Park Transformation Research Articles

Requirements Engineering for an Industrial Symbiosis Tool for Industrial Parks Covering System Analysis, Transformation Simulation and Goal Setting

Industrial Symbiosis (IS) is a collaborative cross-sectoral approach to connect the resource supply and demand of various industries in order to optimize the resource use through exchange of materials, energy, water and human resources across different companies, while generating ecological, technical, social and economic benefits. One of the main goals of IS is the set-up of advanced circular/cascading systems, in which the energy and material flows are prolonged for multiple utilization within industrial systems in order to increase resource productivity and efficiency, while reducing the environmental load. Many Information Communication Technology (ICT) tools have been developed to facilitate IS, but they predominantly focus on the as-is analysis of the IS system, and do not consider the development of a common desired target vision or corresponding possible future scenarios as well as conceivable transformation paths from the actual to the defined (sustainability) target state. This gap shall be addressed in this paper, presenting the software requirements engineering results for a holistic IT-supported IS tool covering system analysis, transformation simulation and goal-setting. This new approach goes beyond system analysis and includes the use of expert systems, system dynamics and Artificial Intelligence (AI) techniques, which turn the IT-supported IS tool to be developed into a comprehensive and holistic instrument with which future scenarios and transformation paths can be simulated.

A Droop-Based Diesel Generator Emulator for Microgrid Frequency Control Studies

In laboratory-scale studies, researchers usually prefer to use diesel generator emulator, instead of real diesel generator due to its flexibility in parameters design. Using diesel generator emulator, the behavior of a real diesel generator is emulated by a voltage source converter with voltage and current control loops in d–q frame. In this paper, an inverter-based prototype of a simple diesel generator emulator is presented for frequency variation studies in laboratory-scale microgrids. The proposed control system includes two separated paths for frequency and voltage. In the first path, two cascaded voltage and current control loops in d–q frame are employed to regulate the voltage like AVR system. In the second path, a proposed transfer function and a P–f droop curve are used to generate the reference frequency for inverse park transformation considering the transfer functions of prim-mover, governor and synchronous machine. The real diesel generator and the diesel generator emulator are simulated in MATLAB/Simulink software and compared to investigate the proposed control system. Also the experimental results verify the performance of the implemented prototype of the proposed diesel generator emulator in AUT microgrid.

Investigations on Three-phase Grid-Connected Inverter using PWM Controllers

In recent years, a Multilevel Inverter (MLI) topology is highly preferred in the various renewable energy applications for converting power due to their merits. In this paper, a three-phase inverter has been designed for grid-connected applications using Proportional Integral (PI) current controller scheme. To generate a sequence, the Level shift (LS) and Phase Shift (PS) Pulse Width Modulation (PWM) methodologies are adapted. This topology has been designed with two stages: the DC-DC conversion stage and DC-AC conversion stage. The DC-DC conversion stage is used to enrich input DC voltage which is obtained from the solar PV array. The PI current controller has been designed to regulate the grid current with park transformation. The performances of the inverter have been examined in terms of Total Harmonic Distortion (THD) using different PWM techniques and also investigated with existing research works. The developed results are verified using MATLAB/ Simulink.

Design and Simulation of Direct and Indirect Back EMF Sliding Mode Observer for Sensorless Control of PMSM

Abstract This article compares two sensorless control algorithms for a permanent magnet synchronous machine (PMSM) based on the back-EMF sliding mode observer (SMO). Indirect SMO (I-SMO) treats the back-EMF voltages as a disturbance. Direct SMO (D-SMO) considers back-EMF voltages as state-space variables. The same phase-locked loop (PLL) is used for both observers for extraction of the rotor position and speed values from the observed back-EMF voltages. In a sensorless control, the observed speed is used as feedback for the PI controller, and the observed position is used in the Park transformations. Both observers have been implemented and tested with standard field-oriented control. Simulation results indicate rather comparable speed and position estimation precision for both, but the D-SMO indicates slightly higher precision in steady-state. Even more, a tuning procedure of the D-SMO is more straightforward when compared to the I-SMO. Thus, the D-SMO was further verified experimentally with the OP 5600 rapid prototyping device and with a 350 W PMSM drive. Experimental results of the D-SMO are included at the end of the paper.

Diagnosis of Short-circuits in Induction Motor Stator Winding Using a Modified Park Transformation

Abstract This paper deals with a novel diagnostic method for finding the stator winding short-circuit damage of induction motor drives. The proposed method is based on a new, simple idea of applying a modified, triple Park transform instead of using a computationally demanding on-line Fast Fourier Transform (FFT) analysis. The diagnostic method is based on the analysis of current and reference voltage vector components, which are the part of the Direct Field Oriented Control structure. The proposed method is verified experimentally using tests results. Further, the influence of speed, load torque and the parameters of PI regulators on the performance of the proposed diagnostic method are also discussed.

Three Phase Four-Wire Inverter for Grid-Disconnected Operation

In this work, the modeling of a three-phase four wires inverter and the design of two control schemes for its grid-disconnected operation are presented. The advantages of the four-wire topology are that by means of a coordinate transformation (Park transformation) it is possible to obtain a decoupled linear model, as well as feeding single-phase and three-phase loads in this operating mode. In the model, two control loops are taken into account: a current loop (controller slave) and a voltage loop (controller master) with the aim that this inverter can regulate its output voltage and when it is supplied to a local load.. The contributions of this work is present in the inverter modeling, the method for obtaining the transfer functions and in the controllers design obtained by this method. The inverter model allows to easily obtain the transfer functions of both loops; this is very important for the control area, considering that using classical control techniques and the methodology proposed in this work, the gains can be obtained directly and not adjusted to trial and error. The main advantage of this proposal is that when the kp and ki gains are obtained through the Bode diagrams, we can obtain generalized integrators; applying the coordinate transformation method to the integral gain that was obtained by the design of the PI controller in direct current (dc); This method is described in detail in the presented work and allows obtaining a new controller called proportional controller plus generalized integrator (P+GI). This controller presents a good performance, since it can follow sinusoidal references, in addition to presenting a better disturbances rejection due to the high gains it presents at the grid frequency and harmonic frequencies of the load.

Reduced Reference Frame Transform: Deconstructing Three-Phase Four-Wire Systems

This paper proposes a new reference frame, namely Reduced Reference Frame (RRF), specially suited for unbalanced three-phase four-wire systems which improves the performance of the classical Fortescue, Clarke and Park transformations. The RRF transfomation allows to represent any unbalanced three-phase sinusoidal magnitude with just two components even if the zero-sequence component is present. For doing so, the RRF transformation takes into account that the abc space-vector trajectory of the transformed three-phase sinusoidal magnitude is always within a plane. The geometric properties of this trajectory are considered for outlining a general classification of the transformation depending on the input voltages and an adequate reference frame within the plane. Then, a step-by-step procedure for computing the transformation matrix is detailed. Once the voltages and currents are transformed into the RRF, it is proposed a power theory which allows to compute the instantaneous active and reactive powers. The paper includes two simulations and an experimental validation through a real-time application to highlight the benefits of the proposal. The paper closes with the main conclusions and some future research lines where this transformation can be applied.

Voltage Vector Directional Control for IPMSM Based on MTPA Strategy

Space vector pulse width modulation (SVPWM) is used in motor control because of its high dynamic response and flexible control. Maximum torque per ampere (MTPA) strategy has become the most commonly used choice for internal permanent magnet synchronous motor (IPMSM). However, complicated coordinate transformations are required in the usual SVPWM algorithm and the performance of the MTPA algorithm can be affected by the parameters variation. This paper proposes a voltage vector directional control (VVDC) method based on the MTPA strategy. The inverse Park transformation is avoided in the proposed control scheme. And the proposed algorithm not only is briefer and clearer in the sector judgment process but also has lesser calculation during the duty cycle generation. In order to realize the MTPA strategy, two voltage feedback closed loops are designed to compensate for the d -axis and q -axis currents. A simple and effective multi-parameter identification method is also presented to solve the parameters variation problem. The effectiveness of the proposed method is verified by simulation and experiments.

Coordinated Derived Current Control of DFIG’s RSC and GSC Without PLL Under Unbalanced Grid Voltage Conditions

This paper proposes a coordinated derived current control strategy of doubly fed induction generator (DFIG) system under unbalanced grid voltage conditions. The rotor-side converter (RSC) and the grid-side converter (GSC) are synchronized to the grid with a virtual phase angle of nominal frequency, which can be simply set as $\theta =\omega _{\mathrm {n}}t$ ( $\omega _{\mathrm {n}}= 100\pi$ ). Consequently, the proposed control strategy can implement in an arbitrary reference frame without phase-locked loop (PLL). The derived d-q axis currents are obtained from the DFIG stator and GSC currents with virtual angle-based Park Transformations. For a simple implementation, a reduced-order vector integrator with a voltage vector multiplier is used to directly regulate the measured powers/currents containing both the dc part and the oscillating part without sequence extractions. By this means, RSC achieves torque ripple reduction and then GSC can rebalance the currents and smooth the active/reactive powers. Finally, the experimental results on a small laboratory setup are presented to validate the effectiveness of the proposed control strategy.

Implementation and Experimental Verification of a Novel Control Strategy for a UPFC-Based Interphase Power Controller

Replacing the phase shifting transformers of interphase power controller with a reduced rating dual unified power flow controller (UPFC) results in a unified interphase power controller (UIPC) with potential for enhanced performance. However, in most cases, the UPFC is controlled as a static phase shifter (SPS), producing marginal improvements. A control approach that allows the minimization of the power ratings of the series voltage source converters (VSCs) of the UIPC was recently proposed. For that, one has to define four control parameters, as opposed to only two in the SPS-based UIPC. This can be done off-line, by means of an optimization procedure that splits the desired transmission line current among the capacitive and inductive branches of the UIPC. In this paper, a control scheme is presented for the implementation of the novel technique. The current sharing factors obtained from the optimization are stored in a lookup table. The gating signals for the VSCs are generated using Park's transformation so as to synthesize the optimal UIPC inductive and capacitive branch currents with proportional resonant controllers and sinusoidal pulse width modulation. The transmission line angle, as well as the magnitude and phase of the desired transmission line current with respect to the voltage at the receiving end voltage, is assumed to be provided by a transmission system operator. Experimental results that include steady state and transient conditions are provided to prove its feasibility.

A Geometric Interpretation of Reference Frames and Transformations: dq0, Clarke, and Park

Transformations between abc, stationary dq0 (αβ0) and rotating dq0 reference-frames are used extensively in the analysis and control of three-phase technologies such as machines and inverters. Previous work on deriving the matrices describing these transformations follows one of two approaches. The first approach derives Clarke's matrix by modifying symmetrical components. Park's matrix can be subsequently found from a rotation matrix. The second approach derives Park's matrix using trigonometric projection by interpreting the transformation as a rotation in the plane of the cross-section of a machine. Then, Clarke's matrix can be found trivially using a reference angle of zero in Park's matrix. This paper presents a third approach to deriving the Clarke and Park transformation matrices: a geometric interpretation. The approach exploits properties of the linear transformation using the Cartesian representation. We introduce the locus diagram of a three-phase quantity and show how these diagrams have applications in power quality. We show that, unlike a phasor diagram, a single locus diagram can fully represent a three-phase system with harmonics.

A Modified Series Voltage Controller for Power Conditioning

A compensation method for mitigation of voltage related power quality problems with the use of Series Voltage Regulator well known as Series Active Power Filter or Dynamic Voltage Restorer is presented in this paper. The classical control algorithm used for series voltage regulator based on the Park transformation is modified by introducing a Selective Harmonic Filter at detection stage of source current in order to compensate harmonic frequencies which mainly affect power frequency voltages. The significant outcomes are sag restoration, reduction of total harmonic distortion and removal of transients from the supply voltage. Thus it makes possible to improve performance of series voltage controller as power conditioner to mitigate various voltage related power quality issues. The proposed approach is cost effective because same series voltage controller can be used as power conditioner by modifying control strategy used. Also it is possible to eliminate use of PI controller from control circuitry. The usefulness and robustness of the proposed mitigation strategy is confirmed by simulation studies. The presented series voltage controller has ability to mitigate the power quality issues arising due to charging of electric vehicles.

Detection and Localization of Open-Phase Fault in Three-Phase Induction Motor Drives Using Second Order Rotational Park Transformation

The open-phase fault in vector-controlled drives is known as one of the most prevalent failures that require immediate detection. It is still challenging to develop a trustable fault diagnosis scheme at light load, transients, and low-speed regions. This paper presents a novel open-phase fault diagnosis strategy for three-phase induction motor drives over the entire speed range and for different load conditions. By taking advantage of the second-order rotational park transformation (SORP), new fault indices are proposed to identify the open-phase location without using any additional sensors or electric equipment. Comparing with root-mean-square (RMS) calculation-based methods, the proposed method detects the fault at least twice faster, with minimal system resources. The presented scheme may be implemented simply and is robust against the operating point changes. Proof of the proposed fault detection and localization method has been shown through experimental tests on a 250-W three-phase induction machine which is controlled by TI-DSP F28335.

Interspecies Park Life: Participatory Experiments and Micro-Utopian Landscaping to Increase Urban Biodiverse Entanglement

This article analyses the design and outcomes of the research project Rewilding Lystrup, which involved a partnership with local authorities in Aarhus, Denmark, to merge two distinct processes: climate adaptation and the biodiversity transformation of a public park. Our key interest in the article is the potential offered by experimental participatory events to support the biodiverse transformation of public areas by creating micro-utopian entanglements of citizens and nonhuman organisms. The article will focus on three experimental participatory events enacted as part of the research project: (1) public dialogues and workshops, (2) the arrival on the scene of charismatic cows, and (3) pop-up events in the form of participatory playing. The article concludes that this kind of material citizenship is a powerful strategy for stimulating public engagement in building more biodiverse futures. The strategy thus materializes micro-utopian spaces where the importance of biodiversity can be rehearsed and sensed by local communities. In this way, a culturally transformative zone of dreaming while doing—or doing dreams—is enacted.

An Improved Modulation Technique With Minimum Switching Actions Within One PWM Cycle for Open-End Winding PMSM System With Isolated DC Bus

Due to the application of dual inverters in the structure of open-end winding permanent-magnet synchronous machine system with isolated dc bus, the double number of switching devices are employed and thus the switching actions within one pulsewidth modulation (PWM) period are relatively high. To reduce the switching actions, an improved modulation technique is proposed in this letter. In the proposed technique, the reference voltages in the synchronous coordinate system are transferred to the three-phase stationary frame through Park transformation and thus the duration time corresponding to the three-phase windings can be directly obtained. On this basis, by synchronously adjusting the duration time of three phases, the maximum one can be adjusted to be the control period while their resultant voltage remains constant. Furthermore, the switching actions are assigned to the switching devices based on the polarity of duration time for each phase, with the principle of keeping the switching device on one side clamped. The novelty of the proposed technique is that it can be universally applied to minimize the number of switching actions within one PWM cycle for any kind of voltage ratio of the system without sector identification. The experimental validation of the proposed scheme is given to validate its effectiveness.

Vector Current Control Derived from Direct Power Control for Grid-Connected Inverters

We propose a vector current control derived from direct power control (VCC-DPC) for a three-phase voltage source inverter (VSI) in the synchronous rotating frame through instantaneous real and reactive powers. The proposed VCC-DPC method has the same control structure as the conventional VCC except for the coordinate transformation, since we obtain the $d$ – $q$ axes currents model of VSI without using Park transformation and the phase-locked loop (PLL) system. Consequently, the proposed method has the same property as the conventional VCC if the PLL extracts the phase angle of the grid voltage correctly. However, with the consideration of the slow dynamics of the PLL, the proposed method has an enhanced dynamical performance feature compared with the conventional VCC. Moreover, it has another benefit that the reduction of the computational burden could be expected since there is no Park transformation and the PLL in the controller implementation. We can guarantee that the closed-loop system with the proposed method is exponentially stable in the operating range. Finally, both simulation and experimental results using a 15-kW-inverter system match the theoretical expectations closely.

A new SOGI-PLL method based on fuzzy logic for grid connected PV inverter

<p>Phase angle detection of the grid voltage is an imperative part of control in most applications, especially for the synchronization of the current injected by the grid-connected photovoltaic inverters. Consequently, fast and accurate detection of the phase angle, frequency and amplitude of the grid voltage are indispensable data to ensure a correct generation of reference signals and operation of the grid connected inverters. We present in this work a new phase-locked loop (PLL) method for single-phase systems. The novelty is to generate an orthogonal voltage system using a second-order generalized integrator (SOGI), followed by a Park transformation, whose quadrature component is forced to zero by the fuzzy logic, in order to obtain rapid detection and a more accurate picture of the phase angle. Furthermore, simulation results with PSIM software will be submitted to verify the performance and effectiveness of the proposed method strategy. Finally, the experimental test will be used to extract the result and discuss the validity of the proposed algorithm.</p><p> </p>

Optimization of efficiency for power system using three phase AC to AC matrix converter with the algorithm of fuzzy controller

This paper suggested a new contribution of three phase AC to AC matrix converter MC via fuzzy logic controller FLC to enhance the whole system. However, the weakness of matrix converter is that the input- output voltage transfer is control to 87% for input and output waveform. Also, matrix converter is more sensitive to the trouble of input voltage which deteriorates the system performance. To overcome these problems, and to improve the efficiency of system, FLC with matrix converter is proposed to minimize the sensitivity to the load, and to increase voltage transfer. In this paper the currents a,b,c are converted to alpha and beta current via Clarke transformation . In this method two FLC are used. The error (between alpha current and reference current) (e) and the change of this error (de) will apply to first FLC. The output of FLC is actual alpha current. In the other hand, the error of beta current and the change of error are also passes through the second FLC to produce the actual beta current. The actual alpha and beta current is converted to direct and quadrature d-q current by park transformation. The d-q current is converted to (a, b, c) out currents by inverse park transformation, the results of this method express that the matrix converter with FLC is more capable, high accuracy with better efficiency as compared with conventional matrix converter system.

Optimization of efficiency for power system using three phase AC to AC matrix converter with the algorithm of fuzzy controller

This paper suggested a new contribution of three phase AC to AC matrix converter MC via fuzzy logic controller FLC to enhance the whole system. However, the weakness of matrix converter is that the input- output voltage transfer is control to 87% for input and output waveform. Also, matrix converter is more sensitive to the trouble of input voltage which deteriorates the system performance. To overcome these problems, and to improve the efficiency of system, FLC with matrix converter is proposed to minimize the sensitivity to the load, and to increase voltage transfer. In this paper the currents a,b,c are converted to alpha and beta current via Clarke transformation . In this method two FLC are used. The error (between alpha current and reference current) (e) and the change of this error (de) will apply to first FLC. The output of FLC is actual alpha current. In the other hand, the error of beta current and the change of error are also passes through the second FLC to produce the actual beta current. The actual alpha and beta current is converted to direct and quadrature d-q current by park transformation. The d-q current is converted to (a, b, c) out currents by inverse park transformation, the results of this method express that the matrix converter with FLC is more capable, high accuracy with better efficiency as compared with conventional matrix converter system.

Comparison and Analysis of Evaluation Indexes regarding China’s Eco-industrial Parks

The industrial park plays a significant role in fueling the economic growth, expanding the foreign trade and promoting the industry cluster. However, due to the blind investment attraction, and the poor perspectiveness and systematicness of the planning, the industrial park also becomes the centralized pollutant emission area. Chinese government has implemented many meaningful explorations in promoting the ecological development of the industrial parks, successively introduced the demonstration eco-industrial park, circular transformation of industrial park, and green park construction, and separately established the evaluation index system and policy guarantee system. This paper reviews the ecological greening development course of China’s industrial parks, thoroughly introduces the evaluation index system of demonstration eco-industrial park, circular transformation index system of the industrial park, and the green park evaluation index system, and compares and analyzes the commonalities and differences of such three sets of index systems from the theoretical basis, target positioning, index requirements, index universality, evaluation methods and many other dimensions, based on which this paper proposes the policy suggestions regarding the ecological greening development of China’s industrial parks.