Load Model for Medium Voltage Cascaded H-Bridge Multi-Level Inverter Drive Systems
08 Jan 2016-Vol. 3, Iss: 1, pp 13-23
TL;DR: In this article, a dynamic load model for the medium voltage cascaded H-bridge multi-level inverter drive and induction motor systems, which is suitable for power system dynamic studies, is proposed.
Abstract: Medium voltage drives (MVDs) are commonly used in high-power applications and show significant impact on the overall system dynamics due to their large size and high power demand. Although detailed switching models for MVDs can be built using MATLAB/Simulink, such models cannot be used in large-scale simulation software for power system dynamic studies. To solve this problem, the dynamic load model for the medium voltage cascaded H-bridge multi-level inverter drive and induction motor systems, which is suitable for power system dynamic studies, is proposed in this paper. Analytical formula of the model is presented. The model includes the aggregated effect of an MVD, an induction motor, and their control system, and thus, it can accurately represent the dynamic responses of the motor drive system under disturbances. Both voltage and frequency dependence are considered in the model. The accuracy of the model is verified by a case study. A sensitivity study is conducted to evaluate the impact of the model parameter variation on dynamic response characteristics. The developed load model can be readily inserted in the large-scale power system simulation software for power system dynamic studies.
Citations
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TL;DR: A power balanced based In-Phase Disposition Trapezoidal Pulse Width Modulation (IPD-TPWM) strategy has solved the problem of low utilization rate of DC-side voltage and unbalanced output power of each unit, and can be conveniently used in N-level CHB inverters.
Abstract: Against to the problems of low utilization rate of DC-side voltage of Cascaded H-bridge (CHB) multi-level inverter Carrier Disposition (CD) modulation strategy and unbalanced output power of each cascaded H-bridge units, a power balanced based In-Phase Disposition Trapezoidal Pulse Width Modulation (IPD-TPWM) strategy is proposed in this article. By selecting an appropriate trapezoidal wave triangulation rate $\delta $ , the modulation strategy can greatly increase the amplitude of the CHB inverter output voltage fundamental wave while ensuring the waveform quality of output phase voltage, and realize the power-balance of H-bridge units within a full modulation ratio range by changing the arrangement of triangular carriers in the vertical direction while using the carrier segment in the half carrier period of the IPD-TPWM strategy as the basic unit. Therefore, it has solved the problem of low utilization rate of DC-side voltage and unbalanced output power of each unit. At the same time, the Total Harmonic Distortion (THD) of output line voltage of the modulation strategy is lower than that of IPD-SPWM strategy in the whole modulation degree, which effectively improves the quality waveform of the output line voltage, and can be conveniently used in N-level CHB inverters. Moreover, the working stress of all the unit switching tubes is the same, the heat dissipation distribution is uniform, the switching loss is effectively reduced, and the service life and system reliability are improved. Finally, the Matlab/Simulink simulation model and experimental platform are established to verify the validity and practicality of the modulation strategy.
27 citations
TL;DR: This study presents a three-phase transformerless battery storage system (BSS) based on a cascaded H-bridge inverter applied to a medium-voltage grid that is able to keep working even with a failure of one of its converters.
Abstract: A distributed generator (DG) based on renewable energy is a promising technology for the future of the electrical sector. DGs may benefit utility companies and customers in a variety of perspectives. However, DGs suffer from intermittent behaviour. Storage systems appear as an attractive solution to support the continuous operation of DGs. The technology within the storage also plays an important role, since DGs and storage are connected in medium-voltage grids. The use of batteries and the DC/AC converter in its conventional structure presents drawbacks in such grids. In this context, this study presents a three-phase transformerless battery storage system (BSS) based on a cascaded H-bridge inverter applied to a medium-voltage grid. The BSS is composed of eight equal series connected H-bridge converters, without bulk transformers, for connection to a distribution grid. Each converter contains 75, 12V/600Ah lead-acid batteries. The converters are controlled through pulse-width modulation at 600Hz. The BSS is able to keep working even with a failure of one of its converters. Reactive energy compensation not compensated by an existent passive filter is also performed. A case study with simulated and experimental results obtained through a hardware-in-the-loop system is presented showing the efficacy of the proposed BSS.
17 citations
TL;DR: A new configuration of the adjustable speed drive is proposed for the medium-voltage industrial induction motor drives (IMDs) with modified sinusoidal pulsewidth modulation strategy, which offers very low switching frequency, low switching losses, enhanced fundamental magnitude, and low total harmonic distortion.
Abstract: In this article, a new configuration of the adjustable speed drive is proposed for the medium-voltage industrial induction motor drives (IMDs). Here, a new configuration of a 40-pulse multiphase staggering modular transformer is proposed for power quality improvement in the vector-controlled induction motor drive (VCIMD) at the utility end. In it the two transformers (T1 and T2) are utilized and both have extended-delta configured input windings with +9° and −9° phase shift and their secondaries have two sets of five-phase ac supplies to achieve a 20-pulse ac–dc conversion. Because of these primary angles, these two transformers are reconfigured as a 40-pulse ac–dc converter. A new cascaded multilevel inverter (C-MLI) is proposed at the drive end. This C-MLI is cascading four two-level voltage source inverters in a unique manner to get nine levels in its line voltage. A modified sinusoidal pulsewidth modulation strategy is utilized, which offers very low switching frequency, low switching losses, enhanced fundamental magnitude, and low total harmonic distortion. The performance of the proposed VCIMD, is evaluated by simulating it in MATLAB Simulink. The performance of the proposed VCIMD is also verified using a scaled down laboratory prototype under various operating conditions such as steady state, starting, load perturbation, speed control, varying load conditions, and over a wide speed range of IMD.
11 citations
Journal Article•
TL;DR: In this paper, the effects of series impedance, existing between an observation point and a load, on the active and reactive power dynamics of power system loads are analyzed, and it is shown that the change is small enough to allow approximation of the transfer function at the original order.
11 citations
10 Jan 2020
TL;DR: A modified multi-winding transformer is designed to fulfil the need of a 7-level CHB-inverter, which also makes the input current closer to sinusoidal and reduces its THD to an acceptable value.
Abstract: In this article, a new structure is used for induction motor drive (IMD). A Δ-polygon configuration based multi-winding transformer is designed in it to get an eighteen pulse AC-DC converter, which fulfill the DC-supply requirement of a 7-level cascaded H-bridge (CHB) inverter. This 7-level CHB-inverter is utilized at the drive end, to drive an induction motor (IM) and it requires less semiconductors switches and DC-supplies than the existing 7-level CHB-inverter. Therefore, a modified multi-winding transformer is designed to fulfil the need of a 7-level CHB-inverter, which also makes the input current closer to sinusoidal and reduces its THD to an acceptable value. A vector control is used to control an IM, which has good performance than v/f control. A new fundamental frequency switching technique (area equalization modulation strategy) is used in this work, to operate a 7-level CHB-inverter at fundamental frequency switching, which reduces the switching losses and increases efficiency of the system. The comparative study is also given to show the effectiveness of the system. Performance of the system is analyzed in MATLAB/Simulink under various operating conditions of IM. The simulated performances are validated from the experimental results captured from the developed laboratory prototype.
9 citations
Cites background or methods from "Load Model for Medium Voltage Casca..."
...In the literature [12]–[14], an eighteen pulse AC-DC converter fed 7-level CHB-inverter based IMD is reported....
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...The CHB-inverter has been successfully implemented for MVIMD in [12]–[14]....
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...Moreover, to get 6-isolated DC-supply from MWT, a small size MWT is needed compared to the MWT given in [12]–[14]....
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...Therefore, the size and cost of the proposed MVIMD are quite less than the existing MVIMD [12]–[14]....
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...Apart from it, in [12]–[14], the MWTs have symmetrical voltage windings on both primary and secondary side....
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References
More filters
08 Jun 1976
TL;DR: A new canonical circuit model is proposed, whose fixed topology contains all the essential inputr-output and control properties of any dc-todc switching converter, regardless of its detailed configuration, and by which different converters can be characterized in the form of a table conveniently stored in a computer data bank to provide a useful tool for computer aided design and optimization.
Abstract: A method for modelling switching-converter power stages is developed, whose starting point is the unified state-space representation of the switched networks and whose end result is either a complete state-space description or its equivalent small-signal low<-f requency linear circuit model. A new canonical circuit model is proposed, whose fixed topology contains all the essential inputr-output and control properties of any dc-todc switching converter, regardless of its detailed configuration, and by which different converters can be characterized in the form of a table conveniently stored in a computer data bank to provide a useful tool for computer aided design and optimization. The new canonical circuit model predicts that, in general;switching action introduces both zeros and poles into the duty ratio to output transfer function in addition to those from the effective filter network.
2,042 citations
"Load Model for Medium Voltage Casca..." refers methods in this paper
...Although a detailed switching model for a VFD, a motor and their control system can be built using Matlab/Simulink, it cannot be inserted in large scale power system simulation software for power system dynamic studies [5]–[10]....
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TL;DR: In this article, a new approach to medium-voltage variable-frequency static AC motor drives was proposed to improve the power quality of the motor by improving motor voltage and current waveforms.
Abstract: A new approach to medium-voltage variable-frequency static AC motor drives offers improvements in power quality. Harmonic current injection into the power lines is below the most severe requirements of IEEE Standard 519-1992. The power factor of this new type of drive exceeds 94% at full load and is above 90% at 10% load. Motor voltage and current waveforms are improved so that torque pulsations are reduced. Peak voltage stress on motor insulation does not exceed peak input line voltage, and no zero sequence voltage is imposed. Drive efficiency exceeds 96%. This paper describes the new approach and some of the results achieved.
841 citations
"Load Model for Medium Voltage Casca..." refers background in this paper
...The phase-shift angle differs by multiples of 20 for 18-pulse drives and by multiples of 15 for 24-pulse drives [17]....
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...The DC voltage feeds a single-phase full bridge inverter, which is delivered to a single-phase load at any voltage up to 480 V [17]....
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...DYNAMIC LOAD MODEL DEVELOPMENT The medium voltage cascaded H-bridge multi-level inverter drives are one of the topologies for very high power applications [17]–[21]....
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...The topology of a 9-power-module 18-pulse medium voltage drive can be found in [17] and [19]....
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...Eighteen-pulse cascaded H-bridge multi-level inverter motor drive system: (a) the topology of a nine-power-module drive [17]; (b) the schematic diagram for each power module [17]; (c) outputs of the single-phase full bridge inverters connected to phase a of an induction motor [20]....
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TL;DR: Sliding-mode and feedback linearization techniques along with large-signal phase plane analysis are presented as methods to analyze, control, and stabilize automotive converters/systems operating with CPLs.
Abstract: Power electronic converters and electric motor drives are being put into use at an increasingly rapid rate in advanced automobiles. However, the new advanced automotive electrical systems employ multivoltage level hybrid ac and dc as well as electromechanical systems that have unique characteristics, dynamics, and stability problems that are not well understood due to the nonlinearity and time dependency of converters and because of their constant power characteristics. The purpose of this paper is to present an assessment of the negative impedance instability concept of the constant power loads (CPLs) in automotive power systems. The main focus of this paper is to analyze and propose design criteria of controllers for automotive converters/systems operating with CPLs. The proposed method is to devise a new comprehensive approach to the applications of power electronic converters and motor drives in advanced automotive systems. Sliding-mode and feedback linearization techniques along with large-signal phase plane analysis are presented as methods to analyze, control, and stabilize automotive converters/systems with CPLs
813 citations
Journal Article•
TL;DR: In this paper, the authors summarized the state of the art of representation of power system loads for dynamic performance analysis purposes, including definition of terminology, discussion of the importance of load modeling, important considerations for different types of loads and different kinds of analyses Typical load model data and methods for acquiring data are reviewed.
Abstract: This paper summarizes the state of the art of representation of power system loads for dynamic performance analysis purposes It includes definition of terminology, discussion of the importance of load modeling, important considerations for different types of loads and different types of analyses Typical load model data and methods for acquiring data are reviewed A list of recent references is included
749 citations
"Load Model for Medium Voltage Casca..." refers background in this paper
...The dynamic load model involves difference or differential equations [1]....
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...The IEEE Task Force on Load Representation for Dynamic Performance recommended that a VFD was effectively constant power load if it was able to ride through voltage sags without tripping [1]....
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...As power systems are designed and operated with a lower stability margin, adequate load models are of major importance [1], [2]....
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Journal Article•
TL;DR: The goal of this paper is to promote better load modeling and advanced load modeling, and to facilitate data exchange among users of various production-grade simulation programs.
Abstract: The authors recommend standard load models for power flow and dynamic simulation programs. The goal of this paper is to promote better load modeling and advanced load modeling, and to facilitate data exchange among users of various production-grade simulation programs. Flexibility of modeling is an important consideration. For transient stability, longer-term dynamics, and small-disturbance stability programs, the authors recommend the structure of multiple load types connected to a load bus. Load types are static including discharge lighting, induction motors, synchronous motors, and transformer saturation. For each load type, multiple models may be connected to the bus. For longer-term dynamics programs, a model for LTC transformers is also recommended.
561 citations