Harmonic Analysis and Controller Design of 15 kV SiC IGBT-Based Medium-Voltage Grid-Connected Three-Phase Three-Level NPC Converter
TL;DR: In this article, the harmonic performance and current distortion of the grid-connected, three-level neutral point clamped converter using 15 kV silicon carbide Insulated Gate Bipolar Transistor (IGBTs) are investigated.
Abstract: Cascaded converters are generally used for medium-voltage (MV) grid-connected applications due to the limitation in the voltage rating of available silicon (Si) power devices. These converters find application in active power filters, STATCOM or as the active front end converters for solid state transformers at the distribution voltage levels. The high voltage wide bandgap semiconductor devices have enabled the grid connected operation of noncascaded converters. This results in high power density, less number of switching devices, and high efficiency for three-phase MV grid interface. This also results in control simplicity without the need for complex dc bus balancing algorithms otherwise needed for cascaded converters. However, such noncascaded, grid-connected converters introduce challenges in maintaining power quality at low currents. This paper investigates the harmonic performance and current distortion of the grid-connected, three-level neutral point clamped converter using 15 kV silicon carbide Insulated Gate Bipolar Transistor (IGBTs). A suitable control scheme for stable harmonic compensation is proposed. The challenges and control performance are explained through frequency domain analysis, simulations, and experimental validation on a developed prototype of the three-phase converter up to 4.16 kV, three-phase MV grid-connected operation.
Citations
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TL;DR: A methodology for the design of flying capacitors for multilevel inverters is presented, based on the harmonic representation of the switching functions, so that it is possible to design theFlying Capacitor Converter for different operation points.
9 citations
TL;DR: In this paper , a control scheme for five-level hybrid flying-capacitor inverters is proposed, which can balance the neutral point voltages across split dc-link capacitors and simultaneously regulate the flying capacitors.
Abstract: In this article, a novel control scheme for five-level hybrid flying-capacitor inverters is proposed, which can balance the neutral-point voltages across split dc-link capacitors and simultaneously regulate the flying-capacitor voltages.Each capacitor voltage is maintained by regulating the currents that flow through the dc-link neutral points and the flying capacitors. The key components affecting these currents are analyzed to construct a control scheme based on the injection of zero-sequence voltage to the modulation voltage reference.This technique eliminates the need for the auxiliary balancing circuit, which was previously used in the conventional operating schemes to regulate the dc-link capacitor voltages and, thus, reduces the device count and converter volume. The effectiveness of the proposed method for maintaining the capacitor voltages within the allowable range has been verified under various operating conditions through the simulation and experimental results.
8 citations
TL;DR: In this article , the impact of silicon-carbide (SiC) switches on the performance of MMC and NPC converters for medium-voltage (MV) applications is investigated.
Abstract: The neutral-point-clamped (NPC) converter and the modular multilevel converter (MMC) are among the most popular converter topologies for medium- and high-voltage applications. This article investigates the impact of silicon-carbide (SiC) switches on the performance of MMC and NPC converters for medium-voltage (MV) applications. Furthermore, two different cases of the circulating current control schemes are considered for the MMC configuration. The experimental prototypes of three-level configurations for both of these topologies are developed to compare and analyze their performances. Furthermore, the double pulse test (DPT) setup is constructed to obtain the device loss characteristics of the switching devices. These characteristics are then used to compute the device losses using the derived loss models. Moreover, in order to generalize the results for wide power range of operation, two sets of devices are considered for the loss analysis of the considered converter configurations. The obtained results for conduction and switching losses are compared for both the converter configurations at various loading conditions. These results provide the operating range for the considered converters to achieve reduced converter losses. Finally, a comparative analysis for the selection of converter configuration based on the obtained results is presented.
8 citations
04 Mar 2018
TL;DR: In this paper, the harmonic currents of an active front-end (AFE) system were analyzed using its input admittance in the synchronous rotating frame in the presence of voltage harmonics at the point of common coupling (PCC).
Abstract: Prediction and control of harmonics injected into the grid from power electronics converters are very important for the power system. This paper analyzes the harmonic currents of an active front-end (AFE) system using its input admittance in the synchronous rotating frame in the presence of voltage harmonics at the point of common coupling (PCC). A voltage harmonic at the PCC of the AFE system with angular frequency of ω may induce current harmonics with angular frequency at not only ω, but also 2ω0-ω. The line angular frequency is ω0. To reduce the induced current harmonics, a grid sensitivity function defined by the grid and AFE impedances should be designed with low magnitude. The proposed analysis and method are validated using simulation and experiments.
7 citations
Cites background from "Harmonic Analysis and Controller De..."
...Actually, along with the ever increasing switching frequency due to the application of advanced power devices, harmonics induced by the interaction between controllers of a converter, grid impedance, and grid disturbance [10] are getting worse, they could be interharmonics that cannot be analyzed using ‘Harmonic admittance matrix’ [5][6]....
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TL;DR: The design methodology proposed is based on the direct location of resonance frequencies, taking into consideration the effect of the grid impedance, and achieves the objectives without the need to increase the number of sensors, neither the use of observers.
Abstract: This paper presents a design methodology of a LCL filter for its application on the interconnection with the grid of a three-phase solid-state transformer, which is based on a three-stage configuration. The filter operates without damping resistors, and the design methodology proposed is based on the direct location of resonance frequencies, taking into consideration the effect of the grid impedance. The developed methodology can be applied to different power levels. In addition, control tuning considerations are proposed in order to avoid resonance points, evaluating the overall performance through the current total harmonic distortion in the point of common coupling. Furthermore, the used dq0 reference control frame achieves the objectives without the need to increase the number of sensors, neither the use of observers. The design methodology is validated by testing the operating system at 10 kW, 100 kW and 1 MW. For 1 MW, it is also implemented on a real-time simulator.
7 citations
References
More filters
TL;DR: Current control techniques for three-phase voltage-source pulsewidth modulated converters, including bang-bang (hysteresis, delta modulation) controllers and predictive controllers with on-line optimization are reviewed.
Abstract: The aim of this paper is to present a review of current control techniques for three-phase voltage-source pulsewidth modulated converters. Various techniques, different in concept, have been described in two main groups: linear and nonlinear. The first includes proportional integral (stationary and synchronous) and state feedback controllers, and predictive techniques with constant switching frequency. The second comprises bang-bang (hysteresis, delta modulation) controllers and predictive controllers with on-line optimization. New trends in current control-neural networks and fuzzy-logic-based controllers-are discussed, as well. Selected oscillograms accompany the presentation in order to illustrate properties of the described controller groups.
2,086 citations
"Harmonic Analysis and Controller De..." refers methods in this paper
...This method is considered unsatisfactory because it cannot completely eliminate the steady-state errors [24], [25]....
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TL;DR: In this paper, the presence of steady-state limit cycles in digitally controlled PWM converters is discussed, and conditions on the control law and quantization resolution for their elimination are suggested.
Abstract: This paper discusses the presence of steady-state limit cycles in digitally controlled pulse-width modulation (PWM) converters, and suggests conditions on the control law and the quantization resolution for their elimination. It then introduces single-phase and multi-phase controlled digital dither as a means of increasing the effective resolution of digital PWM (DPWM) modules, allowing for the use of low resolution DPWM units in high regulation accuracy applications. Bounds on the number of bits of dither that can be used in a particular converter are derived. Finally, experimental results confirming the theoretical analysis are presented.
735 citations
03 Oct 1999
TL;DR: In this article, a technique for interpreting the stationary/rotating frame transformations as modulation processes in the Laplace domain is presented, which moves the control function from one part of the frequency spectrum to another.
Abstract: Stationary frame linear PI current regulators are conventionally regarded as unsatisfactory for AC systems because they cannot eliminate steady state errors. Consequently, synchronous frame regulators are perceived to be superior, since they achieve zero steady state error by acting on DC signals in a rotating frame of reference. However, a synchronous frame regulator is more complex, and requires in particular a way of transforming a measured stationary frame AC current (or error) to rotating frame DC quantities, and transforming the resultant control action back to the stationary frame for implementation. This paper presents a technique for interpreting the stationary/rotating frame transformations as modulation processes in the Laplace domain which move the control function from one part of the frequency spectrum to another. The technique is used to compare stationary and synchronous frame PI regulators on a common basis to better understand the advantages of a synchronous frame regulator, and then to develop a new form of stationary frame resonant regulator which achieves zero steady state error without requiring the complex transformations of a synchronous frame regulator. The performance of this new regulator is evaluated and found to be equivalent to that of the synchronous frame PI regulator.
672 citations
"Harmonic Analysis and Controller De..." refers background or methods in this paper
...second-order model of the PR controller is not straightforward and is prone to higher error in fixed point implementation [25]....
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...This method is considered unsatisfactory because it cannot completely eliminate the steady-state errors [24], [25]....
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TL;DR: In this article, a hybrid system consisting of a proportional integral (PI) controller plus a generic hth harmonic resonant controller implemented in a frame rotating at the n th harmonic frequency is discussed in detail.
Abstract: Voltage source inverters connected to the grid in applications such as active rectifiers, active filters, uninterruptible power supplies, and distributed generation systems need an optimal ac current control. To obtain zero steady-state error at the fundamental frequency (i.e., unity power factor), the use of a standard integrator in a rotating frame is as effective as the use of a resonant controller in a stationary frame. However, the grid voltage harmonics influence the current controller and generate current harmonics unless several integrators in multiple rotating frames or resonant compensators in a stationary frame are adopted. In this letter, a hybrid system consisting of a proportional integral (PI) controller plus a generic hth harmonic resonant controller implemented in a frame rotating at the n th harmonic frequency is discussed in detail. The hth harmonic controller is able to decrease both the (h - n)th and (h + n)th harmonics, while the PI controller is able to decrease other harmonics if the synchronization phase signal adopted for the frame transformation is unfiltered. It is demonstrated that the use of a PI and sixth harmonic resonant compensator is effective for both positive and negative sequence fifth and seventh harmonics; hence, four harmonics are compensated with the proportional integral-resonant (PI-RES) controller implemented in a synchronous frame. Simulation and experimental tests validate the proposed analysis
662 citations
"Harmonic Analysis and Controller De..." refers background in this paper
...A proportional-resonant (PR) controller or a PI-resonant controller can be used in the stationary reference frame for each lower order harmonic to be eliminated [27], [26]....
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01 Jan 2006
583 citations
"Harmonic Analysis and Controller De..." refers background in this paper
...A proportional-resonant (PR) controller or a PI-resonant controller can be used in the stationary reference frame for each lower order harmonic to be eliminated [27], [26]....
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