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公开(公告)号：US11329486B2
公开(公告)日：2022-05-10
申请号：US16607847
申请日：2018-04-27
发明人： Ke Wang , Shunke Sui , Yu Lu , Yunlong Dong , Zhaoqing Hu , Gang Li
摘要： During initiation under an isolated island condition, the amplitude of a voltage reference wave output generated by a flexible DC transmission control and protection system is in a segmented mode, wherein a first segment of the reference wave amplitude begins at zero or a fixed value Ux and rapidly increases to Ua kV at a rate of a kV/s, avoiding a low output voltage reference wave and high error and harmonic content of a sampled voltage and current. A second segment increases to Ub kV at a rate of β kV/s, a third segment increases to Uc kV at a rate of γ kV/s, and the Nth segment increases to a rated voltage of UN kV at a rate of ε kV/s, thereby achieving non-disturbance and shockless initiation of a flexible DC transmission system under an isolated island condition.
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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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公开(公告)号：US10396561B2
公开(公告)日：2019-08-27
申请号：US15027434
申请日：2013-07-01
发明人： Yunlong Dong , Jie Tian , Gang Li , Dongming Cao , Haiying Li , Haibin Liu
摘要： The present invention discloses a coordination control method of a multi-terminal VSC-HVDC transmission system. If a direct current voltage master control station shuts down, a direct current voltage control slave station takes over direct current voltage control, and remaining convertor stations keep original control modes. The takeover steps comprise that under the condition that inter-station communications are effective, the master control station sends a shutdown message to the slave station through the inter-station communications, and when the slave station monitors that the direct current voltage master control station shuts down, the slave station switches a current control mode into a direct current voltage control mode; and under the condition that inter-station communications fail or inter-station communications are absent, the slave station monitors changes of the direct current voltage of a system.
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公开(公告)号：US10923906B2
公开(公告)日：2021-02-16
申请号：US16500189
申请日：2018-05-22
发明人： Yu Lu , Gang Li , Jie Tian , Nannan Wang , Haiying Li , Chongxue Jiang , Shunke Sui
摘要： A fault switch configuration and clearing method in a flexible DC converter station, the flexible DC converter station is configured with a grid side switch and a valve side phase-split switch in the converter station. When a fault occurs, a faulty phase and a non-faulty phase are detected and identified by means of differential protection or low voltage overcurrent. An alternating current zero crossing condition is created by means of firstly turn off the non-faulty phase valve side phase-split switch and the grid side switch, thereby cutting off the faulty phase, disconnecting the connection between a power supply and a fault point, and achieving the clearing for faults. The described fault-clearing method is simple and practical, highly reliable, and connection between the fault point and the power supply is quickly and effectively cut; converter station equipment is effectively protected, and further expansion of the fault is avoided.
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公开(公告)号：US10396562B2
公开(公告)日：2019-08-27
申请号：US16319300
申请日：2017-08-15
发明人： Ruhai Huang , Yu Lu , Yunlong Dong , Lei Pan , Defeng Qiu , Chongxue Jiang , Jiang Lu , Gang Li , Zhaoqing Hu , Nannan Wang , Jiudong Ding , Ke Wang , Xianlai Hu , Hui Wang , Shunke Sui
摘要： A series compensation device suitable to double-circuit lines is disclosed. The device includes one series transformer and one converter. One converter and dual-circuit transmission lines are respectively connected to three windings of one series transformer. In the solution provided in the present application, the device can be independently installed in a power transmission system to be used as a static synchronous series compensator, and can also be used as a component of a unified power flow controller, a convertible static compensator, an interline power flow controller and a unified power quality conditioner to be connected to a power transmission system device in series. The device can save the capacity of a converter, improve the application efficiency of the series compensation device, and reduce the cost and area occupation.
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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：US10476261B2
公开(公告)日：2019-11-12
申请号：US16098878
申请日：2017-04-25
发明人： Gang Li , Yu Lu , Zhaoqing Hu , Jie Tian , Yunlong Dong , Tiangui Jiang , Haiying Li , Yadong Feng , Ke Wang , Jiang Lu , Shunke Sui , Hui Wang , Nannan Wang
摘要： A method for fault positioning and recovery of a voltage source converter includes following steps. Locking a converter station when it is detected that an alternating-current voltage contains a zero sequence voltage or a direct-current voltage contains an unbalanced voltage. Positioning a fault by continuing to detect the zero sequence voltage of an alternating-current side of the converter. Recovering operation of each station after the fault is positioned. The method for fault positioning and recovery is simple, practical, has high reliability, and can effectively detect the problems that each station contains a zero sequence voltage of an alternating-current side and cannot easily position a fault caused due to transmission of the zero sequence voltage of the alternating-current side to an opposite-side alternating-current system via a voltage source converter.
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公开(公告)号：US10283965B2
公开(公告)日：2019-05-07
申请号：US15504323
申请日：2014-04-18
发明人： Yunlong Dong , Gang Li , Jie Tian , Nannan Wang , Chao Liu
摘要： A method for incorporating a non-operating station into an operating system in a multi-terminal flexible DC transmission system. The method includes selecting a STATCOM operation mode for the non-operating station; opening a bypass switch at an AC side and connecting a charging resistor to an AC line; closing the AC incoming-line breaker, and pre-charging a converter valve of the non-operating station through the resistor; closing the bypass switch after the pre-charging; selecting a constant-DC voltage control mode for the non-operating station to perform deblocking; controlling the difference between a non-operating station DC voltage value and an operating system direct voltage value to be within an allowable range; closing the pole-connection device at the DC side of a converter of the non-operating station; and switching the non-operating station from the STATCOM operation mode to a DC operation mode, and incorporating the non-operating station into the operating system.
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10.发明授权公开(公告)号：US10218184B2
公开(公告)日：2019-02-26
申请号：US15533560
申请日：2015-11-24
发明人： Yunlong Dong , Jie Tian , Dongming Cao , Haiying Li , Jiudong Ding , Zhaoqing Hu , Gang Li , Haibin Liu , Yu Lu
摘要： The present invention provides a method for inhibiting multiple inverter stations from entering a passive control mode in an island state. The method includes dividing inverter stations into groups in advance; a principle for group division is dividing inverter stations whose alternating-current sides are connected to each other through an alternating-current line in a normal running condition into a group; priorities of the inverter stations are preset in each group to tune relevant fixed values of the inverter stations for island detection; a tuning principle is that an inverter station with a higher priority has a more sensitive relevant fixed value, and an island state is more easily detected for the corresponding inverter station; an inverter station for which an island state is detected can enter a passive control mode only when all the other inverter stations with priorities higher than the priority of the inverter station in the group send enabling signals.
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