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.

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.

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.

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.

Flow Wars: Systemizing the Attack Surface and Defenses in Software-Defined Networks

Yoon, Changhoon,Lee, Seungsoo,Kang, Heedo,Park, Taejune,Shin, Seungwon,Yegneswaran, Vinod,Porras, Phillip,Gu, Guofei Institute of Electrical and Electronics Engineers, 2017 IEEE/ACM transactions on networking Vol.25 No.6

<P>Emerging software defined network (SDN) stacks have introduced an entirely new attack surface that is exploitable from a wide range of launch points. Through an analysis of the various attack strategies reported in prior work, and through our own efforts to enumerate new and variant attack strategies, we have gained two insights. First, we observe that different SDN controller implementations, developed independently by different groups, seem to manifest common sets of pitfalls and design weakness that enable the extensive set of attacks compiled in this paper. Second, through a principled exploration of the underlying design and implementation weaknesses that enables these attacks, we introduce a taxonomy to offer insight into the common pitfalls that enable SDN stacks to be broken or destabilized when fielded within hostile computing environments. This paper first captures our understanding of the SDN attack surface through a comprehensive survey of existing SDN attack studies, which we extend by enumerating 12 new vectors for SDN abuse. We then organize these vulnerabilities within the well-known confidentiality, integrity, and availability model, assess the severity of these attacks by replicating them in a physical SDN testbed, and evaluate them against three popular SDN controllers. We also evaluate the impact of these attacks against published SDN defense solutions. Finally, we abstract our findings to offer the research and development communities with a deeper understanding of the common design and implementation pitfalls that are enabling the abuse of SDN networks.</P>

Prediction of peak occurrence of Dendrolimus punctatus larvae based on Bayes discriminant method

Qian Guangjing,Song Xueyu,Sun Jiazhao,Zhang Shuping,Zhou Xiazhi,Zhang Guoqing,Zou Yunding,Fang Guofei,Zhang Zhen,Yan Ping,Bi Shoudong 한국곤충학회 2020 Entomological Research Vol.50 No.8

To improve the accuracy of forecasting the peak occurrence of Dendrolimus punctatus Walker, we here used the Bayes discriminant analysis to predict this peak occurrence for the first and second generation of Dendrolimus punctatus larvae based on these data from 1983 to 2016 in Qianshan County, Anhui Province. Our present results showed that this discriminant equation for the first generation was as follows: f (1) = 3.2588-6.2700x1 + 1.2870x2 + 0.7920x3 + 0.4152x4; f (2) = 14.5215- 8.5710x1 + 2.9790x2 + 2.0280x3 + 0.5031x4; f (3) = 3.5264; f (4) = 66.8312- 12.5216x1 + 5.1740x2 + 4.7162x3 + 0.6033x4. And that the prediction accuracy for the first generation was 97.22%. Whilst this discriminant equation for the second generation was as follows: f (1) = 3.536-1.192x5 + 1.338x6 + 0.638x70.025x8; f (2) = 7.317-1.337x5 + 4.240x6 + 1.010x70.295x8; f (3) = 16.488- 3.192x5 + 4.955x6 + 1.900x7–0.411x8; f (4) = 34.502- 4.184x5 + 7.484x6 + 2.583x7–0.443x8. The prediction accuracy for the second generation was 85.71%. Overall, our findings revealed that the Bayes discriminant analysis could screen out key factors to significantly improve the prediction accuracy of peak occurrence of Dendrolimus punctatus larvae.