Abstract: A voltage source converter (VSC) system of a high-voltage direct current (HVDC) system is disclosed. The system includes a number of line-commutated converter (LCC) transformers. Each LCC transformer is operable to transform alternate current (AC) voltage. A number of VSC converter units are connected in series and coupled to the plurality of LCC transformers. Each VSC converter unit is operable to convert between the AC voltage and direct current (DC) voltage. A bypass breaker is connected in parallel with at least one of the VSC converter units and operable to be closed to bypass the at least one VSC converter unit.

Abstract: Embodiments of a modular direct current interconnection device (MDCID) include at least three operation branches, at least one transient branch, and a local controller. Each of the operation branches includes a first terminal coupled to a common node and configured to transmit DC current in a normal mode. The transient branch is coupled between second terminals of different ones of the at least three operation branches and configured to provide a transient DC current path in a fault clearance mode. The local controller is coupled to the operation branches and the transient branch, and the local controller is configured to control operation of the operation branches and the transient branch.

Abstract: A power converter includes a power conversion circuit having a first terminal set and a second terminal set, configured to convert power input via one of the first terminal set and the second terminal set and output the converted power via the other of the first terminal set and the second terminal set; a measurement unit; a controller configured to control the power conversion circuit to generate a voltage/current waveform travelling along the first network with a power supplied by a second power source linked to the second terminal set of the power conversion circuit in response to a condition that a change rate of the measurement of the voltage/current exceeds a threshold; and locate a fault on the first network. The power conversion circuit can be re-used for different modes of operation either for power transmission under normal condition or for fault location under fault condition.

Abstract: The present disclosure relates to a power grid including a converting stage including a plurality of DC/DC converters connected in parallel. At least one of the DC/DC converters is a single-stage isolated DC/DC converter including a voltage control configured to control a voltage of the respective DC/DC converter.

Abstract: The disclosure relates to a power grid, comprising a converting stage comprising a plurality of DC/DC converters. At least one of the DC/DC converters is a single-stage isolated DC/DC converter comprising a voltage control configured to control a voltage of the respective DC/DC converter. The DC/DC converters are connected in series and at least one of the plurality of converters of the converting stage is configured to provide a respective predetermined output voltage to a load.

Abstract: A method can be used to control a flexible interconnection device that includes a number of converters. The method includes receiving a plurality of voltage signals indicating respective voltages of a plurality of load branches and a plurality of current signals indicating respective currents of the plurality of load branches, determining reference active power values for each of the plurality of converters based on the plurality of voltage signals and a plurality of reference voltage signals, determining reference reactive power values for each of the plurality of converters based on the plurality of voltage signals, the plurality of reference voltage signals and the plurality of current signals, and controlling the plurality of converters based on the determined reference active power values and the determined reference reactive power values.

Abstract: Embodiments of a modular direct current interconnection device (MDCID) include at least three operation branches, at least one transient branch, and a local controller. Each of the operation branches includes a first terminal coupled to a common node and configured to transmit DC current in a normal mode. The transient branch is coupled between second terminals of different ones of the at least three operation branches and configured to provide a transient DC current path in a fault clearance mode. The local controller is coupled to the operation branches and the transient branch and the local controller is configured to control operation of the operation branches and the transient branch.

Abstract: A power converter includes a power conversion circuit having a first terminal set and a second terminal set, configured to convert power input via one of the first terminal set and the second terminal set and output the converted power via the other of the first terminal set and the second terminal set; a measurement unit; a controller configured to control the power conversion circuit to generate a voltage/current waveform travelling along the first network with a power supplied by a second power source linked to the second terminal set of the power conversion circuit in response to a condition that a change rate of the measurement of the voltage/current exceeds a threshold; and locate a fault on the first network. The power conversion circuit can be re-used for different modes of operation either for power transmission under normal condition or for fault location under fault condition.

Abstract: Embodiments of present disclosure relates to a modular interconnection device (MID) and an electrical network system. The MID comprises a modular port assembly, a node, a converter and a local controller. The modular port assembly is configured to transmit alternating current and/or direct current. The node is coupled to an AC source via a first switch and the modular port assembly. The first switch is configured to selectively disconnect the modular interconnection device from the AC source. The converter is coupled to the node via a second switch and coupled to a DC source via a third switch. The converter is configured to convert the AC current into DC current or convert DC current into AC current. The local controller is coupled to the first, second and third switches and configured to control operation of the first, second and third switches.

Abstract: Embodiments of present disclosure relates to a modular interconnection device (MID) and an electrical network system. The MID comprises a modular port assembly, a node, a converter and a local controller. The modular port assembly is configured to transmit alternating current and/or direct current. The node is coupled to an AC source via a first switch and the modular port assembly. The first switch is configured to selectively disconnect the modular interconnection device from the AC source. The converter is coupled to the node via a second switch and coupled to a DC source via a third switch. The converter is configured to convert the AC current into DC current or convert DC current into AC current. The local controller is coupled to the first, second and third switches and configured to control operation of the first, second and third switches.

Abstract: Unique systems, methods, techniques and apparatuses of a distribution system are disclosed. One exemplary embodiment is an alternating current (AC) distribution system including a first substation including a first transformer and a protective device; a first distribution network portion coupled to the first transformer; a second substation; a second distribution network portion; a DC interconnection system coupled between the first distribution network portion and the second distribution network portion; and a control system. The control system is structured to detect a fault in the first transformer or the transmission network, isolate the first distribution network from the fault, determine a set point of the DC interconnection system, and operate the DC interconnection system using the set point so as to transfer a portion of the MVAC from the second distribution network portion to the first distribution network portion.

Abstract: A method, system and apparatus for operating a hydraulic turbine. A speed adjustment quantity for the hydraulic turbine and a corresponding change in flow quantity are obtained. A rotation speed of the hydraulic turbine is adjusted based on the speed adjustment quantity. A change ratio of the flow quantity with regard to the speed adjustment quantity is determined based on the speed adjustment quantity and the corresponding change in flow quantity. An adjustment manner in which the rotation speed is further adjusted is determined based on the determined based on the determined change ratio of flow quantity. An adjustment manner in which the rotation speed is further adjusted is determined based on the determined change ratio of flow quantity. It enables the hydraulic turbine to track a maximum efficiency operation point under a given power order and water head in real time at a low cost.

Abstract: An objective of the invention is to provide a bidirectional power valve for current occurring in a high voltage DC conductor, control method therefor, hybrid multi-terminal HVDC System using the same. The bidirectional power valve includes a first power diode arrangement of a first conducting direction, a second power diode arrangement of a second conducting direction; a mechanical disconnector, being connected with the second power diode arrangement in series; wherein: the first power diode arrangement and the series-connected second power diode arrangement and the mechanical disconnector are connected in parallel; and the first conducting direction of the first power diode arrangement and the second conducting direction of the second power diode arrangement are opposite to each other. The current commutation and re-commutation can be achieved with less requirement of the timing accuracy of switching event which makes the usage of a mechanical disconnector and power diode feasible.

Abstract: Systems, methods, techniques and apparatuses of feeder line fault response are disclosed. One exemplary embodiment is a method for operating an alternating current (AC) distribution network including a first feeder line, a second feeder line, and a third feeder line. The method includes isolating a faulted portion of the first feeder line from a healthy portion of the first feeder line; closing a tie switch coupled between the healthy portion and the second feeder line in response to isolating the faulted portion from the healthy portion; determining the second feeder line is experiencing an overload condition after closing the tie switch; and transferring AC power including transferring AC power using a direct current (DC) interconnection system coupled to the third feeder line effective to remove the overload condition from the second feeder line.

Abstract: Systems, methods, techniques and apparatuses of feeder line fault response are disclosed. One exemplary embodiment is a method for operating an alternating current (AC) distribution network including a first feeder line, a second feeder line, and a third feeder line. The method includes isolating a faulted portion of the first feeder line from a healthy portion of the first feeder line; closing a tie switch coupled between the healthy portion and the second feeder line in response to isolating the faulted portion from the healthy portion; determining the second feeder line is experiencing an overload condition after closing the tie switch; and transferring AC power including transferring AC power using a direct current (DC) interconnection system coupled to the third feeder line effective to remove the overload condition from the second feeder line.

Abstract: Unique systems, methods, techniques and apparatuses of a distribution system are disclosed. One exemplary embodiment is an alternating current (AC) distribution system including a first substation including a first transformer and a protective device; a first distribution network portion coupled to the first transformer; a second substation; a second distribution network portion; a DC interconnection system coupled between the first distribution network portion and the second distribution network portion; and a control system. The control system is structured to detect a fault in the first transformer or the transmission network, isolate the first distribution network from the fault, determine a set point of the DC interconnection system, and operate the DC interconnection system using the set point so as to transfer a portion of the MVAC from the second distribution network portion to the first distribution network portion.

Abstract: A voltage source converter (VSC) system of a high-voltage direct current (HVDC) system is disclosed. The system includes a number of line-commutated converter (LCC) transformers. Each LCC transformer is operable to transform alternate current (AC) voltage. A number of VSC converter units are connected in series and coupled to the plurality of LCC transformers. Each VSC converter unit is operable to convert between the AC voltage and direct current (DC) voltage. A bypass breaker is connected in parallel with at least one of the VSC converter units and operable to be closed to bypass the at least one VSC converter unit.

Abstract: An objective of the invention is to provide a bidirectional power valve for current occurring in a high voltage DC conductor, control method therefor, hybrid multi-terminal HVDC System using the same. The bidirectional power valve includes a first power diode arrangement of a first conducting direction, a second power diode arrangement of a second conducting direction; a mechanical disconnector, being connected with the second power diode arrangement in series; wherein: the first power diode arrangement and the series-connected second power diode arrangement and the mechanical disconnector are connected in parallel; and the first conducting direction of the first power diode arrangement and the second conducting direction of the second power diode arrangement are opposite to each other. The current commutation and re-commutation can be achieved with less requirement of the timing accuracy of switching event which makes the usage of a mechanical disconnector and power diode feasible.

Abstract: A method, system and apparatus for operating a hydraulic turbine. A speed adjustment quantity for the hydraulic turbine and a corresponding change in flow quantity are obtained. A rotation speed of the hydraulic turbine is adjusted based on the speed adjustment quantity. A change ratio of the flow quantity with regard to the speed adjustment quantity is determined based on the speed adjustment quantity and the corresponding change in flow quantity. An adjustment manner in which the rotation speed is further adjusted is determined based on the determined based on the determined change ratio of flow quantity. An adjustment manner in which the rotation speed is further adjusted is determined based on the determined change ratio of flow quantity. It enables the hydraulic turbine to track a maximum efficiency operation point under a given power order and water head in real time at a low cost.

Abstract: The application relates to a system for charging a battery of an electrical vehicle. The electrical vehicle charging system of the present application is helpful for decreasing the converter capacity while maintaining the charging capacity and electrical vehicles with various nominal voltages can be charged simultaneously. In one aspect the system for charging an electrical vehicle includes: a plurality of central converters, at least one switch electrically connected to the central converters, at least one transformer electrically connected to an external AC power supply, at least one distributed converter for supplying at least one distributed DC voltage with a level below that of the central converter, and a controller connected to the at least one switch.