Nr Electric Co., Ltd

Nr Engineering Co., Ltd

Nr Electric Power Electronics Co., Ltd.

Haibin Liu

Dongming Cao

Yunlong Dong

Jie Tian

Haiying Li

Yu Lu

Gang Li

Zhaoqing Hu

Jiudong Ding

Nannan Wang

Taixun Fang

Xiang Zhang

Chihan Chen

Guangtai Zhang

Guorong Shen

Chun Liang

Yushan Li

Guoqiang Song

Zeming Zhang

Weiqiang Zhang

The present invention discloses a passive islanding to grid-connection switching method for a VSC HVDC transmission system. When the VSC HVDC transmission system in an island operation state, whether the VSC HVDC transmission system enters an grid-connection state is determined by detecting whether an overcurrent phenomenon has occurred in a converter valve-side three-phase alternating-current or a converter bridge arm current, and detecting a change status of an alternating-current side voltage. The system is controlled to switch from an island operation control mode to a grid-connection control mode. At a moment of switching, the online control mode is smoothly switched to by changing a power instruction and performing phase tracking on a current grid voltage, so that continuous operation of the system is maintained.

Passive islanding-to-grid-connected switch method

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.

Coordination control method of multi-terminal VSC-HVDC transmission system

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.

Method for inhibiting multiple inverter stations from entering passive control mode in island state

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.

Voltage-source multi-level converter, DC power transmission system, and fault processing method and device

A thyristor assembly radiator for a DC converter valve. A water discharging port of an Nradiator is communicated with a water discharging port of an (N&#x2212;2)radiator. A water feeding port of the Nradiator is communicated with a water feeding port of an (N+2)radiator. Or, a water feeding port of the Nradiator is communicated with a water feeding port of the (N&#x2212;2)radiator, and a water discharging port of the Nradiator is communicated with a water discharging port of the (N+2)radiator. A water discharging port of an Mradiator is communicated with a water discharging port of an (M&#x2212;2)radiator, and a water feeding port of the Mradiator is communicated with a water feeding port of an (M+2)radiator, or a water feeding port of an Mradiator is communicated with a water feeding port of the (M&#x2212;2)radiator, and a water discharging port of the Mradiator is communicated with a water discharging port of an (M+2)radiator. Water feeding ports of the last two radiators are communicated. According to the radiator, the number of joints of a cooling system is reduced, the risk of leakage is lowered, the operation reliability of a converter valve is improved, the maintenance difficulty is lowered, and the maintenance time is shortened.

Thyristor assembly radiator for DC converter valve

A submodule distributed control method, device and system are provided. Submodules of each bridge arm are grouped. Each group corresponds to one valve based controller. An upper-level control device calculates a weight of each group according to a bridge arm current, an average voltage of normal submodules in each group, and the number of the normal submodules in each group; calculates, according to the number of submodules to be input in a corresponding bridge arm, the number of submodules being input in each group and delivers the number to the valve based controller. The valve based controller operates according to a voltage balancing policy and a gating method that are provided in the prior art.

Sub-module distributed control method, device and system

Growing community of inventors

Jiangsu, China

Haibin Liu