Pub Date : 2004-11-29DOI: 10.1109/PECON.2004.1461658
S. Islam, M. Mustafa, I. Hasan
New computer algorithm has been developed to select the optimal location of source substation in radial distribution networks. Selection methodology has been developed based on the geo-graphical location of connected substation of source substation, user's defined obstacle area by determining minimal route of the networks based on minimal loss of the networks and economic consideration. For the best location selection of source substation two steps selection method has been implemented for minimizing computer computation time. In the first steps it determines the projected area for the selection of optimal location of source substation. In the seconds step precise calculation is involved. Depending on the precise calculation of area selection computation time will be varied. Simulated example has been introduced for detail explanation of the output of computer algorithms.
{"title":"Optimal source substation location selection in radial distribution networks","authors":"S. Islam, M. Mustafa, I. Hasan","doi":"10.1109/PECON.2004.1461658","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461658","url":null,"abstract":"New computer algorithm has been developed to select the optimal location of source substation in radial distribution networks. Selection methodology has been developed based on the geo-graphical location of connected substation of source substation, user's defined obstacle area by determining minimal route of the networks based on minimal loss of the networks and economic consideration. For the best location selection of source substation two steps selection method has been implemented for minimizing computer computation time. In the first steps it determines the projected area for the selection of optimal location of source substation. In the seconds step precise calculation is involved. Depending on the precise calculation of area selection computation time will be varied. Simulated example has been introduced for detail explanation of the output of computer algorithms.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133440041","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.2004.1461633
A. F. Huweg, S. M. Bashi, N. Mariun
A simulation model of static synchronous compensator (STATCOM) has been constructed on Matlab/Simulink software to examine its capability for voltage sag mitigation due to starting high power induction motor. In this paper, the main structure of Simulink (STATCOM) model is described briefly. Its capability to compensate reactive power to the system when the voltage sag occurs was described. A phase control thyristor (SCR) based voltage source inverter (VSI) is employed for this application. The influences of the initial operation point and DC capacitance are considered. The behavior of this system during voltage sag caused by starting of motor load has been examined. Simulation result shows the fast response and the STATCOM capability for mitigate voltage sag.
{"title":"A STATCOM simulation model to improve voltage sag due to starting of high power induction motor","authors":"A. F. Huweg, S. M. Bashi, N. Mariun","doi":"10.1109/PECON.2004.1461633","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461633","url":null,"abstract":"A simulation model of static synchronous compensator (STATCOM) has been constructed on Matlab/Simulink software to examine its capability for voltage sag mitigation due to starting high power induction motor. In this paper, the main structure of Simulink (STATCOM) model is described briefly. Its capability to compensate reactive power to the system when the voltage sag occurs was described. A phase control thyristor (SCR) based voltage source inverter (VSI) is employed for this application. The influences of the initial operation point and DC capacitance are considered. The behavior of this system during voltage sag caused by starting of motor load has been examined. Simulation result shows the fast response and the STATCOM capability for mitigate voltage sag.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123676226","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.2004.1461651
V. C. Veera Reddy, N. Perumal, Y. Rajasekharareddy
In this paper, a simplified load flow method is developed for solving radial distribution networks that involves only the evaluation of a simple algebraic expression of voltage magnitudes. A general formulation of the network reconfiguration for loss minimization is given for optimization of distribution loss reduction and a solution approach is presented. The solution algorithm for loss minimization has been developed based on a two-stage solution methodology. The first stage of this solution algorithm finds a loop, which gives the maximum loss reduction in the network. For this purpose a simple-to-use formula, called loop loss reduction formula has been developed. To find a branch exchange, which results in the maximum loss reduction in the loop, the second stage applies a proposed technique called distance-center technique. Therefore, the solution algorithm of the proposed method can identify the most effective branch exchange operations for loss reduction, with minimum computational efforts. The software for proposed solution algorithm is capable of performing optimum reconfiguration for a radial distribution network for any number of buses and laterals. The proposed feeder reconfiguration is tested with 33-bus IEEE test system and the results are compared with Baran and Wu's method.
{"title":"Loss reduction in distribution networks by network reconfiguration: a two stage solution approach","authors":"V. C. Veera Reddy, N. Perumal, Y. Rajasekharareddy","doi":"10.1109/PECON.2004.1461651","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461651","url":null,"abstract":"In this paper, a simplified load flow method is developed for solving radial distribution networks that involves only the evaluation of a simple algebraic expression of voltage magnitudes. A general formulation of the network reconfiguration for loss minimization is given for optimization of distribution loss reduction and a solution approach is presented. The solution algorithm for loss minimization has been developed based on a two-stage solution methodology. The first stage of this solution algorithm finds a loop, which gives the maximum loss reduction in the network. For this purpose a simple-to-use formula, called loop loss reduction formula has been developed. To find a branch exchange, which results in the maximum loss reduction in the loop, the second stage applies a proposed technique called distance-center technique. Therefore, the solution algorithm of the proposed method can identify the most effective branch exchange operations for loss reduction, with minimum computational efforts. The software for proposed solution algorithm is capable of performing optimum reconfiguration for a radial distribution network for any number of buses and laterals. The proposed feeder reconfiguration is tested with 33-bus IEEE test system and the results are compared with Baran and Wu's method.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121837375","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.2004.1461652
M. Wanik, Y. Yusuf, S.N. Al-Yousif, K. Umeh
This paper presents a study of resonance and its impact on harmonic distortion in a typical industrial distribution system. The system utilised in the study is described and cases considered are detailed. The study is performed using frequency scan analysis with the aid of PSCAD and Matlab computer programs. The results, which visualize the impedance of the system at various frequencies, represent the impedance seen by harmonic source. The study has successfully revealed the resonance frequencies and associated magnitude of different cases of combined system impedance. The occurrence of resonance at these frequencies explains why harmonic distortion varies with the cases.
{"title":"Simulation of resonance and harmonic amplification in industrial distribution system","authors":"M. Wanik, Y. Yusuf, S.N. Al-Yousif, K. Umeh","doi":"10.1109/PECON.2004.1461652","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461652","url":null,"abstract":"This paper presents a study of resonance and its impact on harmonic distortion in a typical industrial distribution system. The system utilised in the study is described and cases considered are detailed. The study is performed using frequency scan analysis with the aid of PSCAD and Matlab computer programs. The results, which visualize the impedance of the system at various frequencies, represent the impedance seen by harmonic source. The study has successfully revealed the resonance frequencies and associated magnitude of different cases of combined system impedance. The occurrence of resonance at these frequencies explains why harmonic distortion varies with the cases.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115917268","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.2004.1461613
S. Ishak, A. F. Abidin, T. Rahman
Loss minimization in power system is an important consideration research issue. Transmission losses in a power system can be minimized by means of reactive power compensation. Installing static Var compensation (SVC) in a power system has known to be able to improve voltage level in the system and hence minimizing the system losses. This paper presents a technique to determine the location of the SVC in order to minimize loss in the system. The performance of this technique is tested using 14 buses IEEE reliability test system. A load flow programmed written in MATLAB by using artificial immune system (AIS) technique was used to compute power flow. The test result shows that the location and sizing of the SVC identified by the proposed technique has been able to improve the voltage level of the system and also minimize the losses.
{"title":"Static Var compensator planning using artificial immune system for loss minimisation and voltage improvement","authors":"S. Ishak, A. F. Abidin, T. Rahman","doi":"10.1109/PECON.2004.1461613","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461613","url":null,"abstract":"Loss minimization in power system is an important consideration research issue. Transmission losses in a power system can be minimized by means of reactive power compensation. Installing static Var compensation (SVC) in a power system has known to be able to improve voltage level in the system and hence minimizing the system losses. This paper presents a technique to determine the location of the SVC in order to minimize loss in the system. The performance of this technique is tested using 14 buses IEEE reliability test system. A load flow programmed written in MATLAB by using artificial immune system (AIS) technique was used to compute power flow. The test result shows that the location and sizing of the SVC identified by the proposed technique has been able to improve the voltage level of the system and also minimize the losses.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115924837","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.2004.1461620
A. Jidin, Nik Rumzi Nik Idris, N. D. Muhamad
In this paper, a control system of DC motor for speed and torque control based on variable structure systems with sliding mode control approach is presented. The comparisons between classical and sliding mode techniques are investigated and their advantages and disadvantages are identified. The current limiter mechanism to limit the current during start-up, acceleration and deceleration for speed control loop is proposed and presented. The simulation results of the proposed controller show that the variable structure system with sliding mode control approach is superior in rejecting disturbance, has faster response and is less sensitive to parameter variations compared to the conventional PI controller.
{"title":"Sliding mode variable structure control design principles and application to DC drives","authors":"A. Jidin, Nik Rumzi Nik Idris, N. D. Muhamad","doi":"10.1109/PECON.2004.1461620","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461620","url":null,"abstract":"In this paper, a control system of DC motor for speed and torque control based on variable structure systems with sliding mode control approach is presented. The comparisons between classical and sliding mode techniques are investigated and their advantages and disadvantages are identified. The current limiter mechanism to limit the current during start-up, acceleration and deceleration for speed control loop is proposed and presented. The simulation results of the proposed controller show that the variable structure system with sliding mode control approach is superior in rejecting disturbance, has faster response and is less sensitive to parameter variations compared to the conventional PI controller.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131122668","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.2004.1461648
U. Abdullahi, S. M. Bashi, Robiah Yunus, Mohibullah, H. Nurdin
Petroleum and mineral based fluids have, for almost one century, been used for cooling and insulation purposes. Their popularity' stems out of their availability and cheapness. However, recent evidence has shown deficiencies with these fluids. They have low properties especially flash and fire points and most importantly low dielectric break down voltage. The most serious of these shortcomings is the inability to meet up with health and environmental laws. This is because they are not organic and hence not biodegradable; their spillage takes very long time to decompose. These developments have led to seeking alternatives in vegetable based fluids. The fluids tried and confirmed to be used as dielectric fluids include castor oil, coconut oil, soya bean oil, rapeseed oil etc. This work has measured the properties of palm oil against the IEEE C637 and ASTM D section for possible use as a dielectric fluid. The result shows that treated palm oil has break down voltage of 75 kV/mm, flash point >220), fire point (>220) and moisture content (0.08%). Hence this has shown the potential of palm oil as a dielectric fluid. However future work should focus on further investigation before field application. Malaysia as a country stands a lot of gains in this type of research, since it is a world is leader in palm oil production.
{"title":"The potentials of palm oil as a dielectric fluid","authors":"U. Abdullahi, S. M. Bashi, Robiah Yunus, Mohibullah, H. Nurdin","doi":"10.1109/PECON.2004.1461648","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461648","url":null,"abstract":"Petroleum and mineral based fluids have, for almost one century, been used for cooling and insulation purposes. Their popularity' stems out of their availability and cheapness. However, recent evidence has shown deficiencies with these fluids. They have low properties especially flash and fire points and most importantly low dielectric break down voltage. The most serious of these shortcomings is the inability to meet up with health and environmental laws. This is because they are not organic and hence not biodegradable; their spillage takes very long time to decompose. These developments have led to seeking alternatives in vegetable based fluids. The fluids tried and confirmed to be used as dielectric fluids include castor oil, coconut oil, soya bean oil, rapeseed oil etc. This work has measured the properties of palm oil against the IEEE C637 and ASTM D section for possible use as a dielectric fluid. The result shows that treated palm oil has break down voltage of 75 kV/mm, flash point >220), fire point (>220) and moisture content (0.08%). Hence this has shown the potential of palm oil as a dielectric fluid. However future work should focus on further investigation before field application. Malaysia as a country stands a lot of gains in this type of research, since it is a world is leader in palm oil production.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116152672","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.2004.1461638
A. Jusoh
The sub-system interaction and instability phenomena is a common problem in the distributed power system (DPS). The interaction arises because each individual converter has internal control function such as to regulate the converter output voltage, which results in the converter tends to draw a constant power and therefore has a negative incremental input impedance. The constant power and negative input resistance characteristic potentially have a de-stabilizing effect on the electrical supply system. The paper presents the analysis, theoretical design and simulation of a simple DC DPS. The analysis of the LC filter and its damping parameters were given. The effect of the negative input resistance of the CPL on the filter was analysed using small-signal input resistance of the load. The passive damping method was used to reduce the system interaction between the converters. The results were verified by MATLAB Simulink simulation.
{"title":"The instability effect of constant power loads","authors":"A. Jusoh","doi":"10.1109/PECON.2004.1461638","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461638","url":null,"abstract":"The sub-system interaction and instability phenomena is a common problem in the distributed power system (DPS). The interaction arises because each individual converter has internal control function such as to regulate the converter output voltage, which results in the converter tends to draw a constant power and therefore has a negative incremental input impedance. The constant power and negative input resistance characteristic potentially have a de-stabilizing effect on the electrical supply system. The paper presents the analysis, theoretical design and simulation of a simple DC DPS. The analysis of the LC filter and its damping parameters were given. The effect of the negative input resistance of the CPL on the filter was analysed using small-signal input resistance of the load. The passive damping method was used to reduce the system interaction between the converters. The results were verified by MATLAB Simulink simulation.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129006115","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.2004.1461611
Titik Khawa Abdul Rahiiian, Zuhaila Mal Yasin, Wan Noraiiiiii
This paper presents an artificial immune system based optimization approach for solving the economic dispatch problem in a power system. Economic dispatch determines the electrical power to be generated by the committed generating units in a power system so that the generation cost is minimised, while satisfying the load demand simultaneously. The developed artificial immune system optimization technique used the total generation cost as the objective function and represented as the affinity measure. Through genetic evolution, the antibodies with high affinity measure are produced and become the solution. The simulation results reveal that the developed technique is easy to implement, converged within an acceptable execution time and highly optimal solution for economic dispatch with minimum generation cost can be achieved. The result also confirms that AIS based optimization technique can be a useful tool for solving optimal solution in economic dispatch problem, which involves a large number of generating units and at the same time to comply with a large number of constraints.
{"title":"Artificial-immune-based for solving economic dispatch in power system","authors":"Titik Khawa Abdul Rahiiian, Zuhaila Mal Yasin, Wan Noraiiiiii","doi":"10.1109/PECON.2004.1461611","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461611","url":null,"abstract":"This paper presents an artificial immune system based optimization approach for solving the economic dispatch problem in a power system. Economic dispatch determines the electrical power to be generated by the committed generating units in a power system so that the generation cost is minimised, while satisfying the load demand simultaneously. The developed artificial immune system optimization technique used the total generation cost as the objective function and represented as the affinity measure. Through genetic evolution, the antibodies with high affinity measure are produced and become the solution. The simulation results reveal that the developed technique is easy to implement, converged within an acceptable execution time and highly optimal solution for economic dispatch with minimum generation cost can be achieved. The result also confirms that AIS based optimization technique can be a useful tool for solving optimal solution in economic dispatch problem, which involves a large number of generating units and at the same time to comply with a large number of constraints.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131929685","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.2004.1461623
M. Izhar, C. M. Hadzer, M. Syafrudin, S. Taib, S. Idris
The analysis and design of a star delta transformer in series with active power filter linked to grid lines are carried out. The development of active power filter which consists of voltage reference, triangular generator to generate pulse width modulation with half inverters is simulated. The current injection network of half inverter in series with three phase of a star delta transformer which is interconnected to grid lines is also discussed. It is observed that the reduction of harmonics at grid lines was significantly reduced. The simulation results show that the total harmonic distortions are reduced within range of 45% - 50% and 97% - 99% at distributions and neutral lines respectively. Also, the distortions of sinusoidal waveform at grid lines were improved.
{"title":"An analysis and design of a star delta transformer in series with active power filter for current harmonics reduction","authors":"M. Izhar, C. M. Hadzer, M. Syafrudin, S. Taib, S. Idris","doi":"10.1109/PECON.2004.1461623","DOIUrl":"https://doi.org/10.1109/PECON.2004.1461623","url":null,"abstract":"The analysis and design of a star delta transformer in series with active power filter linked to grid lines are carried out. The development of active power filter which consists of voltage reference, triangular generator to generate pulse width modulation with half inverters is simulated. The current injection network of half inverter in series with three phase of a star delta transformer which is interconnected to grid lines is also discussed. It is observed that the reduction of harmonics at grid lines was significantly reduced. The simulation results show that the total harmonic distortions are reduced within range of 45% - 50% and 97% - 99% at distributions and neutral lines respectively. Also, the distortions of sinusoidal waveform at grid lines were improved.","PeriodicalId":375856,"journal":{"name":"PECon 2004. Proceedings. National Power and Energy Conference, 2004.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125926470","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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