IEEJ Transactions on Power and Energy
Online ISSN : 1348-8147
Print ISSN : 0385-4213
ISSN-L : 0385-4213
Volume 117 , Issue 7
Showing 1-27 articles out of 27 articles from the selected issue
  • Eisuke Masada
    1997 Volume 117 Issue 7 Pages 897
    Published: June 20, 1997
    Released: December 19, 2008
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  • Koji Imai
    1997 Volume 117 Issue 7 Pages 898-900
    Published: June 20, 1997
    Released: December 19, 2008
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  • Toshiyuki Hyashi, Takeichi Sakurai
    1997 Volume 117 Issue 7 Pages 901-904
    Published: June 20, 1997
    Released: December 19, 2008
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  • Kohachiro Nishi, Tatsuhito Nakajima, Akihiko Yokoyama
    1997 Volume 117 Issue 7 Pages 905-914
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Recent progress of power electronics technology makes it possible that self-commutated converter using GTOs (Gate Turn-Off thyristors) is considered to be applied to HVDC transmission systems. Since the self-commutated converter can be operated stably without depending on ac-side voltage, the magnitude and the phase angle of the converter output voltage can be controlled independently. Therefore, this type of converter will improve the voltage stability at its ac side. On the other hand, shaft-torsional oscillation of a thermal power plant caused by the interaction between shaft-generator system and control system of the self-commutated converter is still an open problem. In this paper, a linearized model for eigenvalue analysis of a power system including HVDC interconnection with self-commutated converters is described to analyze the effect of the self-commutated converter on the shaft-torsional oscillation of a thermal power plant. Then, numerical results from the eigenvalue analysis of the shaft-torsional oscillation are presented. Results obtained by frequency response method are also reported. The numerical results make it clear that there exist the parameter regions of DC-AVR and ACR control systems of the self-commutated converter where the shaft-torsional oscillation may be caused.
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  • Takaaki Kai, Nobutaka Takeuchi, Tatsunori Sato, Hirofumi Akagi
    1997 Volume 117 Issue 7 Pages 915-920
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    A thyristor-controlled series capacitor (TCSC) is expected as a powerful device to make power transfer capability and transient stability increase. The basic configuration of the TCSC consists of a series of capacitors connected in anti-parallel with thyristorcontrolled reactors, so that the firing angle control of the thyristors makes the TCSC capable of achieving impedance control in a wide range with quick response.
    It is important to clarify the relationship between the fundamental reactance of the TCSC and the firing angle of the thyristors, thus leading to practical applications of the TCSC for the enhancement of the power transfer capability and transient stability in transmission lines. Two relationship equations for TCSC fundamental reactance have already proposed. One is the relationship equation derived from TCSC circuit, source of which is voltage. The other is the relationship equation derived from TCSC circuit, source of which is current. For the case of installing TCSC in the transmission line, it is not clarified that which equation is adequate to analyze power system stability. In this paper, the authors developed whether either of the equation is valid to analyze power system stability.
    1. In the steady state, TCSC fundamental reactance is analyzed, and compared with two equations and EMTP. It is clear that TCSC reactance based on current source is adequate.
    2. Swinging angle of a generator when the firing angle is stepped up is analyzed with EMTP and analytical model using TCSC model based on current source. It is shown that the proposed model is effective for power system stability analysis.
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  • Naoki Kobayashi, Kenichi Tanomura, Akihisa Takei, Tsukushi Hara, Kaoru ...
    1997 Volume 117 Issue 7 Pages 921-929
    Published: June 20, 1997
    Released: December 19, 2008
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    Application of controlled series capacitors with antiparallel thyristor combination across the capacitor segment is one of new and promising countermeasures for enhancement of power system stability. The line reactance can be directly controlled by the controlled series capacitors, hence, it is very effective to apply the capacitors for damping power system disturbances. However, the segmented series capacitors may cause subsynchronous resonance (SSR) that can lead to turbine-generator shaft failure and electrical instability at oscillation frequencies lower than normal system frequency as well as the conventional capacitor may cause. In this paper, we describe the following.
    (1) The response of turbine-generator shaft torque are analytically discussed when the number of inserted series capacitor in power system is changed.
    (2) It is proposed for SSR countermeasure that the control system will be designed to avoid the number of series capacitor segment which may cause SSR in addition to selecting the better on-off timing of series capacitors.
    (3) The effects of the proposed countermeasures are confirmed by the results of EMTP simulation using both simplified two-mass shaft model and detailed five-mass shaft model of turbine-generator.
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  • Osamu Takahashi, Kesao Sato, Ken Goto, Takashi Shirasaki, Jun Sanekata ...
    1997 Volume 117 Issue 7 Pages 930-937
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    An adjustable speed flywheel generator (FWG) can control both active power and reactive power rapidly. We have studied effect of FWG installation to a large-capacity and long-distance transmission system, especially when the system includes loops. In this paper, we describe the selection of FWG location, the selection of stabilizing control input signal, and the required quantities of FWG. FWG location is selected by a PQ-Sensitivity method, which is simple and easy to estimate the effect of both FWG's active and reactive power. As a stabilizing control input signal, we use bus voltage frequency instead of power flow because the flow changes stepwise by opening three-phase single-circuit. Additionally we clarify the required FWG quantities to design, such as FWG's active power and reactive power. We considered FWG's slip to determine the quantity because the capacity of the exciter depends on slip.
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  • Katsuyuki TOMIYAMA, Masakazu SATO, Kouji YAMAJI, Masahiro SEKITA, Masu ...
    1997 Volume 117 Issue 7 Pages 938-944
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    This paper describes a power swing damping control by HVDC power modulation. In a hybrid system (AC transmission system and HVDC system compose a loop transmission system.), a damping control of power swing by control of HVDC power is called power modulation control. The new inter-connection by HVDC link between Shikoku and Kansai power systems composes a loop transmission system by the existing ac transmission system and the new HVDC transmission system, therefore, a power modulation control can be applicable for stabilization of ac system. In this paper, a new developed power modulation control system to damp two power swing modes occurred in 60Hz inter-connected system and the neighbor power system to the HVDC converter station. Characteristics of power swing in ac system, the principle of power swing damping control by power modulation, design method of control system and results of verification tests by digital and analog simulator are described. It is shown that the developed power modulation system applied to the HVDC link is effective for damping two power swing modes.
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  • Taizou Hasegawa, Koji Yamaji, Hiroyuki Irokawa, Masatoshi Takeda, Hiro ...
    1997 Volume 117 Issue 7 Pages 945-952
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    A thyristor valve for a large HVDC system is required to have such characteristics as compactness in size, smaller power consumption and higher reliability. The authors developed a DC500kV thyristor valve using 8kV light-triggered thyristors with 6-inch wafers which can meet above requirements.
    Followings are the results of development and investigation in this paper;
    (1) Studies about the rating of thyristors show that a 8kV thyristor with 6-inch wafer can be the most optimum for the objective valve. Newly developed 8kV light-triggered thyristors provide good characteristics.
    (2) The most optimum parameters of valve components to keep the valve within its allowable level against the critical stresses are made clear from the quantitative analysis.
    (3) An effective test method for valve turn-on test during the arrester discharging is proposed. The test results show that the proposed method can impose proper turn-on stresses on the thyristors.
    (4) A DC 500kV proto-valve developed with the aide of above studies shows that it can satisfy the requirements.
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  • Kenichi Suzuki, Masashi Yajima, Mikiya Nohara, Shigeta Ueda, Hiroyasu ...
    1997 Volume 117 Issue 7 Pages 953-959
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    With the development of high power gate tun-off (GTO) thyristors, large capacity self-commutated power converters have been applied to electric power systems. The self-commutated static var compensator (SVC) contributes to power system stabilization since it dose not fail in commutation due to any power system fault. Pulse width modulation (PWM) control keeps harmonics low. Active and reactive power can be controlled separately and continuously.
    On the other hand, there are two problems, a large loss at the high switching frequency of the GTOs, and excessive current due to DC excitation of the multiple transformer needed for large capacity.
    A 50MVA self-commutated SVC has been installed in the Shin-shinano Substation of Tokyo Electric Power Company where it has been undergoing a field test since March 1992. Recently, we developed a high performance control method, which uses low harmonics PWM control and high response inhibition of DC excitation of the multiple transformer, under the condition of 2-pulse PWM control (GTO switching frequency is 100Hz). The control method has been applied to the 50MVA self-commutated SVC since June 1995.
    In this paper, the control method and the field test results are described.
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  • Takuji CHIDA, Yoshihiko SATO, Jun SUGAWARA, Ryuuichi MORIKAWA, Yoshiak ...
    1997 Volume 117 Issue 7 Pages 960-966
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The increasing complexity of AC power networks requires a high performance power flow control system in order to obtain a desired power flow and enhance static and dynamic stability. One of the most effective power electronic systems to satisfy these requirements is a UPFC (Unified Power Flow Controller) employing self-commutated converters.
    This paper presents basic control strategies and simulation results for the UPFC using EMTP (Electro-Magnetic Transients Program). The simulations were carried out for start and stop operations, power flow change operations in normal system conditions, as well as operations during system fault conditions. Thyristor based bypass switches are used for the protection of the series compensator of the UPFC from system fault currents, and satisfactory protection capability was confirmed.
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  • Hisashi Ooi, Tsutomu Watanabe, Kenichi Kawada, Toshiyuki Hayashi, Hiro ...
    1997 Volume 117 Issue 7 Pages 967-974
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    A technical project is undertaken for a development of multi-terminal HVDC (MTDC) control and protection systems applicable to future long distance HVDC bulk power transmissions and power network interconnections. Through study and digital analyses of the previously proposed MTDC control and protection systems, advanced voltage margin control system and 2-automatic current regulator (2-ACR) control system are developed with new control functions. Then simulator tests are performed for the two systems with power network models expected to be realized in the future. The results of simulator tests are believed that the two MTDC control and protection systems are capable of applying to the future long distance HVDC bulk power transmissions and power network interconnections in Japan.
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  • Kouji YAMAJI, Makoto TANAKA, Masahiro SEKITA, Iwao MATORI
    1997 Volume 117 Issue 7 Pages 975-984
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The large capacity (1400MW) HVDC Link connecting Shikoku and Kansai is under construction to be commissioned in the year of 2000. Its significant features include (1) largest converter capacity ever made in Japan, (2) hybrid mode system configuration in parallel with 500kV AC trunk lines and (3) possibility for an islanded transmission mode with direct connection to the large thermal power plant. Since this HVDC is large in its capacity and plays significant roles in the 60Hz power systems, studies and countermeasures on various subjects arising from AC/DC interaction phenomena are very important. This paper describes mechanisms, analysis results and countermeasures for AC overvoltages, harmonic instability, DC power oscillation and SSTI (turbine-generator subsynchronous torsional interactions) which take place based on AC and DC interactions.
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  • Masahide Hojo, Yasunori Mitani, Kiichiro Tsuji
    1997 Volume 117 Issue 7 Pages 985-990
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Power system stabilizing controllers have become more and more intelligent with the advancement of technologies in power electronics devices and circuit topologies. However, nonlinearities that are inherent in power system dynamics often spoil the robustness of a power system controller designed at an operating point. In this paper we propose a power system stabilizing controller using a variable series impedance unit with a control reference to obtain the prespecified linearized power swing characteristics. It is expected that the control scheme will be robust in the sense that the control parameters do not have to be re-adjusted even if the configuration or the operating point of the power system is changed. Some numerical studies demonstrate the significant effect of the proposed controller, in which a variable series impedance is used, on the power system stabilization.
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  • Junya Matsuki, Keiichi Ikeda
    1997 Volume 117 Issue 7 Pages 991-998
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    This paper presents the results of an investigation on the loop current of a thyristor controlled series capacitor (TCSC). The knowledge of loop current characteristics is important for understanding analytically the equivalent impedance of TCSC, estimating harmonics produced by TCSC, and determining ratings of the TCSC circuit components. However, little has been written on the loop current of TCSC circuit. Therefore, using a laboratoryscale TCSC installed on a laboratory power system, the TCSC currents and voltages were measured and analyzed to investigate the behavior of loop current. A mathematical model of TCSC was also developed to compare with the experimental results and further clarify a relationship between loop current and steady-state impedance characteristics, including effects of TCSC circuit component size on the characteristics. Capacitor voltage harmonics and their impacts on the power system were also investigated.
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  • Koji SAKAMOTO, Hirokazu SUZUKI, Tadao ISHIKAWA, Shigeyuki SUGIMOTO, Ta ...
    1997 Volume 117 Issue 7 Pages 999-1005
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    This paper describes a cooperative control scheme for a dc two-terminal system consisting of voltage-source self-commutated converters. Using this scheme, each terminal can be operated independently, with little data communication. Prototype controllers have also been developed and tested with an analogue power system simulator. The test results have verified that:
    (1) The converter will not fail to carry out commutation even when a voltage dip or waveform distortion has occurred in the ac system.
    (2) Active and reactive power can be controlled without interference.
    (3) In the event of terminal tripping-out as well, the healthy terminal can continue operation without depending on any means of communication between terminals.
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  • Tatsuhito NAKAJIMA, Hirokazu SUZUKI, Kunikazu IZUMI, Shigeyuki SUGIMOT ...
    1997 Volume 117 Issue 7 Pages 1006-1015
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    A technical project is under way to develop a high-performance self-commutated ac/dc converter for future HVDC bulk power transmission and dc interconnection. In the first stage of the project, prototype converter models for a 300 MW self-commutated converter were developed. The models were subjected to factory testing to verify the technologies for series connection of multiple gate turn-off thyristors (GTOs), a gate power supply from the high voltage main circuit, and regeneration of energy in snubber circuits. The converter mounting technologies for the application of the most advanced GTO rated at 6 kV-6 kA-500Hz were also developed and tested. Satisfactory results were obtained.
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  • Masanao Kato, Yasuo Morioka, Yasuhiro Mishima, Yoshiki Nakachi, Minoru ...
    1997 Volume 117 Issue 7 Pages 1016-1023
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The thyristor-controlled series compensator (TCSC) can stabilize a power system by controlling line impedance and in the future, it is expected to provide a scheme for dealing with stability problems. However, detailed reports about control and protection methods of the TCSC are lacking regarding such points as firing angle control of thyristors.
    This paper proposes some new methods to control and to protect the TCSC. First, methods for firing angle control to synchronize a line current, pulse width control, and total impedance control of two TCSC modules are described. Continuous impedance control ranging from capacitive to inductive conditions is possible by these methods. Furthermore, achievement of zero impedance can reduce the influence when the TCSC was installed on transmission lines. Next, the impedance feedback control method is explained which makes the impedance response of the TCSC faster. Finally, protection schemes by cooperative operation of arresters, thyristors and bypass switches are proposed.
    The effectiveness of these control methods is confirmed by EMTP simulations and experiments using the TCSC miniature model for a simulator.
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  • Shigeru Tanabe, Sumio Kobayashi
    1997 Volume 117 Issue 7 Pages 1024-1031
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    We have been developing thyristor valves for high-voltage dc transmission systems for more than 20 years. During this period, the size, power loss and reliability are dramatically improved and one of the technical advancements which support the improvements is to increase the voltage and current rating of thyristors.
    However when thyristor voltage rating becomes higher than 6kV, increasing the voltage rating does not lead size and power loss reduction of the valve because of turn-off characteristic deteriorations.
    This paper describes the method which can optimize the thyristor characteristics in such a way that the size and power loss of valves are minimized. Two different approaches for HVDC and back-to-back systems are presented.
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  • Atsushi Hamada, Kiyoshi Takigawa, Kensuke Kawasaki, Hiromu Ariyoshi
    1997 Volume 117 Issue 7 Pages 1032-1038
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    From a shut down test of generator and electric load in the power system, it is well known that the power disturbance is transmitted from the test point to the other points with constant delay time. The phenomena shows that the electric power system has a similar dynamic characteristic to the distributed constant circuit. On the other hand, in the case of a simulation with lumped constants, such as the detailed conditions in connected generators must be understood, and the analysis becomes complicated. In this paper, the electric power system is expressed with the distributed constant circuit, so that the main disturbance characteristics are obtained without difficulty. Moreover, the possibility of suppressing the disturbance is discussed by employing active sink method.
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  • Hiroshi Hayashida, Yoshiaki Nakagama, Hidenobu Fukuzono, Akira Toyota, ...
    1997 Volume 117 Issue 7 Pages 1039-1049
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Low-voltage control circuits of power stations and substations have a very important role to maintain the high quality and reliability of electric power systems. Digital circuits are widely used in the low-voltage control circuits by introducing integrated circuits. Operation voltages and the insulation level of the control circuits are much smaller than power-frequency voltages and the insulation level of the main circuits. Thus, faults and troubles in the control circuits increase nevertheless those in the main circuits decrease.
    A study on the control circuits is focused on the effective and accurate operation of the power systems by the use of the control circuits. The insulation design of the control circuits, however, has not been investigated satisfactorily. Then, this paper presents measured overvoltages in a low-voltage control circuit model consisting of a control cable and control pannels installed on a grounding net for a lightning impulse voltage being applied on a main circuit consisting of a surge arrester and a potential divider.
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  • Hideo Sakai, Shinya Sunada, Hitoshi Sakurano
    1997 Volume 117 Issue 7 Pages 1050-1055
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The study of remanent magnetization is made at the area of lightning strike. In case of the triggered lightning (Okushishiku, Hokuriku district), the magnetic direction of the specimens shows the clockwise rotation pattern around the point of lightning strike. At the archaeological site of Miyagi prefecture, anticlockwise pattern of the magnetic direction is detected. These results indicate that the stable remanent magnetization is acquired by the strong magnetic field induced surrounding the lightning current both at the negative and positive ground flashes. Also, the detailed analysis of magnetization clarify the electric current flow underground caused by lightning. The study of remanent magnetization will become an useful method to elucidate the underground path of the lightning current.
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  • Hisashi Aichi, Iwao Miyachi
    1997 Volume 117 Issue 7 Pages 1056-1060
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Electric contact members of switchgear are characterized by the configuration such as a point, a line or a plane contact. Particularly, a point contact member that makes a small circular contact spot is considered as the basis of the contact characteristics. Generally, for most of the connectors and the circuit-breakers, the line or the plane contact member is applied. Authors have been developing an unique contact model to measure the contact resistance of any kind. In this model, it is available to select the size, the member, and the configuration of contact spots by macroscopic arrangement of some metal electrodes immersed in electrolyte solution of dilute sulfuric acid. In this paper, the contact resistance of a case that changes from line to plane contact and that of several line contacts in parallel are studied. The experimental results obtained show the characteristics of contact resistance changed from line to plane contact are equivalent to those of a point contact. Moreover, it is cleared that the contact resistance of line contacts in parallel has the same characteristics as that of a long line contact.
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  • Nobuhiko Hayanose, Ai Lee Tan, Yoshitaka Inui, Tetsuji Matsuo, Motoo I ...
    1997 Volume 117 Issue 7 Pages 1061-1068
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    This study is carried out as a part of the wide research of large scale MHD generation system. It has been reported in previous works that large-scale disk generators are probably unstable. Recently, we have shown that disk generators become stable under appropriate conditions of both inflow type and multi-loading. In this paper, we design a large-scale open-cycle disk generator to be stable at steady state. The disk generator is operated with subsonic inflow and two pairs of load. A power transmission system is
    designed considering to connect the disk generator which has two different power outputs. The proposed transmission network mainly consists of cascade-connected line-commutated inverters, harmonic filters, capacitors for phase modification and double-circuit transmission-lines.
    It is found that the performance of the system at steady state is about the same as the designed one and is stable in the region of the inverter control-angle of 130°_??_150°. It is shown that faults in the transmission-line give large fluctuations to the MHD generation system. The control of the inverter angle in addition to cutting off the faulted line is, however, effective to remove the fluctuations.
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  • Shinji Yasuda, Yasuo Nishikori, Minoru Murano, Teruya Kouno
    1997 Volume 117 Issue 7 Pages 1069-1070
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
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  • Hitoshi Kijima
    1997 Volume 117 Issue 7 Pages 1071-1072
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
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  • Koichi Nakamura, Masakazu Uehara, Hitoshi Suzuki
    1997 Volume 117 Issue 7 Pages 1073-1074
    Published: June 20, 1997
    Released: December 19, 2008
    JOURNALS FREE ACCESS
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