOR]

This paper presents a robust controller design for three-phase grid-connected solar PhotoVoltaic (PV) systems to control active power. The controller is designed based on a nonlinear adaptive backstepping approach and the robustness of the proposed scheme is ensured by considering parametric uncertainties as well as external disturbances. In the proposed control strategy, all parameters within the grid-connected solar PV systems are considered as unknown which are then estimated through the adaptation laws. These estimated parameters along with external disturbances are incorporated into the controller to ensure the overall stability of the whole system through the formulation of Control Lyapunov Functions (CLFs). An Incremental Conductance (IC) method is used to track the Maximum Power Point (MPP) at which a constant DC-link voltage is maintained and this voltage is used to obtain the reference value of the current which is used for active power control. A three-phase grid-connected solar PV is used to evaluate the performance of the proposed control scheme under different operating conditions. The simulations results clearly indicate the robustness of the proposed scheme in terms of injecting active power into the grid and improving power quality as compared to an existing adaptive backstepping controller. [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]

This paper presents the design, implementation, and evaluation of a model-based controller for a general scheme of transformerless power converters connected to the grid through an L filter. The proposed controller is aimed at active power injection, and consists of a damping term over the current error in addition to a filter parameter estimation scheme. The latter provides estimates of the filter internal resistance and inductance values. It involves the fundamental and quadrature components of the grid voltage to asymptotically compensate for current harmonic peturbations. As a result, the closed-loop system fulfills the active power injection objective. The proposed controller is tested in an experimental setup and its performance is compared to that of the Proportional-Resonant controller. Experimental results are presented for a single-phase H-bridge inverter; however, the control scheme can be used in several other H-bridge based inverter topologies such as H5 and HERIC. [ABSTRACT FROM PUBLISHER]

Loss of field (LOF) phenomenon in synchronous generators may cause serious damages and voltage drop in the power system, which can result in a blackout. Conventional methods, which detect LOF on the basis of the measured impedance from terminal viewpoint, are slow and may exhibit mal‐operation in the face of other phenomena, e.g. stable power swing (SPS). In this paper, a novel technique is proposed to detect LOF in synchronous generators on the basis of some electrical quantities variations including voltage of terminal (V), current (I), active power (P), reactive power (Q) and power angle (δ). To evaluate the performance of the proposed algorithm, some cases are simulated under various operation conditions. Obtained results show that this algorithm on the basis of V, Q and δ not only can be considered as a fast LOF detector in comparison with the conventional impedance‐based schemes, but also it is a robust and secure technique in the face of SPS and other power system disturbances. The proposed algorithm is tested by using an experimental setup including the laboratory synchronous generators, too. The obtained results show that the proposed technique can exhibit suitable performance in the actual conditions. [ABSTRACT FROM AUTHOR]

In this paper, a new modeling and parameter design method for the thyristor-controlled LC-coupled hybrid active power filter (TCLC-HAPF) is proposed, which includes the analysis of the inner flowed three-phase unbalanced power during unbalanced condition. Different from the conventional method which ignores the inner flowed three-phase unbalanced power, the proposed design method can achieve better performance during unbalanced compensation. To verify the validity and advantages of the proposed modeling and parameter design method of TCLC-HAPF, the mathematical analysis, representative simulation and experimental results for compensating different unbalanced loading situation are presented in comparison with the conventional design method. [ABSTRACT FROM PUBLISHER]

The reliability of power grids has been subject of study for the past few decades. Traditionally, detailed models are used to assess how the system behaves after failures. Such models, based on power flow analysis and detailed simulations, yield accurate characterizations of the system under study. However, they fall short on scalability. In this paper, we propose an efficient and scalable approach to assess the survivability of power systems. Our approach takes into account the phased-recovery of the system after a failure occurs. The proposed phased-recovery model yields metrics such as the expected accumulated energy not supplied between failure and full recovery. Leveraging the predictive power of the model, we use it as part of an optimization framework to assist in investment decisions. Given a budget and an initial circuit to be upgraded, we propose heuristics to sample the solution space in a principled way accounting for survivability-related metrics. We have evaluated the feasibility of this approach by applying it to the design of a benchmark distribution automation circuit. Our empirical results indicate that the combination of survivability and power flow analysis can provide meaningful investment decision support for power systems engineers. [ABSTRACT FROM AUTHOR]

The capacitive-coupling grid-connected inverter (CGCI) is coupled to the point of common coupling via a second-order LC branch. Its operational voltage is much lower than that of a conventional inductive-coupling grid-connected inverter (IGCI) when it serves as a multifunctional inverter to compensate reactive power and transfer active power simultaneously. It is a promising solution for microgrid and building-integrated distributed generator systems. A quasi-proportional-resonant (quasi-PR) controller is applied to reduce the steady-state current tracking errors of the CGCI in this paper. The quasi-PR controller generates the voltage reference for use of carrier-based pulse-width modulation, which can effectively reduce output current ripples. The second-order coupling impedance of the CGCI causes its modeling and controller design to differ from that of the conventional IGCI. A comprehensive design method for the quasi-PR controller in a CGCI is developed. The quasi-PR controller is also compared with a proportional-integration current controller. Simulation results are provided to verify the effectiveness of the quasi-PR controller and its design method in a CGCI. The current tracking errors are greatly reduced when the quasi-PR controller rather than the proportional-integration controller is applied. Experimental results are also provided to validate the CGCI as a multifunctional grid-connected inverter. [ABSTRACT FROM PUBLISHER]

This paper presents a novel dc capacitor voltage balance control method for cascade multilevel static synchronous compensator (STATCOM) and a general analytical method for balance control strategy. Considering that the imbalance of dc capacitor voltage is caused by the inconsistency of active power absorbed and consumed by chain, a balance control strategy based on active voltage vector superposition is proposed, in which an active voltage component is superposed to chain's output voltage to change its absorbed active power. A general analytical method based on vector analysis is also presented, by which the performance of balance control strategy can be analyzed, including stability and regulation capacity. To find out the most appropriate balance control strategy, a comparison still based on vector analysis among the proposed and other two commonly used methods is provided, from which it can be known that the proposed balance control strategy has the advantage of good stability and strong regulation capacity, and simulations are performed to prove it. The effectiveness of proposed control scheme has been verified by experimental results based on a three-phase 36-chain cascade multilevel STATCOM laboratory prototype. [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]

Abstract: This paper compares DSP time domain algorithms of one-phase active power measurement by non-coherent sampling that are superior to some frequency domain algorithms in active power estimation of non-sinusoidal signals. The measurement bias, uncertainty and sampling time necessary for the required accuracy are compared for various data windows with the use of simulations and measurements. Both monofrequency and multifrequency signals are dealt with. Analytical formulas are presented for the active power bias for rectangular and general cosine windows and for standard uncertainty of active power measurement. A simple method is described for correction of the multiplexing delay in power measurement using multiplexing DAQ boards. The information from this paper can also be used for measuring energy consumption and three-phase power. [Copyright &y& Elsevier]

In this paper, the diagnostic of rolling element bearings in variable regime is addressed. In the nonstationary regime, permanent changes of operating system parameters (load and speed) prevent fault diagnostic with classical tools (RMS value and spectral indicator). To overcome this problem, two new indicators are proposed: RMS value and spectral indicator normalized by the active power. To do that, the vibration signal was acquired simultaneously with the current and voltage signals, and then these signals were divided into segments. For each segment, the RMS value (respectively the spectral indicator) and the power active were calculated, then the RMS was divided by the active power. An analytical model of vibration signal was given and a simulation model signal was used to investigate the proposed indicators. For the experimental validation, a test rig was performed to extract signals (vibration, current and voltage signals) at different degradation states of bearings in a variable speed regime. The thrust bearings (SKF 51207) were used with different states of degradation: free fault and faults created with different sizes. Several operating parameters were considered: variable speed (50-950 rpm) and different loads. The experimental tests showed a linear relationship between the classical RMS value and the active power. The results showed a correlation between the proposed indicators and the bearings state in variable regime. Thus, the proposed indicators are very simple and may be implemented in real time for large industrial applications. [ABSTRACT FROM AUTHOR]

Renewable energy is a fast-growing sector given that it does not cause the pollution produced by nuclear and fossil generation systems. The use of renewable energy for distributed generation (DG) is important worldwide not only because it increases profits but also because integrating it into utility systems ensures power supply at points of consumption even when a DG system is disconnected from the main system. Researchers continue to exert efforts in improving islanding detection methods because current detection approaches remain unsatisfactory. Accordingly, this paper presents two new islanding detection methods that are suited for single and multiple DG units. The methods are based on the rate of change in active and reactive power, frequency, and voltage angle. They are tested on single and multiple DG systems with wind turbines and simulated using the Power World Simulator software. The simulation results show that the methods effectively reduce the time spent on islanding detection and efficiently decrease non-detection zones. To verify the accuracy and speed of the proposed methods, the results are compared with those achieved by different islanding detection approaches. [ABSTRACT FROM AUTHOR]

This paper presents the development of an electronic energy meter for residential use; that gives the end user the ability to understand the behavior of energy consumption at home. The built system involves the integrated circuit ADE7753 from Analog Devices as a central module for electronic measurement of energy consumption, and the Microchip PIC18F2550 microcontroller for configuration and calibration of ADE7753 and control and data processing circuit. The system has a display and a graphical user interface via USB communication allows control time billing periods, carry the backing of the processed information, display the current consumption in real time, generate a historical consumption and calculate the approximate cost of the active energy recorded. To validate system performance, field and laboratory testing for different loads and times of measurement is executed, and used as standard equipment electricity meter previously calibrated by INELCA SA, yielding an average percentage error of 0.09940% in the measured energy. [ABSTRACT FROM AUTHOR]

Introduction: Despite of more than a hundred years of electrosurgery, only a few electrosurgical equipment manufacturers have developed methods to regulate the active power delivered to the patient, usually around an arbitrary setpoint. In fact, no manufacturer has a method to measure the active power actually delivered to the load. Measuring the delivered power and computing it fast enough so as to avoid injury to the organic tissue is challenging. If voltage and current signals can be sampled in time and discretized in the frequency domain, a simple and very fast multiplication process can be used to determine the active power. Methods: This paper presents an approach for measuring active power at the output power stage of electrosurgical units with mathematical shortcuts based on a simple multiplication procedure of discretized variables – frequency domain vectors – obtained through Discrete Fourier Transform (DFT) applied on time-sampled voltage and current vectors. Results: Comparative results between simulations and a practical experiment are presented – all being in accordance with the requirements of the applicable industry standards. Conclusion: An analysis is presented comparing the active power analytically obtained through well-known voltage and current signals against a computational methodology based on vector manipulation using DFT only for time-to-frequency domain transformation. The greatest advantage of this method is to determine the active power of noisy and phased out signals with neither complex DFT or ordinary transform methodologies nor sophisticated computing techniques such as convolution. All results presented errors substantially lower than the thresholds defined by the applicable standards. [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]

This paper presents a mathematical model of hydro power units, especially the governor system model for different operating conditions, based on the basic version of the software TOPSYS. The mathematical model consists of eight turbine equations, one generator equation, and one governor equation, which are solved for ten unknown variables. The generator and governor equations, which are different under various operating conditions, are presented and discussed in detail. All the essential non-linear factors in the governor system (dead-zone, saturation, rate limiting, and backlash) are also considered. Case studies are conducted based on one Swedish hydro power plant (HPP) and three Chinese plants. The simulation and on-site measurements are compared for start-up, no-load operation, normal operation, and load rejection in different control modes (frequency, opening, and power feedback). The main error in each simulation is also discussed in detail. As a result, the model application is proved trustworthy for simulating different physical quantities of the unit (e.g., guide vane opening, active power, rotation speed, and pressures at volute and draft tube). The model has already been applied effectively in consultant analyses and scientific studies. [ABSTRACT FROM AUTHOR]