CN104505852A - Isolated island operating device for ultrahigh-voltage direct-current transmission line - Google Patents

Abstract

The present invention relates to the field of power transmission technology, in particular to an island operation device for UHV DC transmission lines, including a special device for switching station islands and a special device for factory building islands, and the special device for switching station islands and the special device for factory building islands are respectively equipped with PLCs The special device for the isolated island of the switching station is connected to the converter station, and the special device for the isolated island of the switching station is connected to the special device for the isolated island of the plant through an interactive signal; the special device for the isolated island of the plant is connected to the governor control cabinet. The invention provides a corresponding island operation device arranged on the side of the power station to cooperate with the island operation, which can quickly cut off the machine when the DC bipolar is blocked in the island operation mode, and quickly eliminate the imbalance between the output power of the generator set and the transmission power of the DC system.

Description

An island operation device for UHV DC transmission lines

technical field

The invention relates to the technical field of power transmission, in particular to an island operation device for an UHV direct current transmission line.

Background technique

UHV DC transmission lines, in addition to networked operation, are also designed to operate in an island mode. In order to avoid power transfer when Chusui DC fails, reduce the impact on the AC grid, simplify the configuration of Chusui DC stability system and improve cloud power transmission capacity , the planning and design of the power grid grid has determined that the relatively independent island operation mode at the sending end will be a normal operation mode during Chusui DC operation. In the island operation mode, the frequency and voltage control strategy of the power station side as the sending end is quite different from that in the network operation mode, and the corresponding system parameters such as speed regulation and excitation should be switched.

When the DC transmission system is converted to the island operation mode, it is different from the network operation mode. In the island operation mode, the frequency and voltage of the sending end cannot be adjusted jointly by the units in the grid, but can only be adjusted by the unit itself and DC frequency control. Under normal circumstances, since the power plant is far away from the converter station, the sending-end power grid is very weak under the DC island operation mode, and the effective short-circuit ratio is very low. The failure of the AC-DC system in the island system may cause the instability of the sending-end system; DC bipolar The overvoltage problem is also very prominent in the case of blocking, threatening the safety of the main equipment of the converter station and the power station, and the imbalance between the output power of the generator set and the transmission power of the DC system is prone to occur.

Contents of the invention

(1) Technical problems to be solved

The object of the present invention is to provide a DC islanding operation device capable of stable and safe operation of UHV DC transmission lines.

(2) Technical solution

The present invention is achieved through the following technical solutions:

An island operation device for UHV DC transmission lines, the island operation device includes a switch station island special device and a factory building island special device, and the switch station island special device and the factory building island special device are respectively equipped with a PLC; the switch The special device for the station island is connected to the converter station, and the special device for the switch station island is connected to the special device for the plant island through an interactive signal; the special device for the plant island is connected to the governor control cabinet.

Among them, optical fiber is used to transmit signals between the special device for the isolated island of the switch station and the special device for the isolated island of the factory building. By using optical fiber to transmit signals, it has good speed and reliability in long-distance signal processing.

Further, two-way communication monitoring devices are provided at both ends of the optical fiber used for signal transmission. Through the two-way communication monitoring device, the failure of the contact can be found in time, so as to ensure the stable operation of the island operation device and avoid potential hidden dangers.

Furthermore, both the switch station island dedicated device and the plant island dedicated device adopt two sets of PLC dual redundant configuration to reduce the failure time of the island dedicated device.

Wherein, the special device for the island of the switching station is connected to the stability control device through the island mode signal, the network mode signal and the DC outage signal, so that the island operation device can accurately determine the DC operation mode and operation state.

Preferably, the DC outage signal is output using a 3S pulse signal to ensure the distance and accuracy of signal transmission.

Further, a manual control circuit is provided on the special device for the island of the factory building. It facilitates the inspection and maintenance of the automatic circuit of the special island device, and ensures that the special device for the island can still function in the extreme case of failure of the automatic circuit.

Wherein, the manual control loop includes a manual switching grid/islanding loop and a manual DC outage loop.

Further, a manual/automatic handle, a manual networking pressing plate and a manual islanding pressing plate are provided on the manual networking/islanding circuit; when the manual/automatic handle is switched to the manual position, the automatic networking/islanding mode is blocked, Ensure the normal operation and easy operation of manual network and island mode.

Further, the manual DC outage circuit is provided with a manual DC outage unlock button, a manual DC outage button and a manual DC outage pressing plate; press the manual DC outage unlock button and the manual DC outage button at the same time, and manually The manual DC shutdown signal can only be sent out under the premise that the DC shutdown pressure plate is put into use. This technical solution can not only facilitate the operation of the manual DC outage mode, but also avoid the occurrence of misoperation.

(3) Beneficial effects

Compared with prior art and product, the present invention has following advantage:

The invention provides a corresponding island operation device on the side of the power station to match the island operation mode, which can quickly cut off the machine when the DC bipolar is blocked in the island operation mode, and quickly eliminate the imbalance between the output power of the generator set and the transmission power of the DC system.

Description of drawings

Fig. 1 is the internal configuration and connection structure diagram of the island operation device of the present invention;

Fig. 2 is a schematic diagram of signal transmission between the stability control device and the island operation device of the present invention;

Fig. 3 is a schematic diagram of the manual switching network/island circuit of the present invention;

Fig. 4 is a schematic diagram of the manual DC outage circuit of the present invention.

Markings in the figure: 1-manual/automatic handle; 2-manual switching network pressure plate; 3-powering network repeater; 4-power island repeater; 5-manual power island pressure plate; 6-manual DC outage unlock button; 7-Manual DC outage button; 8-Manual DC outage pressure plate; 9-Manual DC outage repeater.

Detailed ways

In order to make it easier for those skilled in the art to understand and implement the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, this embodiment provides an island operation device for UHV DC transmission lines, including a switch station island dedicated device and a plant island dedicated device connected to each other, the switch station island dedicated device and the plant island dedicated device A programmable logic controller (ProgrammableLogic Controller, PLC) is provided respectively; the switch station island special device is connected to the converter station, and the switch station island special device is connected to the plant island special device through an interactive signal; the plant island special device is connected to the The governor control cabinet is connected. The transmission grid is equipped with an island operation device, which regulates the governor electrical cabinet in the actuator, and cooperates with the island discrimination device in the converter station, the extreme control device of the converter station and the stability control device. , through PLC control, when DC bipolar is blocked, it can quickly switch between networking and islanding operation mode conversion, quickly eliminate the imbalance between the output power of the generator set and the transmission power of the DC system, and ensure the stable and safe operation of the DC island transmission line.

Among them, optical fiber is used to transmit signals between the special device for the isolated island of the switch station and the special device for the isolated island of the factory building. Although the traditional relay electrical interface method is simple and easy to implement. However, since the straight-line distance between the special device for the island of the switch station and the special device for the island of the factory building is generally about 1,000 meters, the optical fiber interface is better in terms of speed and reliability than the electrical interface for long-distance signal processing, so the optical fiber interface is used between the devices . The optical fiber interface has the following functions:

(1) Rapidity. In the optical fiber interface mode, the speed of signal transmission is greatly improved compared with the traditional relay electrical interface mode. The time for signal transmission in the optical fiber is almost negligible, and the speed of signal exchange is determined by the program execution cycle in the devices at both ends of the optical fiber. It was decided that the island-specific device of the power station should be processed in PLC mode. Due to the influence of the PLC's own scan cycle and the signal processing mechanism between PLCs, the actual time is within 300-500ms. The improvement of signal transmission speed ensures that the actuator can respond to commands faster, and can ensure the stable operation of the main equipment to the greatest extent in case of emergency.

(2) Reliability. Using the optical fiber interface, the signal exchange is completed by the transmission of optical signals, and will not be affected by external electromagnetic interference to cause signal errors. Compared with the traditional relay electrical interface, the anti-interference ability is greatly improved. Moreover, the optical fiber communication protocol has the function of real-time verification of the signal, which can verify the correctness of the data received in each frame while receiving the signal, and eliminate the identified erroneous data to ensure the correctness of the transmitted signal It can effectively prevent the misoperation of the actuator caused by receiving the wrong signal.

Further, two-way communication monitoring devices are installed at both ends of the optical fiber used for signal transmission between the special device for the island of the switchyard and the special device for the island of the factory building. The traditional relay electrical interface method has the possibility of relay contact failure during the operation of the equipment. Since the contact circuit of the relay cannot be effectively monitored, once a contact failure cannot be found in time, it can only be detected when the command signal cannot be executed correctly. It is found that this will bring potential hidden dangers to the stable operation of the system. If the optical fiber interface is used, the two-way communication monitoring devices installed at both ends of the optical fiber can monitor the two-way communication status of the optical fiber at the same time. Once there is a communication problem, the operation and maintenance personnel can be notified in time through the fault alarm of the power station monitoring system, and the fault can be handled in time.

Among them, the switch station island special device and the factory building island special device adopt two sets of PLC dual redundancy configuration, and the hot standby optical fiber is preferably used between the two PLCs of each island special device to realize hot standby redundancy, reducing the failure time of the device .

As shown in Fig. 2, two sets of stability control devices provided in the converter station, including a stability control device A and a stability control device B, are signal-connected to the island-specific device of the switching station respectively. The operation mode and status of the UHVDC transmission system are mainly judged by the island discrimination device, which collects information on the line flow and the position of the circuit breaker in the converter station, and integrates the information from the transmission power station and the receiving station device to determine the DC operation mode and operation status. The status is sent to the extreme control device and the stability control device of the converter station in the form of a switch, and the stability control device forwards the signal to the island operation device. Among them, the switch station island special device is connected to the stability control device in the converter station through the island mode signal, the network mode signal and the DC outage signal.

For the island mode signal and networking mode signal, when the switch station island special device receives the modes of the two sets of safety control devices are valid and consistent, then use this mode; If the mode is valid and the other is invalid, the valid mode will be used; when the special device for the island of the switch station receives the modes of the two sets of safety control devices that are valid but inconsistent, or the modes of the two sets of safety control devices are invalid, an alarm will be sent The signal does not require manual confirmation.

For the DC outage signal, each set of power station stability control device outputs a "DC outage" contact output, using a single-position contact output. Single-position contact output is adopted, and the preferred output adopts 3S pulse signal. The DC outage signal of any set of stabilizing devices is considered valid when the special device for the island of the switchyard receives the DC outage signal.

As shown in Figure 3 and Figure 4, in order to facilitate the power station side to cooperate with the island commissioning test, facilitate the maintenance of the automatic circuit of the island special device, and ensure that the island special device can still function in the extreme case of automatic circuit failure, the power station island dedicated The device is also designed with a manual circuit consisting of a pure relay circuit, which is located in a special device for the isolated island of the plant. There is a manual control circuit on the special device for the isolated island of the factory building. Further, the manual control loop includes a manual grid-connection/islanding loop and a manual DC outage loop. Specifically as shown in Figure 3, there are manual/automatic handle 1, manual networking pressing plate 2, manual islanding pressing plate 5, networking repeater 3 and islanding repeater 4 on the manual networking/islanding loop; When the manual/automatic handle 1 is switched to the manual position, the operation mode of automatic network connection/island connection is blocked at the same time, and the operation mode of network connection/island connection can be manually controlled by pressing the pressure plate 2 of manual network connection and the pressure plate 5 of manual island connection .

Among them, as specifically shown in Figure 4, the manual DC outage circuit is provided with a manual DC outage unlock button 6, a manual DC outage button 7, a manual DC outage pressing plate 8, and a manual DC outage repeater 9 connected in series; In order to prevent misoperation, the manual DC outage signal can be sent only when the manual DC outage unlock button 6 and the manual DC outage button 7 are pressed simultaneously, and the manual DC outage pressing plate 8 is put into operation.

The island operation device can be connected with the power station monitoring system. When switching from networking to island mode or switching from island to networking mode occurs, the power station monitoring system will automatically exit the power station from the automatic generation control (AGC) mode, so that the normal voltage regulation coefficient of the automatic voltage control (AVC) on the power station side will automatically switch, and can manually exit the power system stabilization (PSS) mode; in the island operation mode, when the DC outage signal occurs, the power station will automatically exit the AGC mode. The time after the special device for the isolated island of the switch station receives the signal and the time when the special device for the isolated island of the powerhouse sends the signal are automatically recorded to the monitoring system of the power station, which is convenient for accident recall. When switching from network to island mode or from island to network mode, the AGC function control of power station dispatching will be automatically exited, the normal voltage regulation coefficient of AVC at the power station side will be automatically switched, and the PSS function will be manually exited. In the isolated island operation mode, the dispatching AGC function of Xiaowan station will be automatically exited when the DC outage signal occurs.

The above example is only one implementation of the present invention, and its description is more specific and detailed, but it should not be construed as limiting the patent scope of the present invention. Its specific structure and size can be adjusted accordingly according to actual needs. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims (10)

1. the islet operation device of an extra high voltage direct current transmission line, it is characterized in that, described islet operation device comprises switchyard isolated island special purpose device and factory building isolated island special purpose device, is respectively equipped with PLC in described switchyard isolated island special purpose device and factory building isolated island special purpose device; Described switchyard isolated island special purpose device is connected with current conversion station, and is connected by interactive signal between this switchyard isolated island special purpose device with factory building isolated island special purpose device; Described factory building isolated island special purpose device is connected with speed regulator control cubicle.

2. the islet operation device of extra high voltage direct current transmission line according to claim 1, is characterized in that, adopts optical fiber transmission signal between this switchyard isolated island special purpose device and factory building isolated island special purpose device.

3. the islet operation device of extra high voltage direct current transmission line according to claim 2, is characterized in that, the two ends for the optical fiber of signal transmission are provided with two-way communication supervising device.

4. the islet operation device of extra high voltage direct current transmission line according to claim 1, is characterized in that, switchyard isolated island special purpose device and factory building isolated island special purpose device all adopt two cover PLC dual redundant configuration.

5. the islet operation device of extra high voltage direct current transmission line according to claim 1, is characterized in that, described switchyard isolated island special purpose device is connected with stable control device with direct current stoppage in transit signal by isolated island mode signal, networking mode signal.

6. the islet operation device of extra high voltage direct current transmission line according to claim 5, is characterized in that, described direct current stoppage in transit signal adopts 3S output of pulse signal.

7. the islet operation device of the extra high voltage direct current transmission line according to any one of claim 1 ~ 6, is characterized in that, described factory building isolated island special purpose device is provided with Non-follow control loop.

8. the islet operation device of extra high voltage direct current transmission line according to claim 7, is characterized in that, described Non-follow control loop comprises manually throws networking/isolated island loop and manual direct current stoppage in transit loop.

9. the islet operation device of extra high voltage direct current transmission line according to claim 8, is characterized in that, described manual throwing networking/isolated island loop is provided with manual/auto handle, manually throws networking pressing plate and manual throwing isolated island pressing plate; When described manual/auto handle switches to manual position, the island mode and locking automatic switching is networked/thrown.

10. the islet operation device of extra high voltage direct current transmission line according to claim 8, is characterized in that, described manual direct current stoppage in transit loop is provided with manual direct current stoppage in transit unlock button, manual direct current stoppage in transit button and manual direct current stoppage in transit pressing plate; Press manual direct current stoppage in transit unlock button and manual direct current stoppage in transit button at the same time, and under the prerequisite of manual direct current stoppage in transit pressing plate input, manual direct current stoppage in transit signal just can be sent.