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Direct current (DC) microgrid has recently gained potential interest since it supports easy integration of distributed generators (DGs) and energy storage devices (ESDs). However, most DGs and ESDs are integrated into the DC bus with the power electronic converter/inverter. Thus, controlling large-scale power electronic-based generators, loads, and ESDs becomes a challenging task. This paper introduces a new control strategy for the DC microgrid to regulate the bus voltage and power sharing among the DGs, ESDs, resistive loads, and constant power loads (CPLs). Each battery's state of charge (SoC) is utilized in the double control loop to determine the charging/discharging speed. Besides, an additional fractional-order proportional-integral voltage compensation loop is introduced to regulate the DC bus voltage. The SoC-based inner loops assist in the automatic balancing of battery charges, while the compensation loop minimizes the DC bus voltage deviation. A detailed small-signal model is derived to design the controller parameter. The optimization approach is applied to the developed model with the objective of reducing the integral square error of the step response. The DC microgrid system with the designed controller is tested with the simulation study. The results depict that the bus voltage deviation is reduced by 63.27% while the SoC balancing is faster for both charging and discharging modes. [ABSTRACT FROM AUTHOR]

To simultaneously solve the problems of the state-of-charge (SOC) equalization and accurate current distribution among distributed energy storage units (DESUs) with different capacities in isolated DC microgrids, a multi-storage DC microgrid energy equalization strategy based on the hierarchical cooperative control is proposed. In the primary control layer, the link between the droop coefficient and SOC is established through a logarithmic function, and the droop coefficient is adaptively adjusted according to the SOC value in order to achieve fast SOC equalization. In the secondary control layer, by designing a coordinated state factor, only one PI controller is required to eliminate the influence of the line impedance on the accurate distribution of the output current and the DC bus voltage drop. In the communication layer, local nodes only need to communicate with neighboring nodes without the need for a central controller, and the dynamic consistency algorithm is used to obtain the average value information about the energy storage system (ESS). Finally, the feasibility and effectiveness of the proposed control strategy are verified by experimental analysis on the DC microgrid hardware-in-the-loop experimental platform. [ABSTRACT FROM AUTHOR]

Abstract To improve the reliability of Two-level three phase voltage source inverters, a uniform fault tolerant strategy based on space vector pulse width modulation is proposed for different leg faults. The reconstructed topologies of inverters with different bridge arm faults are different, which makes the basic voltage vector phase of each reconstructed topology inconsistent, resulting in different calculations. Therefore, the coordinate transformation is applied to place the basic voltage vectors of each reconstructed topology on the synchronous stationary αβ coordinate system so that the calculations of the reconstructed topology under different bridge arm faults are unified, thus reducing the complexity of fault-tolerant control. Aiming at the three-phase current asymmetry caused by the neutral point voltage oscillation in inverter topology reconstruction, a transient compensation method of neutral point voltage offset for the α-axis component of the reference voltage vector is introduced to suppress the adverse effects. The compensation method directly offers a neutral point voltage offset value after Clarke transformation and corrects the α-axis component of the reference voltage vector, avoiding the integral calculation in the conventional voltage compensation algorithm. The correctness and effectiveness of the proposed fault-tolerant control strategy are verified experimentally.

In the realm of isolated direct-current microgrids with varying distributed energy storage unit capacities, a new energy equalization strategy is proposed. This method involves an innovative approach that integrates an improved state-of-charge equalization control integrated with a sigmoid function to adaptively adjust the droop coefficient, aiming to accelerate the state-of-charge equalization rate. Furthermore, a virtual voltage drop equalization control is designed to dynamically adjust the output current of each distributed energy storage unit through a simple proportional–integral controller. This eliminates the influence of line impedance on accurate current distribution, improving overall accuracy. Additionally, a dynamic consistency algorithm is employed to gather average information about the distributed energy storage system, reducing communication line pressure as local nodes only exchange information with neighboring nodes. Integrating the aforementioned modules, the strategy proposed in this paper achieves rapid state-of-charge equalization, precise distribution of output current, and stable maintenance of the bus voltage. Finally, rigorous analysis of experimental results under various operating conditions verifies the feasibility and effectiveness of this control strategy by using the RT-LAB.

In islanded operation, precise power sharing is an immensely critical challenge when there are different line impedance values among the different-rated inverters connected to the same electrical network. Issues in power sharing and voltage compensation at the point of common coupling, as well as the reverse circulating current between inverters, are problems in existing control strategies for parallel-connected inverters if mismatched line impedances are not addressed. Therefore, this study aims to develop an improved decentralized controller for good power sharing with voltage compensation using the predictive control scheme and circulating current minimization between the inverters' current flow. The controller was developed based on adaptive virtual impedance (AVI) control, combined with finite control set–model predictive control (FCS-MPC). The AVI was used for the generation of reference voltage, which responded to the parameters from the virtual impedance loop control to be the input to the FCS-MPC for a faster tracking response and to have minimum tracking error for better pulse-width modulation generation in the space-vector form. As a result, the circulating current was maintained at below 5% and the inverters were able to share an equal power based on the load required. At the end, the performance of the AVI-based control scheme was compared with those of the conventional and static-virtual-impedance-based methods, which have also been tested in simulation using MATLAB/Simulink software 2021a version. The comparison results show that the AVI FCS MPC give 5% error compared to SVI at 10% and conventional PI at 20%, in which AVI is able to minimize the circulating current when mismatch impedance is applied to the DGs. [ABSTRACT FROM AUTHOR]

The insulated core transformer (ICT) power supply is widely employed in electron beam accelerators (EBAs) due to its high power, heightened efficiency, and stable operation. However, the segmented-core structure of the ICT power supply increases magnetic leakage, which leads to it adversely affecting the consistency of the output voltages in the rectifier stages. Currently, numerous studies focus on stage voltage compensation, including turns compensation, capacitor compensation, dummy primary winding compensation, and full-parameter compensation. This paper presents a unified simulation model and an improved gradient-based genetic algorithm, which can also optimize the parameters of the four compensation methods. Based on this, the performance of the power supply using the four compensation methods under different ICT energy levels and power supply requirements is studied, and the selection suggestions are given. This work fills the gap in the performance comparison and application research of various compensation methods. [ABSTRACT FROM AUTHOR]

More and more distributed generations (DGs), such as wind, PV or battery bank sources, are connected to electric systems or customer loads. However, the locations of these DGs are based on the highest energy that can be potentially harvested for electric power generation. Therefore, these locations create different line impedances based on the distance from the DGs to the loads or the point of common coupling (PCC). This paper presents an adaptive virtual impedance (AVI) in the predictive control scheme in order to ensure power sharing accuracy and voltage stability at the PCC in a microgrid network. The reference voltage from mismatched feeder impedances was modified by utilizing the suggested AVI-based predictive control for creating equal power sharing between the DGs in order to avoid overburdening any individual DG with low-rated power. The AVI strategy used droop control as the input control for generating equal power sharing, while the AVI output was used as the reference voltage for the finite control set–model predictive control (FCS-MPC) for creating a minimum voltage error deviation for the cost function (CF) for the inverter's vector switching pattern in order to improve voltage stability at the PCC. The proposed AVI-based controller was tested using two DG inverter circuits in a decentralized control mode with different values of line impedance and rated power. The performance of the suggested controller was compared via MATLAB/Simulink with that of a controller based on static virtual impedance (SVI) in terms of efficiency of power sharing and voltage stability at the PCC. From the results, it was found that (1) the voltage transient magnitude for the AVI-based controller was reduced within less than 0.02 s, and the voltage at the PCC was maintained with about 0.9% error which is the least as compared with those for the SVI-based controller and (2) equal power sharing between the DGs increased during the change in the load demand when using the AVI-based controller as compared with using the SVI-based controller. The proposed controller was capable of giving more accurate power sharing between the DGs, as well as maintaining the voltage at the PCC, which makes it suitable for the power generation of consumer loads based on DG locations for future energy communities. [ABSTRACT FROM AUTHOR]

To simultaneously solve the problems of the state-of-charge (SOC) equalization and accurate current distribution among distributed energy storage units (DESUs) with different capacities in isolated DC microgrids, a multi-storage DC microgrid energy equalization strategy based on the hierarchical cooperative control is proposed. In the primary control layer, the link between the droop coefficient and SOC is established through a logarithmic function, and the droop coefficient is adaptively adjusted according to the SOC value in order to achieve fast SOC equalization. In the secondary control layer, by designing a coordinated state factor, only one PI controller is required to eliminate the influence of the line impedance on the accurate distribution of the output current and the DC bus voltage drop. In the communication layer, local nodes only need to communicate with neighboring nodes without the need for a central controller, and the dynamic consistency algorithm is used to obtain the average value information about the energy storage system (ESS). Finally, the feasibility and effectiveness of the proposed control strategy are verified by experimental analysis on the DC microgrid hardware-in-the-loop experimental platform.

By optimizing the design of the conventional low-voltage current limiting controller (VDCOL), the continuous commutation failure on the receiving end of the traditional LCC-HVDC transmission system is effectively suppressed. In order to overcome low insensitivity of conventional VDCOL under mild and moderate faults, the dc current deviation value is superimposed into the starting voltage of the VDCOL in the form of a compensation voltage to enhance sensitivity of the VDCOL to the dynamic changes of the dc current during mild and moderate faults. In the face of severe faults, the conventional VDCOL adopts a linear adjustment method with a fixed slope, which is bad for suppressing continuous commutation failure. Aiming at this problem, a nonlinear VDCOL strategy is adopted, which the dc current command and the dc voltage are a nonlinear function relationship with a variable slope with the increasing or decreasing of the dc voltage. In the PSCAD/EMTDC simulation platform, the proposed control strategy is verified using the International Council on Large Electric Systems (CIGRE) standard model. Simulation results reveal that the proposed nonlinear VDCOL strategy with improved voltage compensation method can well suppress continuous commutation failures in the case of single-phase and three-phase short-circuit faults, and it is beneficial to restore dc voltage and transmission power and ensure the normal operation of the HVDC transmission system.

The insulated core transformer (ICT) power supply is widely employed in electron beam accelerators (EBAs) due to its high power, heightened efficiency, and stable operation. However, the segmented-core structure of the ICT power supply increases magnetic leakage, which leads to it adversely affecting the consistency of the output voltages in the rectifier stages. Currently, numerous studies focus on stage voltage compensation, including turns compensation, capacitor compensation, dummy primary winding compensation, and full-parameter compensation. This paper presents a unified simulation model and an improved gradient-based genetic algorithm, which can also optimize the parameters of the four compensation methods. Based on this, the performance of the power supply using the four compensation methods under different ICT energy levels and power supply requirements is studied, and the selection suggestions are given. This work fills the gap in the performance comparison and application research of various compensation methods.

Copyright of Electric Drive is the property of Electric Drive Editorial Office 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 work presents a method of voltage insertion into the grid with harmonic distortions through a dynamic voltage restorer (DVR) for protection of sensitive loads to short-term voltage sags. The aim is to recover the nominal voltage level at the load by restoring only the fundamental frequency component without compensating the harmonic contents. Corrections carried out in this manner are justified as the DVR is a device dedicated to restore the amplitude of the sensitive load to its rated value, based on rapid variations from the power grid. The correction of distortions is not suitable for this equipment as harmonics are permanent problems and originate from nonlinearities of electrical loads. Therefore, the batteries that supply the DVR do not support the correction of permanent problems, only for rapid variations. Thus, it allows an extension in the lifespan of the batteries (needed in this type of compensator). Collaterally, restoring only the fundamental decreases the total harmonic distortion of the load, thus allowing this method to make a double contribution to improving the system's power quality. For this purpose, a recursive least-square estimation is developed, suitable for voltages with harmonic content, here called HRLS. The construction of the reference voltage to be produced by the DC–AC converter also considers the synchronism with the fundamental component of the grid, which allows an optimization of the voltage level used on the DC-link. Correction scenarios only inserting the fundamental, as well as with harmonic content, are tested in simulation to compare performance in the use of the compensator power. The same scenarios are also tested on an experimental platform developed in the laboratory to confirm the proposal. [ABSTRACT FROM AUTHOR]

This paper explores new design methods for correcting unbalanced power distribution networks in order to improve the power quality and reliability for sensitive industrial loads. While traditional compensators typically need to be connected to all the three phases of the AC network, this paper proposes a novel three-phase voltage balancing compensator that can operate with a connection to only two of the three phases. The new concept is based on the phasor symmetrical component theory, which can be implemented using either mechanically switched reactors (MSRs), TCRs (thyristor-controlled reactors) or VSCs (Voltage source converters). Three methods are presented to calculate the value of the proposed two-phase compensator, i.e., discrete solution, analytical solution and novel simplified solution. The discrete solution is solved via the exhaustive search method, which was successfully used by StruthersTech to correct the power quality of an unbalanced industrial power system. The analytical solution is based on the nodal voltage of analysis method. The simplified solution derives a practical albeit approximated relationship between the negative sequence source voltage and zero sequence load voltage, thus avoiding the need to solve nonlinear equations. Dynamic simulations are implemented using MATLAB/Simulink Simscape Blockset to validate the effectiveness of the proposed two-phase voltage balancing method.

This article presents a control scheme that simultane-ously solves the problems of negative-sequence voltage compensation and negative-sequence current sharing in grid-connected microgrids using grid-feeding inverters. State-of-the-art schemes have previously solved these problems with low-performance control solutions or, alternatively, with high-performance solutions but paying the cost of high control-data traffic in the communication network. The proposed control scheme improves the performance of previous schemes for grid-feeding inverters with the following characteristics: 1) negative-sequence voltage compensation at any point of the microgrid, 2) accurate negative-sequence current sharing, and 3) low control-data traffic. In terms of implementation, two key points of the proposed control scheme are: the voltage compensation is based on a band-pass filter with complex coefficients and the current sharing is reached only with local current measurements. In the theoretical analysis, the system model is based on transfer functions with complex coefficients. This fact facilitates the control design due to 1) the system model is linear in this complex domain and 2) the multiple-input single-output model can be represented as a single-input single-output model for voltage compensation. The characteristics of the proposed control are validated by means of experimental results measured in a laboratory microgrid. [ABSTRACT FROM AUTHOR]

Copyright of Electric Drive is the property of Electric Drive Editorial Office 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.)

To meet the augmented load power demand, the doubly-fed induction generator (DFIG) based wind electrical power conversion system (WECS) is a better alternative. Further, to enhance the power flow capability and raise security margin in the power system, the STATCOM type FACTS devices can be adopted as an external reactive power source. In this paper, a three-level STATCOM coordinates the system with its dc terminal voltage is connected to the common back-to-back converters. Hence, a lookup table-based control scheme in the outer control loops is adopted in the Rotor Side Converter (RSC) and the grid side converter (GSC) of DFIG to improve power flow transfer and better dynamic as well as transient stability. Moreover, the DC capacitor bank of the STATCOM and DFIG converters connected to a common dc point. The main objectives of the work are to improve voltage mitigation, operation of DFIG during symmetrical and asymmetrical faults, and limit surge currents. The DFIG parameters like winding currents, torque, rotor speed are examined at 50%, 80% and 100% comparing with earlier works. Further, we studied the DFIG system performance at 30%, 60%, and 80% symmetrical voltage dip. Zero-voltage fault ride through is investigated with proposed technique under symmetrical and asymmetrical LG fault for super-synchronous (1.2 p.u.) speed and sub-synchronous (0.8 p.u.) rotor speed. Finally, the DFIG system performance is studied with different phases to ground faults with and without a three-level STATCOM.

This paper presents a fractional-order sliding mode control scheme based on an RBF neural network (RBFFOSMC) for a direct three matrix converter (DTMC) operating under unbalanced grid voltages. The RBF neural network (RBF NN) is designed to approximate a nonlinear fractional-order sliding mode controller. The proposed method aims to achieve constant active power whilst maintaining a near unity input power factor. First, an opportune reference current is accurately generated according to the reference power and the RBFFOSMC is designed in a dq reference frame to achieve a perfect tracking of the input current reference. An almost constant active power, free of low-frequency ripples, is then supplied from the grid after compensating for the output voltage. Simulation and experimental studies prove the feasibility and effectiveness of the proposed control method. [ABSTRACT FROM AUTHOR]

These days, demand for small volume and low cost of the home automation device is getting higher and higher. Converter with single-stage scheme has advantages of simple structure, low cost, and small theoretical volume, but it often suffers bad output accuracy in low output voltage applications. This brief proposes a constant voltage compensation circuit for AC/DC converters to improve the output accuracy which can also be used in a BUCK AC/DC converter with low output voltage. To verify the feasibility of the proposed compensation method, a BUCK controller based on the proposed circuit is implemented in Episil $0.5~\mu \text{m}$ /40V-HVCMOS process and occupies a die size of $0.99{\times }0.8$ mm2. By the help of the proposed circuit, the output accuracy of the prototype with single-stage structure, which has advantages of small volume and low cost, can reach as high as those converters with multi-stage structure. Test results show that the load regulation of the prototype is about 1.3% with 3.3V output and less than 0.9% with 5V and 12V outputs. [ABSTRACT FROM AUTHOR]

Copyright of Electric Drive is the property of Electric Drive Editorial Office 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.)

The traditional V–I droop control is commonly used to realize current sharing among distributed generators (DGs). Provided that the influence of line resistance cannot be neglected, there exists a trade-off between voltage deviation and current sharing accuracy when designing the droop coefficient. An adaptive nonlinear droop control in the DC power system with constant power load (CPL) is proposed in this paper to achieve accurate current sharing among source converters and reduce the DC bus voltage deviation. In the proposed method, the output current is shared among neighboring source converters via a low-bandwidth communication (LBC) network to adaptively adjust the dynamic regulation coefficient, which is equivalent to the droop coefficient adjustment. The correctness and effectiveness of the proposed method have been preliminarily verified via the simulation of two source converters and a single CPL based on Matlab/Simulink and further validated by the hardware-in-the-loop (HIL) experiment based on Real-Time Laboratory (RTLab) and DSP F28335 with the LBC network implemented by enhanced controlled area network (eCAN) in DSP F28335. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd 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.)

To effectively mitigate the commutation failure (CF) of the line-commutated converter high-voltage direct current (LCC-HVDC) transmission system, a dynamic series voltage compensator (DSVC) scheme is proposed. The DSVC consists of three integrated gate-commutated thyristor (IGCT)-based full-bridge submodule (FBSM) chains to match the bulk power transmission of the LCC-HVDC. Inserted between the transformer and the AC port of the inverter, the DSVC assists the commutation process by superposing the transient voltage to the AC line voltage and increasing the commutation margin of the inverter valve. Operation and control strategies, which are two critical techniques for the DSVC, are designed based on the working states of the FBSMs, assisting the commutation process and balancing the DSVC capacitor dynamic voltages. The CF detection method is another critical technique of the DSVC control and is improved considering the reverse time of the LCC-HVDC thyristors. Compared with the topologies proposed in existing literature, the DSVC has better performances in safe and stable operation due to the urgent control strategy considering situations beyond its ability. A detailed EMT simulation shows that the DSVC can respond quickly to mitigate CFs and validate the effectiveness of the overall design and key techniques. Furthermore, the operation and control strategy can limit the current stress once it is beyond the capability of the DSVC, which guarantees its feasibility and practicability. [ABSTRACT FROM AUTHOR]

In this article, Asymmetrical voltage source Multilevel Inverter based Transformerless Dynamic Voltage Compensator (ASMLI-TDVC) for load Voltage Quality (VQ) enrichment is proposed. The ASMLI-TDVC is controlled such that it compensates different levels of VQ problems with lesser Total Harmonic Distortion (THD). Synchronized voltage injection achieved through series transformer from traditional DVC leads to rise in the size of DVC and make system cumbersome. ASMLI based on less switch count topology is utilized for TDVC to overcome these aforementioned issues. Simulation studies of ASMLI-TDVC are carried out using Matlab Simulink software. Further, an experimental model is developed and tested in real-time using OP4500. Results prove that dynamic compensation for VQ improvement is achieved by ASMLITDVC. [ABSTRACT FROM AUTHOR]

In the application of electric railway traction, induction machines may suffer momentary power interruptions. Restarting control while machine running is a critical part of such applications, but residual flux in the free-running rotor deteriorates conventional controller performances, leading to inrush current and torque impact. Thus, this article proposes an improved feed-forward current controller that compensates voltage variations in the restart process. The residual rotor flux, as well as the induced back electromotive force, is estimated only with the measured speed in the free-running stage. The exact electromotive force is compensated at the restart moment, and the following current re-establishing stage. Based on the feed-forward compensation, the restart impact is eliminated and the restart current is controlled accurately in the predefined trajectories. Verified by experiments, the restart controller provides flexible restart manipulations. [ABSTRACT FROM AUTHOR]

In this study, power quality (PQ) improvement has been addressed, in the form of total harmonic distortion (THD) minimisation, as well as, voltage regulation using two cascaded schemes. The first scheme is the optimised triple action controller (TAC)‐based pulse width modulated voltage source inverter. TAC consists of a proportional resonant controller, selective harmonic compensator, and a new added current‐assisted feed forward controller. The second scheme is the optimised cascaded dual‐level control of a standalone microgrid. Cascaded level control consists of droop, secondary, and synchronisation control loops. The two approaches have been optimised for best parameter selection out of the possible solution space using a particle swarm optimisation algorithm to satisfy the study objectives. The optimisation objectives/constraints were to minimise THD and minimise overshoot/undershoot, rise time, and steady‐state error for voltage compensation under two disturbance scenarios, sudden load change, and voltage flicker injection as a power frequency disturbance. These research results have been compared to other existing simulation and experimental work. The results proved to be better in output voltage, frequency, response time, and THD. Furthermore, the proposed schemes ensure power factor improvement, high efficiency, overall system PQ, and reliability at various load conditions. [ABSTRACT FROM AUTHOR]

Insulated core transformer (ICT) electron accelerator offers many advantages including high efficiency of energy conversion, high-power output, low cost, and high reliability. It is a superior type of E-beam systems for the radiation processing in the low energy region (<1MeV). The ICT power supply is the core component of the electron accelerator. The structure of the ICT cores is segmented, and it results in large magnetic flux leakage at the gaps between the cores. Therefore, the output voltages of different disks are non-uniform, which highly affected the performance of the ICT power supply. In order to reduce the non-uniformity caused by the magnetic flux leakage, a hybrid compensation method with optimizing the number of turns in secondary windings and adding dummy primary windings is presented in this paper. The compensation scheme is designed for an 800kV/50mA ICT power supply. The result shows the consistent output high voltage of disks is achieved and the non-uniformity is ≤ 6.5% from no-load to full-load when the output high voltage is 800kV. This design effectively improves the uniformity of the electrical field distribution, increases the utilization of the rectifier components and reduces the size of the power supply. [ABSTRACT FROM AUTHOR]

At present, more and more communication-based methods are proposed for reactive power adjustment in islanded microgrid (IMG). However, the use of communication data will inevitably cause communication problems, for e.g., delay, packet loss, and communication failure. Among them, the random communication failure (RCF) is common and harmful. To realize the stable operation of IMG and the rational sharing of reactive power under the consideration of this problem, a cyber-physical cooperative hierarchical control strategy is proposed in this article, which include cyber and physical layers in control structure. In these two layers, the main designs are as follows. In the cyber layer, to solve the RCF problem, we have designed the corresponding observer, controller, and prediction compensation part; and to improve the frequency stability, a secondary control method is designed. In the physical layer, to share reactive power reasonably, a reactive power control method based on synchronous voltage regulation is proposed; to suppress the possible disturbance in the data used in the physical layer, a novel sliding-mode controller is designed; and to improve the voltage stability during adjusting power, a voltage compensation strategy is proposed. The effectiveness of proposed methods is finally verified by experiments. [ABSTRACT FROM AUTHOR]

This study introduces a distributed secondary control method‐based adaptive pinning control for inverter‐based distributed generations (DGs) in an isolated microgrid (MG) structure with frequency and voltage compensation and power sharing. Without MG centre controller or energy management system, local DGs' controllers have no global information of the whole communication network, which is the second smallest eigenvalue of the Laplacian matrix. In practice, the large coupling weight gains are mostly selected. However, a sufficient large coupling weight may cause instability. It is difficult to choose the coupling weight in the fully distributed complex network. To solve the above problems, the authors investigate a pinning control for synchronisation using the local adaptive pinning algorithm on coupling weight gains. The proposed method has the advantage that the consensus controller design is independent of the Laplacian matrix associated with the communication network. And the collective dynamics of the communication network can be adjusted to steady states without global information. However, the adaptive pinning control scheme is not suitable for the multi‐disturbance situation, which will accumulate the coupling weight and even cause integral saturation. Therefore, an improved strategy is proposed to adapt to the load changing conditions for islanded MGs. [ABSTRACT FROM AUTHOR]

This paper presents a new control algorithm for a distribution static synchronous compensator (DSTATCOM) based on consumer's voltage unbalance assessment. The proposed controller quantifies, in real time, the parcels of voltage unbalances due to the supplier (utility) and consumer by using local measurements of voltages and currents. The compensator mathematical model is used to derive small signal models in such a way to design controllers to compensate for the negative sequence voltage caused by a consumer. Two inner control loops, designed in synchronous reference frame, assure the DSTATCOM tracks the reference signals generated by the voltage controllers. Digital simulation results obtained with an unbalanced distribution network are used to validate the proposed methodology. The comparison of the results shows that the capacity of the compensator can be significantly reduced when only the unbalanced voltage portion caused by the load is compensated. [ABSTRACT FROM AUTHOR]

The article presents an active bridge system that enables the solution of a significant problem consisting in ensuring correct indications of temperature values in a wide measuring range for a Pt100 temperature sensor with properties defined by the standard (EN-60751 + A2). The presented active bridge system combines the properties of the measuring amplifier with the stabilization of the current value in the branch in which the Pt100 sensor was placed. The article focuses on the comparison of the temperature measurement in a typical resistance bridge and the measurement made in the developed active bridge, which has also become the subject of a patent. For the performed tests, in which the correctness of the temperature measurement system operation was verified, and on the basis of the obtained results, the quality of temperature measurements was compared in a wide range of changes.

This paper proposes a power electronic module that uses a switched capacitor for retaining the integrity of the dc-link voltage of a variable speed drive (VSD) during a 0.2 s short-term power interruption (STPI). Ride-through was achieved through switched capacitor onto the dc bus. However, this technique presents a challenge of the high inrush currents during a ride through compensation. In this work both analytical and experimental investigations were conducted in order to reduce the in-rush currents and its impact on the performance of the VSD during the STPI. Inrush peak currents were reduced by approximately 90%. Experimental results showed torque pulsations of 12.8% and 14.3% at the start and end of dc-link voltage compensation, respectively. A method for sizing the switched capacitor and the inrush limiting resistors is proposed. This methodology is based on the use of readily available nameplate information of the VSD and the electric motor. The proposed module can be retrofitted to existing VSDs that are based on v/f control.

A real-time control platform progressed for the power quality (PQ) change in a conveyance framework has been displayed in this paper. A DSP-based control platform is demonstrated for voltage sag compensation for dynamic voltage restorer in conjunction with a voltage source inverter (VSI) to enhance PQ. The output of VSI is controlled by activating IGBTs by SPWM control technique. A driver circuit is developed along with a filter circuit to compensate load voltage when sag occurs in a distribution system supplying a sensitive load of single-phase induction motor. The developed control platform has been asserted with a DSP processor TMS320F28027F, and its effectiveness has been shown by carrying a few experiments. [ABSTRACT FROM AUTHOR]