Master–slave modulated model predictive control to optimize current tracking for parallel cascaded H‑bridge power supplies

Bichen Yan,Haihong Huang,Haixin Wang 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.1

Conventional distributed control has achieved a great deal of success in multi-parallel cascaded H-bridge (CHB) power supplies. However, conventional distributed controllers can have a seriously imbalanced output power due to a mismatch of the hardware or control parameters and form an unstable circulating current path between the CHB converters, which can lead to a couple of problems. (1) The stability and tracking performance of the branch current can become degraded. (2) The current-sharing reactor can be easily saturated. To optimize all the branch currents of multiple parallel CHB power supplies, a master–slave carrier-based model predictive control method is proposed in this paper. This control strategy can achieve an optimized current tracking performance and effective circulating current suppression. In addition, through carriers, H-bridge interleaving and branch synchronization can be easily achieved, which fixes the switching frequency. Thus, the advantages of model predictive control and interleaving can be combined. Based on the generalized branch current predictive model derived in this paper, when more than two paralleled CHB converters have different output powers, an optimized branch current response can be achieved and circulating current can be eliminated. Simulation and experimental results verify the effectiveness of the proposed method.

Tracking/Erosion Resistance Analysis of Nano-Al(OH)₃ Filled Silicone Rubber Insulating Materials for High Voltage DC Applications

Kannan, P.,Sivakumar, M.,Mekala, K.,Chandrasekar, S. The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.1

HVDC technology has become popular as an economic mode of bulk power transmission over very long distances. Polymeric insulators in HVDC power transmission lines are affected by surface tracking and erosion problems due to contamination deposit, which pose a greater challenge in maintaining the reliability of the HVDC system. In addition, polymeric insulators are also naturally affected by aging due to various environmental stresses, which in turn accelerates the surface tracking and erosion problems. Research works towards the improvement of tracking and erosion resistance of polymeric insulators by adding nano-sized fillers in the base material are being carried out worldwide. However, surface tracking and erosion performance of nano-filled aged polymeric insulators for HVDC applications are not well reported. Hence, in the present work, tracking and erosion resistance of the nano $Al(OH)_3$ filled silicone rubber insulation material has been evaluated under DC voltages at different filler concentrations and aged conditions, as per IEC 60587 test procedures. Leakage current and contact angle measurements were carried out to understand the surface hydrophobicity. Moving average technique was used to analyze the trend followed by leakage current. Water aged specimen shows less tracking resistance when compared with thermal aged specimen. It is observed that nano-filler concentration of 5% is even sufficient to get better tracking/erosion resistance under DC voltages.

Classification of Bridge Current and Analysis of Heat Transfer Characteristics in Polyvinyl-Chloride-Sheathed Flat Cord Under Tracking

Seung-Wook Jee 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.1

In this study, we examine the tracking happen in a polyvinyl-chloride-sheathed flat cord (PVCSFC), which is widely used as a distribution cord. The study classifies the bridge current via the formed conductive paths during tracking in the PVCSFC. Further, it attempts to distinguish the characteristics of heat generation and heat transfer by kind of bridge current. When the PVCSFC is in the static state, the bridge currents flow only through the electrolyte bridge. In the case of the carbonized PVCSFC, the bridge currents flow through one or more conductive paths. One is the electrolyte bridge, the other is the bridge that is consisted electrolyte and carbonized insulation. Currents flowing through different conductive paths have different heat generation and transfer characteristics. As the bridge current flowing in the conductive path consisting of electrolyte and carbonized insulation increases, the temperature difference between the surface of the PVCSFC and ambient air also increases correspondingly.

Classification of Bridge Current and Analysis of Heat Transfer Characteristics in Polyvinyl-Chloride-Sheathed Flat Cord Under Tracking

Jee, Seung-Wook,Lee, Chun-Ha,Lee, Kwang-Sik The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.1

In this study, we examine the tracking happen in a polyvinyl-chloride-sheathed flat cord (PVCSFC), which is widely used as a distribution cord. The study classifies the bridge current via the formed conductive paths during tracking in the PVCSFC. Further, it attempts to distinguish the characteristics of heat generation and heat transfer by kind of bridge current. When the PVCSFC is in the static state, the bridge currents flow only through the electrolyte bridge. In the case of the carbonized PVCSFC, the bridge currents flow through one or more conductive paths. One is the electrolyte bridge, the other is the bridge that is consisted electrolyte and carbonized insulation. Currents flowing through different conductive paths have different heat generation and transfer characteristics. As the bridge current flowing in the conductive path consisting of electrolyte and carbonized insulation increases, the temperature difference between the surface of the PVCSFC and ambient air also increases correspondingly.

Tracking/Erosion Resistance Analysis of Nano-Al(OH)₃ Filled Silicone Rubber Insulating Materials for High Voltage DC Applications

P. Kannan,M. Sivakumar,K. Mekala,S. Chandrasekar 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.1

HVDC technology has become popular as an economic mode of bulk power transmission over very long distances. Polymeric insulators in HVDC power transmission lines are affected by surface tracking and erosion problems due to contamination deposit, which pose a greater challenge in maintaining the reliability of the HVDC system. In addition, polymeric insulators are also naturally affected by aging due to various environmental stresses, which in turn accelerates the surface tracking and erosion problems. Research works towards the improvement of tracking and erosion resistance of polymeric insulators by adding nano-sized fillers in the base material are being carried out worldwide. However, surface tracking and erosion performance of nano-filled aged polymeric insulators for HVDC applications are not well reported. Hence, in the present work, tracking and erosion resistance of the nano Al(OH)₃ filled silicone rubber insulation material has been evaluated under DC voltages at different filler concentrations and aged conditions, as per IEC 60587 test procedures. Leakage current and contact angle measurements were carried out to understand the surface hydrophobicity. Moving average technique was used to analyze the trend followed by leakage current. Water aged specimen shows less tracking resistance when compared with thermal aged specimen. It is observed that nanofiller concentration of 5% is even sufficient to get better tracking/erosion resistance under DC voltages.

Retrievals of Sea Surface Current Vectors from Geostationary Satellite Data (Himawari-8/AHI)

김희영,박경애,김희애,정성래,정성훈 한국기상학회 2020 Asia-Pacific Journal of Atmospheric Sciences Vol.56 No.2

An operational sea surface current (SSC) retrieval algorithm was developed using consecutive Himawari-8/AHI data based on a feature tracking method. Comparative analyses were conducted to determine the appropriate input data for the SSC retrieval algorithm. Investigation of the input data revealed some limitations in the use of single-band brightness temperatures caused by atmospheric features under moist conditions, especially in the mid- and low-latitude regions. Because of the motion of atmospheric features, cloud and cloud-contaminated pixels tended to contribute to the overestimation of SSC. To reduce overestimation, sea surface temperature images were used as input data and the feature tracking method was applied to calculate the displacement of the surface current vectors. The estimated currents were subjected to a quality control process to remove erroneous vectors. The accuracy of the retrieved surface currents was assessed by comparing the results with the qualitycontrolled currents obtained from surface drifters in the full-disk region of Himawari-8/AHI. The results revealed that the estimated current speeds and directions agreed with the drifter-based calculated values—the root-mean-square (bias) errors were 0.35 ms−1 (0.11 ms−1) and 33.28° (5.47°), respectively. The estimated current field showed diverse dynamic ocean features, such as a rotating feature around a mesoscale eddy and the characteristic meandering pattern of the Kuroshio Current. Hourly varying surface current fields from geostationary satellite data with high spatio-temporal resolution are expected to augment oceanic and atmospheric applications in real time.

ITX 차량 운행에 의한 AF 무절연 궤도회로의 귀선전류 영향 분석

백종현(Jong-Hyen Beak),김용규(Yong-Kyu Kim),윤용기(Yong-Ki Yoon),장동욱(Dong-wook Jang),신동호(Dong-Ho Shin) 대한전기학회 2013 전기학회논문지 Vol.62 No.4

Depending on the operating characteristics, track circuit is installed for the purpose of control directly or indirectly of the signal device, point switch machine and other security device. These are mainly used for train detection, transmission of information, broken train detection and transmission of return current. Especially, the return current is related to signal system, power system and catenary line, and track circuit systems. It is one of the most important component shall be dealt for the safety of track side staff and for the protection of railway-related electrical system according to electrification. Therefore, an accurate analysis of the return current is needed to prevent the return current unbalance and the system induced disorder and failure due to an over current condition. Also, if the malfunction occurred by the return current harmonics, it can cause problems including train operation interruption. In this paper, we presented measurement and analysis method at return current and it"s harmonics by train operation. By the test criteria, we evaluated for safety. Hereafter, it is expected to contribute to the field associated with it.

동일한 주파수를 사용하는 AF궤도회로 사이의 이격거리에 대한 연구

김민규(Kim Min-Kyu),김상엽(Kim Sang Yeop),김민석(Kim Min-Seok),김종수(Kim Jong-Soo),이종우(Lee Jong-Woo) 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.11월

Electric railway system consist of rolling stock, track, signal and streetcar line system. Track circuit system is vital system due to checking the location of trains. Track circuits are divided by using frequency and isolated electrically. Currently, there is not a regulation for the distance between track circuits using identical frequency. In case of installing additional track circuits in large stations or marshalling yard, the problem which is that the signal is not exactly transmitted to the track circuit occurs due to the mutual interference. In other words, the track circuit properly is not operated on account of wrong induction current by the mutual inductance between track circuits. In this paper, we suggest the electrical model between track circuits and numerically calculate demanded parameters in electrical model. It is demonstrated by using Maxwell program. Also, we define the mutual inductance without the mutual interference phenomenon between track circuits and then demonstrate the amplitude of resistance and self inductance by using Matlab program. The distance between track circuits satisfying the mutual inductance which does not happen to the mutual interference phenomenon is presented about the distance of track circuit. It is proved by using Matlab and PSpice program as the amplitude of mutual induced current.

해양환경을 고려한 수중기동표적 위치추적체계 최적배치에 관한 연구

김태형,김성용,한민수,송경준 한국군사과학기술학회 2023 한국군사과학기술학회지 Vol.26 No.5

The tracking accuracy of buoy-based LBL(Long Base Line) systems can be significantly influenced by sea environmental conditions. Particularly, the position of buoys that may have drifted due to sea currents. Therefore it is necessary to predict and optimize the drifted-buoy positions in the deploying step. This research introduces a free-drift simulation model using ocean data from the European CMEMS. The simulation model’s predictions are validated by comparing them to actual sea buoy drift tracks, showing a substantial match in averaged drift speed and direction. Using this drift model, we optimize the initial buoy layout and compare the tracking performance between the center hexagonal layout and close track layout. Our results verify that the optimized layout achieves lower tracking errors compared to the other two layout.

노력도 주변해역의 해수유동특성

추효상 전남대학교 수산과학연구소 2016 수산과학연구소논문집 Vol.24 No.-

In order to estimate the tidal currents around the Noryokto island located at the entrance of the Deukryang bay in the south sea of Korea, tide, tidal currents and drogue tracking observations were carried out at the north, east and south of Noryokto island in spring tide. Semi-diurnal tide is dominant and the tide difference is lager than Nokdong and Whejin harbour. The tide is slow of phase more than that in Nokdong harbour. The currents flow SE in ebb and E~NW in flood at the south of the island, where the flow has the severe and prolonged southeast flows but week and brief span of the northwest flows. The flows show the rotational form and southeastward tide-induced residual currents at the south of the island. The drogues flow southeast and have anti-clockwise circulation in ebb along the southern coast and Noryokto horbour. In the east of island, the drogues shift to north and northeast due to the wake in ebb. They flow west in flood and east in ebb at the channel between Jukdo island and Noryokto island. Drogues passed through the channel flow east and southeast swiftly near Noryokto island but circulate clockwise sluggishly near Jukdo island in ebb.