Phase Shift Control for Series Active Voltage Quality Regulators

Guochun Xiao,Guofei Teng,Beihai Chen,Jixu Zhang 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4

A phase shift algorithm based on the closed-loop control of dc-link voltage implemented on a series active voltage quality regulator (A VQR) is proposed in this paper. To avoid pumping-up the dc-link voltage, a general phase shift compensation strategy is applied. The relationships among the operation variables are discussed in detail, which is very important for guiding the design of both the main circuit and the control system. Then on the basis of an investigation of the dc-link voltage pumping-up from viewpoint of the active power flow, a novel phase shift control method based on the closed-loop of the dc-link voltage is proposed. This method can adjust the phase of the output voltage gradually and automatically according to the dc-link voltage variation without introducing a phase jump. The effectiveness of the proposed strategy is verified through simulations of a single-phase SkV A prototype and laboratory experiments on both a single-phase SkV A and a three-phase ISkV A prototype.

Phase Shift Control for Series Active Voltage Quality Regulators

Xiao, Guochun,Teng, Guofei,Chen, Beihai,Zhang, Jixu The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4

A phase shift algorithm based on the closed-loop control of dc-link voltage implemented on a series active voltage quality regulator (AVQR) is proposed in this paper. To avoid pumping-up the dc-link voltage, a general phase shift compensation strategy is applied. The relationships among the operation variables are discussed in detail, which is very important for guiding the design of both the main circuit and the control system. Then on the basis of an investigation of the dc-link voltage pumping-up from viewpoint of the active power flow, a novel phase shift control method based on the closed-loop of the dc-link voltage is proposed. This method can adjust the phase of the output voltage gradually and automatically according to the dc-link voltage variation without introducing a phase jump. The effectiveness of the proposed strategy is verified through simulations of a single-phase 5kVA prototype and laboratory experiments on both a single-phase 5kVA and a three-phase 15kVA prototype.

Novel Active Voltage Quality Regulator with Adaptive DC-Link Voltage Control

Xiao, Guochun,Zeng, Zhong,Liu, Kai,Hu, Zhiliang,Wang, Zhaoan The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.6

In this paper, a novel Active Voltage Quality Regulator (AVQR) topology with a thyristor rectifier and an adaptive dclink voltage control strategy are proposed. The proposed AVQR can efficiently mitigate the long duration variations (e.g. undervoltages/overvoltages), voltage imbalances and voltage harmonics. Compared with conventional AVQRs, it can regulate the load voltage very well with a much lower dc-link voltage. This is accomplished by replacing the diode rectifier with a thyristor rectifier. Moreover, its dc-link voltage can vary with the deviations of the supply voltage through the proposed adaptive dc-link voltage control strategy. All of these contribute to its significantly higher efficiency for online operating, which is very important and attractive for many applications. The proposed topology and control strategy are theoretically analyzed in detail. Simulation results are also provided in the paper. Finally, the feasibility and effectiveness of the proposed method are verified by means of experimental results from a 2kVA prototype. Both of the simulation and experimental results show that the proposed AVQR can achieve a much higher efficiency and similar regulation performance when compared with the conventional ones.

Novel Active Voltage Quality Regulator with Adaptive DC-Link Voltage Control

Guochun Xiao,Zhong Zeng,Kai Liu,Zhiliang Hu,Zhaoan Wang 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.6

In this paper, a novel Active Voltage Quality Regulator (AVQR) topology with a thyristor rectifier and an adaptive dclink voltage control strategy are proposed. The proposed AVQR can efficiently mitigate the long duration variations (e.g.undervoltages/overvoltages), voltage imbalances and voltage harmonics. Compared with conventional AVQRs, it can regulate the load voltage very well with a much lower dc-link voltage. This is accomplished by replacing the diode rectifier with a thyristor rectifier. Moreover, its dc-link voltage can vary with the deviations of the supply voltage through the proposed adaptive dc-link voltage control strategy. All of these contribute to its significantly higher efficiency for online operating, which is very important and attractive for many applications. The proposed topology and control strategy are theoretically analyzed in detail. Simulation results are also provided in the paper. Finally, the feasibility and effectiveness of the proposed method are verified by means of experimental results from a 2kVA prototype. Both of the simulation and experimental results show that the proposed AVQR can achieve a much higher efficiency and similar regulation performance when compared with the conventional ones.

Concomitant PIK3CA and TP53 Mutations in Breast Cancer: An Analysis of Clinicopathologic and Mutational Features, Neoadjuvant Therapeutic Response, and Prognosis

Xiao-Yi Lin,Lijuan Guo,Xin Lin,Yulei Wang,Guochun Zhang 한국유방암학회 2023 Journal of breast cancer Vol.26 No.4

Purpose: PIK3CA and TP53 are the most prevalently mutated genes in breast cancer (BC). Previous studies have indicated an association between concomitant PIK3CA/TP53 mutations and shorter disease-free survival. As its clinical utility remains largely unknown, we aimed to analyze the prognostic and predictive roles of this co-mutation. Methods: We retrospectively analyzed patients who were diagnosed with BC at Guangdong Provincial People’s Hospital (GDPH) who underwent next-generation sequencing. The correlation of concomitant PIK3CA/TP53 mutations with clinicopathological and mutational characteristics, and neoadjuvant systemic therapy (NST) responses was analyzed. The Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) dataset was used to verify associations between concurrent mutations and survival outcomes. Results: In the GDPH cohort, concomitant PIK3CA/TP53 mutations were associated with more aggressive phenotypes, including human epidermal growth factor receptor 2 positive status, hormone receptor negative status, high Ki-67 expression, high histological grade, advanced TNM stage, and additional genetic alterations. Co-mutations also portended a worse response to NST, especially taxane-containing regimens, when compared with the TP53 mutant alone (odds ratio, 3.767; 95% confidence interval, 1.205–13.087; p = 0.028). A significant association was observed between concomitant PIK3CA/TP53 mutations and poor survival outcomes in the METABRIC cohort. Conclusion: Concomitant PIK3CA/TP53 mutations not only suggested unfavorable features and poor prognosis in BC but also conferred less benefit to NST than TP53 mutations alone.

A Fast Sorting Strategy Based on a Two-way Merge Sort for Balancing the Capacitor Voltages in Modular Multilevel Converters

Fangzhou Zhao,Guochun Xiao,Min Liu,Daoshu Yang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2

The Modular Multilevel Converter (MMC) is particularly attractive for medium and high power applications such as High-Voltage Direct Current (HVDC) systems. In order to reach a high voltage, the number of cascaded submodules (SMs) is generally very large. Thus, in the applications with hundreds or even thousands of SMs such as MMC-HVDCs, the sorting algorithm of the conventional voltage balancing strategy is extremely slow. This complicates the controller design and increases the hardware cost tremendously. This paper presents a Two-Way Merge Sort (TWMS) strategy based on the prediction of the capacitor voltages under ideal conditions. It also proposes an innovative Insertion Sort Correction for the TWMS (ISC-TWMS) to solve issues in practical engineering under non-ideal conditions. The proposed sorting methods are combined with the features of the MMC-HVDC control strategy, which significantly accelerates the sorting process and reduces the implementation efforts. In comparison with the commonly used quicksort algorithm, it saves at least two-thirds of the sorting execution time in one arm with 100 SMs, and saves more with a higher number of SMs. A 501-level MMC-HVDC simulation model in PSCAD/EMTDC has been built to verify the validity of the proposed strategies. The fast speed and high efficiency of the algorithms are demonstrated by experiments with a DSP controller (TMS320F28335).

PR and Harmonic Compensation Control Scheme with Current State Feedback for an Single-Phase Active Voltage Quality Regulator

Ye Zhuhuan,Xiao Guochun,Zeng Zhong,Teng Guofei,Jia Yaoqin 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

In this paper, a new control scheme of a proportional resonant (PR) + harmonic compensation (HC) combined with inductor current state feedback and load current feed-forward for an Active Voltage Quality Regulator is proposed. The inductor current state feedback is used to enhance the stability and increase the damping factor to eliminate the resonant peak of output LC filter. The load current feed forward is implemented to compensate the voltage drop due to the inductor state feedback and suppress the load disturbance. Meanwhile, a combined PR and HC control structure is added into the outer voltage regulation loop to achieve zero steady-state error and compensate harmonics respectively. Theoretical analysis has been achieved and the analytical results are validated by simulation studies and experimental tests on a single-phase 2㎸A prototype, which verify the feasibility and effectiveness of the proposed controller.

Control Strategy Based on Equivalent Fundamental and Odd Harmonic Resonators for Single-Phase DVRs

Teng, Guofei,Xiao, Guochun,Hu, Leilei,Lu, Yong,Kafle, Yuba Raj The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4

In this paper, a digital control strategy based on equivalent fundamental and odd harmonic resonators is proposed for single-phase DVRs. By using a delay block, which can be equivalent to a bank of resonators, it rejects the fundamental and odd harmonic disturbances effectively. The structure of the single closed-loop control system consists of a delay block, a proportional gain and a set of zero phase notch filters. The principle of the controller design is discussed in detail to ensure the stability of the system. Both the supply voltage and the load current feedforwards are used to improve the response speed and the ability to eliminate disturbances. The proposed controller is simple in terms of its structure and implementation. It has good performances in harmonic compensation and dynamic response. Experimental results from a 2kW DVR prototype confirm the validity of the design procedure and the effectiveness of the control strategy.

An LCCL Filter and Its Application to a Half-Bridge APF

Jingyang Fang,Guochun Xiao,Yan Zhang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In this paper, a novel high order power filter is proposed, named the LCCL filter. Compared with the traditional LCL filter, the LCCL filter composes a parallel resonant branch loop at the switching frequency by paralleling a small capacitor with the line side inductor. The parallel resonance enables the line side branch loop to exhibit infinite impedance at the switching frequency. Particularly, it can attenuate the switching frequency current ripple components much better than the LCL filter, thus decreases grid current THD. Compared with an LLCL filter, the LCCL filter exhibits better attenuation ability in the high frequency domain when the source impedance is considered. Besides, a capacitorcurrent- based active damping controller is easy to design on the basis of the LCCL filter. A half-bridge APF is taken as an example in this paper to discuss the parameter selection and the controller design method based on the LCCL filter. At last, simulation and experimental results validate the feasibility of the proposed LCCL filter.

Control Strategy Based on Equivalent Fundamental and Odd Harmonic Resonators for Single-Phase DVRs

Guofei Teng,Guochun Xiao,Leilei Hu,Yong Lu,Yuba Raj Kafle 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4

In this paper, a digital control strategy based on equivalent fundamental and odd harmonic resonators is proposed for single-phase DVRs. By using a delay block, which can be equivalent to a bank of resonators, it rejects the fundamental and odd harmonic disturbances effectively. The structure of the single closed-loop control system consists of a delay block, a proportional gain and a set of zero phase notch filters. The principle of the controller design is discussed in detail to ensure the stability of the system. Both the supply voltage and the load current feedforwards are used to improve the response speed and the ability to eliminate disturbances. The proposed controller is simple in terms of its structure and implementation. It has good performances in harmonic compensation and dynamic response. Experimental results from a 2kW DVR prototype confirm the validity of the design procedure and the effectiveness of the control strategy.