JP2689506B2 - Sampling synchronization method for digital protection relay - Google Patents

Description

The present invention relates to a sampling synchronization method of a digital protection relay device for protecting a loop transmission system.

B. Summary of the Invention The present invention provides a central relay device arranged along a loop power transmission system and coupled by a double loop line, and a digital protection relay device for obtaining sampling data at each terminal device. By determining the sampling timing of each terminal device from the reception timing of the sampling synchronization timing signal through the two systems, sampling synchronization in the central relay device and each terminal device,
That is, the same time sampling can be performed.

C. Conventional technology Fig. 3 shows the system configuration of the loop digital protection relay device that controls the protection of the loop power transmission line.

In the figure, substation J and the busbars of _four consumers D _{1 to} D ₄
31 is connected by a power transmission line 32 in a loop, and each customer D _{1 to} D ₄
Inside, a current transformer 34 provided at the end of the power transmission line 32, and a terminal device for inputting analog data from the current transformer 34, converting it into an optical signal, and transmitting / receiving a signal to / from an adjacent customer. 35 and the bus 31
And a circuit breaker 36 for cutting off the power from the system.

Further, in the substation J, the central communication device 37 having the same function as the terminal device 35, the function of converting an optical signal into digital data and the analysis processing of the data, and further, when the analysis result is abnormal A central relay device 38 including a microcomputer or the like for outputting a disconnection command of a circuit breaker 36 to a terminal device 35 in each customer through a central communication device 37.
And a current transformer 34 for directly inputting an analog signal to the central relay device 38.

Further, each terminal device 35, the central communication device 37 and the central relay device 38 are connected by an optical fiber cable 39, and the optical fiber cable 39 outputs an optical signal output from the terminal device 35 in each customer and the central relay device 38. It becomes the path of the optical signal as a cutoff command output from the.

In the loop-type digital protective relay having such a system configuration, the analog data collection (hereinafter referred to as sampling) of the terminal device 35 in each customer and the data transmission to the central relay device 38 are performed by the central relay device. It is performed by the sampling signal output from.

As this sampling signal, an optical signal output at a certain frequency in consideration of the data transmission rate in the system and the memory capacity and processing speed of the microcomputer in the central relay device is used, and via the above-mentioned optical fiber cable 39. Is transmitted to the terminal device of each consumer.

However, since a transmission delay occurs while this sampling signal is transmitted through the optical fiber cable or each terminal device 35, the sampling of each terminal device 35 and the central relay device 38 is not performed at the same time, and the central relay device is not sampled. The terminal device farther from 38 (D _{4 in} this case) has a larger sampling delay. Furthermore, a part of the optical fiber cable is missing,
When the optical signal is loop-back transmitted, the optical transmission path becomes longer and the sampling delay may be doubled as compared with the normal time.

Therefore, the sampling synchronization method of the conventional loop protection relay device adopts the transmission delay fixed compensation method in consideration of the above-mentioned transmission delay.

That is, as shown in the time chart of FIG. 4, the central relay device 38 transmits a sampling signal to the central communication device 37 T time ago based on the sampling time t ₂ of the device itself. This sampling signal consists of a flag (F) and a sampling synchronization signal (S), and is sequentially transmitted from the central communication device 37 to each customer as a timing command FS for synchronization.

The timing command signal transmitted from the central communication device 37 is sent to the terminal device of the customer D _{1 at} the subsequent stage and further to the customer D ₁
Are sequentially transmitted to the customer D ₂ with a transmission delay.
Upon arrival of the timing command FS, each terminal device sequentially performs sampling at times t ₁ , t ₃ , and t ₄ , respectively.

As described above, in the conventional method, the central relay device 38 transmits the sampling signal to each terminal device in advance T time in advance in consideration of the transmission delay to each terminal device 35, so that the central relay device sampling and the time t ₂ as a reference, all terminals in the sampling allowable limit time T 'in it can be set so as to complete the sampling.

The allowable time limit T'is determined by the accident determination accuracy of the protective relay device and is usually a value of several degrees in terms of AC electrical angle.

D. Problems to be Solved by the Invention In the conventional fixed transmission delay compensation method, although the terminal device of each customer is set to complete sampling within a predetermined time, the transmission delay is removed in principle. It doesn't mean that.

Therefore, even if the power transmission system is normal, a time error occurs in the obtained sampling data, and the accuracy of the accident determination deteriorates.

Further, under the condition that the sampling signal is looped back and transmitted due to a defect of the optical fiber cable or the like when the power transmission system is long, the transmission delay becomes extremely large. In this case, the allowable time limit T'has to be made large, which causes a problem that the accident determination accuracy deteriorates in the entire protective relay device.

The present invention has been made in view of the above points, and an object of the present invention is to enable data sampling in a central relay device and each customer terminal device to be performed at the same time, and to provide a digital protection relay device as a whole. It aims to provide a sampling synchronization method with high accident determination accuracy.

E. Means for Solving the Problem In order to achieve the above-mentioned object, the present invention has two systems, that is, a system 1 and a system 2 in which the transmission directions are opposite to each other along the loop transmission system and the transmission delay times are the same. In a digital protective relay device in which multiple terminal devices are connected by a heavy loop line and the central relay device and terminal devices obtain the sampling data of the power transmission system and perform the protection calculation, from the central communication device connected to the central relay device. A signal is transmitted to each loop at a transmission timing for sampling synchronization, and the transmitted signal makes a round through each terminal device connected to the loop lines of the 1-system and 2-system and reaches each central communication device. The right-handed delay time T ₁ and the left-handed delay time T ₂ required to obtain are calculated, and when the delay time is T ₁ = T ₂ , only (T ₁ + T ₂ ) / 4 time and loopback transmission is performed.
T ₁ ≠ T ₂ times T _1/2, T _2/2 times by each 1 system at a timing adjusted to the time prior to be timing synchronized with the timing for each sampling synchronization from the central communication device 2 based loop line A signal is transmitted, and each terminal device sets an intermediate time between the sampling synchronization timing signal received through the 1-system loop line and the sampling synchronization timing received through the 2-system loop line as the sampling timing. As a result, even if the reception delay of the terminal device with respect to the central relay device changes depending on its position, synchronization is obtained by the intermediate time of the reception timings of the timing signals that pass through the reverse loops of the 1st system and the 2nd system.

F. Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention.
The terminal apparatus 35 ₁ to 35 ₄ from the central communication unit 37, the loop line R ₂ in 1 system with loop lines R ₁ in (clockwise), 2 system (counterclockwise)
The information transmission lines are connected by. The coupling by the double loop transmission line can eliminate the communication failure by returning to the disconnection at one place of the transmission line or the like. There are various methods for determining the presence / absence of loopback transmission. One of them is, when a failure occurs in a loop line or the like, the terminal device in the vicinity of the failure detects an error and shifts to the loopback operation, and an error occurs in the transmission signal frame. The generated information is added to the data and sent to the central communication device. By recognizing this signal, the central communication device identifies that it is in the return state.

In this configuration, the central communication device 37 includes a processing device 1 for data collection and communication control, and a transmission / reception means, and also a timing setting unit 2 and a delay setting circuit for setting a transmission timing for sampling synchronization. Department (DE
Using the loop line R ₁ has a L) and transmits the terminal apparatus 35 ₁ to 35 ₄ in the timing signal for sampling synchronization periodically.

The central communication unit 37, a timer 3 for counting the time T ₁ of the sampling synchronization timing signal until reception by round terminal apparatus 35 ₁ to 35 ₄ through the loop line R _1,
Counting the time T ₂ of the time to cycle through the terminal device 35 ₁ to 35 ₄ through the loop line R ₂ reversed and a timer 4.

These timers 3 and 4 are clocked in such a manner that the signals transmitted from the central communication device 37 are loop lines R ₁ and R ₁
But is intended for measuring the time T _1, T ₂ to come to round _2, around the right when the transmission line R _1, R ₂ becomes folded state,
In order to be able to measure the counterclockwise T ₁ and T ₂ , the timer 4 starts the timing at the transmission timing of R ₁ , and the timing is ended by the reception from R ₂ . Similarly, the timer 3 also starts timing of the timer 3 at the transmission timing of R ₂ and ends the timing when receiving from R ₁ .

The time T ₁ and T ₂ are timed in such a manner that the transmission lines R ₁ and R ₂ are provided in the same pipe so that their transmission delay times are the same, and that the timing signals for sampling synchronization of the 1-system and 2-system are This is possible because the calls are sent at the same timing.

That is, in the state where the return transmission is not performed, the transmission timings are controlled so that they are at the same time, so the timers 3 and 4 start timing at the same time, and the timer 3 equivalently transmits T ₁ to R ₁ . Delay, timer 4 can measure T ₂ as transmission delay of R ₂ .

Terminal device 35 ₁ to 35 _4, as representatively shown in the terminal apparatus 35 _1, provided with a 14 and 15 for sampling synchronization system 1 and 2
The timing information transmitted by the central communication device is obtained from the receivers 11 ₁ and 11 _{2 of the} system, the sampling synchronization timing is extracted by the processing device 12, the time difference is measured by the timer 15, and the processing device 12 performs T ₃ by software processing. / 2 is obtained and this is set in the subordinate synchronization unit 14.

Slave synchronization unit 14 of the terminal apparatus 35 ₁ to 35 _4, the central communication unit 37
Upon receiving the timing information by the receiving unit 11 ₁ or 11 ₂ from the difference in reception timing clocked by the timer 15, the processing unit 12 at the timing of T _3/2 to set the local end inside the sampling signal Take a subordinate synchronization that forcibly adjusts the timing.

That is, the timer 15 can measure the time difference between the sampling timings from the receiving unit 11 ₁ and the receiving unit 11 ₂ at either timing, and the receiving unit 11 ₁ (or 1
1 ₂ ) to start timing with the sampling synchronization timing signal from the central communication device 37, and the receiving unit 11 ₂ (or 11 ₁ )
The timing is terminated by the timing signal for sampling synchronization from the central communication device 37 through, and the timing for sampling is obtained with a 1/2 hour delay from the earlier received timing on the R ₁ or R ₂ side.

Further, since the return terminal cannot measure T ₃ , the timing point extracted from the receiving sections 11 ₁ and 11 ₂ is the timing to be sampled.

In the sampling synchronization with the configuration described above, the central communication device 37 sends the sampling synchronization timing signal to the loop lines R ₁ and R ₂ as a delay timing signal, respectively, and outputs the time T ₁ and T ₂ until one cycle. Timed to timers 3 and 4, loop line
R _1, obtain the transmission delay time T _1, T ₂ at R _2.

Based on the transmission delay times T ₁ and T ₂ , the central communication device 37
Adjusts the transmission timing of the sampling synchronization timing signal to the loop line. Terminal device 35 ₁ to 35 ₄ which has received the timing signal is 1/2 of the reception differential time between both the timing signals at each timer 15 (intermediate time) to the sampling timing.

The sampling timing of the central communication device 37 is
It is a time delayed by a predetermined time from the transmission timing. Predetermined time when the T ₁ = T ₂ and _{(T 1 + T 2) /} 4, and _{T 1/2, T 2/} 2 if T ₁ ≠ T _2, delayed from the respective transmission timings.

Such sampling synchronization becomes the time chart shown in FIG. Fig (A), the loop line shows the sampling synchronization time chart for normal normal, the transmission from the loop lines R ₁ terminal apparatus 35 ₁ is received at time t _1, it is received from the loop line R ₂ when carried out in time t _2, the terminal apparatus 35 ₁ obtains a sampling timing that matches the timing of the time T ₃ to ½ of the time delay. Note that T ₀ indicates the sampling cycle.

Further, loop lines R _1, R ₂ is provided in the central communication unit 37 and each of the terminal devices 35 ₁ to 35 ₄ same pipe to be laid, even the same transmission delay time becomes the transmission distance is the same, Furthermore, since the circuit delays in each terminal device are the same,
The transmission delay times in both loop lines R ₁ and R ₂ are equal, and in FIG. 2, it is an isosceles triangle whose bases are times T ₁ and T ₂ .

Such timing is sampling timing at the same time regardless of the position of the terminal device.

FIG. 2 (B) shows a case of loopback communication due to disconnection in the loop line. For example, when the loop line R _1, R ₂ between the terminal device 35 ₃ and 35 ₄ is disconnected, sending from the central communication unit 37 in the loop line R ₁ to the terminal device 35 ₁ → 35 ₂ → 35 _3, the terminal device 35 _{The data} is returned at ₃ and transmitted through the loop line R ₂ to 35 ₂ → 35 ₁ → the central communication device 37, and the terminal device 35 ₄ is directly transmitted and received from the central communication device 37 by the loop lines R ₂ and R ₁ .

In this line state, by adjusting the transmission timing of each sampling synchronization timing signal from the central communication device 37 from the line state and the times T ₁ and T ₂ , the terminal device 35 ₁
35 ₄ can obtain the same simultaneous sampling and normal.

Simultaneous sampling does not synchronize at the sampling timing, but synchronizes at a low frequency such as a commercial frequency, synchronizes once between the central relay device and each terminal device, and then obtains the sampling frequency based on this synchronization. It may be a sampling synchronization method.

For example, the protective relay device synchronizes with the basic frequency of the target power system, 50 Hz, as a timing signal, and each terminal creates 600 Hz with reference to this 50 Hz and uses this as the sampling frequency.

G. Effect of the Invention As described above, according to the present invention, the
Since it is a synchronization method that obtains the sampling timing of each terminal device from the deviation of the reception timing of the sampling synchronization timing signal that passes through the two systems, the same time sampling can be performed regardless of the position of the terminal device, and the accuracy of accident determination is high. It has the effect of collecting data.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 (A) is a sampling synchronization time chart in a normal time in the embodiment, and FIG. 2 (B) is a time chart when a line is looped back in the embodiment. FIG. 3 is a configuration diagram of a protective relay device in a loop power transmission system, and FIG. 4 is a conventional sampling time chart. 35 ₁ , 35 ₄ ...... Terminal device, 37 ...... Central communication device, 2 ...... Timing signal generator, 3, 4 ...... Timer, 14 …… Dependent synchronization part, 15 …… Timer.

Claims (2)

(57) [Claims] 1. A plurality of terminal devices are coupled by a double loop line of a 1-system and a 2-system in which transmission directions are opposite to each other along a loop-shaped transmission system and the transmission delay times are the same, and a central relay is provided. In a digital protective relay device that obtains the transmission system sampling data at the device and terminal device and performs the protection calculation, a signal is sent from the central communication device connected to the central relay device to each loop at the transmission timing for sampling synchronization. , And the outgoing signal makes one round through each terminal device connected to the loop lines of the 1st and 2nd lines, and the clockwise delay time T ₁ and the counterclockwise delay required to reach the central communication device, respectively. time
When T ₂ is calculated and T ₁ = T ₂ , the delay time is (T ₁ + T ₂ ) / 4,
And from the central communication device 1 system and 2 system loop lines at T ₁ ≠ T ₂ times T _1/2, T ₂ / only 2 times timings respectively adjusted to a time earlier than the timing to be synchronized to be folded transmission Each of them outputs a sampling synchronization timing signal, and each terminal device samples an intermediate time between the sampling synchronization timing signal received through the 1-system loop line and the sampling synchronization timing received through the 2-system loop line. A method for sampling synchronization of a digital protective relay device, which is characterized in that the timing should be set. 2. The sampling synchronization method for a digital protective relay device according to claim 1, wherein the sampling synchronization timing signal is synchronized with a commercial frequency and the sampling frequency is obtained with reference to the synchronization.