Pub Date : 2004-11-29DOI: 10.1109/PECON.2004.1461650
I. Musirin, T. Rahman
This paper presents the voltage stability based weak area clustering technique in power system. The technique employed voltage stability and line outage contingency analyses. From the voltage stability analysis, the sensitive lines in a system during stressed condition are identified, while line outage contingency analysis identified the critical line outages. A pre-developed voltage stability index was utilised as an indicator to voltage stability condition of the system. The weak areas formed by the lines are identified as the sensitive lines from voltage stability analysis and at the same time the critical line outages identified from line outage contingency analysis. The results show that the lines, which are identified as the weak ones from voltage stability analysis, would also cause critical outages. The proposed technique was implemented on IEEE reliable test system and the results show that distinct weak areas were identified when the system was closed to the stressed condition.
{"title":"Voltage stability based weak area clustering technique in power system","authors":"I. Musirin, T. Rahman","doi":"10.1109/PECON.2004.1461650","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461650","url":null,"abstract":"This paper presents the voltage stability based weak area clustering technique in power system. The technique employed voltage stability and line outage contingency analyses. From the voltage stability analysis, the sensitive lines in a system during stressed condition are identified, while line outage contingency analysis identified the critical line outages. A pre-developed voltage stability index was utilised as an indicator to voltage stability condition of the system. The weak areas formed by the lines are identified as the sensitive lines from voltage stability analysis and at the same time the critical line outages identified from line outage contingency analysis. The results show that the lines, which are identified as the weak ones from voltage stability analysis, would also cause critical outages. The proposed technique was implemented on IEEE reliable test system and the results show that distinct weak areas were identified when the system was closed to the stressed condition.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115464122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2004-11-29DOI: 10.1109/PECON.2004.1461609
K. Umeh, A. Mohamed
This paper presents a new method for identifying the different types of single phase nonlinear loads as sources of harmonic disturbances in a power system. The method combines the use of signal processing and artificial intelligence techniques. Fast Fourier transform and fractal analyses have been used to extract features of the harmonic signatures of the various nonlinear loads from the sampled input current waveforms. Intelligent and automatic harmonic load recognition process is achieved by using a rule-based expert system. The expert system has been verified using real measurements and the results show that the system give accurate identification of the single phase nonlinear loads such as personal computer, fluorescent lights, uninterruptible power supply and oscilloscope.
{"title":"A rule-based expert system for harmonic load recognition","authors":"K. Umeh, A. Mohamed","doi":"10.1109/PECON.2004.1461609","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461609","url":null,"abstract":"This paper presents a new method for identifying the different types of single phase nonlinear loads as sources of harmonic disturbances in a power system. The method combines the use of signal processing and artificial intelligence techniques. Fast Fourier transform and fractal analyses have been used to extract features of the harmonic signatures of the various nonlinear loads from the sampled input current waveforms. Intelligent and automatic harmonic load recognition process is achieved by using a rule-based expert system. The expert system has been verified using real measurements and the results show that the system give accurate identification of the single phase nonlinear loads such as personal computer, fluorescent lights, uninterruptible power supply and oscilloscope.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116771825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2004-11-29DOI: 10.1109/PECON.2004.1461637
A. A. Mohd Zin, H. Mohd Hafiz, M. S. Aziz
Safe operation of a power system requires that system frequency be kept within a specified range. When the generation is insufficient due to disturbances, the frequency might fall under the minimum allowable value, which may lead to system blackout if not properly counteracted. This frequency decline may be corrected by shedding certain amount of load so that the system is back into balanced state. This paper reports a case study on Malaysia's TNB system. UFLS scheme used by TNB was reviewed. Then modification and improvement was made to reflect the current changes in the system making the scheme more up to date. Effect of having more stages to reduce over shedding and combination of different amount of load at each stage are discussed.
{"title":"A review of under-frequency load shedding scheme on TNB system","authors":"A. A. Mohd Zin, H. Mohd Hafiz, M. S. Aziz","doi":"10.1109/PECON.2004.1461637","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461637","url":null,"abstract":"Safe operation of a power system requires that system frequency be kept within a specified range. When the generation is insufficient due to disturbances, the frequency might fall under the minimum allowable value, which may lead to system blackout if not properly counteracted. This frequency decline may be corrected by shedding certain amount of load so that the system is back into balanced state. This paper reports a case study on Malaysia's TNB system. UFLS scheme used by TNB was reviewed. Then modification and improvement was made to reflect the current changes in the system making the scheme more up to date. Effect of having more stages to reduce over shedding and combination of different amount of load at each stage are discussed.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":"356 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122340515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2004-11-29DOI: 10.1109/PECON.2004.1461647
M. Mohibullah, A. Radzi, M. Hakim
Hydro power plants convert potential energy of water into electricity. It is a clean source of energy .The water after generating electrical power is available for irrigation and other purposes. The first use of moving water to produce electricity was a waterwheel on the Fox River in Wisconsin in 1882. Hydropower continued to play a major role in the expansion of electrical service early in this century around the world. Hydroelectric power plants generate from few kW to thousands of MW. They are classified as micro hydro power plants for the generating capacity less than 100 KW. Hydroelectric power plants are much more reliable and efficient as a renewable and clean source than the fossil fuel power plants. This resulted in upgrading of small to medium sized hydroelectric generating stations wherever there was an adequate supply of moving water and a need for electricity. As electricity demand soared in the middle of this century and the efficiency of coal and oil fueled power plants increased, small hydro plants fell out of favor. Mega projects of hydro power plants were developed. The majority of these power plants involved large dams, which flooded big areas of land to provide water storage and therefore a constant supply of electricity. In recent years, the environmental impacts of such large hydro projects are being identified as a cause for concern. It is becoming increasingly difficult for developers to build new dams because of opposition from environmentalists and people living on the land to be flooded. Therefore the need has arisen to go for the small scale hydro electric power plants in the range of mini and micro hydro power plants. There are no micro hydro power plants in Malaysia and the smallest category of hydro power plants in Malaysia is mini hydro with a capacity between 500 kW to 100 kW. This paper discusses the conceptual design and development of a micro hydro power plant .The overall estimation and calculation of a 50 kW power plant has been carried out. Software is also developed using MATLAB to calculate the total head, discharge rate, type of turbine for the micro hydro power plants, once the capacity is known.
{"title":"Basic design aspects of micro hydro power plant and its potential development in Malaysia","authors":"M. Mohibullah, A. Radzi, M. Hakim","doi":"10.1109/PECON.2004.1461647","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461647","url":null,"abstract":"Hydro power plants convert potential energy of water into electricity. It is a clean source of energy .The water after generating electrical power is available for irrigation and other purposes. The first use of moving water to produce electricity was a waterwheel on the Fox River in Wisconsin in 1882. Hydropower continued to play a major role in the expansion of electrical service early in this century around the world. Hydroelectric power plants generate from few kW to thousands of MW. They are classified as micro hydro power plants for the generating capacity less than 100 KW. Hydroelectric power plants are much more reliable and efficient as a renewable and clean source than the fossil fuel power plants. This resulted in upgrading of small to medium sized hydroelectric generating stations wherever there was an adequate supply of moving water and a need for electricity. As electricity demand soared in the middle of this century and the efficiency of coal and oil fueled power plants increased, small hydro plants fell out of favor. Mega projects of hydro power plants were developed. The majority of these power plants involved large dams, which flooded big areas of land to provide water storage and therefore a constant supply of electricity. In recent years, the environmental impacts of such large hydro projects are being identified as a cause for concern. It is becoming increasingly difficult for developers to build new dams because of opposition from environmentalists and people living on the land to be flooded. Therefore the need has arisen to go for the small scale hydro electric power plants in the range of mini and micro hydro power plants. There are no micro hydro power plants in Malaysia and the smallest category of hydro power plants in Malaysia is mini hydro with a capacity between 500 kW to 100 kW. This paper discusses the conceptual design and development of a micro hydro power plant .The overall estimation and calculation of a 50 kW power plant has been carried out. Software is also developed using MATLAB to calculate the total head, discharge rate, type of turbine for the micro hydro power plants, once the capacity is known.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122393353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2004-11-29DOI: 10.1109/PECON.2004.1461643
K. S. Rama Rao, Y. Meng, S. Taib, M. Syafrudin
A successful energy management control system using a personal computer (PC) is developed in this paper to avoid wastage of energy by human carelessness. A small residential building model is considered and a PC is used as a tool to monitor the electrical system. Sensors are considered to monitor the number of persons entering or leaving and the computer system switch on/off the electrical equipment, and able to count the number of people in each room in the building. The system continue to count when more people enter the rooms. When all the peoples leave the rooms the system will switch off all the electrical equipments to make sure that there is no wastage of energy. This paper shows that energy savings is achieved in a building by having a proper interface using a PC with minimum hardware and software.
{"title":"PC based energy management and control system of a building","authors":"K. S. Rama Rao, Y. Meng, S. Taib, M. Syafrudin","doi":"10.1109/PECON.2004.1461643","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461643","url":null,"abstract":"A successful energy management control system using a personal computer (PC) is developed in this paper to avoid wastage of energy by human carelessness. A small residential building model is considered and a PC is used as a tool to monitor the electrical system. Sensors are considered to monitor the number of persons entering or leaving and the computer system switch on/off the electrical equipment, and able to count the number of people in each room in the building. The system continue to count when more people enter the rooms. When all the peoples leave the rooms the system will switch off all the electrical equipments to make sure that there is no wastage of energy. This paper shows that energy savings is achieved in a building by having a proper interface using a PC with minimum hardware and software.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123309617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2004-11-29DOI: 10.1109/PECON.2004.1461628
S.H. Hamad, S. M. Bashi, I. Aris, N. Mailah
In this work, the performance of a closed-loop adjustable speed drive for single-phase induction motor using voltage amplitude control. A microcontroller M68HC11E-9 has been used to implement such techniques. The microcontroller senses the speed's feedback signal and consequently provides the pulse width variation signal that sets the gate voltage of the chopper, which in turn provides the required voltage for the desired speed. A buck type chopper has been used to control the input voltage of a fully controlled single phase isolated gate bipolar transistor (IGBT) bridge inverter. PWM technique has been employed In this inverter to supply the motor with ac voltage. The simulation and laboratory results proved that the drive system can be used for the speed control of a single-phase induction motor with wide speed range.
{"title":"Speed drive of single-phase induction motor","authors":"S.H. Hamad, S. M. Bashi, I. Aris, N. Mailah","doi":"10.1109/PECON.2004.1461628","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461628","url":null,"abstract":"In this work, the performance of a closed-loop adjustable speed drive for single-phase induction motor using voltage amplitude control. A microcontroller M68HC11E-9 has been used to implement such techniques. The microcontroller senses the speed's feedback signal and consequently provides the pulse width variation signal that sets the gate voltage of the chopper, which in turn provides the required voltage for the desired speed. A buck type chopper has been used to control the input voltage of a fully controlled single phase isolated gate bipolar transistor (IGBT) bridge inverter. PWM technique has been employed In this inverter to supply the motor with ac voltage. The simulation and laboratory results proved that the drive system can be used for the speed control of a single-phase induction motor with wide speed range.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":"248 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123365514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2004-11-29DOI: 10.1109/PECON.2004.1461639
C.S. Hoong, T. Taib., K. Rao, I. Daut
This paper presents the development of an automatic voltage regulator (AVR) for synchronous generator in industries applications. The AVR operates as a voltage stabilizer and controller because the output voltage is controlled and regulated through a power electronic system. It is observed that the automatic voltage regulator managed to achieve up to 2% voltage regulation at full load operation of 500 W. A thyristor controller is used to control the excitation voltage. The design also includes protection such as noise suppressor, radio frequency interference (RFI), surge protection, current limiter and electronic control system.
{"title":"Development of automatic voltage regulator for synchronous generator","authors":"C.S. Hoong, T. Taib., K. Rao, I. Daut","doi":"10.1109/PECON.2004.1461639","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461639","url":null,"abstract":"This paper presents the development of an automatic voltage regulator (AVR) for synchronous generator in industries applications. The AVR operates as a voltage stabilizer and controller because the output voltage is controlled and regulated through a power electronic system. It is observed that the automatic voltage regulator managed to achieve up to 2% voltage regulation at full load operation of 500 W. A thyristor controller is used to control the excitation voltage. The design also includes protection such as noise suppressor, radio frequency interference (RFI), surge protection, current limiter and electronic control system.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131645237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2004-11-29DOI: 10.1109/PECON.2004.1461629
P. C. Tan, Z. Salam
This paper presents a new single-phase two-wire hybrid active power filter configuration that interconnects a passive high-pass filter in parallel with an active power filter and a photovoltaic system. The proposed configuration can improves the filtering performance of the conventional active power filter, as well as simultaneously supply the power from the photovoltaic arrays to the load and utility. Furthermore, the derivation of arrays to the load and utility. Furthermore, the derivation of extension p-q theorem. This paper describes the proposed hybrid active power filter with photovoltaic system. It primarily focuses on the power circuit control system and the compensation current reference derivation. The proposed system effectively filters harmonics under 1 kHz but also higher frequency to achieve wideband harmonics compensation. The THD of source current is reduced from 76.83 % to 3.21 %. The simulation results that verify the theoretical predictions of the proposed configuration is presented.
{"title":"A new single-phase two-wire hybrid active power filter using extension p-q theorem for photovoltaic application","authors":"P. C. Tan, Z. Salam","doi":"10.1109/PECON.2004.1461629","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461629","url":null,"abstract":"This paper presents a new single-phase two-wire hybrid active power filter configuration that interconnects a passive high-pass filter in parallel with an active power filter and a photovoltaic system. The proposed configuration can improves the filtering performance of the conventional active power filter, as well as simultaneously supply the power from the photovoltaic arrays to the load and utility. Furthermore, the derivation of arrays to the load and utility. Furthermore, the derivation of extension p-q theorem. This paper describes the proposed hybrid active power filter with photovoltaic system. It primarily focuses on the power circuit control system and the compensation current reference derivation. The proposed system effectively filters harmonics under 1 kHz but also higher frequency to achieve wideband harmonics compensation. The THD of source current is reduced from 76.83 % to 3.21 %. The simulation results that verify the theoretical predictions of the proposed configuration is presented.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115323949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2004-11-29DOI: 10.1109/PECON.2004.1461646
N. Yahaya, K. C. Chew
paper is to compare the switching energy losses of the silicon carbide Schottky diode with the silicon PiN diode. The comparison is done using an inductive load chopper circuit simulated with Pspice, a type of circuit analysis software. Both diode models used for the simulation are from Infineon; the silicon carbide Schottky (SDP04S60, 4 A/600 V) and silicon PiN (IDP06E60, 6 A/600 V).
{"title":"Comparative study of the switching energy losses between Si PiN and SiC Schottky diode","authors":"N. Yahaya, K. C. Chew","doi":"10.1109/PECON.2004.1461646","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461646","url":null,"abstract":"paper is to compare the switching energy losses of the silicon carbide Schottky diode with the silicon PiN diode. The comparison is done using an inductive load chopper circuit simulated with Pspice, a type of circuit analysis software. Both diode models used for the simulation are from Infineon; the silicon carbide Schottky (SDP04S60, 4 A/600 V) and silicon PiN (IDP06E60, 6 A/600 V).","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125044146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2004-11-29DOI: 10.1109/PECON.2004.1461642
M. Dehghani, A. Afshar
A decentralized feedback control scheme is proposed for optimization of large-scale systems. First, local controllers are used to optimize each subsystem, ignoring the interconnections. Next, an additional compensating controller was applied to minimize the effect of interactions and improve the performance of the overall system. At the cost of the suboptimal performance, this optimization strategy ensures stability of the systems under structural perturbations. To account for the modeling uncertainties, both a local Kalman filter and recursive least square algorithm are used to estimate all local states and interactions for each subsystem. The controller uses these estimates, optimizes a given performance index and then regulates the system. A sample three-bus system is given to illustrate the proposed methodologies.
{"title":"Decentralized stochastic control of multi-machine power systems","authors":"M. Dehghani, A. Afshar","doi":"10.1109/PECON.2004.1461642","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461642","url":null,"abstract":"A decentralized feedback control scheme is proposed for optimization of large-scale systems. First, local controllers are used to optimize each subsystem, ignoring the interconnections. Next, an additional compensating controller was applied to minimize the effect of interactions and improve the performance of the overall system. At the cost of the suboptimal performance, this optimization strategy ensures stability of the systems under structural perturbations. To account for the modeling uncertainties, both a local Kalman filter and recursive least square algorithm are used to estimate all local states and interactions for each subsystem. The controller uses these estimates, optimizes a given performance index and then regulates the system. A sample three-bus system is given to illustrate the proposed methodologies.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129613448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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