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1. 发明授权

US11283352B2 Modular multilevel dynamic switching DC-DC transformer 有权
公开(公告)号：US11283352B2
公开(公告)日：2022-03-22
申请号：US16085585
申请日：2018-01-29
申请人： Tianjin University
发明人： Bin Li , Weixin Zhang
IPC分类号： H02M3/158 , H02M1/42
摘要： The present invention discloses a modular multilevel dynamic switching DC-DC transformer, which consists of N DC-DC sub-modules connected in series. Each of the DC-DC sub-modules is of a symmetrical structure capable of realizing bidirectional power flow, which consists of two half-bridge sub-modules and isolating switches S1, S2 between capacitors C1, C2 of the two half-bridge sub-modules. The capacitors C1, C2 are disposed in parallel between the half-bridge sub-modules and the isolating switches. Assuming that the power flows in the primary side of the DC-DC transformer and flows out from the secondary side; the half-bridge sub-module located on the primary side of the DC-DC transformer is referred to as a primary-side sub-module; and, the half-bridge sub-module located on the secondary side of the DC-DC transformer is referred to as a secondary-side sub-modules. By turning on or off the switching devices, the switch-on or switch-off of the primary-side sub-module or the secondary-side sub-module can be realized, leading to the dynamic switching in four different operating states of the DC-DC transformer and realizing the voltage conversion and energy exchange. Compared with the prior art, the present invention is able to change the transformer ratio dynamically, realizing the control of the DC power flow, and, greatly decreases the number of sub-modules, has remarkable economic efficiency, can effectively reduce the size of DC-DC transformers, and it is advantageous for popularization.

2. 发明授权

US11121539B2 DC solid-state circuit breaker with self-adapt current limiting capability and the control method thereof 有权
公开(公告)号：US11121539B2
公开(公告)日：2021-09-14
申请号：US16306580
申请日：2017-06-22
申请人： Tianjin University
发明人： Bin Li , Jiawei He
IPC分类号： H02H3/08 , H02H3/087 , H02H3/02 , H02H1/06
摘要： The present invention discloses a DC solid-state circuit breaker with self-adapt fault current limiting capability. The topology of the DC solid-state circuit breaker is a H-bridge circuit consisting of two unidirectional breakable bridge arms and two series-connected diode bridge arms, wherein the two unidirectional breakable bridge arms are connected in series to the two series-connected diode bridge arms in a same direction to form two series branches, respectively; the series branches are connected in parallel; a series branch formed by a DC reactor L and a DC biased power supply is connected to the PCC between the two unidirectional breakable bridge arms and the PCC between the two series-connected diode bridge arms; the DC line is connected to the two PCCs, respectively.

3. 发明申请

US20220224100A1 ADAPTIVE FAULT CLEARING SCHEME FOR MMC VSC-HVDC GRID BASED ON SOURCE-GRID COORDINATION 有权
公开(公告)号：US20220224100A1
公开(公告)日：2022-07-14
申请号：US17360152
申请日：2021-06-28
申请人： Tianjin University
发明人： Xiaolong Chen , Xiaowen Han , Yongli Li , Bin Li , Botong Li
IPC分类号： H02H3/093 , H02H3/06 , H02H7/26
摘要： The invention discloses an adaptive fault clearing scheme for an MMC VSC-HVDC grid based on source-grid coordination. A grid-side circuit breaker topology is disposed at each end of each DC line of the MMC VSC-HVDC grid to coordinate with a source-side control strategy when a fault occurs to the DC line so as to isolate the fault together. When a system runs stably, the voltage regulation controller does not actuate, after the fault occurs, the voltage regulation controller is started, and the output voltage regulation coefficient decreases, so that voltage at outlets of the converters drops accordingly, and coordinates with voltage of the pre-charging capacitor of the grid-side circuit breaker topology to realize fault isolation based on source-grid coordination. The adaptive fault clearing scheme provided by the invention greatly improves the speed of fault isolation.

4. 发明授权

US11563323B2 Islanding detection method in DC microgrids based on MPPT trapezoidal voltage disturbance 有权
公开(公告)号：US11563323B2
公开(公告)日：2023-01-24
申请号：US17157187
申请日：2021-01-25
申请人： Tianjin University
发明人： Xiaolong Chen , Zhiying Yang , Yongli Li , Bin Li , Botong Li
IPC分类号： H02J1/10 , H02S40/30 , H02S10/00 , H02S50/00 , H02J3/00 , H02J13/00
摘要： The invention discloses an islanding detection method in DC microgrids based on MPPT trapezoidal voltage disturbance. The steps are as follows: start the MPPT strategy; set the starting signal threshold of disturbance; measure the output current of PVA at the maximum power; calculate the same environmental factor of PVA with different capacities under the same light intensity and temperature in real time; when the environmental factor is greater than the starting signal threshold of the disturbance, periodic trapezoidal disturbance is carried out to the PVA port voltage reference; if the PCC voltage Upcc exceeds the threshold set by the passive method, it is judged as islanding; otherwise, it is judged whether the change rule of Upcc is consistent with the change rule of the calculated PCC voltage Upccp under the trapezoidal disturbance; If it is consistent, it is judged as islanding; otherwise, it is pseudo islanding.

5. 发明授权

US11029367B2 Method for identifying fault types of high voltage direct current transmission line 有权
公开(公告)号：US11029367B2
公开(公告)日：2021-06-08
申请号：US16314260
申请日：2018-01-29
申请人： TIANJIN UNIVERSITY
发明人： Bin Li , Hong Qiu
IPC分类号： G01R31/58 , G01R31/52
摘要： There is provided a method for identifying fault types of HVDC physical transmission line, including: measuring positive and negative voltage values and current values at a j-terminal and k-terminal of the HVDC physical transmission line, and converting them to voltage and current values under mode components; calculating differential current values of travelling wave at the j-terminal and k-terminal under zero-mode and one-mode components of the HVDC physical transmission line, respectively; comparing with the calculated differential current value at the one-mode components under the current time t and the same at time t−t0 to determine whether the HVDC physical transmission line is faulty; converting differential current values of the travelling wave at the j-terminal and k-terminal under the mode components to differential current values under the maximum amount, respectively; calculating fault type coefficients of both terminals; and identifying the fault types based on the fault type coefficients.

6. 发明授权

US11038338B2 Micro-loss combined mechanical DC circuit breaker and its control method 有权
公开(公告)号：US11038338B2
公开(公告)日：2021-06-15
申请号：US16573750
申请日：2019-09-17
申请人： TIANJIN UNIVERSITY
发明人： Weijie Wen , Bin Li
IPC分类号： H02H3/087 , H01H9/54
摘要： The present disclosure relates to a micro-loss combined mechanical DC circuit breaker and its control method, consisting n ports, n load current paths and a main breaker; wherein the n load current paths are parallel with the main breaker, and each load current path is divided into an upper bridge arm and a lower bridge arm at a connection point; each port is electrically connected to the connection point of a load current path; the upper bridge arm of each load current path is made of an ultra-fast mechanical switch; the lower bridge arm of each load current path is made of a residual current breaker and a fast closing switch; the main breaker consists of a high-voltage capacitor in series with a low-voltage capacitor that is pre-charged.

7. 发明授权

US11444450B2 Adaptive fault clearing scheme for MMC VSC-HVDC grid based on source-grid coordination 有权
公开(公告)号：US11444450B2
公开(公告)日：2022-09-13
申请号：US17360152
申请日：2021-06-28
申请人： Tianjin University
发明人： Xiaolong Chen , Xiaowen Han , Yongli Li , Bin Li , Botong Li
IPC分类号： H02H3/06 , H02H3/093 , H02H7/26
摘要： The invention discloses an adaptive fault clearing scheme for an MMC VSC-HVDC grid based on source-grid coordination. A grid-side circuit breaker topology is disposed at each end of each DC line of the MMC VSC-HVDC grid to coordinate with a source-side control strategy when a fault occurs to the DC line so as to isolate the fault together. When a system runs stably, the voltage regulation controller does not actuate, after the fault occurs, the voltage regulation controller is started, and the output voltage regulation coefficient decreases, so that voltage at outlets of the converters drops accordingly, and coordinates with voltage of the pre-charging capacitor of the grid-side circuit breaker topology to realize fault isolation based on source-grid coordination. The adaptive fault clearing scheme provided by the invention greatly improves the speed of fault isolation.

8. 发明申请

US20210408788A1 ISLANDING DETECTION METHOD IN DC MICROGRIDS BASED ON MPPT TRAPEZOIDAL VOLTAGE DISTURBANCE 有权
公开(公告)号：US20210408788A1
公开(公告)日：2021-12-30
申请号：US17157187
申请日：2021-01-25
申请人： Tianjin University
发明人： Xiaolong Chen , Zhiying Yang , Yongli Li , Bin Li , Botong Li
IPC分类号： H02J1/10 , H02S40/30 , H02S10/00 , H02S50/00 , H02J13/00
摘要： The invention discloses an islanding detection method in DC microgrids based on MPPT trapezoidal voltage disturbance. The steps are as follows: start the MPPT strategy; set the starting signal threshold of disturbance; measure the output current of PVA at the maximum power; calculate the same environmental factor of PVA with different capacities under the same light intensity and temperature in real time; when the environmental factor is greater than the starting signal threshold of the disturbance, periodic trapezoidal disturbance is carried out to the PVA port voltage reference; if the PCC voltage Upcc exceeds the threshold set by the passive method, it is judged as islanding; otherwise, it is judged whether the change rule of Upcc is consistent with the change rule of the calculated PCC voltage Upccp under the trapezoidal disturbance; If it is consistent, it is judged as islanding; otherwise, it is pseudo islanding.

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