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公开(公告)号：US10700525B2
公开(公告)日：2020-06-30
申请号：US16079967
申请日：2017-01-19
发明人： Wenqiang Zhao , Nannan Wang , Yongping Wang , Jiang Lu , Chuanjun Bai , Yu Lu
摘要： A method and apparatus for controlling a hybrid direct-current (DC) transmission system. The method comprises: adjusting the total number of inserted sub-modules of a modular multi-level converter and the polarity of an output level of the inserted sub-modules in real time, according to a DC voltage of a rectifier station at other end; or adjusting the total number of inserted sub-modules of a modular multi-level converter and the polarity of an output level of the inserted sub-modules in real time, according to the magnitude of a DC current or DC power; or adjusting the total number of inserted sub-modules of a modular multi-level converter and the polarity of an output level of the inserted sub-modules in real time, according to both the magnitude of the DC current and the DC voltage of the rectifier station at the other end. The method can effectively control the DC voltage and the direct current of a hybrid DC transmission system, avoiding the power transmitting breakdown.
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公开(公告)号：US20190252885A1
公开(公告)日：2019-08-15
申请号：US16345426
申请日：2017-11-24
发明人： Jiang Lu , Yu Lu , Yunlong Dong , Nannan Wang , Yongping Wang , Wenqiang Zhao , Jie Tian , Haiying Li
摘要： Provided is an on-line input and quit control method for a voltage-source converter unit. The method achieves the on-line input of a voltage-source converter unit by means of performing steps, such as charging control, deblocking transfer control and operation adjustment control, on a voltage-source converter to be input, and achieves the on-line quitting of the voltage-source converter unit by means of performing steps, such as direct-current voltage reduction control, bypass transfer control and converter blocking control, on a voltage-source converter to be quit. Correspondingly, provided is an on-line input and quit control device for a voltage-source converter unit, which can achieve the on-line steady input and quitting of a voltage-source converter in a series-type hybrid direct-current power transmission system or a series-type flexible direct-current power transmission system, without affecting the normal and stable operation of other already running converters.
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公开(公告)号：US11146071B2
公开(公告)日：2021-10-12
申请号：US16770458
申请日：2018-11-28
发明人： Jiang Lu , Yu Lu , Yunlong Dong , Yongping Wang , Jie Tian , Haiying Li , Zhaoqing Hu , Nannan Wang , Ke Wang , Jiudong Ding
摘要： A coordinated control method for series voltage source converter valve groups comprises: allocating a total direct-current voltage reference value or a total active power reference value at the end where a direct-current electrode series voltage source converter valve group is located according to the total number of voltage source converter valve groups in series; for a direct-current voltage control end, controlling the direct-current voltage of each valve group according to the assigned direct-current voltage reference value for each valve group; for an active power control end, controlling the active power of each valve group according to the assigned active power reference value for each valve group and based on adding the active power compensation amount of the valve group which has voltage equalization effects on the valve group. Correspondingly, also providing a coordinated control device for series voltage source converter valve groups. The direct-current voltage equalization of each valve group in operation of the direct-current voltage control end or the active power control end of the series voltage source converter valve group is achieved.
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公开(公告)号：US20210222673A1
公开(公告)日：2021-07-22
申请号：US16759309
申请日：2018-10-23
发明人： Jiacheng Wang , Yu Lu , Nannan Wang , Zhaoqing Hu , Yunlong Dong , Gang Li , Chongxue Jiang
摘要： The invention relates to an island converter overload limit method and device for a bipolar flexible DC transmission system, and belongs to the field of DC transmission. During stable island operation, both bipolar converters adopt a voltage-frequency droop control strategy; and once it is detected that one converter is overloaded, the control mode of the overloaded converter is automatically switched to active-wattless power control from voltage-frequency droop control to fulfill an overload limit function. The method effectively avoids an overload of the bipolar flexible DC transmission system under island operation, effectively maintains the AC voltage and frequency stable, and has important guiding significance for applying island systems to DC power grids.
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5.发明授权公开(公告)号：US10797487B2
公开(公告)日：2020-10-06
申请号：US16345426
申请日：2017-11-24
发明人： Jiang Lu , Yu Lu , Yunlong Dong , Nannan Wang , Yongping Wang , Wenqiang Zhao , Jie Tian , Haiying Li
摘要： Provided is an on-line input and quit control method for a voltage-source converter unit. The method achieves the on-line input of a voltage-source converter unit by means of performing steps, such as charging control, deblocking transfer control and operation adjustment control, on a voltage-source converter to be input, and achieves the on-line quitting of the voltage-source converter unit by means of performing steps, such as direct-current voltage reduction control, bypass transfer control and converter blocking control, on a voltage-source converter to be quit. Correspondingly, provided is an on-line input and quit control device for a voltage-source converter unit, which can achieve the on-line steady input and quitting of a voltage-source converter in a series-type hybrid direct-current power transmission system or a series-type flexible direct-current power transmission system, without affecting the normal and stable operation of other already running converters.
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公开(公告)号：US11374411B2
公开(公告)日：2022-06-28
申请号：US16759309
申请日：2018-10-23
发明人： Jiacheng Wang , Yu Lu , Nannan Wang , Zhaoqing Hu , Yunlong Dong , Gang Li , Chongxue Jiang
摘要： The invention relates to an island converter overload limit method and device for a bipolar flexible DC transmission system, and belongs to the field of DC transmission. During stable island operation, both bipolar converters adopt a voltage-frequency droop control strategy; and once it is detected that one converter is overloaded, the control mode of the overloaded converter is automatically switched to active-wattless power control from voltage-frequency droop control to fulfill an overload limit function. The method effectively avoids an overload of the bipolar flexible DC transmission system under island operation, effectively maintains the AC voltage and frequency stable, and has important guiding significance for applying island systems to DC power grids.
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公开(公告)号：US11355932B2
公开(公告)日：2022-06-07
申请号：US16644225
申请日：2018-05-22
发明人： Nannan Wang , Yu Lu , Yunlong Dong , Jie Tian , Chongxue Jiang , Jiacheng Wang , Gang Li , Jiudong Ding , Haiying Li
摘要： Disclosed are a control method and system for a parallel converter system, including a common AC voltage controller and a separate current controller for each converter; the AC voltage controller generates an active current, a wattless current, and a system voltage phase reference value and, by means of communication, sends same to the current controller of each converter in island control mode to be a converter control signal; the active and wattless current outputted by each converter, along with the corresponding current reference value, accomplish the objective of the parallel converter system collectively controlling the amplitude and frequency of an AC bus voltage. The method and system are highly reliable and effectively ensure the synchronization of a plurality of converters.
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公开(公告)号：US11190020B2
公开(公告)日：2021-11-30
申请号：US16643472
申请日：2018-05-07
发明人： Nannan Wang , Yu Lu , Yunlong Dong , Jie Tian , Dongming Cao , Haiying Li , Chongxue Jiang , Jiacheng Wang
摘要： A DC voltage coordination control method is applied to a multi-terminal VSC-HVDC power transmission system or a VSC-HVDC power grid system. When a lower-level control is used in the active power control mode, the active power reference value of the converter is generated according to the converter DC voltage and the converter DC voltage active power curve; it also includes an upper-level control to adjust the control mode and active power setting value of the lower-level control to ensure the steady-state performance of the system. This method has low dependence on communication, avoids the problem that the fixed slope and margin cannot meet all operating conditions, and is suitable for large-scale VSC-HVDC systems, and has scalability.
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9.发明授权公开(公告)号：US10181799B2
公开(公告)日：2019-01-15
申请号：US15735204
申请日：2017-01-19
发明人： Nannan Wang , Wenqiang Zhao , Yongping Wang
摘要： Disclosed in the present invention is a hybrid back-to-back direct current transmission system. The system includes an LCC converter and a VSC converter in a back-to-back connection, and a first changeover switch, a second changeover switch, a third changeover switch and a fourth changeover switch. The first changeover switch is connected to a first alternating current system and the LCC converter; the second changeover switch is connected to the first alternating current system and the VSC converter; the third changeover switch is connected to a second alternating current system and the VSC converter; and the fourth changeover switch is connected to the second alternating current system and the LCC converter. In forward power delivery, the first changeover switch and the third changeover switch are closed; and in reverse power delivery, the second changeover switch and the fourth changeover switch are closed. Thereby, it is ensured that the VSC converter always performs inversion operation in any power direction, so as to avoid the problem of potential commutation failure for the LCC converter when being in inversion operation. Also provided is a fast power flow reversal control method of the hybrid back-to-back direct current transmission system.
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10.发明授权公开(公告)号：US10164428B2
公开(公告)日：2018-12-25
申请号：US15308842
申请日：2015-02-05
发明人： Guorong Shen , Jie Tian , Dongming Cao , Haiying Li , Yunlong Dong , Nannan Wang , Haibin Liu , Yu Lu
摘要： The disclosure is related to a voltage-source multi-level converter including a phase unit. The phase unit includes first and second bridge arms, each includes modules and reactor connected in series. In the first bridge arm, a first terminal of first reactor is connected to alternating-current terminal of the phrase unit, a second terminal thereof is connected to a first terminal of the first modules, and second terminal of the first modules is connected to first DC terminal of the phrase unit. In the second bridge arm, a first terminal of the second reactor is connected to the alternating-current terminal, a second terminal thereof is connected to a first terminal of the second modules, and a second terminal of the second modules is connected to second DC terminal of the phrase unit. Then, a parallel fault shunt circuit is connected between the second terminals of the first and second reactors.
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