Second Order Ripple Reduction in Switched Boost Inverter For Standalone Nanogrid Applications
01 Nov 2019-
TL;DR: A sliding mode control based voltage and current control method method is proposed so as to reduce the SHCs in Switched Boost Inverter (SBI), which results in excellent voltage regulation during load changes.
Abstract: The switched boost inverters are single stage topologies that boost dc voltage and convert it to required ac voltage. It requires lesser number of components and is more efficient compared to conventional two stage dc-dc-ac methods. The dc-ac conversion results in second order harmonic currents (SHCs) to be reflected at the source end. It causes various problems such as heating or failure of sources, oscillations in maximum power point tracking. The active or passive filters for SHCs may increase component count as well as increase overall cost of the system. In this paper, a sliding mode control based voltage and current control method method is proposed so as to reduce the SHCs in Switched Boost Inverter (SBI). Also, the transients during dc or ac load variations are kept within allowed range. This results in excellent voltage regulation during load changes. The proposed controller is validated through simulation for different types of load and upto 50 % load variations.
Citations
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TL;DR: In this paper , the authors present a comprehensive review of different effects of second-order ripple on different sources and the methodologies adopted to mitigate the ripples in distributed power generation environments.
Abstract: Second-order ripples occur in the voltage and current during any DC–AC power conversion. These conversions occur in the voltage source inverters (VSIs), current source inverters (CSIs), and various single-stage inverters (SSIs) topologies. The second-order ripples lead to oscillating source node currents and DC bus voltages when there is an interconnection between the AC and DC microgrids or when an AC load is connected to the DC bus of the microgrid. Second-order ripples have various detrimental effects on the sources and the battery storage. In the storage battery, they lead to the depletion of electrodes. They also lead to stress in the converter or inverter components. This may lead to the failure of a component and hence affect the reliability of the system. Furthermore, the second-order ripple currents (SRCs) lead to ripple torque in wind turbines and lead to mechanical stress. SRCs cause a rise in the temperature of photovoltaic panels. An increase in the temperature of PV panels leads to a reduction in the power generated. Furthermore, the second-order voltage and current oscillations lead to a varying maximum power point in PV panels. Hence, the maximum power may not be extracted from it. To mitigate SRCs, oversizing of the components is needed. To improve the lifespan of the sources, storage, and converter components, the SRCs must be mitigated or kept within the desired limits. In the literature, different methodologies have been proposed to mitigate and regulate these second-order ripple components. This manuscript presents a comprehensive review of different effects of second-order ripples on different sources and the methodologies adopted to mitigate the ripples. Different active power decoupling methodologies, virtual impedance-based methodologies, pulse width modulation-based signal injection methodologies, and control methods adopted in distributed power generation methods for DC microgrids have been presented. The application of ripple control methods spans from single converters such as SSIs and VSIs to a network of interconnected converters. Furthermore, different challenges in the field of virtual impedance control and ripple mitigation in distributed power generation environments are discussed. This paper brings a review regarding control methodologies to mitigate and regulate second-order ripples in DC–AC conversions and microgrids.
3 citations
TL;DR: In this paper , the main challenges and critical areas in operating on weak and very weak grids are discussed, as well as a discussion of the applicability of grid-connected converters in strong and weak grids with high inductance content.
Abstract: Grid-connected converters (GCCs) are used extensively for the integration of DC power sources with AC power sources. However, since it is a complex topic, there are many possibilities for regulating grid-injected currents, as well as different modulation techniques for generating full-bridge PWM voltages. The control techniques are directly related to the type of output filter, as well as to the topology of the converter, since a complex plant can require more sophisticated controllers to keep the system stable, and with good regulation performance. Furthermore, a discussion of the applicability of these converters in weak and very weak grids with high inductance content has recently been growing, which adds a greater degree of complexity to the control structure of the converter. In this brief overview are outlined some topics about topologies, output filters, and control, focusing on the current regulation of grid-connected converters. In addition, a discussion of the main challenges and critical areas in operating on weak and very weak grids is also presented.
1 citations
References
More filters
TL;DR: These new networks exhibit some unique advantages, such as the increased voltage gain and reduced voltage stress in the voltage-fed trans-ZSIs and the expanded motoring operation range in the current- fed trans- ZSIs, when the turns ratio of the transformer windings is over 1.
Abstract: This paper extends the impedance-source (Z-source) inverters concept to the transformer-based Z-source (trans-Z-source) inverters. The original Z-source inverter (ZSI) employs an impedance network of two inductors and two capacitors connected in a special arrangement to interface the dc source and the inverter bridge. It has buck and boost function that cannot be achieved by traditional voltage-source inverters and current-source inverters. In the proposed four trans-Z-source inverters, all the impedance networks consist of a transformer and one capacitor. While maintaining the main features of the previously presented Z-source network, the new networks exhibit some unique advantages, such as the increased voltage gain and reduced voltage stress in the voltage-fed trans-ZSIs and the expanded motoring operation range in the current-fed trans-ZSIs, when the turns ratio of the transformer windings is over 1. Simulation and experimental results of the voltage-fed and the current-fed trans-ZSIs are provided to verify the analysis.
450 citations
21 Jun 2010
TL;DR: These new networks exhibit some unique advantages, such as the increased voltage gain and reduced voltage stress in the voltage-fed trans-ZSIs and the expanded motoring operation range in the current- fed trans- ZSIs, when the turns ratio of the transformer windings is over 1.
Abstract: This paper extends the impedance-source (Z-source) inverters concept to the transformer based Z-source (trans-Z-source) inverters. The original Z-source inverter (ZSI) employs an impedance network of two inductors and two capacitors connected in a special arrangement to interface the dc source and the inverter bridge. It has overcome the conceptual limitations of the traditional voltage-source inverter and the current-source inverter. In the proposed trans-Z-source inverters, the impedance network consists of a transformer and one capacitor. While maintaining the main features of the previously presented Z-source network, the new networks exhibit some unique advantages, such as the increased voltage gain in the voltage-fed trans-ZSIs and the expanded motoring operation range in the current-fed trans-ZSIs when the turns-ratio of the transformer windings is over 1. Simulation and experimental results of one of the voltage-fed trans-Z-source inverters are provided to verify the analysis.
354 citations
"Second Order Ripple Reduction in Sw..." refers background in this paper
...Based on application, different topologies of ZSIs have been proposed in literature such as voltage fed trans-ZSIs and current fed trans-ZSI [1] to improve performence....
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TL;DR: A class of quasi- SBIs (qSBIs) that offers several advantages when compared with a conventional SBI, including reducing the voltage stress on the capacitor, increasing the boost voltage factor, and improving input current profiles are presented.
Abstract: A switched boost inverter (SBI) can replace a $Z$ -source inverter (ZSI) in low-power applications because it has one less $LC$ pair than the ZSI. This paper presents a class of quasi-SBIs (qSBIs) that offers several advantages when compared with a conventional SBI, including reducing the voltage stress on the capacitor, increasing the boost voltage factor, and improving input current profiles. Operating principles, steady-state analysis, and comparisons with conventional inverters are presented. A prototype based on a TMS320F28335 digital signal processor is built to verify the operating principle of the proposed qSBIs.
195 citations
"Second Order Ripple Reduction in Sw..." refers methods in this paper
...Different topologies of q-ZSIs such as Embedded type, DC linked type has been compared in [3]....
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TL;DR: In this paper, a second-order generalized integrator based quadrature signal generator (SOGI-QSG) with a fourth-order transfer function is proposed, after referring to the relationship between standard FOS and second order system.
Abstract: The second-order generalized integrator based quadrature signal generator (SOGI-QSG) is able to produce in-quadrature signals for many applications, such as frequency estimation, grid synchronization, and harmonic extraction. However, the SOGI-QSG is sensitive to input dc and harmonic components with unknown frequencies (e.g., interharmonics). To overcome the drawback, this letter begins by analyzing the dynamic response of SOGI-QSG from the first-order system (FOS) perspective. A second-order SOGI-QSG (SO-SOGI-QSG) with a fourth-order transfer function is then proposed, after referring to the relationship between standard FOS and second-order system. The proposed method is subsequently found to inherit the simplicity of the SOGI-QSG, while demonstrates better disturbance attenuation. Its parameter design procedure is also easy to understand, and can be followed step-by-step without difficulty. Performance of the proposed SO-SOGI-QSG is finally validated by experimental results presented in this letter.
193 citations
"Second Order Ripple Reduction in Sw..." refers background in this paper
...Hence, αβ components in a fixed reference frame are generated by passing output ac through a quadrature second order general integrator (QSOGI) [10]....
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...The quadrature components of input voltages are obtained by passing the ac voltage through a QSOGI signal generator see Fig.9....
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...T = [ sin(ωt) −cos(ωt) cos(ωt) sin(ωt) ] [ Vd Vq ] = T [ Vα Vβ ] Hence, αβ components in a fixed reference frame are generated by passing output ac through a quadrature second order general integrator (QSOGI) [10]....
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TL;DR: In this article, the SBI is proposed as a power electronic interface in dc nanogrid and a dq synchronous-reference-frame-based controller for SBI, which regulates both dc and ac bus voltages to their respective reference values under steady state as well as under dynamic load variation in the Nanogrid.
Abstract: Switched boost inverter (SBI) is a single-stage power converter derived from Inverse Watkins Johnson topology. Unlike the traditional buck-type voltage source inverter (VSI), the SBI can produce an ac output voltage that is either greater or less than the available dc input voltage. Also, the SBI exhibits better electromagnetic interference noise immunity when compared to the VSI, which enables compact design of the power converter. Another advantage of SBI is that it can supply both dc and ac loads simultaneously from a single dc input. These features make the SBI suitable for dc nanogrid applications. In this paper, the SBI is proposed as a power electronic interface in dc nanogrid. The structure and advantages of the proposed SBI-based nanogrid are discussed in detail. This paper also presents a dq synchronous-reference-frame-based controller for SBI, which regulates both dc and ac bus voltages of the nanogrid to their respective reference values under steady state as well as under dynamic load variation in the nanogrid. The control system of SBI has been experimentally validated using a 0.5-kW laboratory prototype of the SBI supplying both dc and ac loads simultaneously, and the relevant experimental results are given in this paper. The low cross regulation and the dynamic performance of the control system have also been verified experimentally for a 20% step change in either dc or ac load of SBI. These experimental results confirm the suitability of the SBI and its closed-loop control strategy for dc nanogrid applications.
153 citations
"Second Order Ripple Reduction in Sw..." refers background or methods or result in this paper
...Averaged model can be obtained by equating average voltage and current through a capacitor and inductor respectively to be zero in a time period [4]....
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...The parameter values used for simulation are similar to those in [4]....
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...The modulation indices obtained from PI control is d-axis modulation index md and q-axis modulation index mq [4]....
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...The PWM generation logic is similar to that in [4] see Fig....
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...The paper uses a single stage switched boost inverter derived from Inverse Watkins Johnson topology to feed ac and dc loads simultaneously [4] for a standalone nanogrid application....
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