Quadrature Currents Research Articles

Performance Analysis of Advanced Metaheuristics for Optimal Design of Multi-Objective Model Predictive Control of Doubly Fed Induction Generator

Finite control set model predictive control (FCS-MPC) is an attractive control method for electric drives. This is primarily due to the ease of implementation and robust responses. When applied to rotor current control of the Doubly Fed Induction Generator (DFIG), FCS-MPC has thus far exhibited promising results when compared to the conventional Proportional Integral control strategy. Recently, there has been research conducted regarding the reduction in switching frequency of FCS-MPC. Preliminary studies indicate that a reduction in switching frequency will result in larger current ripples and a greater total harmonic distortion (THD). However, research in this area is limited. The aim of this study is two-fold. Firstly, an indication into the effect of weighting factor magnitude on current ripple is provided. Thereafter, the research work provides insight into the effect of such weighting factor on the overall current ripple of FCS-MPC applied to the DFIG and attempts to determine an optimal weighting factor which will simultaneously reduce the switching frequency and keep the current ripple within acceptable limits. To tune the relevant weighting factor, the utilization of swam intelligence is deployed. Three swarm intelligence techniques, particle swarm optimization, the African Vulture Optimization Algorithm, and the Gorilla Troops Optimizer (GTO), are applied to achieve the optimal weighting factor. When applied to a 2 MW DFIG, the results indicated that owing to their strong exploitation capability, these algorithms were able to successfully reduce the switching frequency. The GTO exhibited the overall best results, boasting steady-state errors of 0.03% and 0.02% for the rotor direct and quadrature currents whilst reducing the switching frequency by up to 0.7%. However, as expected, there was a minor increase in the current ripple. A robustness test indicated that the use of metaheuristics still produces superior results in the face of changing operating conditions. The results instill confidence in FCS-MPC as the control strategy of choice, as wind energy conversion systems continue to penetrate the energy sector.

Power control of an autonomous wind energy conversion system based on a permanent magnet synchronous generator with integrated pumping storage

Wind energy plays a crucial role as a renewable source for electricity generation, especially in remote or isolated regions without access to the main power grid. The intermittent characteristics of wind energy make it essential to incorporate energy storage solutions to guarantee a consistent power supply. This study introduces the design, modeling, and control mechanisms of a self-sufficient wind energy conversion system (WECS) that utilizes a Permanent magnet synchronous generator (PMSG) in conjunction with a Water pumping storage station (WPS). The system employs Optimal torque control (OTC) to maximize power extraction from the wind turbine, achieving a peak power coefficient (Cp) of 0.43. A vector control strategy is applied to the PMSG, maintaining the DC bus voltage at a regulated 465 V for stable system operation. The integrated WPS operates in both motor and generator modes, depending on the excess or shortfall of generated wind energy relative to load demand. In generator mode, the WPS supplements power when wind speeds are insufficient, while in motor mode, it stores excess energy by pumping water to an upper reservoir. Simulation results, conducted in MATLAB/Simulink, show that the system efficiently tracks maximum power points and regulates key parameters. For instance, the PMSG successfully maintains the reference quadrature current, achieving optimal torque and power output. The system’s response under varying wind speeds, with an average wind speed of 8 m/s, demonstrates that the generator speed closely follows turbine speed without a gearbox, leading to efficient power conversion. The results confirm the flexibility and robustness of the control strategies, ensuring continuous power delivery to the load. This makes the system a feasible solution for isolated, off-grid applications, contributing to advancements in renewable energy technologies and autonomous power generation systems.

Behavior analysis of dual-star permanent magnet synchronous generator with inter-turn short fault

ABSTRACT The dual-star PMSMs (DSPMSM) are widely used in high-power applications due to their robustness and reliability. As they mostly work in harsh environments, they are commonly subject to many faults. One of the most dangerous faults is the inter-turn short fault (ITSF), which induces torque vibrations and overheating inside the machine, and may lead to other faults. To properly handle this issue, it must be correctly understood, and the relationship between different machine’s quantities (speed, dq currents, fault ratio and resistance) and the severity of the fault (torque’s oscillations and short-circuit current) must be established. In this context, this paper presents a detailed analysis of the DSPMSM behavior under a single ITSF, considering the influence of the mentioned quantities and the PWM converter on torque oscillations and short-circuit current. A mathematical model of the machine is developed, and a hysteresis current controller is used to impose the desired direct and quadrature axis stator currents. Simulation tests are conducted by considering different scenarios. Simulation results showed that to reduce fault severity, a trade-off between speed reduction and flux weakening must be accomplished, consequently accepting some performance degradation. Also, results showed the complex behavior of the short-circuit current, as it does not rely linearly on fault parameters.

Control of an Outer Rotor Doubly Salient Permanent Magnet Generator for Fixed Pitch kW Range Wind Turbine Using Overspeed Flux Weakening Operations

This paper deals with the analysis of the dynamic performance of a generator with a doubly salient exterior rotor excited by permanent magnets inserted in the stator yoke. The electrical generator works at low speed and is devoted to a wind energy conversion system. Indeed, the studied generator is a robust high-torque machine and can be directly coupled to the turbine blades. It must therefore assure the energy conversion for wind speeds lower or higher than its base speed. In fact, the control technique used in this work covers the two main operating zones: below the base speed and above it. In the first case, the maximum torque per ampere control law is developed; however, when the base speed is reached, the flux decay control law is implemented and, consequently, the system works above the nominal conditions. Fuzzy logic controllers are employed to regulate direct and quadrature machine currents and DC voltage in order to obtain satisfactory regulation performances. The ensemble of the wind turbine and electrical machine with technical control is performed in Matlab/Simulink software. The simulation results obtained show the capability of the machine to operate at variable speeds, ensuring efficient energy conversion under and over the nominal speed.

IMPROVED ADAPTIVE NONLINEAR CONTROL FOR VARIABLE SPEED WIND-TURBINE FED BY DIRECT MATRIX CONVERTER

This paper proposes a robust decoupling power algorithm based on a doubly fed induction generator (DFIG) for variable speed wind-turbine (WT). The DFIG rotor circuit is fed by the direct matrix converter (DMC), which presents several features such as no need to the dc-bus voltage, sinusoidal supply, rotor side waveforms, bidirectional power flow, and adjustable input power factor. The 18 bidirectional switches are controlled using the Venturini modulation technique. On the other hand, the DFIG stator circuit is connected directly to the grid. The nonlinear control strategy based on feedback linearization is applied to control the stator power (Ps and Qs) independently using the rotor quadrature and direct currents (irq and ird), which present the images of the previous stator powers. Some limitations appear in the power algorithm using the conventional pi controller, especially in power tracking, error, and quality. In this context, the model reference adaptive controller (MRAC) presents an alternative solution, a robust and efficient controller proposed instead of the pi controllers to control stator powers. Finally, the simulation results confirm that the proposed algorithm could work under hard conditions and demonstrate that the wind energy conversion system (WECS) provides enhanced dynamic responses in transient and steady states and good power quality delivered to the grid.

Evaluating the performances of PI controller (2DOF) under linear and nonlinear operations of DFIG-based WECS: A simulation study

Owing to different stochastic characteristics of wind energy systems, there would commonly be uncertainties in the processes of wind energy conversion that may ultimately cause to severely degrade the quality of electric power production. These uncertainties include time-varying fluctuations of mechanical & electrical parameters that can be generated during both linear, and nonlinear operating behaviors of doubly fed induction generator-based wind energy conversion system (DFIG WECS). In order to handle a wind power quality problem, the previous studies largely focused on adjustment of mechanical parameters particularly based on blade pitch angle control by proposing different control strategies, and controller models. This work proposes a rarely studied electrical parameter control method that is particularly used to implement the regulation of rotor current components & electromagnetic torque in a DFIG WECS, based on Indirect Field Oriented Control (IFOC) strategy. Accordingly, a novel Proportional Integral controller model that employs a 2-Degree-of-Freedom [PI (2DOF)] is illustrated for an enhanced control of the rotor current components (quadrature & direct currents), electromagnetic torque under a 2MW DFIG WECS, which is operationally assumed to behave both linearly & nonlinearly. Herein, nonlinear operating behavior signifies a voltage dip that was assumed to be resulting when the system's normal (linear) voltage would suddenly drop by 90%. Furthermore, the overall model of the DFIG system was simulated in MATLAB-SIMULINK environment to evaluate the performances of PI controller (2DOF) under the system's stated operating behaviors. Based on the simulation signal statistics, the quadrature current distortion levels & DC mean values were mainly considered as the criteria for evaluating the controller performances. Finally, the proposed PI controller (2DOF) model has been tested to achieve an enhanced power quality in comparison with the traditional PI controller model.

Virtual Sensor Using a Super Twisting Algorithm Based Uniform Robust Exact Differentiator for Electric Vehicles

The highly efficient Interior Permanent Magnet Synchronous Motor (IPMSM) is ubiquitous choice in Electric Vehicles (EVs) for today’s automotive industry. IPMSM control requires accurate knowledge of an immeasurable critical Permanent Magnet (PM) flux linkage parameter. The PM flux linkage is highly influenced by operating temperature which results in torque derating and hence power loss, unable to meet road loads and reduced life span of electrified powertrain in EVs. In this paper, novel virtual sensing scheme for estimating PM flux linkage through measured stator currents is designed for an IPMSM centric electrified powertrain. The proposed design is based on a Uniform Robust Exact Differentiator (URED) centric Super Twisting Algorithm (STA), which ensures robustness and finite-time convergence of the time derivative of the quadrature axis stator current of IPMSM. Moreover, URED is able to eliminate chattering without sacrificing robustness and precision. The proposed design detects variation in PM flux linkage due to change in operating temperature and hence is also able to establish characteristics of fault detection. The effectiveness and accuracy in different operating environments of the proposed scheme for nonlinear mathematical IPMSM model with complex EV dynamics are verified thorough extensive simulation experiments using MATLAB/Simulink.

Fault Ride-Through (FRT) Behavior in VSC-HVDC as Key Enabler of Transmission Systems Using SCADA Viewer Software

The world’s energy consumption and power generation demand will continue to rise. Furthermore, the bulk of the energy resources needed to satisfy the rising demand is far from the load centers. The aforementioned requires long-distance transmission systems and one way to accomplish this is to use high voltage direct current (HVDC) transmission systems. The main technical issues for HVDC transmission systems are loss of synchronism, variation of quadrature currents, amplitude, the inability of station 1 (rectifier), and station 2 (inverter) to either inject, or absorb active, or reactive power in the network in any circumstances (before a fault occurs, during having a fault in network and after a fault cleared), and the variations of power transfer capabilities. Additionally, faults impact power quality such as voltage dips and power line outage time. This paper presents a method of overcoming the aforementioned technical issues using voltage-source converter (VSC) based HVDC transmission systems with SCADA VIEWER software and dynamic grid simulator. The benefits include having a higher capacity transmission system and proposed best method for control of active and reactive power transfer capabilities. Simulation results obtained using MATLAB validated the experimental results from SCADA Viewer software. The results indicate that the station’s rectifier or inverter can either inject or absorb either active power or reactive power in any circumstance. Also, the reverse power flow under different modes of operation can ride through faults. At a 100.0% power transfer rate, the rectifier injected 775.0 W into the network. At a 0.0% power transfer rate, the rectifier injected 164.0 W into the network. At a −100.0% rated power, the rectifier injected 1264.0 W into the network and direction was also changed.

Speed controller design for three-phase induction motor based on dynamic adjustment grasshopper optimization algorithm

Three-phase induction motor (TIM) is widely used in industrial application like paper mills, water treatment and sewage plants in the urban area. In these applications, the speed of TIM is very important that should be not varying with applied load torque. In this study, direct on line (DOL) motor starting without controller is modelled to evaluate the motor response when connected directly to main supply. Conventional PI controller for stator direct current and stator quadrature current of induction motor are designed as an inner loop controller as well as a second conventional PI controller is designed in the outer loop for controlling the TIM speed. Proposed combined PI-lead (CPIL) controllers for inner and outer loops are designed to improve the overall performance of the TIM as compared with the conventional controller. In this paper, dynamic adjustment grasshopper optimization algorithm (DAGOA) is proposed for tuning the proposed controller of the system. Numerical results based on well-selected test function demonstrate that DAGOA has a better performance in terms of speed of convergence, solution accuracy and reliability than SGOA. The study results revealed that the currents and speed of TIM system using CPIL-DAGOA are faster than system using conventional PI and CPIL controllers tuned by SGOA. Moreover, the speed controller of TIM system with CPIL controlling scheme based on DAGOA reached the steady state faster than others when applied load torque.

Unified adaptive neuro-fuzzy inference system control for OFF board electric vehicle charger

This paper illustrates the control algorithm design for a two stage off board bidirectional smart electric vehicle (EV) charger architecture. The proposed EV charger is controlled to perform four quadrant operation (i.e. vehicle-to-grid (V2G) and grid-to-vehicle (G2V)) while compensating the load harmonics, simultaneously. Here, the 3-phase AC-DC converter and DC-DC converter are two main components, where the first one is controlled to regulate DC-link voltage as well as reactive power and current harmonics of nearby non-linear load while the second one regulates the exchange of active power. Generally, the AC-DC converter is controlled via two control loops, i.e. outer loop and inner loop. However, setting the gains of almost four proportional integral (PI) controllers and determining decoupling terms for inner control loops is very difficult, especially under the dynamic operating conditions. Therefore, an adaptive neuro-fuzzy inference system (ANFIS) has been designed to estimate the direct and quadrature axis reference currents directly while regulating two different quantities in single step only and hence, named as unified ANFIS controller. The proposed EV charger is simulated in MATLAB/Simulink and controller performance is validated with scaled down hardware model in real time.

New Resistorless Third-Order Quadrature Sinusoidal Oscillators

This paper introduces four new resistorless, third-order, electronically tunable, quadrature sinusoidal oscillators using three operational transconductance amplifiers (OTAs) and three capacitors. The proposed third-order quadrature sinusoidal oscillators (TOQSOs) provide noninteracting control of the oscillation condition (OC) and oscillation frequency (OF) by changing the transconductance of different OTAs, to produce sustained oscillations and offer quadrature output voltages and currents. Two of the proposed quadrature oscillator circuits have capacitor control of OF, a feature, useful in capacitive transducers. The presented TOQSO structures have good frequency stability and exhibit low active and passive sensitivities. PSPICE simulations using CMOS OTAs along with hardware results (using off-the-shelf available OTA IC LM13700) have also been provided to confirm the workability of the presented circuits.

New Sensorless Vector Control System With High Load Capacity Based on Improved SMO and Improved FOO

In the existing sensorless vector control system of permanent magnet synchronous motor (PMSM), direct differential calculation or phase-locked loop (PLL) control is often used to estimate the rotor speed, but this method has some problems of weak load capacity and slow dynamic response. A new sensorless vector control method based on an improved sliding mode observer (SMO) and improved full-order observer (FOO) is proposed in this paper. The cut-off frequency of the low-pass filter is designed as a function of speed, the back EMF is fed back into the stator current estimation mathematical model, and the adaptive rate of feedback gains coefficient is proposed for improving the traditional SMO. The disturbance feedback matrix is introduced for improving the traditional FOO, and the estimated load torque is feedforward compensated to the given end of the quadrature current. An integrated system of corresponding algorithms is established, a test platform is built. The experimental results show that the speed and load torque estimation performance of the improved observer is better than that of the traditional observer in the process of sudden load change. The sensorless vector control system based on the proposed observer has a high dynamic response, load capacity, and reliability.

Design and analysis of 73-106 GHz CMOS injection-locked frequency divider

ABSTRACT A 73 ~ 106 GHz divide-by-2 injection-locked frequency-divider (ILFD2) using 90 nm CMOS technology is presented. To achieve a wide locking range, an optimal transistor width ratio of the injection transistor (or mixer) and cross-coupled transistors (CCT) is adopted. To enhance the operation frequency, distributed LC network is used as the load of the CCT. To enhance the input sensitivity, an input power matching network is included in the injection transistor. In addition, for further locking ranging enlargement, the inductive peaking and forward-body-bias techniques are used in the injection transistor for raising its quadrature output current (or conversion gain). The ILFD2 consumes 4.92 mW, and achieves an excellent phase noise of – 106.2 dBc/Hz (at 1 MHz offset from the output frequency of 50 GHz). The ILFD2 achieves a wide locking-range of 33 GHz (73–106 GHz (36.9%)), covering the 77 GHz automotive radar frequency band and the 94 GHz imaging radar frequency band. The ILFD2 can be operated at a low input power of – 60 dBm, one of the best input sensitivities ever reported for a W-band CMOS ILFD2. The core area of the ILFD2 is only 0.014 mm2.

Meta-heuristic optimization algorithms based direct current and DC link voltage controllers for three-phase grid connected photovoltaic inverter

This paper deals with improving the effectiveness of the control system for the DC/AC grid connected photovoltaic (PV) inverter. The three-phase DC/AC grid connected PV inverter control system consists of two main control loops: (i) external loop to control the DC link voltage. (ii) An internal control loop for regulating the inverter current by controlling both direct and quadrature currents (Id, Iq) that are provided by the inverter phase-locked loop (PLL). The main component of each control loop is the proportional-integral (PI) controller, whose optimal gains are challenging tasks. The optimal PI controller gains should be selected to achieve multi-objectives such as increasing inverter efficiency, stability and power factor while decreasing the total harmonic distortion (THD) in the inverter output current as well as voltage. For this purpose, various meta-heuristic techniques (MHTs) are suggested with a comprehensive comparative study such as: (i) Whales Optimization Algorithm (WOA), (ii) Grey Wolf Optimization (GWO) algorithm, (iii) Antlions Optimization algorithm (ALO) and (iv) Moth Flame Optimization (MFO) algorithm. The numerical results attained through MatlabTM-Simulink reveal that the WOA technique is more superior than the three others studied MHTs in enhancing the inverter efficiency, stability and power factor with minimum THD.

A 210–291-GHz (8×) Frequency Multiplier Chain With Low Power Consumption in 0.13-μm SiGe

This letter presents a 210–291-GHz $8\times $ multiplier chain in the 0.13- $\mu \text{m}$ SiGe Bipolar CMOS (BiCMOS) technology for the broadband generation of carrier signals, imaging, and spectroscopy. It consists of three cascaded Gilbert-cell doublers with compact input matching networks to generate quadrature collector currents in the switching quad for broadband flat conversion gain. The multiplier chain generates a saturated output power of −7.7 dBm at 244.5 GHz with a 3-dB bandwidth of 81 GHz. It consumes 0.24 W of dc power and occupies 0.86 mm 2 of chip area.

Direct Power Compensation in AC Distribution Networks with SCES Systems via PI-PBC Approach

Here, we explore the possibility of employing proportional-integral passivity-based control (PI-PBC) to support active and reactive power in alternating current (AC) distribution networks by using a supercapacitor energy storage system. A direct power control approach is proposed by taking advantage of the Park’s reference frame transform direct and quadrature currents ( i d and i q ) into active and reactive powers (p and q). Based on the open-loop Hamiltonian model of the system, we propose a closed-loop PI-PBC controller that takes advantage of Lyapunov’s stability to design a global tracking controller. Numerical simulations in MATLAB/Simulink demonstrate the efficiency and robustness of the proposed controller, especially for parametric uncertainties.

Grid impedance estimation for grid-tie inverters based on positive sequence estimator and morphological filter

This paper proposes a method for estimating the appropriate grid impedance for applications in which distributed generators are connected to the grid through three-phase inverters. The method is based on variations in active and reactive power injected by the inverters into the power system. These variations give rise to changes in the direct synchronous voltage $$v_{d}$$ and in the synchronous direct and quadrature currents $$i_{d}$$ and $$i_{q}$$ at the point of common coupling between the inverter and the power grid. These changes serve to compute the grid resistance and inductance seen by the inverter. This paper suggests the usage of a previously proposed technique for estimating the positive sequence from the grid voltage, so the method is robust against harmonic distortions. The technique is improved, employing a Fourier filter. To further enhance the method, a morphological filter is incorporated to filter out the synchronous currents. This filter is suitable to be applied in DC signals, like the ones related to synchronous reference frames. A complete evaluation of the proposed method is performed through simulations in MATLAB/Simulink environment. The results show that the positive sequence estimator and the morphological filter significantly increase the accuracy of the grid impedance estimation.

Estimation of the Mechanical Position of Reciprocating Compressor for Silent Stoppage

This paper proposes the solution for decreasing of the reciprocating compressor noise and vibrations, which happens at stoppage. These vibrations and resulting noise are caused by the gas pressure in the cylinder, which impacts the compressor's piston and can reverse the motor at stoppage. To avoid this situation the motor must be stopped, when the gas is not pressurized, i.e., at the desired mechanical position, however motor is not equipped with a mechanical position sensor as the control system utilizes an electrical speed and position estimator. As a rule, it is impossible to estimate the mechanical position using an electrical position, however it has been noticed that at low speeds a detrimental feature of reciprocating compressors – varying load torque can help identify the mechanical position. Load torque impacts the quadrature current, making it oscillate at the mechanical frequency of the motor, so this mechanical frequency and position can be estimated using a Phased Locked Loop (PLL) algorithm, applied to the quadrature current.

24-GHz Injection-Locked Frequency Tripler With Third-Harmonic Quadrature Phase Generator

This paper presents a quadrature injection-locked frequency tripler (ILFT) adopting third-harmonic phase shifters for quadrature signal injection at the third-harmonic band. Two capacitively degenerated differential transconductor pairs inject quadrature currents to the main I/Q LC tanks. The degeneration networks are optimally designed to create quadrature injection signals at the third harmonic of injection signal. The presented third-harmonically quadrature phasing technique increases an injection-locking range effectively with the minimizing injection signal loss compared with prior conventional injection techniques employing phase shifters at the fundamental frequency. The proposed ILFT is implemented in 130-nm CMOS technology. The measured injection-locking range is 3.3% (~800 MHz) at the 23.6-GHz center frequency with 0-dBm input injection power. The locking range of the proposed ILFT is twice wider than that of prior state-of-the-art ILFTs adopting single differential signal injections or polyphase filter-based quadrature signal injections. The proposed ILFT consumes 10.4 mW, and the chip size is 0.5 × 0.25 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> without pads.

Rotor Resistance Estimation for Induction Machines Using Carrier Signal Injection With Minimized Torque Ripple

This paper presents a technique for estimating the rotor resistance of an induction machine over the machine's entire speed and torque range. This technique is based on injecting a relatively low-frequency carrier signal into the reference of the rotor flux linkage magnitude and extracting the induction machine's response to the carrier signal, which is then used in a model reference adaptive system. This paper also presents a technique to minimize the torque ripple generated by the carrier signal. This technique utilizes the rotor flux linkage reference in conjunction with a proportional-integral-resonant feedback plus feedforward control to generate references for the direct and quadrature axis stator currents. This paper also improves tracking of the torque and rotor flux linkage in direct field-oriented control of the induction machine through employing electromotive force and resistive compensation methods for tracking q-axis and d-axis reference stator currents, respectively. Simulation and experimental results demonstrate the effectiveness of the technique over the entire operating range.