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This paper presents the performance analysis of a five-level T-type multilevel inverter (MLI) based six-phase induction motor drive (SPIMD) for high-power industrial applications. In the adopted T-type MLI, the sensorless self-capacitor voltage balancing control is designed, which controls the voltage across the capacitor at half the magnitude of the direct current (DC) source value, creating a symmetrical five-level output voltage waveform. Moreover, self-capacitor voltage balancing control reduces complexity and improves system performance. The SPIMD with distributed neutral is taken as the load, and the whole system is simulated using MATLAB/Simulink software. The system's performance is determined by considering the power loss and efficiency. This paper also presents a comparative performance analysis of the adopted T-type, cascaded h-bridge (CHB) and Flying Capacitor (FC) MLI-based SPIMD. Finally, a prototype is developed as a proof of concept and tested experimentally to validate the analytical development of the adopted system. [ABSTRACT FROM AUTHOR]

This paper designs a novel coordinated control scheme to improve the control performance of voltage source converters (VSC) based multi-terminal high voltage direct current (MTDC) transmission network by merging the benefits of adaptive drooping and voltage margin controllers. In this proposed scheme, the droop coefficient is used to manage the DC voltage and maintain power sharing by shifting the control modes of the rectifiers and inverters in the presence of considerable power disturbances. The droop coefficient is planned based on the stability limit of DC voltage. The performance of the designed control scheme is compared to that of existing coordinated control and voltage margin droop control approaches. A ±400 kV five-terminal VSC-MTDC network is developed in PSCAD to verify the planned control method. The simulation results indicate that the proposed control scheme can achieve good performance for controlling the DC voltage and maintaining active power in the MTDC system. [ABSTRACT FROM AUTHOR]

The variable DC link direct torque control (DTC) for induction motors was proposed in this paper utilizing an artificial neural network (ANN). Variable DC-link voltage is utilized as the inverter's controlling input to improve the induction motor's performance. By injecting the dynamically variable dc-link voltage, inverter switching losses are decreased and inverter efficiency is increased. Two significant limitations are the torque ripple in DTC and the speed regulation of induction motors at low speeds. The driveline of an electric vehicle is modeled, and the suggested control is put into practice to enhance low-speed speed regulation, high dynamic performance, and minimal torque ripple. With variable DC-link voltage based on ANN, an improvement in torque and speed is made possible. Additionally, the suggested strategy minimizes the current ripples. To verify the improved efficacy of the electric driveline under various operating scenarios, a proposed control of the electric driveline is implemented using MATLAB SIMULINK, and the results are compared with the conventional scheme. The recommended speeds for the three speed ranges are as follows: 300 rpm for low speed, 900 rpm for medium speed, and 1275 rpm for high speed. The torque ripples decreased from 0.39 to 0.24 in the low-speed region, 0.38 to 0.24 in the medium-speed region, and 0.36 to 0.24 in the high-speed region while the motor was operated at a constant load torque of 2 N-m. The torque ripples decreased from 0.4 to 0.274 in the low speed region, 0.4 to 0.274 in the medium speed zone, and 0.2 to 0.274 in the medium speed region when the motor operated at various speed regions with a constant load. The main effect of running the motor at different load torques, such as 1.5 N-m, 2.5 N-m, and 2.0 N-m, is shown in Table 9 and numerical data of torque ripples is presented in Table 9. [ABSTRACT FROM AUTHOR]

The two-stage power converter is currently the most widespread topology for three-phase grid-connected photovoltaic (PV) systems. The PV power is injected to the grid through the regulation of the dc-link voltage. This method is commonly called the voltage control method, whereby the current is controlled indirectly. This paper focuses on the modelling of power converters and the parameter design of proportional-integral (PI) controllers, based on the bandwidth of the inner current loop and the outer voltage loop. It is assumed that the inner loop has a bandwidth that is ten-fold bigger than that of the outer loop, in order to fully decouple the dual loops. The PI parameters are thus determined through this relationship, and two sets of simulations are run to validate the methodology used. Results show that the controllers give highly satisfactory performance even in the presence of transients introduced by rapidly varying irradiance model. [ABSTRACT FROM AUTHOR]

This paper reports the optimization of voltage controlled resistive switching devices in terms of device and circuit level parameters in a memristor-based circuit in order to demonstrate profound non-linear characteristics for high performance NVM applications. The pinched hysteresis loop has been correlated to the different stages of formation and rupture of conductive filaments in memristors. A qualitative study of the VTEAM model has also been presented. The memristor circuit has been simulated for varying device and circuit level parameters and options to optimize the circuit to achieve high degree of power-aware non-linearity in the characteristics of the memristor have been demonstrated in this paper. The effect of window functions on the non-linear behavior of memristors has been presented towards the end of the paper. [ABSTRACT FROM AUTHOR]

The power system network is complex and diverse in nature because of the random and irregular existence of renewable sources, various types of varying and constant loads. Under these circumstances, the stabilization of DC link voltage and obtaining reduced power fluctuations are the main control aspect of DC microgrid (MG) system. This paper explores a Kalman filter (KF) based voltage–current control algorithm for the battery unit to control the medium voltage direct current (MVDC) bus voltage accurately with trivial oscillations as compared to the traditional VI algorithm. The stability and monitoring of DC microgrids are greatly influenced by gathering sufficient and precise information. Since installing several sensors on DC MGs is costly and increases DC MG ripple. In this work, an extended Kalman filter (KF) is used to estimate the current of the lead-acid battery. Hence the current represents an important factor in guaranteeing safe operations. Where the Kalman Filter, which improves the estimation efficiency, to reach a good performance in the current prediction. By updating the proposed approach provides smooth and noise-less operation from the measured DC voltage. The control strategy established for electric vehicle (EV) in this paper is to improve the overall charging ability of the EV only if the system's total power is greater than the load level by means of the current loop management technique. The feasibility of the designed MG system with the established battery management mechanism and the Escape Ford EV performance is studied using MATLAB/Simulink platform. [ABSTRACT FROM AUTHOR]

Finite control set model predictive control (FCS-MPC) has recently been applied to solve the real-time measurement problems of DC-Microgrid (DC MG). The details of DC MG stochastic modeling have not been presented through the discretization of DC/DC converters that approximate the DC MG stochastic model. Additionally, a detailed description of the simulations and real-time verifications is not included. In this paper, we propose an improved FCS-MPC that provides details stochastic model of DC MG via validations. The proposed approach utilizes the linear Kalman filtering algorithm (LKFA) via the DC MG stochastic average dynamic equation model. The model has been approximated using LKFA and the DC MG stochastic model. The stochastic FCS-MPC handles the real-time information required to achieve the proposed approach. A highly effective algorithm is presented that allows a sample time to be executed for the operation of the DC MGs in the second prediction model. A DC grid estimated voltage reference has been developed using LKFA, state feedback regulation, and integral action. By using the reference, DC grid voltage estimation and currents are regulated via a weighted expected cost function, and provide equal power sharing capability. Improved FCS-MPC effectiveness was evaluated through Simulink simulation and real-time validation. [ABSTRACT FROM AUTHOR]

This paper discusses a multiarea multi-source system in combined automatic load frequency control (ALFC) and an automatic voltage regulator (AVR) model. The multiarea system comprises thermal and wind in Area-1, thermal-geothermal in Area-2, and hydrothermal plant in Area-3. Appropriate nonlinearity constraints are provided for both hydro and thermal plants. A maiden attempt has been made to employ a cascade proportional-derivative (PD) with filter coefficient (N) and PID with filter coefficient (N) (CPDN-PIDN) as a secondary controller in the combined ALFC-AVR system and optimized controller gains using artificial flora algorithm (AFA). It is examined that the CPDN-PIDN controller yields better dynamics responses than the PI and PIDN controllers. Analyze reflects that the system performance enhanced in the presence of AVR loop. This paper discusses the effect of renewable sources like wind and geothermal on the system dynamics. Analysis reveals that the geothermal power plant is more reliable than the wind plant. The parameter variations of the temporary and permanent droop and hydro turbine time constant (HTTC) of the hydro plant are examined through system responses. System response deteriorates significantly as permanent droop and HTTC are reduced. Peak overshoot and undershoot are reduced considerably as the temporary droop value is increased. Sensitivity analysis reveals that the AFA optimized CPDN-PIDN controller parameters obtained under the nominal condition are resilient enough and need not be reset with the system's substantial random variation. An experimental justification has been provided of the investigated system using a real-time simulation with the OPAL-RT OP4510 real-time setup. [ABSTRACT FROM AUTHOR]

This paper introduces a current regulator for a three-phase Neutral-Point Clamped rectifier. The current regulator maintains power quality parameters at both sides of the rectifier for any perturbed conditions. The controller adapts itself according to any change in load or supply voltage. The current controller senses the DC-bus potential difference and modifies the input controlling signals to generate desired gate pulses for driving the converter efficiently. Simulation results exhibit the effectiveness of the newly proposed control technique under various operating conditions. [ABSTRACT FROM AUTHOR]

Traditional central control system is unable to deal with the optimal control tasks of modern distribution networks due to its low reliability, high computation and communication burden and poor expansibility. Based on distributed collaboration principle, this paper presents a multiple-object distributed optimisation control strategy for distribution network utilising DG grouping method. Distributed control strategy for node voltage control group is developed by taking the capacity utilisation ratio (CUR) of DG as the consensus variable, to comply with the feature of high resistance/reactance ratio of distribution network feeder line. Distributed control strategies for exchanged power control groups, which respectively takes CUR and power factor as the consensus variable, are formulated according to the different conditions of exchanged power imbalance. The parameter tuning method for three kinds of distributed optimisation control strategies are presented. The correctness and effectiveness of the proposed method are verified by simulation examples in the IEEE 14-node system, and simulation results on the IEEE 33-node test system are presented to show the robustness of the method to the disturbances related with distributed generation. [ABSTRACT FROM AUTHOR]

This paper presents a Multi-stage Switch Inductor Switch Capacitor High Gain DC-DC Converter for microgrid application designed with integrated Active Switch Capacitor (ASC) and Active Passive Inductor Cell (APIC). The closed loop control of a proposed voltage lift DC-DC converter is performed to ensure the constant output voltage disregarding the change in input voltage. The new high gain extendable DC-DC boost converter topology is capable of providing high-gain voltage with low duty cycle and it is extendable by increasing the number of APIC network. Analytical modelling of the proposed converter is carried out to obtain the technical specifications. The open loop and closed loop simulation model of the proposed converter is developed in the MATLAB/Simulink environment to analyse the performance of the converter. The microcontroller-based hardware model of the proposed converter of power rated 200 W (18/200 V at 50% duty ratio) is developed and tested in open loop to validate the simulation results and experimental set-up results are reported. [ABSTRACT FROM AUTHOR]

In this paper, a maiden application of combined voltage and frequency control ensures voltage, frequency, and power regulation in diverse standalone low voltage AC microgrid (MG) networks by combining flexible improved droop control (IDC) with a novel fractional-order controller (FOC) proposed. An effort is made to design an IDC into the control loop based on virtual power, virtual negative resistance, inductance, and FOC to ensure power decupling and compensate voltage source converter (VSC) based distributed generators feeder voltage drop. A maiden proportional fractional integral derivative filter plus double derivative (P I λ D F D 2) controller is used to precisely monitor VSC voltage and current reference value for reducing the control errors. The controller robustness regarding system parameters uncertainties, unmodeled dynamics, and disturbance in the MG system is ensured by a new memetic salp swarm algorithm by finding optimal P I λ D F D 2 controller parameters. Several simulation studies in the MATLAB Simulink environment were conducted to verify the efficacy of the proposed technique. The suggested control methodology is also investigated by hardware in the loop using the OPAL-RT real-time simulator platform to demonstrate the controllers practical functional realization. The findings confirmed the efficacy of the proposed strategy. [ABSTRACT FROM AUTHOR]

This paper presents a path-finder algorithm (PFA) of meta-heuristic optimization for the performance enhancement of the bias compensated normalized maximum correntropy criteria (BCNMCC) based voltage source converter (VSC) control for a three-phase three-wire grid-tied dual-stage PV system. The DC link voltage ( V DC ) variations during induced dynamic conditions are minimized by PFA optimized PI controller which also generates an accurate loss component of current ( I d1 ) for enhancing the VSC control performance. The BCNMCC algorithm effectively performs the system identification and echo cancellation in the presence of Gaussian noises. An accurate I d1 improves the VSC ability to accurately extract the fundamental load current component and to produce precise weight signals. The BCNMCC performs multifunctional operations, i.e., reactive power compensation, harmonics elimination, load balancing, and power balancing at point of common coupling during steady-state and various dynamic conditions, i.e., grid-islanding & re-synchronization, irradiation variation, unbalanced load and fixed power mode. The proposed system is capable of operating under grid-tied and isolated mode due to the seamless transition of a VSC control from grid current control (GCC) to voltage control. The seamless transition of VSC control does not induce any major transients at the source and on the load side of the system. The hybrid energy storage system (HESS) with a battery, fuel-cell and ultra-capacitor further improves the reliability of the PV system and the stability of the overall system during both grid-tied and isolated operations. The proposed system performs satisfactorily under steady-state and diverse dynamic states as per IEEE519 standards. [ABSTRACT FROM AUTHOR]

In this paper, a novel and simplified model representing current-output phase-shift full-bridge DC-DC LCLC resonant converter in arc welding application is thoroughly presented. First, a switched model written in state space representation and featuring a bilinear form is proposed. The latter facilitates the derivation of both the reduced and full order averaged models in continuous conduction mode (ROAM and FOAM). Although the FOAM can be employed in linear or nonlinear control schemes and the derivation of steady state behavior, in this paper the ROAM is considered in designing both voltage mode control and current mode control by using the classical PID and the fractional order PID controllers. Simulation confirms that the switched model, ROAM and FOAM are quite accurate compared to the circuit simulation using SimPowerSystem toolbox of MATLAB/SIMULINK. Results clearly showed that depending on the switching frequency, the proposed topology can be applied either in constant voltage characteristic or dropped characteristic welding machines fulfilling either zero current Switching (ZCS) or zero voltage switching (ZVS). Besides, the fractional order PID controller seems to be more adapted for arc welding application than its traditional version. [ABSTRACT FROM AUTHOR]

Controlling of voltage and frequency in the microgrid is a challenging issue and many controllers are suggested for this purpose. Proportional-Integral-Derivative (PID) controller is simple and efficient when its coefficients are optimally adjusted. Recently, evolutionary algorithms are used to optimally adjust the PID coefficients. In this paper, four evolutionary algorithms, particle swarm optimization, genetic algorithm, imperialist competitive algorithm and selfish herd optimization, are applied to set the PID controller coefficients and tested in the frequency and voltage control of the microgrid. Settling time, overshoot and stability margin are three main factors in the control response of PID which are considered for generating the fitness function to be optimized in terms of the PID coefficients. The proposed microgrid includes inverter-based distributed generators and different loads. Load change and different faults may cause the degradation of frequency and voltage where using of the PID controller leads to better control of these parameters. Simulation results show the efficiency of all four algorithms where particle swarm optimization performance is better than other three algorithms. Experimental results also verify the simulation results discussed in the paper. [ABSTRACT FROM AUTHOR]

This paper deals with unified method of voltage and frequency control of an interconnected three unequal-area systems with the Automatic Load Frequency Control (ALFC) and Automatic Voltage Regulator (AVR) loop. Every area comprises a reheat thermal and the combined cycle gas turbine (CCGT) plant. Concerning the pragmatic system, adequate governor dead band (GDB), boiler system, and generation rate constraint (GRC) are considered in all individual plants. The Tilt-Integral-Derivative with Filter (TIDF) controller is considered in the ancillary controller of the ALFC loops, core controller of the AVR loops, and air-flow, temperature controller of the CCGT Plants. The optimized controller gains are realized through the metaheuristic algorithm called Harris Hawks Optimization algorithm along with the integral square error as a performance index considering a 1% step load perturbation in Area-1. The critical analysis shows that the performance of the TIDF controller is superlative to the classical controllers, such as PI and PID, concerning all time-domain indices. With the TIDF controller, the impacts of the AVR loop, boiler system, and the CCGT plants are analyzed on the unified ALFC and AVR study separately. Sensitivity analysis unveils the sturdiness of the TIDF controller against the change in magnitude of the step load perturbation in Area-1. Finally, the proposed unified ALFC and AVR system of three unequal-area CCGT-thermal plants is analyzed with the OPAL-RT hardware set-up for its real-time validation. [ABSTRACT FROM AUTHOR]

This paper presents a novel architecture of femto power-delay super threshold voltage level shifter (LS) for network on-chip voltage control, developed using feedback topology for error aware interconnections data transmission. The proposed LS utilises eight MOS transistors with low aspect ratios for level up or level down. The developed LS can shift as low as 0.12–1.25 V with a tremendous reduction in delay and power consumption. Implemented in 65 nm CMOS technology, the post-layout simulation substantiates the achievement of voltage translation. The proposed LS incurs energy per cycle of 44 fJ during up shift; the average of level up and level down static power consumption is 3.61 nW, while VDDL is 0.3 V and VDDH is 1.2 V at a frequency of 1 MHz. The layout area of the proposed LS is 3.21 µm × 2.13 µm. [ABSTRACT FROM AUTHOR]

This paper discusses the modelling and control of a combined load frequency control (LFC) and automatic voltage regulator (AVR) system for a multi-area power system network with each generating area includes thermal, diesel, and solar thermal power plant. Superconducting magnetic energy storage is incorporated with the LFC loop to provide auxiliary control against instantaneous changes in active power demand. Model Predictive Controller (MPC) has been employed in this study to improve the performance of AVR and LFC loops, and controller weights are fine-tuned with the help of Harris Hawks Optimization (HHO) approach. The effectiveness of the proposed MPC-HHO algorithm has been examined by comparing its transient performance indices with that of conventional MPC, PID, FOPID, fuzzy PID, integral double derivative with derivative filter controller as well as Particle Swarm Optimization and Sine Cosine Algorithm based Model Predictive Controllers. The proposed MPC-HHO controller gives superior results than the above-mentioned controllers. [ABSTRACT FROM AUTHOR]

This paper presents an interval type-2 fuzzy logic (IT2FL) controlled single-phase enhanced power quality-based photovoltaic distributed generation (PVDG) system. The objective of this paper is to develop a PV inverter with the features of real power injection and power quality enhancement (PQE) capability such as reactive power compensation and grid current harmonics reduction at the point of common coupling (PCC). To overcome the problems of conventional controllers requiring intricate mathematical model, an IT2FL controller (IT2FLC) is proposed for the dc-link voltage control. A prototype model of the proposed system is developed in the laboratory and is tested with the help of dSPACE DS1104 platform. Finally, the performance of IT2FLC-based PVDG system is compared with a conventional PI-based PVDG system on the basis of both simulation and experimental results. [ABSTRACT FROM AUTHOR]

Stand-alone photovoltaic systems (SAPs) based on three-phase inverters have found high attention, recently. However, unbalanced loading condition is inevitable condition for these inverters. To prepare a current flow for inevitable fourth wire current, four-leg inverter is a beneficial solution. To sinusoidal load voltage shaping, the control method is very important since it must maintain three-phase balanced sinusoidal load voltages. Among different linear and non-linear control methods, deadbeat (DB) method offers high simplicity as well as good accordance for digital implementation. But, it suffers from two sampling period delay which deteriorates the load voltage quality and sometimes results in instability of the control system. In this paper, new DB control method with delay compensation strategy is proposed which not only have the usual benefits of the DB control method but also it overcomes the aforementioned weakness. Finally, a 3 kW laboratory test bench based on DSP-based digital control board is provided to consider the result of the proposed control methods. Several tests under various inverter loads such as no load, full linear load and 100% unbalanced load are done to evaluate the benefits of the proposed system. [ABSTRACT FROM AUTHOR]

A single-phase two-stage AC/DC/AC converter topology is investigated in this paper, which involves multi-winding transformer-fed multi-cell AC/DC and cascaded H-bridge multi-level (CHBMLI) DC/AC converter stages. Both the converter stages utilize current control using the fixed and uniform switching methods, which simultaneously achieve the regulation of the DC link voltages of all the cells. The proposed control loop for the AC/DC converter stage uses a single-voltage sensor to control the DC link voltages of all the cells using self-voltage regulating property of the multi-winding transformer. This single-control loop uses the feedback of the instantaneous AC current at the primary of the transformer and any one of the DC link voltage to achieve the input AC current control and multiple DC link voltage control. The fixed frequency ramp comparison current control in AC/DC stage of the converter provides a uniform switching cycle among all the units. A phase-shifted multi-carrier PWM (PS-MCPWM)-based fixed frequency current control of the DC/AC converter comprising CHBMLI provides equal loading across all DC links of the AC/DC converter. The results are verified through PSCAD simulations and experimental results are obtained through the LabVIEW FPGA controller implemented for two-cell, five-level converter topology. [ABSTRACT FROM AUTHOR]

The direct torque control (DTC) of permanent magnet synchronous motor (PMSM), which includes flux and torque double closed-loops, requires constant flux and high calculation accuracy. Besides, uncertain flux estimation will cause torque ripples. To solve these problems, in this paper, twelve-sector direct torque control (DTC) without flux closed-loop for PMSM is proposed. To reduce the requirement on constant flux and high calculation accuracy and to simplify the structure of the system, the flux closed-loop is removed from the control system. To suppress the torque ripple, a twelve-sector space voltage vector control scheme is adopted which increases the switch states of the inverter. The number of nonzero voltage vectors is increased from 6 to 12 without increasing the hardware equipment of the system. The sections of the voltage vectors are redefined and the torque ripples are reduced. The hardware-in-the-loop simulation results show the effectiveness and feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

The direct-drive Permanent Magnet Linear Generator (PMLG)-based Ocean Wave Energy Converter (OWEC) generates variable AC voltage, which cannot be directly utilized by the load. This paper presents a two-stage methodology to convert variable AC voltage to a constant amplitude AC voltage. First, a standard rectifier is used to convert variable AC voltage into variable DC voltage. After that, a cascaded buck-boost inverter is employed to achieve the constant frequency AC voltage. Systematic design and circuit analysis, along with working principle and voltage control strategy, are presented. A small scale laboratory prototype of PMLG associated with buck-boost inverter is developed to validate the proposed concept. [ABSTRACT FROM AUTHOR]

The intensity difference between the echo signals from the water surface and bottom during bathymetry LiDAR operation requires a photomultiplier tube (PMT) gain self-adjustment. Otherwise, noise echo signals are collected, while weak and useful signals are not. For this reason, this paper proposes a PMT gain self-adjustment system for the high-accuracy detection of LiDAR echo signals. The developed system uses a field programmable gate array (FPGA) collector as a feedback signal generator, an STM32 controller as the PMT gain and voltage control signal generator and a DA module as the PMT gain voltage conversion circuit. The system controls the PMT gain voltage by judging the feedback signal to achieve PMT gain self-adjustment. The system was verified in an indoor tank, building roof, and outdoor pond experiments. By comparing the experiments, the developed system is shown to detect laser energy intensity with a sensitivity of at least 2.26 times stronger than the traditional system, and can measure water depth at least 2.5 times deeper than the traditional system. Therefore, it can be concluded that the proposed PMT gain self-adjusting system can effectively adapt to the changes in laser energy, improve the measurement of water depth, control the amplitude of the echo signals, increase the accuracy of water depth detection, reduce the saturation of the PMT detector, and protect PMT from damages. [ABSTRACT FROM AUTHOR]

Precise and fast estimation of system frequency during distorted voltage has become the main challenge for phase locked loop (PLL) for wind energy conversion system (WECS). In this paper, moving average filter (MAF)-based PLL is proposed to solve this issue for permanent magnet synchronous generator (PMSG)-based WECS. MAF allows suitable measurement of frequency and eliminates dc offset, harmonics, and unbalance in voltage. Also scheme is able to perform harmonics reduction. Model of the proposed system for simulation is prepared in MATLAB/Simulink and its performance analysis is carried through a comparative simulation study with conventional synchronous-reference-frame (SRF) PLL, adaptive-frequency-loop PLL, type-1 PLL, and type-3 PLL. Simulation results verify that the proposed controller extracts the maximum-power from wind and stabilizes the system voltage and frequency during any variable/distorted working conditions. System performs considerably excellent during dynamic and steady-state condition. [ABSTRACT FROM AUTHOR]

A low-power voltage spike detection (VSD) circuit for a cap-less low-dropout regulator (LDO) is presented in this paper. The LDO is based on the cascoded flipped voltage follower (CAFVF) topology, and the transients in the output voltage are controlled by the spike detection circuits and these circuits get activated only during the transient period. The overshoot voltage spike detection (OVSD) circuit senses the output voltage via intermediate voltage V X and reduces the current through the power MOSFET by charging the gate capacitance C P and restores the output voltage whenever the output voltage rises. The undershoot voltage spike detection (UVSD) circuit directly detects the output voltage and increases the current through the power MOSFET by discharging the gate capacitance C P and restores back the output voltage whenever the output voltage drops. The VSD circuit consumes only a bias current of 9 μ A in the steady state. This LDO is implemented in 180 n m CMOS technology and achieved a good load transient response with 500 n s settling time with the maximum voltage spike of 250 m V over the load current range of 100 μ A to 50 m A. [ABSTRACT FROM AUTHOR]

This paper presents a temperature controlled voltage regulated boost converter for running low power electronics using thermoelectric energy harvesting. The modulation of gate driver clock using different oscillator frequencies in the boost converter and temperature difference across thermoelectric module regulates the output voltage in the converter to different levels. At temperature differences of 22°C, 34°C, and 56°C across the sides of thermoelectric modules, the d.c. voltages of 0.49, 0.7, and 0.87 V from thermoelectric generator (TEG) are boosted to a maximum output of 21.66,41, and 47.54 V across a 10 µF capacitor at 39 kHz gate driving frequency. Further, the output voltage is varied by changing the frequency of pulse across gate. In addition, the converter delivers a maximum output power of 2.26 mW when the supply voltage is 0.87 V from the TEG. The converter also provides regulated power across different load resistances for charging rechargeable batteries. Such sustainable systems may be utilized by converting waste heat from vehicles, sun or factories into desired d.c. voltages useful in electronics. [ABSTRACT FROM AUTHOR]

The Z-source inverter (ZSI) is a prominent single-stage power conversion topology compared to traditional voltage source inverter (VSI)/ current source inverter (CSI). It adds the additional buck–boost capability to input voltage with improved reliability. However, the non-minimum phase (NMP) behavior is the major disadvantage of ZSI due to the existence of the right half plane (RHP) zero in the converter transfer functions. The existences of RHP zero destabilize the wideband feedback loops, which imply high gain instability and introduce the constraints on controller design. This paper presents different types of controllers and its design to maintain the required capacitor voltage with better transient response for non-minimum phase ZSI. Different tuning algorithms have been considered for both proportional–integral (PI), and integral–proportional (IP) control schemes. Also, the unified control algorithm has been implemented with both simple boost pulse width modulation (SBPWM) and a modified space vector pulse width modulation (MSVPWM) schemes to obtain the required capacitor voltage. The converter performance is comprehensively analyzed for different controllers and observations are tabulated. The complete analysis has been carried out using the MATLAB/Simulink environment for the proposed models. [ABSTRACT FROM AUTHOR]

Connecting renewable energy-based distributed generations (DGs) through a DC-Link can create autonomous power supply units (APSUs). Three phase four-leg inverter is a beneficial solution to supply unbalanced loads which is inevitable in a typical APSU. The four-leg inverter can provide sinusoidal-shaped voltages but a high performance control method should be used. Sliding mode control (SMC) is a well-known non-linear control method with high robustness, high stability in a wide range of operation and fast dynamic response. However, it mainly suffers from high chattering problem, variable switching frequency and steady-state error which deteriorate all the previous advantages. In this paper, first, detailed model of the four-leg inverter in the abc reference frame considering the inductor series resistance is derived. Second, a high performance SMC method with zero steady-state error, fixed switching frequency and considerably reduced chattering voltage is proposed to control the output voltage of the four-leg inverter. The proposed method guarantees fast dynamic response and high robustness against model parameter mismatches and load variations. Finally, an improved SMC is also proposed to attenuate the chattering problem more effectively. Several experimental results on a 3-kW test bench are presented to verify the superior performance of the proposed methods. [ABSTRACT FROM AUTHOR]

Combined voltage and frequency control is a critical control problem of modern power system to avoid blackouts. This paper discusses the simultaneous voltage and frequency control for an interconnected multi-source multi-area power system having two areas of equal generating capacity, each containing thermal, diesel, and wind units. A centralized model predictive controller (MPC) scheme is suggested to minimize voltage and frequency fluctuations. For effective control, a normalized performance criterion has been considered, and recently appeared Harris hawks optimization (HHO) algorithm has been integrated for the optimal tuning of MPC weights for the first time. The effectiveness of the proposed MPC-HHO controller has been verified after comparing its transient response performance indices with that of various existing controllers available in the literature. Quantitatively, the proposed controller yields a minimum performance index value, i.e. 0.000741, and it has been observed that the proposed MPC-HHO controlled system has 79.28%, 68.89%, 77.19%, and 81.96% better settling time for frequency deviation in area 1 when compared with PIλDF-LSA, FOIDF-LSA, MFO-FOPID, and PID-FA controllers, respectively. Further, the stochasticity in wind power generation has been considered with the help of Monte Carlo simulation of Autoregressive Integrated Moving Average model (ARIMA) model for practical wind speed data from National Renewable Energy Laboratory. The stability of the proposed controller has been verified using eigenvalues and Bode plot analysis, where the MPC-HHO controlled system was having more gain and phase margin values as compared to the PID controlled system. Furthermore, the robustness of the approach has been successfully evaluated by considering the nonlinearities, and parameter sensitivity analysis has been conducted after varying the parameters of voltage and frequency control loops and reevaluating the transient performance of the controlled system. Besides this, a separate case study wherein the most recent concepts like Electric Vehicle (EV) integration with grid and Virtual Inertia (VI) have been applied in addition to the proposed controller to provide auxiliary control support in the system. It has been validated that EV-VI coordinated MPC-HHO controller provides quality transient response under different scenarios including reduced inertia and stochastic load variations. [ABSTRACT FROM AUTHOR]

Aiming at the deficiencies and shortcomings of traditional reactive power compensation devices in controlling and improving voltage quality, a bilevel programming model for the coordinated optimal allocation of active and reactive power capacity of photovoltaic power generation systems, wind-driven generators, shunt capacitors and static var compensators is established based on chance-constrained programming. In the optimization model, the randomness and intermittence of the output power of the distributed generation and the reactive power regulation ability of the distributed generation are considered. The correlation of illumination, wind speed and load fluctuation is considered and affected by seasonal variation. Latin hypercube sampling method is used to deal with the correlation of random variables. Monte Carlo probabilistic power flow method is used to calculate the power flow of distribution network with intermittent distributed generation systems. The location and capacity of active and reactive power sources in outer programming are optimized by adaptive artificial fish swarm algorithm, and the allocation scheme of active and reactive power sources determined by outer programming is optimized by inner adaptive artificial fish swarm algorithm. The two-layer nested adaptive artificial fish swarm algorithm is used to solve the optimal allocation problem constructed in this paper, and the optimal allocation scheme of active and reactive power supply capacity is determined. Taking IEEE33 distribution system as an example, the feasibility and applicability of the proposed model and algorithm are verified. [ABSTRACT FROM AUTHOR]

This paper presents a novel fault ride-through (FRT) capability with the use of active converters (Vienna rectifier-I and five-level three-phase modular multilevel converter (MMC)) integrated with permanent magnet synchronous generator (PMSG) supplying AC load. The DC-link fault is controlled with the use of fault blocking diode and MMC sub-module (SM) based wind power plant (WPP). A 16 kW, 60 Hz, PMSG and wind turbine (WT) integrated with the machine-side converter (MSC), and grid-side converter (GSC) are utilized as wind farm components, along with direct current (DC) transmission grid. This topology contributes to the stability and reliability of the system by ensuring continuous output power under transient fault conditions. The functional response of the system is presented using power simulator (The PowerSim, Rockville, USA) software to demonstrate the performance of the proposed controller. [ABSTRACT FROM AUTHOR]

This paper presents a multi-advantageous control technique for two-stage converters, namely DC-DC boost converter and three-phase voltage source inverter (VSI) in stand-alone energy-stored solar photovoltaic (SPV) system. Two-stage converter traditionally used two simultaneous control actions – DC-side control logic for boost converter and AC-side voltage control loop for VSI to maintain standard load voltage, thereby variable load powers are supported. Here, both duty ratio and modulation index (MI) are mutually adjusted to maintain load powers. In contrast, proposed single loop control philosophy only regulates duty ratio for supporting active and reactive load powers under varying solar or load conditions, but MI is always kept at fixed value of one per unit. With fixed and highest value of MI, significant benefits are obtained as reduction of voltage stress on power semiconductor switches and improved harmonic spectrums at VSI's output. Simulation and down-scaled experimental works are performed to validate proposed control concept. [ABSTRACT FROM AUTHOR]

In bathymetric Airborne LiDAR (Light Detection And Ranging) for the measurement of various water depths, the echo of the laser signal is amplified by an amplifier circuit, the water surface is usually saturated, which results in a serious effect on the bottom echo signal. Therefore, this paper designs a LiDAR echo signal detection timing control system. The system adopts the STMicroelectronics32 (STM32) controller as the gated signal generator; acts on the photomultiplier tube (PMT) photoelectric conversion circuit; and adjusts the amplitude, frequency, period, and duty cycle of the gating trigger signal to achieve timing control, thus allowing the system to directly avoid the reception of overly strong surface echo signals and increasing the accuracy of the experimental results. The system combines PMT adjustable voltage control gain technology applies the weak underwater echo signal that is amplified to facilitate subsequent collection. In the actual measurement, using STM32 instead of the traditional signal generator, which can reduce the power consumption and load capacity of the system. The experimental results show that the system can amplify the underwater signal by at least 6-fold while avoiding the effect of the surface echo signal. [ABSTRACT FROM AUTHOR]

This paper deals with the performance of a three-phase permanent magnet synchronous generator (PMSG) for stand-alone pico-hydro generation feeding single-phase load using improved third-order generalized integrator (ITOGI). The proposed control algorithm is used for load balancing, harmonics mitigation and reactive power compensation when a three-phase PMSG feeds a single-phase nonlinear load. A PMSG, voltage source converter (VSC), three-phase diode bridge rectifier (DBR) circuit connected in series with an IGBT switch-based DC–DC converter and a single-phase consumer load are parallelly interfaced at the point of common interface (PCI). The voltage and frequency of the proposed system are controlled in a decoupled manner. The VSC is used for voltage control by providing reactive power compensation along with the power quality improvement. The duty ratio from the frequency controller to IGBT switch connected in series with DBR circuit regulates the system frequency by feeding excess power into an auxiliary load. An ITOGI-based control algorithm is used to extract the fundamental component of load current for power quality improvement by providing proper switching pulses to VSC. The comparative analysis of already existing major state of art techniques is given with proposed ITOGI-based control technique using a Bode diagram and a step response. An appropriate tuning procedure is provided for deciding the control parameters for this algorithm. Simulated behaviour of proposed system and experimental test results are demonstrated using the prototype developed in the laboratory. The feasibility of this control strategy is illustrated using dynamic and steady-state performances of the proposed system feeding the single-phase consumer loads. [ABSTRACT FROM AUTHOR]

This paper discusses comparative analysis of Buck-Boost and SEPIC (Single Ended Primary Inductance) converters used in DC link voltage control technique to reduce torque ripple in Brushless Direct Current Motors (BLDCM). The aim of this study is to prove the efficiency of the aforementioned two converters, which have been adopted in many studies to reduce torque ripples caused by commutation, on the same motor parameters. Although BLDCM has many advantages, ripples in the generated torque have limited the use of these motors in applications requiring precise speed and torque. In this study, BLDCM was analyzed exhaustive mathematically and electrically and the problem that caused commutation torque ripples was explained in detail. The DC link voltage control has been proposed to suppressing torque ripples in the BLDCM. In addition, the link voltages required for reducing the torque ripples were obtained separately via both the Buck-Boost and the SEPIC converters. These converter topologies are examined under certain speed and torque conditions and the results were compared. When the results are evaluated together, it was observed that both converters performed the very closely performance each other. However, the Buck-Boost converter produced the desired voltage levels with less oscillation than the SEPIC converter. [ABSTRACT FROM AUTHOR]

This paper proposes an optimal voltage regulation scheme (OVRS) for distribution systems with rich photovoltaic (PV). Various regulation devices are optimally controlled in a coordinated manner: PV inverter, D-STATCOM, step voltage regulator (SVR), and on-load-tap-changer (OLTC). A data structure algorithm is proposed to split the distribution system into layered zones considering the radial structure of the system. The solution process of the proposed scheme is accomplished by a meta-heuristic optimizer. OVRS addresses the voltage violations while yielding a coordinated operation of the various control devices. The proposed OVRS involves three control levels to completely prevent voltage violations. In the first control level, the PV inverter and D-STATCOM mitigate rapidly the local voltage deviation through injecting/absorbing optimized reactive power. The second control level is a decentralized-based control scheme that utilizes the voltage control devices in each zone to handle the voltage violations if any. For each zone, the control devices in the upper-stream zones (parent zones) are managed by the third control level to ensure cooperative control actions. The simulation results on the 119-bus distribution system, with clear, low fluctuation, and high fluctuation of solar radiation profiles, demonstrate the effectiveness of the proposed OVRS. [ABSTRACT FROM AUTHOR]

This article investigates the combined analysis of load frequency control (LFC) and Automatic voltage regulation (AVR) for two-area hybrid system. Classical PID controller is habituated as secondary controller. A novel differential evolution artificial electric field algorithm (DE-AEFA) is proposed in this paper to tune controller parameters. Initially, DE-AEFA algorithm is applied to test system 1 comprising two-area non-reheat thermal turbines. Later on, the study is extended to combined model named test system 2 to investigate combined LFC and AVR problem. Further, the system is extended to the incorporation of HVDC link with the existing AC tie-line in parallel. System dynamic performance is predominantly enhanced by AC/DC rather than only AC tie-line. The proposed scheme robustness is demonstrated by conducting sensitivity analysis. [ABSTRACT FROM AUTHOR]

The wind-diesel-based isolated hybrid power system requires dynamic reactive power compensation for the fast recovery of voltage under load and input changes. Dynamic compensation techniques give a better voltage response but at a high cost; in contrast, the static compensator reduces the compensation cost by compromising on the voltage response. The use of, both, static as well as dynamic compensators together may give cost-effective reactive power compensation for predefined transient limits of voltage response. This paper presents the pricing of reactive power compensation under steady-state and dynamic conditions of a system with fixed capacitor (FC) and STATCOM. The main contributions of the paper are: (1) evaluation of reactive power compensation using FC as a static and STATCOM as a dynamic compensator, (2) fast recovery of voltage response using genetic algorithm-based tuning of the STATCOM controller's gain constant, (3) evaluation of reactive power compensation cost for steady and dynamic conditions due to change in load and/or input demand, and (4) comparison of responses obtained for the optimized case with a pre-existing reference compensation method. [ABSTRACT FROM AUTHOR]

This paper proposes a novel three-phase inverter based on buck converter and an efficient control method for the operation. The inverter circuit is comprised of moderate numbers of elements in terms of reducing design density and cost and improving operation capabilities. Unlike the similar studies in the literature, an efficient inverter control method that is feedforward supported closed-loop control is applied to the inverter to augment the response performance of the inverter output on different operation conditions. The inverter topology has a modular structure for each output phase that provides independent control of output voltage and frequency. Thus, the inverter can provide close to sine wave output voltage to supply balanced or unbalanced wye-connected three-phase loads or independent single-phase loads. Both simulation and experimental test studies are done for the proposed inverter. The inverter is designed for 1.5 kW, 0–100 Vp and 0–50 Hz operating rates. The test results prove both the theoretical and real-time accuracy of the proposed inverter for producing close to sine wave output voltages with less than 5% total harmonic distortion (THD) values on different working points. [ABSTRACT FROM AUTHOR]

In this paper, the graphene oxide was successfully prepared in 10 min via the electrolysis process. In the experiment, we can effectively and precisely control the spacing and thickness of graphene oxide layers for the first time by controlling the electrolytic voltage. Then GO was well analyzed by various spectroscopic techniques such as FTIR, Raman and UV-Vis. Furthermore, the growth mechanism has been discussed. Only when we accurately control the time and speed of inserting sulfuric acid molecules can we prepare graphene oxide with excellent properties, which is more conducive to its further application of the graphene-based composites. [ABSTRACT FROM AUTHOR]

Modular multilevel converter (MMC) is a promising highly modular converter. However, the problems of voltage balancing control strategies in the MMC should be studied in detail. In order to improve the effect of voltage balancing, reduce the amount of calculation, and simplify the switch control of the submodules (SMs), this paper proposes a method that using a matrix to control the switch signals of the SMs based on the nearest level control (NLC) method. First, by sorting the capacitor voltage of the SMs, the required SMs are selected according to the NLC method. Since each arm contains N SMs, it is assumed that each SM corresponds to an N-dimensional column vector. The nth element of column vector corresponding to the nth SM is 1, and the others are 0. Then, the column vectors corresponding to all the SMs are used to form an N × N identity matrix. Secondly, assuming that the identity matrix is E, when the i-th SM is selected, a column vector corresponding to it is selected, such as a(i)= E(:, i), where E(:, i) is the i -th column of E; then, the sum of a(i) is calculated to obtain the switch signals of all SMs of each arm, so as to control the SMs. Finally, the simulation was set up on the Matlab/Simulink, and the proposed method is studied and analyzed. [ABSTRACT FROM AUTHOR]

Domino circuit topology for high-speed operation, robustness and lower power consumption is quintessential in design of digital systems. In this paper, various high speed and robust mechanisms are proposed to enhance the speed of Clock-Delayed Dual Keeper Domino (CDDK) circuit. Delayed enabling of keeper circuit in CDDK domino circuit reduces contention between keeper circuit and Pull-Down network (PDN). The speed of transition at the dynamic node of the CDDK domino circuit is enhanced through imposing techniques namely (i) controlled clock delay time in enabling the keeper transistor, (ii) keeper control signal voltage swing variation, (iii) sizing of keeper transistors and (iv) deploying an additional conditional discharge path. The robustness of CDDK circuit is increased by upsizing the keeper transistor without degrading the speed by stack arrangement of dual keeper transistors. The simulation of enhancement techniques has been performed using Cadence® Virtuoso ADEL and ADEXL environments employing UMC 90nm technology library. The simulation results of wide fan-in 64-input OR gate demonstrate that CDDK technique with additional discharge path offer 38% increase in speed and CDDK technique with keeper transistor upsizing offers 52% increase in noise gain margin without speed degradation while comparing with the conventional domino logic circuit. [ABSTRACT FROM AUTHOR]

This paper introduces a split-capacitor shunt Active Power Filter (SC-APF) based on Synchronous Reference Frame (SRF) theory. This topology is used in compensating the currents of 3-Ph unbalanced non-linear loads. The voltage control loop used in SRF which is only suitable in controlling Four-Leg APF (FL-APF) is modified to control Spilt-Capacitor APF (SC-APF). The proposed scheme provides compensating the 3-Ph unbalanced non-linear loads with lower number of switches, passive elements, and sensors. The performance of the SC-APF with the modified calculation algorithm is verified through simulation and experimental studies. [ABSTRACT FROM AUTHOR]

In order to extract maximum power from a Photovoltaic (PV) panel different Maximum Power Point Tracking (MPPT) algorithms have been developed, among which Perturb and Observe (P&O) MPPT algorithm is widely used. The P&O algorithm can be executed either by direct duty ratio or by voltage reference control. Both have drawbacks in tracking time and oscillation around MPP. In the latter case, the reference voltage generated by the algorithm is fed to a controller (PI/PID) to generate the corresponding duty ratio. The gains of PID controller are calculated under the standard test conditions (STC) (1000 W/m2, 25°C) of PV panel and the same values are used for other operating conditions too, which does not provide satisfactory performance under varying operating conditions. In this paper, an adaptive method is proposed to calculate the controller gains for different operating conditions without using any additional sensors. The proposed method establishes a linear relation between the PID gains calculated for the STC and those for other operating conditions, and this relation adaptively changes the PID gains for different operating conditions. It is observed from the simulations and experimental results that the proposed adaptive method precisely tracks the maximum power and optimizes the perturbation characteristics. [ABSTRACT FROM AUTHOR]

In order to effectively use a memristor in analog circuits, its memristance should be adjusted to a desired value between its limits. Since the maximum and minimum required memristance typically varies considerably between different types of memristors, it is almost impossible to tune the resistance of each memristor based on a reference resistor. Which is mostly done using some programmer circuits. Moreover, those programming strategies involving pulses are time-consuming and they impose high hardware headroom. In this paper, a novel CMOS circuit is presented for programming memristors. A Wheatstone bridge circuit is used to measure the current memristance, while the programming current is flowing through the device. Using such an approach reading the state and its adjustment are done simultaneously, which reduces the programming latency. In the proposed method, instead of tuning the memristance, the state of the memristor will be set to the desired value, which is proportional to a control voltage. The low programming latency, six-bit accuracy, and use of a simple circuit for programming, are the main advantages of our solution. The proposed circuit is designed and laid out in 0.35 µm CMOS technology and takes 0.0273mm2. Furthermore, the proposed approach is applied to a memristor emulator to demonstrate its correct operation in real applications. [ABSTRACT FROM AUTHOR]

This paper presents the design of an embedded control system and its implementation on a DC-AC bidirectional converter for the interconnection of a DC Microgrid (MG) with the AC Main Network (MN). This control system was designed in LabVIEW and implemented on the NI myRIO platform, and it was used for the synchronization of the MG with the MN. Its main goal is to keep the stability of the DC bus when energy is supplied to or extracted from the MN. The MG is composed of two 500 W photovoltaic panel arrays (PAs), each with a Boost DC-DC converter to generate a DC bus of 190 V, and a DC-AC bidirectional converter that interconnects the MG with the MN. The control system was tested considering nonl-inear loads such as computers, commercial fluorescent lamps, and LED, with the aim to analyze the response of the system to real life conditions. Results show that the embedded control system is capable to stabilize the DC bus at a voltage level of 190 V ± 5% when interacting with the different non-linear loads connected to the MG. This is an improvement on the control of the voltage variation previously presented in the literature of 190 V ± 10%. [ABSTRACT FROM AUTHOR]

Z-Source inverters (ZSIs) are one of the most promising single-stage power converters in modern industrial applications. However, these ZSIs exhibit non-minimum phase behaviour as a result of right half-plane (RHP) zero in the converter transfer functions and impose a constraint on the controller design. A detailed mathematical model of the converter plays a crucial role in the design of an efficient control strategy. This paper presents a detailed mathematical model of non-ideal ZSI using averaged modelling approaches and its comparisons are summarised. The pole-zero and step response plots reveals the impact of parasitic elements and parameter variations on system steady-state and dynamic performance. Finally, the effects are outlined, which gives a basic guideline to the designers in the converter performance optimisation such as the feedback control bandwidth, damping factor, resonant frequency, and overshoot/undershoot in the desired output. The sensitivity function is defined for a voltage gain of ZSI with respect to system parasitic elements and snubber parameters. In order to validate the theoretical analysis of converter dynamics, a laboratory prototype model of 50 watts ZSI is developed. Further, a hardware implimentation of PID-based capacitor voltage control is shown to check the effectiveness of the derived transfer functions on closed-loop performance. [ABSTRACT FROM AUTHOR]

In this paper, a gain-boosting transconductor with widely input linear range and tunable control voltage is presented. A novel self-biased topology is employed in the negative feedback path of the gain-boosting structure to improve the linearity of the proposed transconductor. In fact, this self-biased topology results in a linear change for the drain voltage of the input drivers under the variation of the control voltage, while the input drivers operate in the triode region. In order to confirm the improved performance of the proposed transconductor, it is employed in a third order Butterworth low pass Gm-C filter. Therefore, the self-biased topology allows having more control on the cutoff frequency of the Gm-C filter. The proposed transconductor is designed and simulated in a 0.18 µm CMOS technology under a 1.8 V power supply. The small signal transconductance of the proposed circuit can change from 2.5 to 104.3 µA/V by tuning the control voltage. In addition, simulation results of the mentioned filter also show that the cutoff frequency properly changes between 500 KHz and 20.6 MHz, while third-order intercept point (IIP3) for this filter is between 7.55 and 21.4 dBm for different applications. [ABSTRACT FROM AUTHOR]

Voltage violation is an important factor that restricts grid-connected photovoltaic system. The utilization of PV plant's reactive power capability is an effective measure to mitigate voltage violation. This paper proposes two-stage voltage control strategy to enhance the voltage support capability of photovoltaic grid-connected system. In first stage, adaptive gains are set according to the maximum reactive capacity of each PV plant in order to distribute reactive power among PV plants more reasonably, avoiding certain PV plants operating in the limit state for a long time. In second stage, when the reactive power capacity is insufficient, the priority of active power curtailment for each PV plant is calculated in real time. Active power curtailment control will be performed in PV plants with high priority to released more reactive power capacity for voltage support. The simulation results carried out by PSCAD/EMTDC software demonstrated that this strategy can effectively solve the voltage violation problem. Meanwhile, the proposed strategy not only can exploit reactive capacity of each PV plant as much as possible to avoid certain PV plants operating in the limit state for a long time, but also can reduce the amount of active power curtailment when reactive power adequacy is insufficient. [ABSTRACT FROM AUTHOR]