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Neutral point voltage (NPV) balancing control and leakage current (LC) reduction methods are considered to improve the reliability of transformerless three-level T-type (3LT2) inverter. MVPWM method can control the inverter operation to eliminate the LC; however, is powerless to balance the NPV. Alternatively, DPWM methods can be implemented to balance the NPV. In this paper, a hybrid method for transformerless 3LT2 inverter is proposed to simultaneously minimize the LC and accomplish balancing control in case of NPV unbalancing. The proposed method applies MVPWM switching patterns to eliminate LC while the NPV is balanced. If the NPV becomes unbalanced, it applies specific switching patterns of the DPWM methods as alternative patterns to balance the NPV with minimal LC. Accordingly, the proposed method not only maintains the LC elimination advantage of the MVPWM method but also realizes the NPV balancing capability without any topology modification or adding electrical components. Noteworthy, even the NPV balancing is accomplished with minimal flow of the LC. The proposed method is carrier-based PWM, which shortens execution time and simplifies practical implementation. Experimental tests have been accomplished to demonstrate the effectiveness of the proposed method on adding the NPV balancing capability with minimal LC to the MVPWM method.
Mohammadreza Lak; Yue-Ting Tsai; Bing-Rong Chuang; Tzung-Lin Lee; Mohammad Hassan Moradi. A Hybrid Method to Eliminate Leakage Current and Balance Neutral Point Voltage for Photovoltaic Three-Level T-Type Inverter. IEEE Transactions on Power Electronics 2021, 36, 12070 -12089.
AMA StyleMohammadreza Lak, Yue-Ting Tsai, Bing-Rong Chuang, Tzung-Lin Lee, Mohammad Hassan Moradi. A Hybrid Method to Eliminate Leakage Current and Balance Neutral Point Voltage for Photovoltaic Three-Level T-Type Inverter. IEEE Transactions on Power Electronics. 2021; 36 (10):12070-12089.
Chicago/Turabian StyleMohammadreza Lak; Yue-Ting Tsai; Bing-Rong Chuang; Tzung-Lin Lee; Mohammad Hassan Moradi. 2021. "A Hybrid Method to Eliminate Leakage Current and Balance Neutral Point Voltage for Photovoltaic Three-Level T-Type Inverter." IEEE Transactions on Power Electronics 36, no. 10: 12070-12089.
Increasing installation of photovoltaic (PV) in the distribution power system has resulted in serious voltage rise, limiting grid-connectable power. This scenario becomes significant in the low-voltage resistive feeder. This paper proposes a decentralized control for distributed PV inverters to mitigate voltage rise. Instead of MPPT (maximum power point tracking) mode, the proposed PV inverter is able to curtail its real power and compensate the reactive power according to the impedance at the installation location. The drooped characteristics between the output power and the impedance are developed so that the PV inverters are able to cooperatively suppress voltage rise based on their local voltage measurement only. Therefore, PV inverters are allowed to supply more power to the utility within voltage limitation. Simulations are conducted to guarantee the proposed control on improvement of voltage rise considering different parameter of feeder. A lab-scaled prototype circuit is established to verify effectiveness in a resistive feeder.
Tzung-Lin Lee; Shang-Hung Hu; Shih-Sian Yang. Decentralized Control of PV Inverter to Mitigate Voltage Rise in Resistive Feeder. E3S Web of Conferences 2018, 69, 01009 .
AMA StyleTzung-Lin Lee, Shang-Hung Hu, Shih-Sian Yang. Decentralized Control of PV Inverter to Mitigate Voltage Rise in Resistive Feeder. E3S Web of Conferences. 2018; 69 ():01009.
Chicago/Turabian StyleTzung-Lin Lee; Shang-Hung Hu; Shih-Sian Yang. 2018. "Decentralized Control of PV Inverter to Mitigate Voltage Rise in Resistive Feeder." E3S Web of Conferences 69, no. : 01009.
An adaptive control of DPWM implementable in clamped-three-level inverters with two strings of PV panels in cascaded connection is proposed in this paper. The proposed modulation is developed based on the so-called circuit-level decoupling concept. It is able to provide balance line voltage even under unbalanced dc links. The unequal dc voltages appeared due to asymmetric MPPTs are controlled by proper injection of zero-sequence voltage to the common mode voltage while the total dc voltage is regulated based on the voltage commands generated by the MPPT of each string. Thus, both PV strings are able to be operated based on their MPPTs while there is almost no low-order harmonic distortion at the inverter output current. Compared with the previous methods, the high capability of the proposed method is evaluated by simulation study and experimental tests.
Mohammad M. Hashempour; Meng-Ying Yang; Tzung-Lin Lee. An Adaptive Control of DPWM for Clamped-Three-Level Photovoltaic Inverters With Unbalanced Neutral-Point Voltage. IEEE Transactions on Industry Applications 2018, 54, 6133 -6148.
AMA StyleMohammad M. Hashempour, Meng-Ying Yang, Tzung-Lin Lee. An Adaptive Control of DPWM for Clamped-Three-Level Photovoltaic Inverters With Unbalanced Neutral-Point Voltage. IEEE Transactions on Industry Applications. 2018; 54 (6):6133-6148.
Chicago/Turabian StyleMohammad M. Hashempour; Meng-Ying Yang; Tzung-Lin Lee. 2018. "An Adaptive Control of DPWM for Clamped-Three-Level Photovoltaic Inverters With Unbalanced Neutral-Point Voltage." IEEE Transactions on Industry Applications 54, no. 6: 6133-6148.
In this paper, the power quality (PQ) improvement of multi-area microgrids (MAMGs) is addressed. To this aim, mitigation of voltage harmonics and unbalance is considered by using distributed generators (DGs) and active power filters (APFs) in a proper way. As a novel approach, the main goal of the proposed method is to pick out redundant APFs and/or significantly reduce of DGs and APFs compensation workload by making collaboration between areas toward integrated PQ improvement of the MAMG. To achieve the desired PQ indices of different areas, supervisory control is planned for proper utilization of available compensators in time. By supervisory control, harmonic propagation between areas and the system unbalance are dealt with and systemic PQ improvement of the MAMG is provided. To this aim, scheduling framework is used to track the PQ situation of each area. Evaluation of the proposed control is carried out by a comprehensive simulation study in MATLAB/Simulink.
Mohammad M. Hashempour; Tzung-Lin Lee; Mehdi Savaghebi; Josep M. Guerrero. Real-Time Supervisory Control for Power Quality Improvement of Multi-Area Microgrids. IEEE Systems Journal 2018, 13, 864 -874.
AMA StyleMohammad M. Hashempour, Tzung-Lin Lee, Mehdi Savaghebi, Josep M. Guerrero. Real-Time Supervisory Control for Power Quality Improvement of Multi-Area Microgrids. IEEE Systems Journal. 2018; 13 (1):864-874.
Chicago/Turabian StyleMohammad M. Hashempour; Tzung-Lin Lee; Mehdi Savaghebi; Josep M. Guerrero. 2018. "Real-Time Supervisory Control for Power Quality Improvement of Multi-Area Microgrids." IEEE Systems Journal 13, no. 1: 864-874.
This paper investigates the open-circuit faults of switching devices in the three-level T-Type inverter and proposes a new tolerant control method. The three-phase current and variation of the neutral-point voltage are detected to determine the fault switch. A carrier-based pulse width modulation is developed to tolerate switch fault by transiting from three-level to two-level switching. This makes the modulation scheme easier to be implemented compared to space vector modulation. For the neutral-point fault, the fault phase is operated by two-level modulation to produce the same rating voltage. On the other hand, the inverter is able to produce balanced voltage with reduced rating by keeping the phase of half-bridge fault to the neutral-point voltage. The neutral-point voltage is also able to be balanced by using two-level modulation since it does not contribute the neutral-point current. The performance and effectiveness of the proposed tolerant control is verified by a laboratory build.
Tzung-Lin Lee; Bing-Feng Li; Meng-Ying Yang; Yue-Ting Tsai. A Carrier-Based PWM for Three-Level T-Type Inverter to Tolerate Open-Circuit Fault. IEEE Transactions on Power Electronics 2017, 33, 8787 -8796.
AMA StyleTzung-Lin Lee, Bing-Feng Li, Meng-Ying Yang, Yue-Ting Tsai. A Carrier-Based PWM for Three-Level T-Type Inverter to Tolerate Open-Circuit Fault. IEEE Transactions on Power Electronics. 2017; 33 (10):8787-8796.
Chicago/Turabian StyleTzung-Lin Lee; Bing-Feng Li; Meng-Ying Yang; Yue-Ting Tsai. 2017. "A Carrier-Based PWM for Three-Level T-Type Inverter to Tolerate Open-Circuit Fault." IEEE Transactions on Power Electronics 33, no. 10: 8787-8796.
The three-level T type inverter has been extensively used in photovoltaic (PV) generation. Various PV panels in cascaded connection normally require unequal dc voltage to accomplish separate maximum power point tracking (MPPT). This paper proposes a DPWM-controlled three-level T type inverter for two strings of PV panels in cascaded connection. The proposed modulation is developed based on the so-called circuit-level decoupling principle so that the inverter is able to generate balanced line voltage even in unequal dc voltage. The different dc voltages of PV strings are controlled by injection of zero-sequence voltage while total dc voltage is regulated to control the real power of the inverter. Thus both PV strings are able to operate at their respective MPPT while there is almost no low-order harmonic distortion at the inverter output. The proposed method was experimentally evaluated.
Mohammad M. Hashempour; Meng-Ying Yang; Tzung-Lin Lee. A DPWM-controlled three-level T-type inverter for photovoltaic generation considering unbalanced neutral-point voltage. 2017 IEEE Energy Conversion Congress and Exposition (ECCE) 2017, 3856 -3862.
AMA StyleMohammad M. Hashempour, Meng-Ying Yang, Tzung-Lin Lee. A DPWM-controlled three-level T-type inverter for photovoltaic generation considering unbalanced neutral-point voltage. 2017 IEEE Energy Conversion Congress and Exposition (ECCE). 2017; ():3856-3862.
Chicago/Turabian StyleMohammad M. Hashempour; Meng-Ying Yang; Tzung-Lin Lee. 2017. "A DPWM-controlled three-level T-type inverter for photovoltaic generation considering unbalanced neutral-point voltage." 2017 IEEE Energy Conversion Congress and Exposition (ECCE) , no. : 3856-3862.
The three-level T-type inverter has received much interest in energy storage system due to high efficiency. This paper proposes a modulating method for three-level T-type to produce balanced three-phase output voltage with no low-order distortion even for different voltage of battery banks in series connection. In addition, the zero-sequence injection is realized to control the neutral current so that the battery banks can be discharged based on requirement of individual state-of-charge (SOC). Simulation results are provided to verify the proposed approach.
Fang-Ta Liu; Mohammad M. Hashempour; Tzung-Lin Lee. Modulation of three-level T-type inverter supplied by series battery banks at different SOC condition. 2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia (IFEEC 2017 - ECCE Asia) 2017, 1954 -1959.
AMA StyleFang-Ta Liu, Mohammad M. Hashempour, Tzung-Lin Lee. Modulation of three-level T-type inverter supplied by series battery banks at different SOC condition. 2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia (IFEEC 2017 - ECCE Asia). 2017; ():1954-1959.
Chicago/Turabian StyleFang-Ta Liu; Mohammad M. Hashempour; Tzung-Lin Lee. 2017. "Modulation of three-level T-type inverter supplied by series battery banks at different SOC condition." 2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia (IFEEC 2017 - ECCE Asia) , no. : 1954-1959.
Power factor displacement and voltage fluctuation might produce due to high reactive power consumption of loads or long distribution lines. These power quality problems need more consideration in islanded microgrids (MGs) due to operating in low voltage grid with the absence of main grid. In this line, a novel control strategy for static synchronous compensator (STATCOM) is proposed in this paper to integrally correct power factor and mitigate voltage fluctuation in permissible ranges. In the previous approaches, auxiliary devices are used to compensate a certain point while, depending on load condition and distribution lines lengths, power quality of the other points except of the considered point might need compensation rather. In a different approach, the proposed strategy considers all the DGs buses for power factor correction and all the points of common coupling (PCCs) for voltage regulation. To this aim, communication network is applied. The proposed method is evaluated by MATLAB/Simulink.
Mohammad M. Hashempour; Tzung-Lin Lee. Integrated power factor correction and voltage fluctuation mitigation of microgrid using STATCOM. 2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia (IFEEC 2017 - ECCE Asia) 2017, 1215 -1219.
AMA StyleMohammad M. Hashempour, Tzung-Lin Lee. Integrated power factor correction and voltage fluctuation mitigation of microgrid using STATCOM. 2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia (IFEEC 2017 - ECCE Asia). 2017; ():1215-1219.
Chicago/Turabian StyleMohammad M. Hashempour; Tzung-Lin Lee. 2017. "Integrated power factor correction and voltage fluctuation mitigation of microgrid using STATCOM." 2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia (IFEEC 2017 - ECCE Asia) , no. : 1215-1219.
This paper presents a seamless transition method for a droop-controlled inverter. The droop control is suitable to make the inverter work as a voltage source in both islanded and grid-connected modes, however, the transfer between theses modes can result in a big inrush current that may damage the system. The proposed method allows the droop-controlled inverter to improve the transient response when transferring between modes, by detecting the inrush current, activating a current control loop during transients, and then transferring back to droop-controlled mode smoothly by using a virtual inductance loop. In addition, a local phase-locked-loop (PLL) is proposed to align the inverter voltage with the grid in order to reduce the transient current during the transition. Therefore, the droop-controlled inverter is able to operate in both grid-connected and islanded modes, providing as well a smooth transition between them, requiring neither synchronization signals nor grid-side information. The control algorithm and design procedure are presented. Experimental results from a laboratory prototype validate the effectiveness of the proposed method.
Shang-Hung Hu; Tzung-Lin Lee; Chun-Yi Kuo; Josep M. Guerrero. A Riding-through Technique for Seamless Transition between Islanded and Grid-Connected Modes of Droop-Controlled Inverters. Energies 2016, 9, 732 .
AMA StyleShang-Hung Hu, Tzung-Lin Lee, Chun-Yi Kuo, Josep M. Guerrero. A Riding-through Technique for Seamless Transition between Islanded and Grid-Connected Modes of Droop-Controlled Inverters. Energies. 2016; 9 (9):732.
Chicago/Turabian StyleShang-Hung Hu; Tzung-Lin Lee; Chun-Yi Kuo; Josep M. Guerrero. 2016. "A Riding-through Technique for Seamless Transition between Islanded and Grid-Connected Modes of Droop-Controlled Inverters." Energies 9, no. 9: 732.
Bidirectional power converters for electric vehicles (EVs) have received much attention recently, due to either grid-supporting requirements or emergent power supplies. This paper proposes a hybrid modulation of the three-phase dual-active bridge (3ΦDAB) converter for EV charging systems. The designed hybrid modulation allows the converter to switch its modulation between phase-shifted and trapezoidal modes to increase the conversion efficiency, even under light-load conditions. The mode transition is realized in a real-time manner according to the charging or discharging current. The operation principle of the converter is analyzed in different modes and thus design considerations of the modulation are derived. A lab-scaled prototype circuit with a 48V/20Ah LiFePO4 battery is established to validate the feasibility and effectiveness.
Yen-Ching Wang; Fu-Ming Ni; Tzung-Lin Lee. Hybrid Modulation of Bidirectional Three-Phase Dual-Active-Bridge DC Converters for Electric Vehicles. Energies 2016, 9, 492 .
AMA StyleYen-Ching Wang, Fu-Ming Ni, Tzung-Lin Lee. Hybrid Modulation of Bidirectional Three-Phase Dual-Active-Bridge DC Converters for Electric Vehicles. Energies. 2016; 9 (7):492.
Chicago/Turabian StyleYen-Ching Wang; Fu-Ming Ni; Tzung-Lin Lee. 2016. "Hybrid Modulation of Bidirectional Three-Phase Dual-Active-Bridge DC Converters for Electric Vehicles." Energies 9, no. 7: 492.
The synchronization between DG and microgird is required in order to prevent high inrush current. This high inrush current may trigger the protection or danger the facility in the system. On the other hand, anti-islanding inverters shall always detect islanding condition when they connect to microgrid. It is required that disconnecting from microgrid in two seconds whenever islanding occurred. General speaking, there are two method to detect islanding-passive and active method. This paper developed a voltage-controlled inverter which could connect to microgrid with synchronization and detect islanding condition actively. According to second harmonic voltage injection method, the proposed inverter detects the second harmonic current to decide whether islanding is happened.
Shang-Hung Hu; Hsueh-Tsung Tsai; Tzung-Lin Lee. Islanding detection method based on second-order harmonic injection for voltage-controlled inverter. 2015 IEEE 2nd International Future Energy Electronics Conference (IFEEC) 2015, 1 -5.
AMA StyleShang-Hung Hu, Hsueh-Tsung Tsai, Tzung-Lin Lee. Islanding detection method based on second-order harmonic injection for voltage-controlled inverter. 2015 IEEE 2nd International Future Energy Electronics Conference (IFEEC). 2015; ():1-5.
Chicago/Turabian StyleShang-Hung Hu; Hsueh-Tsung Tsai; Tzung-Lin Lee. 2015. "Islanding detection method based on second-order harmonic injection for voltage-controlled inverter." 2015 IEEE 2nd International Future Energy Electronics Conference (IFEEC) , no. : 1-5.
High penetration of PV generation may result in serious voltage rise in the distribution power system due to reverse power flow. This paper presents a decentralized voltage control for PV inverters to mitigate voltage fluctuations. Instead of operating in MPPT (maximum power point tracking) mode, each PV inverter is able to adjust its real power and reactive power based on resistive and inductive characteristics at its installation location, respectively. In this way, dispersed PV inverters on the feeder are able to cooperatively reduce voltage rise based on individual installation voltage only. Therefore, more PV inverters are allowed to deliver their power to the utility without violating voltage regulation. In this paper, various case studies were conducted to verify effectiveness of the proposed method by using power-flow analysis and time-domain simulation.
Tzung-Lin Lee; Shih-Sian Yang; Shang-Hung Hu. Design of decentralized voltage control for PV inverters to mitigate voltage rise in distribution power system without communication. 2014 International Power Electronics Conference (IPEC-Hiroshima 2014 - ECCE ASIA) 2014, 2606 -2609.
AMA StyleTzung-Lin Lee, Shih-Sian Yang, Shang-Hung Hu. Design of decentralized voltage control for PV inverters to mitigate voltage rise in distribution power system without communication. 2014 International Power Electronics Conference (IPEC-Hiroshima 2014 - ECCE ASIA). 2014; ():2606-2609.
Chicago/Turabian StyleTzung-Lin Lee; Shih-Sian Yang; Shang-Hung Hu. 2014. "Design of decentralized voltage control for PV inverters to mitigate voltage rise in distribution power system without communication." 2014 International Power Electronics Conference (IPEC-Hiroshima 2014 - ECCE ASIA) , no. : 2606-2609.
A seamless transition method has been presented for a droop-controlled inverter to transfer between islanded and grid-connected operations. A so-called virtual inductance and local phase-locked-loop (PLL) were proposed to realize this transition with no grid synchronization. This paper presents designing of variable virtual inductance to suppress inrush current, including exponentially-decaying, ramp-decaying, and constant virtual inductances. In addition, phase error of the PLL and the transient of the droop control are included. Simulations and preliminary experiments are provided.
Shang-Hung Hu; Chun-Yi Kuo; Tzung-Lin Lee. Design of virtual inductance for droop-controlled inverter with seamless transition between islanded and grid-connected operations. 2012 IEEE Energy Conversion Congress and Exposition (ECCE) 2012, 4383 -4387.
AMA StyleShang-Hung Hu, Chun-Yi Kuo, Tzung-Lin Lee. Design of virtual inductance for droop-controlled inverter with seamless transition between islanded and grid-connected operations. 2012 IEEE Energy Conversion Congress and Exposition (ECCE). 2012; ():4383-4387.
Chicago/Turabian StyleShang-Hung Hu; Chun-Yi Kuo; Tzung-Lin Lee. 2012. "Design of virtual inductance for droop-controlled inverter with seamless transition between islanded and grid-connected operations." 2012 IEEE Energy Conversion Congress and Exposition (ECCE) , no. : 4383-4387.
Voltage fluctuations resulting from variable output power of renewable energy sources are strictly challenging power quality in distributed-generation systems. This paper presents a control method for distributed static synchronous compensator (D-STATCOM) to alleviate variation of both positive- and negative-sequence voltages. The D-STATCOM simultaneously operates as fundamental positive-sequence admittance and fundamental negative-sequence conductance to restore the positive-sequence voltage to the nominal value as well as reduce the negative-sequence voltage to an allowable level. Both admittance and conductance are dynamically tuned to improve voltage-regulation performances in response to load changes and power variation of renewable sources. A proportional-resonant current regulator with selectively harmonic compensation is realized to control the fundamental current of the D-STATCOM as well as reduce the harmonic current, which could be an advantage in practical applications due to high voltage distortion in low-voltage microgrids. Voltage-regulation performances are discussed for different D-STATCOM locations as well as different D-STATCOM currents. Computer simulations and laboratory tests validate effectiveness.
Tzung-Lin Lee; Shang-Hung Hu; Yu-Hung Chan. D-STATCOM With Positive-Sequence Admittance and Negative-Sequence Conductance to Mitigate Voltage Fluctuations in High-Level Penetration of Distributed-Generation Systems. IEEE Transactions on Industrial Electronics 2011, 60, 1417 -1428.
AMA StyleTzung-Lin Lee, Shang-Hung Hu, Yu-Hung Chan. D-STATCOM With Positive-Sequence Admittance and Negative-Sequence Conductance to Mitigate Voltage Fluctuations in High-Level Penetration of Distributed-Generation Systems. IEEE Transactions on Industrial Electronics. 2011; 60 (4):1417-1428.
Chicago/Turabian StyleTzung-Lin Lee; Shang-Hung Hu; Yu-Hung Chan. 2011. "D-STATCOM With Positive-Sequence Admittance and Negative-Sequence Conductance to Mitigate Voltage Fluctuations in High-Level Penetration of Distributed-Generation Systems." IEEE Transactions on Industrial Electronics 60, no. 4: 1417-1428.
Active rectifiers are becoming increasingly popular and viable in high-power applications with requirement of bidirectional power flow. This paper presents a resonant current compensator with enhancement of harmonic impedance for LCL-filter based active rectifiers. Together with a fundamental resonant control, an improved harmonic compensator is realized to enhance harmonic impedance as well as reject current distortion. Based on this method, dc voltage regulation of the rectifier with unity-power-factor operation could be accomplished in the stationary reference frame with no phase-locked-loop used even in distorted line voltages. This is a significant advantage in terms of phase lagging of frame transformation and computing effort of digital signal processing. Controlling considerations of dc voltage based on the so-called nonlinear feedback-linearization are presented. Supporting results from computer simulations as well as laboratory tests validate effectiveness.
Tzung-Lin Lee; Shang-Hung Hu. Resonant current compensator with enhancement of harmonic impedance for LCL-filter based Active rectifiers. 2011 Twenty-Sixth Annual IEEE Applied Power Electronics Conference and Exposition (APEC) 2011, 1538 -1543.
AMA StyleTzung-Lin Lee, Shang-Hung Hu. Resonant current compensator with enhancement of harmonic impedance for LCL-filter based Active rectifiers. 2011 Twenty-Sixth Annual IEEE Applied Power Electronics Conference and Exposition (APEC). 2011; ():1538-1543.
Chicago/Turabian StyleTzung-Lin Lee; Shang-Hung Hu. 2011. "Resonant current compensator with enhancement of harmonic impedance for LCL-filter based Active rectifiers." 2011 Twenty-Sixth Annual IEEE Applied Power Electronics Conference and Exposition (APEC) , no. : 1538-1543.
Fluctuating power resulting from renewable energy sources is strictly challenging power quality in Microgrid systems. This paper presents a Distributed-STATCOM (D-STATCOM) to alleviate variation of both positive-sequence and negative-sequence voltages at the fundamental frequency. The D-STATCOM operates as separate conductances at the fundamental positive- and negative-sequence frequency, respectively, to restore the positive-sequence voltage to the nominal value as well as suppress the negative-sequence voltage to an allowable level. The conductance commands are dynamically tuned according to voltage fluctuation at the installation location, so voltage variation could be reduced in response to load change and variable renewable energy. A resonant current regulation is implemented for fundamental current tracking as well as harmonic current reduction due to high voltage distortion in low-voltage Microgrid. This feature is a significant advantage in practical applications. Supporting results from computer simulations are provided to validate effectiveness.
Tzung-Lin Lee; Shang-Hung Hu; Yu-Hung Chan. Design of D-STATCOM for voltage regulation in Microgrids. 2010 IEEE Energy Conversion Congress and Exposition 2010, 3456 -3463.
AMA StyleTzung-Lin Lee, Shang-Hung Hu, Yu-Hung Chan. Design of D-STATCOM for voltage regulation in Microgrids. 2010 IEEE Energy Conversion Congress and Exposition. 2010; ():3456-3463.
Chicago/Turabian StyleTzung-Lin Lee; Shang-Hung Hu; Yu-Hung Chan. 2010. "Design of D-STATCOM for voltage regulation in Microgrids." 2010 IEEE Energy Conversion Congress and Exposition , no. : 3456-3463.
Increasing demand of electric-power reliability in industrial parks or in urban areas has led to the development of closed-loop distribution power systems. The harmonic resonance between power-factor-correction capacitors and system inductors may cause significant voltage distortion along the feeder. This paper proposes a discrete frequency-tuning active filter installed at the middle point of a closed-loop line for harmonic-resonance suppression. The active filter operates as a variable conductance for individual harmonic frequency according to the corresponding harmonic-voltage distortion. This algorithm allows the damping conductance of each harmonic frequency to be separately and autonomously adjusted in response to variation of both harmonic sources and resonant capacitors. Therefore, the unintentional “whack-a-mole” phenomenon, due to mismatching between the active filter and the line, can be avoided even if the active-filter location deviates from the middle point. Voltage distortion throughout the closed-loop line can be definitely maintained below an allowable level with lower peak current and lower rms current compared to the conventional voltage-detection active filter. Computer simulations based on a 11.4 kV/15 MVA system and a scaled-down platform in the laboratory are developed to validate the effectiveness of the proposed approach.
Tzung-Lin Lee; Shang-Hung Hu. Discrete Frequency-Tuning Active Filter to Suppress Harmonic Resonances of Closed-Loop Distribution Power Systems. IEEE Transactions on Power Electronics 2010, 26, 137 -148.
AMA StyleTzung-Lin Lee, Shang-Hung Hu. Discrete Frequency-Tuning Active Filter to Suppress Harmonic Resonances of Closed-Loop Distribution Power Systems. IEEE Transactions on Power Electronics. 2010; 26 (1):137-148.
Chicago/Turabian StyleTzung-Lin Lee; Shang-Hung Hu. 2010. "Discrete Frequency-Tuning Active Filter to Suppress Harmonic Resonances of Closed-Loop Distribution Power Systems." IEEE Transactions on Power Electronics 26, no. 1: 137-148.
Harmonic resonances of the distribution power system have become a significant issue in recent years, due to extensive use of either nonlinear loadings or inverter-based distributed generation systems. This paper presents resonant current regulation to enhance the damping capability of the discrete frequency tuning active filter for suppressing power system harmonics. The resonant current regulator, which is composed of various parallel band-pass filters tuned at harmonic frequencies, is implemented so that the active filter can operate as variable conductance for each harmonic frequency without increasing overall gain of controller. Compared to the active filter with proportional control, the current tracking capability and the associated damping performances can be improved in the proposed method, especially for higher order harmonics due to severe phase lagging. Therefore, harmonic resonances can be definitely avoided and voltage distortion for each harmonic frequency can be separately suppressed to conform with harmonic regulation. The required damping conductance to maintain the harmonic voltage at an allowable level is also significantly reduced. Operation principles are explained and test results validate the effectiveness of the proposed approach.
Tzung-Lin Lee; Shang-Hung Hu. Design of resonant current regulation for discrete frequency tuning active filter. The 2010 International Power Electronics Conference - ECCE ASIA - 2010, 2271 -2275.
AMA StyleTzung-Lin Lee, Shang-Hung Hu. Design of resonant current regulation for discrete frequency tuning active filter. The 2010 International Power Electronics Conference - ECCE ASIA -. 2010; ():2271-2275.
Chicago/Turabian StyleTzung-Lin Lee; Shang-Hung Hu. 2010. "Design of resonant current regulation for discrete frequency tuning active filter." The 2010 International Power Electronics Conference - ECCE ASIA - , no. : 2271-2275.
Active front-end converters with bidirectional power flow capability have been extensively used for utility applications of power electronics. Large passive filters are normally required at the grid side of the converter to mitigate switching EMI noise. This may become a critical issue, in terms of installation space and potential resonance of the passive filter. This paper proposes a hybrid active front-end converter and its power flow control method. The hybrid converter is composed of a capacitor and a voltage source converter in series connection. Bidirectional real power of the converter can be controlled by the output voltage vector perpendicular to the grid voltage, and reactive power delivery of the converter for grid voltage regulation can be determined by the output voltage vector parallel to the grid voltage. Due to series connection capacitor, the converter can be operated between a low-voltage DC side and high-voltage grid side without any low-frequency transformer, which is the significant advantage of the proposed method. A harmonic resistance is also emulated in the proposed method to assure stable operation of the converter for unintentional voltage spike coming from the power system. Operation principles are explained in detail, and computer simulations and experimental results are provided to validate the effectiveness of the proposed approach.
Tzung-Lin Lee; Zong-Jie Chen; Shang-Hung Hu. Design of a power flow control method for hybrid active front-end converters. 2009 International Conference on Power Electronics and Drive Systems (PEDS) 2009, 133 -138.
AMA StyleTzung-Lin Lee, Zong-Jie Chen, Shang-Hung Hu. Design of a power flow control method for hybrid active front-end converters. 2009 International Conference on Power Electronics and Drive Systems (PEDS). 2009; ():133-138.
Chicago/Turabian StyleTzung-Lin Lee; Zong-Jie Chen; Shang-Hung Hu. 2009. "Design of a power flow control method for hybrid active front-end converters." 2009 International Conference on Power Electronics and Drive Systems (PEDS) , no. : 133-138.