JP2945099B2 - Digital protection controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a digital protection control device for a power system.

(Prior Art) Sampling signals for generating digital data of a digital protection controller of a power system are individually generated according to the purpose of use of each digital protection controller for independence and reliability of the device. Is formed.
For this reason, the following three methods have been conventionally used to obtain the required data.

In this method, all the electric quantities required for a device are input by the own station, and digital data is created based on a sampling signal of the device.

FIG. 5 shows an example. In FIG. 5, 1 is a bus,
2 is a transmission line, 3 is a circuit breaker, 4 is a current transformer (CT), 5 is an electric transformer for bus (B / PD), 6 is a voltage transformer for line (L / PD), and 7 is an electric transformer. The digital protection control device of the other station, and 8 is the digital protection control device of its own station. Since the device 8 of the own station is a digital protection control device that requires the bus voltage data of the other station, the device 8 takes direct analog electric quantity from the bus voltage transformer (B / PD) 5 and converts it into digital data at the own station. How to convert.

When fetching data digitized by a sampling signal of a signal source of another station which is not synchronized with the sampling signal of the own station, the digital data and the sampling timing of the data are transferred, and the sampling timing of the own station is compared. This is a method of obtaining a shift and regenerating data based on the sampling timing of the own station.

FIG. 6 shows a schematic configuration thereof. The components 1 to 8 are the same as in FIG. However, the digital protection control device 7 of the other station is provided with a timing processing section 75 for transmitting bus voltage data in accordance with the sampling timing of its own sampling signal source 73. In addition, a sampling timing extracting unit 85a of another station is added to the own station.

When data digitized by a sampling signal of a signal source of another station is required, the sampling timing of the own station is adjusted to the timing of another station.

In this case, the sampling signal of the own station is synchronized with the sampling signal of another system.

(Problems to be Solved by the Invention) There is a disadvantage that the hardware scale for digitization becomes large, and there is a disadvantage that it becomes complicated to accurately detect the sampling timing shift, and the device is simple. Although possible, there is a disadvantage that the independence of the device cannot be maintained and the reliability is reduced.

Accordingly, it is an object of the present invention to provide a digital protection control device that does not increase the hardware scale and accurately determines the sampling timing difference between the own and other stations.

[Configuration of the invention]

(Means for Solving the Problems) In the present invention, when data digitized by sampling signals from different signal generation sources is required, the connection state of the power system among the data of the other station and the own station becomes the same. The quantity of electricity is obtained, the difference between the sampling synchronizations of the two stations is obtained from this data, and the processing is performed using the data and the difference between the other stations.

FIG. 1 shows the configuration of the present invention. Reference numeral 7 denotes another digital protection control device in an electric power plant, and reference numeral 8 denotes a digital protection control device which requires data of the digital protection control device 7 of another station in its own station. The figure shows an example in which data of the bus voltage transformer (B · PD) 5 is required. Other station signal source 73
Is asynchronous with the sampling signal SP1 of the signal source 83 of the own station. Reference numeral 87 denotes a system link condition, for example, a pallet switch condition indicating a closed state of the circuit breaker. Own station data 82, other station data and system conditions
The following processing is performed by the arithmetic processing unit 86 from 87. That is, if the circuit breaker is turned on on the system side, the bus voltage and the line voltage are equal, and the received other station is digitized (B
Using the fact that the data of (PD) 5 and the data of (L · PD) 6 digitized by the sampling signal of the own station are equal, the sampling time of the data of the other station with reference to the sampling signal of the own station is used. The difference (corresponding to the phase difference) is obtained by the phase difference calculation means 88, and the protection control calculation processing is performed based on the difference.

(Operation) FIGS. 2 (a) and 2 (b) show a process for obtaining the sampling time difference between the data of the own station and the data of the other station. For simplicity, set sampling interval to 1/12 of 1 cycle at fundamental frequency
(30 degree intervals). FIG. 2A shows the exchange of data between the two stations. In the figure, if the circuit breaker is turned on, the bus voltage (VB) is equal to the line electricity (VL). In the digital protection control device 7 of the other station, the VB is digitized in accordance with the sampling signal SPc of the device, and transmitted to the digital protection control device 8 of the own station. The own station receives the transmission delay time Td as VB and assigns a number in the order of arrival. The own station digitizes VL in accordance with its own sampling signal SP1 and similarly numbers the VL. Then, the phase difference between VB and VL is obtained using the data of the same number of VB and VL. FIG. 2 (b) shows an example in which data obtained by using the data separated by 90 degrees is obtained by the following equation.

Is obtained as

Here, m: indicates a time series (sampling value every 30 degrees) (Example) FIG. 3 shows the configuration of the example. 1 is a bus, 2 is a transmission line, 3 is a circuit breaker, 4 is a current transformer (CT), 5 is a bus voltage transformer (B / PD), and 6 is a line voltage transformer (LP).
D), 7 are other digital protection and control devices in the substation, 8
Is a digital protection control device that requires data from seven other stations in its own station, and is a device that performs protection by exchanging data with the opposite terminal of the transmission line. 9 is the transmission device. The digital protection control device 7 of the other station is (B · PD)
Input transformer 71 that takes in voltage input from 5, signal source
It comprises an analog-to-digital converter 72 for digitizing according to a sampling signal SPc of 73 and a transmitting section 74 for transmitting digital data. The digital protection control device 8 of the own station includes an input transformer 81 for receiving inputs from the CT 4 and the (L · PD) 66, an analog / digital converter 82 for digitizing according to the sampling signal SP1 of the signal source 83, and an opposite terminal. Transmission unit 8 for exchanging data
4, a receiving unit 85 that receives and processes data from another station 7,
It is composed of an arithmetic unit 86. 3a shows a pallet switch condition indicating the closed state of the circuit breaker.
Has been given to.

FIG. 4 shows the operation of the embodiment. S1 indicates pre-processing, which performs reception processing such as creation of own station data and checking and numbering of other station data, and S2 selects the same amount of electricity as a system to select three or representative phases of the power system. select. In S3, it is determined whether or not the amounts of electricity selected by the determination unit for determining whether or not the systems are linked indicate the same value. S4 is a case where the link condition is satisfied. At this time, the phase difference (θ) is calculated from the own station data and the other station data of the same electric quantity. S5 is a case where the link condition is not satisfied, and the value of θ at the time when the link condition is satisfied is held at the previous value and used for the arithmetic processing. S6 is a processing routine for performing arithmetic processing using θ and transmitting other station data and θ. Taking the case of the transmission line protection device as an example, it is as follows.

In the case of a transmission line protection device in which the bus voltage used for the synchronous reclosing after the interruption of the transmission line is digitized by another device, the sampling signal between the transmission line protection devices is synchronized. , The voltage data between the opposite buses is not synchronized. Therefore, the phase difference (θ) between the data of the other station (data of (B · PD) 5) and the data of the own station in a state linked before the accident is obtained, and the data of the other station ((B · PD) 5
) Is always transmitted to the opposite terminal. After the accident is shut off, the synchronous reclosing circuit performs the synchronization determination in consideration of the phase difference.

As described above, when the bus voltage data is asynchronous with the sampling signal between the power transmission protection devices, the bus voltage itself is input to the power transmission line protection device, and no additional hardware is required. It is not necessary to determine the deviation from the sampling timing of the local station and re-create data based on the sampling timing of the own station, and the deviation (θ) of the bus voltage data from the own station data can be obtained from the prior state of the system. .

In the above-described embodiment, the link condition of the system has been described using the pallet switch of the circuit breaker. However, any means may be used as long as it can be identified as the same electric quantity.

〔The invention's effect〕

Therefore, according to the present invention, when the local station needs data digitized by a different sampling signal of another station in the power system protection control device, the local station and the other station are switched from the power system connection state. Since the phase difference of the quantity of electricity that can be determined as common data is obtained, a digital protection control device that can use the data created by different sampling signals of other stations as it is can be obtained by using the phase difference.

[Brief description of the drawings]

FIG. 1 is a block diagram of the digital protection control device of the present invention, FIG. 2 is a data configuration diagram showing sampling timing of the present invention, FIG. 3 is a diagram showing an embodiment of the present invention, and FIG. FIG. 5, FIG. 5 and FIG.
FIG. 1 is a configuration diagram of a conventional digital protection control device. DESCRIPTION OF SYMBOLS 1 ... Bus 2 ... Transmission line 3 ... Circuit breaker 4 ... Current transformer (CT) 5 ... Bus voltage transformer (B / PD) 6 ... Line voltage transformer (L / PD) 7,8 ... Digital protection controller 73,83 ... Signal source, 86 ... Processor 88 ... Phase difference calculation means

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02H 3/00 H02H 3/02

Claims (1)

(57) [Claims] 1. A digital protection control device for converting an electric quantity of an electric power system into digital data in accordance with a sampling signal from a signal source different from that of another station and performing digital processing. Input means for capturing digital data detected by another station that can be determined to be the same and processed according to a predetermined sampling signal and digital data obtained from the sampling signal of the own station;
If the power system to which the own station and the other station are connected is linked, the phase difference is obtained based on the digital data of the own station and the other station, and if not linked, the phase difference at the previous link is output. And correcting the digital data of the own station using the phase difference obtained by the phase difference calculating means, and transmitting the phase difference and the digital data of the other station to the opposite station. Digital protection control device characterized.