{"created":"2021-03-01T05:59:57.893386+00:00","id":7512,"links":{},"metadata":{"_buckets":{"deposit":"068c7339-ecfb-4705-b9fb-e1ef4ec53cdc"},"_deposit":{"id":"7512","owners":[],"pid":{"revision_id":0,"type":"depid","value":"7512"},"status":"published"},"_oai":{"id":"oai:kitami-it.repo.nii.ac.jp:00007512","sets":["2:6"]},"author_link":["38489"],"item_7_date_granted_63":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2010-09-10"}]},"item_7_degree_grantor_61":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"北見工業大学"}]}]},"item_7_degree_name_60":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（工学）"}]},"item_7_description_14":{"attribute_name":"フォーマット","attribute_value_mlt":[{"subitem_description":"application/pdf","subitem_description_type":"Other"}]},"item_7_description_4":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"This thesis deals with different approaches to stabilize a grid-connected wind farm. Due to the\nenvironmental and economical concerns, it is expected that a huge number of wind farms are going to\nbe connected with the existing networks in the near future. Therefore, it is essential to analyze both\nsteady state and transient characteristics of the grid connected wind farms. In this study,\nSuperconducting Magnetic Energy Storage (SMES) system is considered to stabilize a grid-connected\nwind farm composed of fixed-speed wind turbine generator system (WTGS). The SMES has both\nactive and reactive power compensation abilities with high response speed. Therefore, the steady state\nand transient performance of the wind farm can be enhanced extensively.\nWind power fluctuation due to randomly varying wind speed is still a serious problem for power\ngrid companies or transmission system operators (TSO), especially in the case of fixed-speed wind\ngenerators. The wind power fluctuation usually occurs in the time scale of few sec to several hours,\ndepending on the wind condition, wind turbine size, topology, etc. Considering the future energy\nsystems with high wind power penetration, it is essential to emphasize the research on wind power\nsmoothing. However, reference power generation is still an unsolved problem for wind generator\noutput power smoothing, because more energy storage capacity is needed in the case of constant\nreference line power. In this study, wind power fluctuation in the time scale of minute range is\nfocused, where SMES system with variable reference line power is proposed to smooth the output\npower and to maintain the terminal voltage of the wind farm to the rated value. As a result, the energy\nstorage capacity of SMES can be made comparatively small.\nAnother salient feature of this thesis is the minimization of frequency fluctuation of power\nsystem with high wind power penetration. As the output power from wind farm fluctuating due to\nwind speed variations becomes large, fluctuations of the network frequency and voltage also become\nlarge. As the wind turbine dynamics and governor control systems have the significant influence on\nthe system frequency, effects of different governor control system models have been investigated.\nHowever, adopting only wind turbine pitch controller and governor control system is not sufficient to\nmaintain network frequency of the power system with high wind power penetration to the desired\nlevel. Though the pitch control system can maintain the system frequency if the wind power\ngeneration is in a few percentage of the total power capacity, but it would be difficult when the wind\npower penetration becomes 10% or larger.\nFluctuation of power system frequency due to large incorporation of wind farm output power to\nthe grid has some adverse effect on power system operation. Therefore, in this study, SMES is\nproposed to mitigate the power system frequency oscillation caused by wind farm. It is expected that\nlarge SMES capacity give better smoothing performance. However, large capacity will definitely\nincrease the system overall cost. Therefore, the optimum size determination of SMES is one of the key points from the viewpoint of cost-effectiveness. So in this study, an evaluation method of SMES\npower rating has also been analyzed. Moreover, the minimum energy storage capacity of SMES unit\nto mitigate the frequency fluctuation is determined. The simulation results show that, using the\nproposed SMES system, the wind farm output fluctuations can be decreased, and hence the frequency\nof the grid system can be maintained within an acceptable range. Wind farm grid voltage can also be\nmaintained to the rated value by the proposed system.\nBetween the two types oftrends, the fixed-speed WTGS has inferior fault ride through capability\ncompared to that of variable speed WTGS. Therefore, fixed-speed wind generator that uses the\nsquirrel-cage induction generator needs additional tool to enhance the fault ride through capability.\nThis is because it requires large reactive power to recover the air gap flux when a short circuit fault\noccurs in the power system. If sufficient reactive power is not supplied, then the electromagnetic\ntorque of wind generator decreases significantly. Then wind generator and turbine speeds increase\nrapidly due to large difference between mechanical and electromagnetic torques. As a result, the\ninduction generator becomes unstable and it requires to be disconnected from the power system.\nHowever, the recent trend is to decrease the shut down operation because a shut down of large wind\nfarm can have a serious effect on power system operation. In this study, a pulse width modulation\n(PWM) based voltage source converter (VSC) and two-quadrant DC-DC chopper using insulated gate\nbipolar transistor are proposed for controlling SMES to enhance the fault ride through capability of\nfixed-speed WTGS. Comprehensive study is carried out to enhance the transient stability of multimachine\npower system including wind farm by using the proposed SMES. Two-mass drive train\nmodel ofWTGS is used in the analysis as the drive train modeling has great influence on the dynamic\ncharacteristics of WTGS. Both symmetrical and unsymmetrical faults are considered for transient\nstability analysis of WTGS as the type of fault that occurs in a power system is quite uncertain.\nSimulation results clearly show that the proposed SMES can enhance the transient stability of wind\ngenerators. It is also observed that SMES helps not only in regulating the voltage, but also in\nmitigating the rotor speed instability, thus it can improve the stability of entire power system. It is also\npresented that the value of compensating capacitor in wind farm can be reduced by a certain\npercentage from the original rated value because the rest of the reactive power drawn by the wind\nfarm at steady state can be supplied by the SMES. Transient stability has also been evaluated\nconsidering stability index. From these results, it can be understood that the proposed controlled\nSMES can improve the transient stability of entire power system.\nConsidering all aspects of proposed SMES system, it is found that the SMES is a good tool to be\nintegrated with fixed-speed wind farm. Therefore, the integration of the proposed SMES system into a\nwind farm can be an effective means of mitigating the frequency fluctuations of the grid system which\nconsequently improve the stability and reliability of entire power system.","subitem_description_type":"Abstract"}]},"item_7_dissertation_number_64":{"attribute_name":"学位授与番号","attribute_value_mlt":[{"subitem_dissertationnumber":"10106甲第107号"}]},"item_7_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.19000/00007506","subitem_identifier_reg_type":"JaLC"}]},"item_7_select_15":{"attribute_name":"著者版フラグ","attribute_value_mlt":[{"subitem_select_item":"ETD"}]},"item_access_right":{"attribute_name":"アクセス権","attribute_value_mlt":[{"subitem_access_right":"open access","subitem_access_right_uri":"http://purl.org/coar/access_right/c_abf2"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"MD, rafiqul islam sheikh","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"38489","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-11-22"}],"displaytype":"detail","filename":"Sheikh.pdf","filesize":[{"value":"8.3 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"Sheikh.pdf","objectType":"fulltext","url":"https://kitami-it.repo.nii.ac.jp/record/7512/files/Sheikh.pdf"},"version_id":"2c4745f1-c939-4c4b-9f3d-fb7481cb8b71"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"doctoral thesis","resourceuri":"http://purl.org/coar/resource_type/c_db06"}]},"item_title":"Stabilization of a Grid-Connected Wind Farm by Using SMES","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Stabilization of a Grid-Connected Wind Farm by Using SMES","subitem_title_language":"en"}]},"item_type_id":"7","owner":"1","path":["6"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2011-11-21"},"publish_date":"2011-11-21","publish_status":"0","recid":"7512","relation_version_is_last":true,"title":["Stabilization of a Grid-Connected Wind Farm by Using SMES"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2022-12-13T02:23:08.051307+00:00"}