Dq Theory Research Articles

Intelligent controller based WECS fed unified power flow conditioner for PQ enhancement

<p>The dominance of non-linear loads, sustainable energy sources and power electronic devices in modern power system has in turn compromised the system stability by introducing numerous power quality (PQ) issues. A wind energy conversion system (WECS) fed unified power flow conditioner (UPFC) architecture is suggested in this work since maintaining optimal PQ is important for both the supply authorities and customers. The proposed approach supports both clean energy generation and PQ enhancement. The UPFC aids with accomplishing control over reactive power flow, active power flow, phase angle, impedance and voltage. The reference current for the UPFC is generated using DQ theory. Moreover, a shunt and series compensators of an UPFC are controlled using cascaded fuzzy logic controller (CFLC). The stability of the DC voltage obtained from doubly fed induction generator (DFIG) based WECS is also controlled using a CFLC. The simulation model for the presented WECS fed UPFC is developed in MATLAB and its performance is evaluated.</p>

An highly efficient optimized PI controller fed SEPIC converter for hybrid renewable sources based microgrid system

This paper proposes an electric power generation that is self-sufficient with the adopting of Hybrid Renewable Energy Sources (HRES) including solar and wind which in turn contributes a cleaner and sustainable environment. The proposed system provides uninterrupted power supply during any weather conditions and the excess energy is stored in battery which energizes the grid at times of deficit power supply from HRES. The incorporation of converter and control approach ensures the balanced flow of power in the grid connected system. A Single-Ended Primary Inductance-Converter (SEPIC) is employed in this work for the enhancing of voltage from the PhotoVoltaic (PV) system. An improved Grey Wolf Optimized (GWO) Proportional Integral (PI) controller facilitates the effective control of SEPIC thereby improving the transient response. A Doubly Fed Induction Generator (DFIG) based wind system is integrated as an alternate source with PI based control. The control of the battery is carried out by the Artificial Neural Network (ANN) and grid synchronization is accomplished with the aid of PI based dq theory. The simulation of the proposed work is carried out by Matlab and the proposed work generates improved outputs with efficiency 95.8% and a reduced THD of 1.3%.

Improving Power Quality by DSTATCOM Based DQ Theory with Soft Computing Techniques

The development of non-linear loads at consumers has significantly impacted power supply systems. Since, the poor power quality has been found in the three-phase distribution system due to unbalanced loads, harmonic current, undesired voltage regulation, and extreme reactive power demand. To overcome this issue, Distributed STATicCOMpensator (DSTATCOM) is implemented. DSTATCOM is a shunt-connected Voltage Source Converter (VSC) that has been utilized in distribution networks to balance the bus voltage in terms of enhancing reactive power control and power factor. DSTATCOM can provide both rapid and continuous capacitive and inductive mode compensation. A rectified resistive and inductive load eliminates current harmonics in a three-phase power supply. The synchronous fundamental DQ frame is a time-domain approach developed from three-phase system space vector transformations has been designed using MATLAB/Simulink. The DQ theory is used to produce the reference signal for the Pulse Width Modulation (PWM) generator. In addition, a traditional Proportional Integral Derivative (PID) controller is designed and compared with proposed soft computing approaches such as Fuzzy–PID and Artificial Neural Network (ANN-PID) and compared accurate reference current determination for Direct Current (DC) bus through DC link. An Analytical explores the proposed control strategies given to establish superior outcomes. Finally, total harmonic distortion analysis should be taken for performance analysis of the proposed system with IEEE standards.

An Adaptive Fuzzy Sliding Mode Control Design For Multiuse Grid Interconnected Inverter to intensify power quality in microgrid

: This paper presents a vigorous control design and a robust controller for a Multifunctional grid interconnected inverter [MFGII] beneath disturbed load conditions. This MFGII controller algorithm uses DQ theory to assess the unacceptable parts of grid current such as harmonics, and required load reactive current. This decoupled method of control design makes normal Grid interconnected inverter to MFGII and also helps in reducing the computational burden which further makes the system more robust. Furthermore, Adaptive Fuzzy sliding mode control (AFSMC) algorithm prepares the system sturdy and effective in improving the dynamic performance during uncertainties. Henceforward, settling time and overshoot are reduced with fast dynamic response. The MFGII infuses the RES to grid at PCC which in addition to Real power injection also provides reactive power compensation, balance the load and mitigate harmonics. The results obtained from FOSMC are compared with AFSMC under the variation of solar irradiation and load.

An Optimized PI Controller-Based SEPIC Converter for Microgrid-Interactive Hybrid Renewable Power Sources

With the use of hybrid renewable sources for example solar and wind turbines, an autonomous electric power generation system based on self-sufficient electric power generation is built in order to promote a smart and ecologically friendly environment. The three-phase inverter that links this scattered generating unit to the grid is in charge of ensuring that it is properly connected to the grid. While the energy produced by the hybrid unit is being utilized, it is also being stored in the batteries so that it may be used to transport power when other sources of power are not available, such as when the grid is down. This stand-alone power conversion and storage system is being built with the aid of power electronic converters and controllers, among other components, in order to ensure balanced power flow operation. To produce PWM pulses for the generator side converter, a PI controller is utilized. On the PV side, an improved PI controller is used to drive the SEPIC converter, which increases the transient responsiveness of the converter while it is being controlled by the controller. In order to communicate with the grid, the generated electricity is routed via a three-phase inverter that is controlled according to the DQ theory. The challenges connected with poor power quality are substantially resolved by the converters that have been presented. For simplicity of use, an automated control function has been introduced; in addition, an interactive MATLAB model of the system is being developed for minor and medium-scale microgrid applications; also, a prototype is being created to verify the simulation results.

A Novel Controller for Microgrid Interactive Hybrid Renewable Power Sources

In this paper, a self-sufficient electric power generation is proposed by using hybrid renewable sources like solar and wind turbines to favor a smart and green environment. This distributed generation unit is connected to the grid through an 3Φ inverter. The power drawn from the hybrid unit is stored in the batteries to transfer power during the non-availability of power sources. This standalone power conversion and storage system are developed by using power electronic converters and controllers to ensure balanced power flow operation. A PI (Proportional Integral) controller is utilized for generating the PWM (Pulse Width Modulation) pulses for the wind side converter. The GWO (Grey Wolf Optimization) optimized PI controller is used to control the PV (Photovoltaics) side SEPIC (Single-Ended Primary-Inductor Converter) for improvising the transient response of the system. The generated power is interfaced with grid through a three phase inverter, which is controlled by dq (Direct-axis and Quadrature-axis) theory. The power quality problems are effectively eliminated with the proposed converters. Thus, a continuous stable power is fed into the grid through the proposed approach. An automatic control is enabled for easy operation. The system is modeled in MATLAB and a prototype is developed to verify the simulation results.

Electromagnetic torque prediction and harmonic reduction of interior permanent magnet synchronous motor for electric vehicles using an analytical method

Interior permanent magnet synchronous motors (IPMSMs) have been widely used as drive machines in electric vehicles (EVs) due to their high torque density. However, the torque ripple of IPMSMs will result in severe noise and vibration. This paper proposes a new analytical method for electromagnetic torque prediction and harmonic reduction of IPMSM. On the basis of dq theory, an analytical model of electromagnetic torque is firstly established by taking the permanent magnet flux harmonics and the cross-coupling effect into consideration. And the specific sources and orders of torque harmonics are also determined. Then, the torque-angle characteristics are further studied. In particular, the permanent magnet (PM) torque and the reluctance torque are separated and quantitatively analyzed via the proposed analytical model. Finally, a theoretical method of reducing the specific order torque harmonic by PM shifting is derived and proposed from the perspective of avoiding resonance. The accuracy and effectiveness of the proposed analytical method are verified by finite-element analysis. The results show that the proposed analytical model is accurate enough to predict the electromagnetic torque performance of IPMSM. Moreover, the electromagnetic torque harmonics with specific orders can be effectively reduced by shifting the PM to an appropriate angle.

Mathematical Modeling of THD Mitigation Using HAPF for UPS System with Experimental Analysis via Hybrid Interface of Optical USB and Power Quality Meter

This paper discusses a novel analysis scheme based on the hybrid interface of Optical USB and Power Quality Meter for measuring Total Harmonic Distortion (THD) that exists in the Uninterruptable Power Supply (UPS) system and connected load. The designed hybrid interface experimentally analyzes the power quality and harmonics of the Uninterrupted Power Supply (UPS) system, and mitigation is proposed with the proposed Single-Phase Hybrid Active Power Filter (HAPF) based on instantaneous Power Theory (PQ) with hysteresis control technique and synchronous frame reference (DQ) with hysteresis control techniques at nonlinear load. This study authenticates and gives appropriate measurements in analyzing the harmonics and voltage distortion during conversion of power. The designed work offers the compensation and elimination of harmonic currents using PQ and DQ theory at different nonlinear loads. The proposed HAPF for the UPS system has demonstrated the significant reduction in THD using proposed Power Theory (PQ) with hysteresis control technique from 46.58% to 1.51% and by using DQ theory with hysteresis control technique has reduced THD from 46.58% to 1.38%. Finally, the results are compared between PQ and DQ. It is validated via results that DQ theory eliminated harmonics and also having less THD as compared to PQ-theory. Furthermore, one of the key aspects of the work is the analysis of power quality using Optical USB Interface (OC4USB) and FLUKE series power quality analyzer.

New PQ theory for power quality improvement using modular multilevel converter based UPFC system

The source current harmonics reduction techniques were found to be unpredictable and disparity under different loading conditions. The presence of uncertainity issue in harmonics elimination is due to nonlinear loads. Filters can be used to eliminate the harmonics and power quality issues. But these filters are not cost effective to provide dynamic performance under various loading conditions. The target of this paper is to minimize source current harmonics with optimum voltage stability under different loading conditions. A new Unified Power Flow controller is developed whose series compensator is replaced by modular multilevel converter to achieve high modular level with reduced harmonics and fast current limiting during the fault short circuit and shunt compensator is replaced with four switches and one capacitor combination to achieve the twin benefit of more reliable power system and good voltage stability for different loadings. DDSRF (Decoupled Double Synchronous Reference Frame) theory is utilized in the proposed converter for generating the reference current from the AC supply. DDSRF theory generates sinusoidal harmonics with the opposite phase to the load current. The UPFC can suck or injects the responsive power in the PCC. After DDSRF theory, hysteresis controller is used to produce PWM pulse for the shunt and series compensator. The proposed DDSRF theory is compared with existing dq theory to show its effectiveness in terms of THD analysis. The PI and fuzzy logic methodology is utilized to control the capacitor DC rail voltage. The proposed approach is simulated using Matlab under various loading condition and hardware is developed using Spartan 6E FPGA Controller.

Control strategies for harmonic mitigation and power factor correction using shunt active filter under various source voltage conditions

This paper gives a new insight into the concept of load compensation using shunt active filter (SAF) under ideal and non-ideal source voltage conditions. A novel approach based on an improved instantaneous active and reactive current component method is proposed. The performance of the proposed control strategy has been compared with instantaneous reactive power theory, symmetrical component theory and dq theory. SAF has been realized by three-phase voltage source converter. Reference currents generated by control strategies has been tracked by a SAF in a hysteresis band control scheme. The performance of the proposed scheme is evaluated in terms of reactive power compensation, reduction in magnitude of source currents, compensator currents, and harmonic compensation as per IEEE-519 standard. To ascertain the viability of the proposed control algorithm, the performance is evaluated under different source voltage conditions with the IEEE Standard-1459 power definitions. Variation in magnitude as well as harmonic content of source voltage has been considered. Under balanced sinusoidal source voltage condition, all control strategies congregate to similar results. Under unbalanced sinusoidal source voltage condition, dq theory and proposed theory have shown similar performance. However, under distorted source voltage conditions, an improved instantaneous active and reactive current component theory presents superior performance. A three-phase, three-wire distribution system supplying non-linear load is considered for simulation study. Simulation results from a complete model of SAF are presented to validate and compare the control strategies.

Investigation of the $dq$-Equivalent Model for Performance Prediction of Flux-Switching Synchronous Motors With Segmented Rotors

An equivalent <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> model of three-phase flux-switching synchronous motors employing a segmental rotor is constructed and tested for predicting steady-state performance. Both the wound-field and permanent-magnet excited motors are represented. The unconventional topologies of the two types of motors present significant departure from the basic assumptions of the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> theory, even though the motors may be operated from a drive incorporating generic <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> control regimes. The equivalent <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> inductances and flux linkages are calculated from finite-element simulation results and applied in predicting the steady-state performance of the motor. It is found that the credibility of the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> model to predict the performance of the motors over the operating range is assured and is enhanced by incorporating <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -coupling inductances in the model.

A dq axis theory of the magnetic, thermal, and mechanical properties of Curie motor

A dq axis theory of a thermomagnetic Curie motor is presented. This theory allows one to estimate the performances of a Curie motor from its geometrical, magnetic, and thermal properties. The proposed approach shows that the thermomagnetic Curie motor is equivalent from a magnetic point of view to a dc electric machine. The physical meaning of the parameters used in the dq theory of Curie motor is explicated. The theory is validated by using experimental data.

Performance estimation of interior permanent-magnet brushless motors using the voltage-driven flux-MMF diagram

The flux-magnetomotive force (flux-MMF) diagram, or energy conversion loop, is a powerful tool for computing the parameters of saturated interior permanent-magnet brushless motors, especially when the assumptions underlying classical dq theory are not valid, as is often the case in modern practice. Efficient finite-element computation of the flux-MMF diagram is possible when the motor current is known a priori, but in high-speed operation the current regulator can lose control of the current waveform and the computation becomes rather than current-driven. This paper describes an efficient method for estimating the motor performance-average torque, inductances-by solving the voltage-driven problem. It presents experimental validation for a two-pole brushless interior permanent-magnet motor. The paper also discusses the general conditions under which this method is appropriate, and compares the method with alternative approaches.