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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 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]

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]

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]

Energy flow in sinusoidal systems is analyzed without problems by means of the traditional power definitions such as: apparent, active, and reactive, but these definitions are not properly applied in nonlinear loads. These loads present several distortions which are not correctly measured with the prevailing instruments designed for measuring energy and power. This is because a generalized set of power definitions is not available. In this paper, an alternative set of energy and power definitions is suggested for non-sinusoidal systems. Each definition is obtained through the analysis of power in the time domain. The proposed definitions add information to alleviate the power and energy measurement problem of the power meters, offer alternative indexes to measure the energy distribution, and allow calculations in transient and steady states. Furthermore, an experimental measurement of the proposed powers by means of a half-wave rectifier is shown. [ABSTRACT FROM AUTHOR]

SUMMARY Due to wind power fluctuation, it is difficult to make generating schedule of power system with wind power. This paper presents a new approach to make generating schedule using electrical relationships between generators and loads. A two-layer structure is used in the approach, i.e. generating schedule is made and revised in on-line time scale in upper layer, and automatic generating control (AGC) is carried out in real-time time scale in lower layer. Both generating schedule-making and AGC are implemented using power transmission factors among wind farms, related traditional generators and loads. And generating schedule is revised taking the operation limit of generators and transmission congestion into consideration. At last, the technical and economic benefits are analyzed in case study. The results show that the approach can effectively track fluctuation and forecasting error of wind power and enhance the operation quality of entire power system. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, a multilayer control is proposed for inverters that are able to operate in parallel without intercommunications. The first control layer is an improved droop method that introduces power proportional terms into the conventional droop scheme, letting both active and reactive power to be shared among the inverters. The second layer is designed to compensate the voltage deviations caused by the aforementioned droop control, thus improving the load-voltage regulation of the system. The third layer is a quasi-synchronization control that roughly adjusts the angle of the inverter to be close to the common ac bus. This layer ensures that the phase difference of each inverter is inside a limited margin with the help of the phase signal sensed from the common ac bus. The principle of operation of the control scheme has been analyzed in detail. A small-signal model has been developed in order to study the system dynamics, which can be used for adjusting the main control parameters. A prototype consisting of a two 35-kVA-inverter system has been built and tested in order to verify the feasibility of the proposed approach. [ABSTRACT FROM AUTHOR]

Errors may creep in when measuring power by conventional methods due to the inductance and capacitance of the coils and the induced eddy current in the metal parts of the instruments through the alternating magnetic field of the current coil. Apart from these, if a fault occurs in any of the potential transformer secondary circuits or the potential coil of the measuring equipment, a conventional meter cannot detect it, which results in underregistration. In this paper, a microprocessor-based three-phase real, reactive, and apparent power measurement system is developed, which displays the power being fed to a load under both normal and faulty conditions. The microprocessor provides a simple, accurate, reliable, and economical solution to these problems. A framework of the hardware circuitry and the assembly language program for the evaluation of power values is given, and the problems to which attention should be paid to execute the proposed algorithm using the microprocessor are discussed. Illustrative laboratory test results confirm the validity and accurate performance of the proposed method in real-time. [ABSTRACT FROM AUTHOR]

This paper presents analytical details of how active and reactive power output of a stand-alone proton-exchange-membrane (PEM) fuel cell power plant (FCPP) is controlled. This analysis is based on an integrated dynamic model of the entire power plant including the reformer. The validity of the analysis is verified when the model is used to predict the response of the power plant to: 1) computer-simulated step changes in the load active and reactive power demand and 2) actual active and reactive load profile of a single family residence. The response curves indicate the load-following characteristics of the model and the predicted changes in the analytical parameters predicated by the analysis. [ABSTRACT FROM AUTHOR]