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
More filters
TL;DR: This review comprehensively reviews the SST topologies suitable for different voltage levels and with varied stages, their control operation, and different trends in applications and provides recommendations for the improvement of future SST configuration and development.
Abstract: Solid-state transformer (SST) is an emerging technology integrating with a transformer power electronics converters and control circuitry. This paper comprehensively reviews the SST topologies suitable for different voltage levels and with varied stages, their control operation, and different trends in applications. The paper discusses various SST configurations with their design and characteristics to convert the input to output under unipolar and bipolar operation. A comparison between the topologies, control operation and applications are included. Different control models and schemes are explained. Potential benefits of SST in many applications in terms of controllability and the synergy of AC and DC systems are highlighted to appreciate the importance of SST technologies. This review highlights many factors including existing issues and challenges and provides recommendations for the improvement of future SST configuration and development.
175 citations
Cites background from "Harmonic Analysis and Controller De..."
...However, it brought to the challenges in maintaining the power quality at low current/low load conditions [61], [62]....
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TL;DR: A novel virtual space vector modulation, named as RCMV_VSVPWM, is proposed in this paper to reduce CMV and eliminate NP voltage oscillation for NPC TLI, and the highlight of the method is zero average NP current in one control cycle and lower CMV.
Abstract: This paper briefly reviews the common-mode voltage (CMV) and neutral point (NP) voltage for neutral point clamped three-level inverter (NPC TLI). Then, the space vector pulsewidth modulation (SVPWM) and traditional virtual SVPWM (VSVPWM) are discussed in terms of these two issues, revealing the drawbacks in reducing CMV or eliminating NP voltage oscillation. A novel virtual space vector modulation, named as RCMV_VSVPWM, is proposed in this paper to reduce CMV and eliminate NP voltage oscillation for NPC TLI. By selecting vectors with lower CMVs, a set of novel virtual voltage vectors are generated. The highlight of the method is zero average NP current in one control cycle and lower CMV. Furthermore, the active NP voltage control suitable for RCMV_VSVPWM is presented and evaluated. The corresponding experimental results are given, which are well-consistent with theoretical analysis.
82 citations
TL;DR: This paper investigates the use of the multilevel modular converter (MMC) for harmonics mitigation due to its high bandwidth compared with conventional converters and proves the capability of the MMC to mitigate harmonics up to the thirteenth order, while maintaining a low effective switching frequency and thus, low switching losses.
Abstract: Due to the increase of power electronic-based loads, the maintenance of high power quality poses a challenge in modern power systems. To limit the total harmonic distortion in the line voltage and currents at the point of the common coupling (PCC), active power filters are commonly employed. This paper investigates the use of the multilevel modular converter (MMC) for harmonics mitigation due to its high bandwidth compared with conventional converters. A selective harmonics detection method and a harmonics controller are implemented, while the output current controller of the MMC is tuned to selectively inject the necessary harmonic currents. Unlike previous studies, focus is laid on the experimental verification of the active filtering capability of the MMC. For this reason an MMC-based double-star STATCOM is developed and tested for two representative case studies, i.e., for grid currents and PCC voltage harmonics. The results verify the capability of the MMC to mitigate harmonics up to the thirteenth order, while maintaining a low effective switching frequency and thus, low switching losses.
52 citations
Cites background from "Harmonic Analysis and Controller De..."
...Several open-loop control schemes using grid voltage feed-forward have been proposed to compensate the grid harmonic voltage [10]–[13], but they are not sufficient to suppress line current harmonics due to dead time effect [14]....
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...Both implementations are equivalent in terms of computational burden [10] and thus, high bandwidth is necessary for the current control loops in order to have satisfactory results in the elimination of steady-state errors [14]....
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...At medium voltage and low current, there is little margin for error and thus, feedforward compensation schemes are not preferred, whereas feedback-based approaches are recommended [14]....
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TL;DR: A state-of-the-art review for SST proposed topologies, controllers, and applications is introduced and strengths, weaknesses, opportunities, and threats (SWOT) analysis along with a brief review of market drivers for prospective commercialisation are elaborated.
Abstract: With the global trend to produce clean electrical energy, the penetration of renewable energy sources in existing electricity infrastructure is expected to increase significantly within the next few years. The solid state transformer (SST) is expected to play an essential role in future smart grid topologies. Unlike traditional magnetic transformer, SST is flexible enough to be of modular construction, enabling bi-directional power flow and can be employed for AC and DC grids. Moreover, SSTs can control the voltage level and modulate both active and reactive power at the point of common coupling without the need to external flexible AC transmission system device as per the current practice in conventional electricity grids. The rapid advancement in power semiconductors switching speed and power handling capacity will soon allow for the commercialisation of grid-rated SSTs. This paper is aimed at introducing a state-of-the-art review for SST proposed topologies, controllers, and applications. Additionally, strengths, weaknesses, opportunities, and threats (SWOT) analysis along with a brief review of market drivers for prospective commercialisation are elaborated.
38 citations
TL;DR: A power management strategy to address the unpredictability of the solar irradiance fluctuations with two main operation modes: first, the load-feeding mode to minimize the grid power consumption by maximizing the local load consumption from both the PV and the EBU; second, the grid- feeding mode to smooth out the PV output fluctuation and to control the ramp rate to a desired value when supplying the grid.
Abstract: The unpredictability of the solar irradiance fluctuations can result in both photovoltaic (PV) power output fluctuations and high ramp rates. This can lead to significant voltage fluctuations with high ramp rates at the point of common coupling. Traditionally, the energy buffer units (EBUs) are used to smooth out the power fluctuations using the moving average method or the PV power gradient control. However, these methods can only smooth out the power at the output of grid inverter without considering the local load. This paper proposes a power management strategy to address this issue with two main operation modes: first, the load-feeding mode to minimize the grid power consumption by maximizing the local load consumption from both the PV and the EBU; second, the grid-feeding mode to smooth out the PV output fluctuation and to control the ramp rate to a desired value when supplying the grid. Furthermore, the EBU can be fully charged during the off-peak period or at night by the grid to take advantage of the time-of-use electricity price. The proposed control strategy is first simulated using MATLAB/Simulink and then a laboratory prototype platform is built and tested to verify the feasibility and the effectiveness of the proposed power management strategy with ramp-rate control.
38 citations
Cites background from "Harmonic Analysis and Controller De..."
...is becoming an attractive topology for interfacing renewable energy sources to the grid [23]–[25]....
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References
More filters
20 Jun 2004
TL;DR: In this paper, a new exact small-signal z-domain model for the combination modulator and converter is derived, which is characterized by its capability to quantify the different dynamics of the converter for different modulators, its ease of use and its ability to predict the values of the control variables at the true sampling instants of the real system.
Abstract: As the performance of digital signal processors has increased rapidly during the last decade, there is a growing interest to replace the analog controllers in low power switching converters by more complicated and flexible digital control algorithms. Compared to high power converters, the control loop bandwidths for converters in the lower power range are generally much higher. Because of this, the dynamic properties of the uniformly-sampled pulse-width modulators used in low power applications become an important restriction to the maximum achievable bandwidth of control loops. Though frequency- and Laplace-domain models for uniformly-sampled pulse-width modulators are very valuable as they improve the general perception of the dynamic behavior of these modulators, the direct discrete design of the digital compensator requires a z-domain model for the combination modulator and converter For this purpose a new exact small-signal z-domain model is derived. In accordance with the zero-order-hold equivalent commonly used for 'regular' digital control systems, this z-domain model gives rise to the development of a uniformly-sampled pulse-width-modulator equivalent of the converter. This z-domain model is characterized by its capability to quantify the different dynamics of the converter for different modulators, its ease of use and its ability to predict the values of the control variables at the true sampling instants of the real system.
181 citations
"Harmonic Analysis and Controller De..." refers methods in this paper
...The digitization effects such as sampling time and others can be compensated using the models discussed in [32]–[36] for better performance....
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...This issue of digital control is known and can be solved based on techniques available in [32]–[36]....
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TL;DR: This paper first analyzes the limitations of the standard resonant current control operating under abnormal grid conditions and then introduces a control scheme that improves the current harmonic distortion in such adverse conditions without increasing the computational load of thestandard current control.
Abstract: The resonant current control has been extensively employed to reduce the current harmonic distortion in a wide range of grid-connected distributed generation applications, including photovoltaic (PV) inverters, wind and water turbines, and fuel-cell inverters. However, the performance of these systems is deteriorated when the utility grid voltage experiences abnormal conditions such as voltage harmonics and imbalances. Several advanced control solutions have been recently introduced to cope with this problem but at the cost of a significant increase in the control computational load. This paper first analyzes the limitations of the standard resonant current control operating under abnormal grid conditions and then introduces a control scheme that improves the current harmonic distortion in such adverse conditions without increasing the computational load of the standard current control. This theoretical contribution is validated by means of selected experimental results from a three-phase PV inverter.
179 citations
"Harmonic Analysis and Controller De..." refers background or methods in this paper
...In the literature, several methods have been proposed to eliminate lower order harmonics from grid current at lower grid voltage and higher currents [18]–[28]....
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...Therefore, in the closed-loop control, these harmonics propagate and pollute the total control loop [18]–[22]....
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24 Oct 2005
TL;DR: In this paper, the potential of a transformerless STATic synchronous COMpensator (STATCOM) intended for installation on the 6.6-kV industrial and utility distribution systems is discussed.
Abstract: This paper discusses the potential of a transformerless STATic synchronous COMpensator (STATCOM) intended for installation on the 6.6-kV industrial and utility distribution systems. The STATCOM consists of a five-level diode-clamped pulsewidth-modulation converter rated at 1 MVA and a voltage-balancing circuit rated at 6 kVA. Moreover, this paper designs, constructs, and tests a 200-V 10-kVA STATCOM based on a five-level converter with a carrier frequency of 3 kHz and a voltage-balancing circuit with a switching frequency of 3 kHz. The STATCOM and its experimental waveforms verify the viability and effectiveness of the 6.6-kV transformerless STATCOM.
179 citations
TL;DR: With the proposed full-feedforward schemes, the injected grid current harmonics and unbalance caused by grid voltages can be greatly reduced.
Abstract: This paper investigates the feedforward schemes of grid voltages for a three-phase LCL-type grid-connected inverter. The full-feedforward functions of grid voltages are derived for the stationary α- β frame, synchronous d - q frame, and decoupled synchronous d - q frame-controlled three-phase LCL-type grid-connected inverters. The derived full-feedforward functions mainly consist of three parts which are proportional, derivative, and second derivative parts. The use of the traditional proportional feedforward function in the three-phase LCL -type grid-connected inverter will result in the amplification of the high-frequency injected grid current harmonics. With the proposed full-feedforward schemes, the injected grid current harmonics and unbalance caused by grid voltages can be greatly reduced. The effectiveness of the proposed feedforward schemes is verified by the experimental results.
177 citations
TL;DR: In this article, the authors proposed a sampling algorithm for digital signal processing (DSP) controlled 2 kW power factor correction (PFC) converters, which can improve switching noise immunity greatly in average current-control power supplies.
Abstract: This paper proposes a novel sampling algorithm for digital signal processing (DSP) controlled 2 kW power factor correction (PFCs) converters, which can improve switching noise immunity greatly in average-current-control power supplies. Based on the newly developed DSP chip TMS320F240. a 2 kW PFC stage is implemented. The novel sampling algorithm shows great advantages when the converter operates at a frequency above 30 kHz.
114 citations