NR Electrical Co.

Nanjing, China

NR Electrical Co.

Nanjing, China

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Patent
NR Electrical Co. and NR Electrical Engineering Co. | Date: 2017-03-01

The invention discloses a high voltage/ultrahigh voltage direct current transmission inverter side frequency control implementing method, comprising the following steps: transmitting a deviation between the inverter side power grid frequency and rated frequency to the inverter side frequency controller, wherein the frequency controller regulates and outputs a modulation quantity by adopting self-adaptive parameters according to different operation conditions; when the interstation communication is normal, the modulation quantity output of the inverter side frequency controller causes the rectifier side and the inverter side to form a new power/current order through the interstation communication, thus realizing the inverter side frequency control by changing the size of the transmission power; when the interstation communication is abnormal, converting the inverter side to current control from voltage control and converting the rectifier side to voltage control from current control; superposing the modulation quantity output of the inverter side frequency controller to the power/current order of the inverter side, changing the size of the transmission power to realizing the inverter side frequency control. The method realizes the fast efficient regulation function on the inverter side frequency, and effectively solves the problem of the inverter side frequency control for the interstation communication failure.


Patent
NR Electrical CO. and NR Electrical ENGINEERING CO. | Date: 2015-01-12

A unified power flow controller for a double-circuit transmission line comprises at least one parallel-connection transformer, three current converters, at least two series-connection transformers, a parallel-connection side switching circuit, a series-connection side switching circuit and a direct current common bus. The series-connection transformers connected with at least one group of by-pass switches in parallel. The three current converters connected to each loop line in series after being connected with at least one series-connection transformer through the series-connection side switching circuit. The three current converters connected to an alternating current system after connected with at least one parallel-connection transformer through a parallel-connection side switching circuit starting circuit. The three current converters are connected to the direct current common bus through a transfer switch.


Patent
NR Electrical Co. and NR Electrical Engineering Co. | Date: 2015-01-22

A high voltage/ultrahigh voltage direct current transmission inverter side frequency control implementing method includes: transmitting a deviation between the inverter side power grid frequency and rated frequency to the inverter side frequency controller, wherein the frequency controller regulates and outputs a modulation quantity by adopting self-adaptive parameters according to different operation conditions; when the interstation communication is normal, the modulation quantity output of the inverter side frequency controller causes the rectifier side and the inverter side to form a new power/current order through the interstation communication; when the interstation communication is abnormal, converting the inverter side to current control from voltage control and converting the rectifier side to voltage control from current control; superposing the modulation quantity output of the inverter side frequency controller to the power/current order of the inverter side, changing the size of the transmission power to realizing the inverter side frequency control.


Patent
NR Electrical Co. and NR Electrical Engineering Co. | Date: 2016-10-19

The present invention discloses a tripolar VSC-HVDC system and method, wherein a rectifier and an inverter consist of a three-phase six-bridge arms modular multilevel converter (MMC) respectively, and two converter valves are arranged on the DC side of the rectifier and inverter respectively, the midpoint of upper and lower converter valves of the rectifier and inverter are connected with a pole 3 DC line by a smoothing reactor, triggering of the upper and lower converter valves is controlled to change the DC voltage polarity of the pole 3 periodically, and tripolar DC transmission is realized by modulating current orders of the three poles. The technical solution provided by the invention can make full use of the three conductors for power transmission, has the characteristics of small occupied space of the converter station, low total conversion cost and high reliability, and it is particularly suitable for the implementation of conversion an AC line to a DC line for capacity increasing in large-sized urban power supply systems lacking in land resources.


Patent
NR Electrical Co. and NR Electrical Engineering Co. | Date: 2016-08-31

The present invention discloses a signal name based method for automatic signal exchange between multiple embedded CPU boards, including the following steps: dividing CPU boards into master board and slave board, where during an initialization phase, each slave board sends signal registration information to the master board; after the master board collects the signal registration information of all the slave boards, reading, from a configuration file, an exchange relationship between an output signal and an input signal that is represented by a connection line between signal names, calculating and allocating a data bus address to which the output signal and the input signal are mapped, and sending memory addresses, data types, and bus addresses of signals to each slave board; after a slave board receives the memory addresses, the data types, and the bus addresses of the signals from the master board, saving same as output signal tables and input signal tables; and during an operation phase, writing, by a signal sender, a value of an output signal into a corresponding bus address according to the output signal tables, and reading, by a receiver, a value of an input signal from a corresponding bus address according to the input signal tables. With this method, signal exchange between CPU boards may be intuitively and simply adjusted, and the correctness of signal exchange is ensured. The present invention further provides an apparatus for implementing automatic signal exchange.


Patent
Zhejiang Electrical Power Test, Research Institute, State Grid Corporation of China and NR Electrical Co. | Date: 2016-04-13

A low-frequency band suppression enhanced anti-reversal power system stabilizer is presented by the invention. Currently the widely used PSS2B power system stabilizer needs lead elements above Order 2 to meet the phase compensation requirement of DC blocking signal of active power, thus quickly increasing high-frequency band gain, restricting allowable total setting gain of PSS, limiting low-band gain and reducing low-frequency band suppression ability of power system stabilizer. The invention will add generator speed signal (which is treated by DC blocking element and corrected by parallel proportional differential PD) and active power signal P_(e )(which is treated by DC blocking element and gained by gain factor K_(s3)) to get equivalent synthetic mechanical power of power system stabilizer. The actual active power signal gained by gain factor K_(S1 )can meet the requirement of phase compensation through Order 1 lead and lag elements, thus increasing allowable total setting gain of PSS and improving the ability of low-frequency band oscillation suppression.


Patent
NR Electrical Co. and NR Engineering Co. | Date: 2016-04-13

Embodiments of the present invention disclose a differential protection method for current source converter, including: sampling, by a relay protection device, secondary side currents of current transformers on two sides of a protected current source converter, to obtain incomer-side three-phase currents, and outgoer-side three-phase currents; rectifying the incomer-side three-phase currents and the outgoer-side three-phase currents, to obtain an incomer-side input current and an outgoer-side output current which are equivalent; converting the incomer-side input current and the outgoer-side output current according to a current ratio of the current transformers on the two sides, to acquire a transient differential current and a transient restraint current; acquiring a differential current and a restraint current according to the transient differential current and the transient restraint current; and achieving differential protection according to the differential current and the restraint current. The embodiments of the present invention further disclose a relay protection device correspondingly.


Patent
NR Electrical Co. and NR Engineering Co. | Date: 2016-03-23

Disclosed are a sub-module structure formed of an energy storage element, a first turn-off device, a second turn-off device, a third turn-off device, a freewheeling diode, a series resistor, and diodes respectively in antiparallel connection with the turn-off devices, and a converter completely or partially formed of the sub-modules. Also disclosed are a relevant protection unit and a control method for the converter. The converter can be locked when a direct current (DC) fault occurs to prevent an alternating current (AC) system from injecting a fault current into a DC network, so that a transient fault of the DC network can be removed without tripping an AC line switch, thereby rapidly restarting the system. A charging resistor is comprised in the sub-module so that a charging resistor disposed at an AC side of the converter can be reduced and even may not be dispose.


Patent
NR Electrical Co. and NR Engineering Co. | Date: 2016-08-03

The present invention discloses a direct current (DC) voltage control method, including: determining, when it is determined that a DC voltage primary control station loses a DC voltage control function, whether the DC voltage primary control station can communicate with the DC voltage secondary control station, and if yes, sending, by the DC voltage primary control station, information about the DC voltage primary control station losing the DC voltage control function to the at least one DC voltage secondary control station and enabling a DC voltage control function of one DC voltage secondary control station, so as to adjust a DC voltage; before the DC voltage control function of the DC voltage secondary control station is enabled, if the DC voltage exceeds an operation range, enabling, by the at least one DC voltage secondary control station, a DC voltage auxiliary control function, so as to adjust emitted or absorbed active power; and when the DC voltage primary control station cannot communicate with all of or some of the at least one DC voltage secondary control station, and if the DC voltage exceeds the operation range, enabling, by at least one DC voltage secondary control station, a DC voltage auxiliary control function, so as to adjust current emitted or absorbed active power, and determining, according to a policy, one DC voltage secondary control station to enable a DC voltage control function, so as to adjust the DC voltage. The present invention further discloses an apparatus for implementing the method. With the present invention, DC voltage oscillation of a system, which is caused when a DC voltage primary control station stops running, may be reduced:


Patent
NR Electrical Co. and NR Engineering Co. | Date: 2016-03-16

Embodiments of the present invention disclose a packet synchronization method and system of an intelligent substation process layer network, wherein the method includes: recording transmission delay on a network transmission device in a sampled value (SV) packet sent by a merging unit; and implementing, by a SV data receiving device, packet synchronization according to the transmission delay on the network transmission device recorded in the SV packet, so as to achieve that the SV data receiving device synchronizes received packets of different merging units, and accordingly ensure that the SV data receiving device can correctly perform data calculation and actions. Such a method can solve the problem that the current process layer network relies too much on a time synchronization network.

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