JPS60183921A - Protective relay system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a protective relay system (hereinafter abbreviated as relay) for protecting an electric power system.

[Prior art]

A conventional system of this type is shown in FIG.

The figure shows a simulated power system diagram, where 1 is a
2 indicates the rear power supply at the end.

Reference numerals 3 and 4 indicate the busbars at the a and b ends, respectively, 5 the transformer that introduces voltage to the relay 6, and 7 the entire power transmission line.

Next, the operation will be explained. The following calculation is performed using the data whose electrical angle is 90° apart from each other after sampling all the voltages introduced from the transformer 5 to the relay 6 at a predetermined sampling frequency as each voltage v(t) and v(t-90°). Process.

v"(t)+v" (t -90°)...(1)
Now, if voltage v(tl =VSina+t), voltage v(t
-90°) is multiplied by Vsin (ωt -90°).

Substituting these into equation (1) above, we get "S""a)t +V"sin" (oct -g
□°)=V″5in2ωt+V”(-cosωt)2
= V” (5in2ωt +cos” (, +t)
= V', and the square value of the thickness of the voltage can be obtained. This square value is compared with a preset set value, and when it is smaller than the set value, the full electrical command is output.

Conventional protective relaying methods use only the voltage at the relay setpoint point for all calculation processing as described above, so when the fault point of the power/system , or when the background power supply is strong, the voltage at the relay installation point does not drop, resulting in disadvantages such as the sensitivity of the relay becomes extremely poor or it becomes inoperable.

[Summary of the invention]

This invention was developed in order to eliminate the drawbacks of the conventional ones as described above, and it corrects the voltage at the relay installation point using the 'α current at the relay installation point and the preset impedance of the transmission line. However, it is an object of the present invention to provide a protective relay system that accurately improves the sensitivity of a relay by performing predetermined arithmetic processing using the corrected voltage obtained as a result.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The entire drawings of an embodiment of the present invention will be described below. In Fig. 3, which shows a simulated power system diagram, 1 and 2 are the back power sources at the a end and b end, respectively, 3.4 are the bus bars at the a end and b end,
5.6 is the current to relay 8.

Shows current transformers and transformers that introduce voltage.

FIG. 6 is a block diagram showing the signal processing of the relay 8.
82 is a voltage calculation processing unit that calculates the total voltage of the opposite end; 82 is an average voltage processing unit that calculates the average voltage of the own end and the opposite end;
Reference numeral 83 denotes a minimum voltage calculation unit that calculates the total minimum voltage, and 84 represents a voltage change rate calculation unit.

Reference numeral 86 denotes a determination processing section composed of a minimum voltage calculation section 83 and a voltage change rate calculation section 84.

Next, the entire operation of the present invention will be explained with reference to the vector diagrams of FIGS. 4, 5, and 6. Now back power supply 1 and back power supply 2
When the phase difference angle becomes 90° due to step-out, a vector diagram as shown in FIG. 4 is obtained. However, the center point of step-out is between ends a and b.

FIG. 4 shows 1TJL pressure V+ r V! +Vx,
V4 k1 each hma Back power supply shown in the figure 1. Rear power supply 2. This is the voltage vector of bus 3.4. Current ■ is bus 3
The current flowing from to the bus bar 4, Zt, is a preset power transmission line impedance. If the transmission line is almost L, the current I is the voltage vI and the voltage ■, as shown in Figure 4.
is a right angle. As is clear from the figure, in order to determine the voltage of the bus 4 at the bus 3, it is recommended to calculate the relationship between the voltage 3, the power transmission impedance zt, and the current l. Further, the average voltage is calculated as (VJ + v4) x D = Vh, and a predetermined calculation is performed using the smallest voltage among the voltages v, , v, , and vh.

As shown in FIG. 4, when the center point of step-out is between the busbars 3 and 40, the average voltage vh becomes the minimum.

It is clear that if the magnitude of the average voltage vh is calculated and a command is issued when it is smaller than a set value, the sensitivity will be higher than when the voltage V or the voltage ■ is used. Next, the fifth
As shown in the vector diagram in the figure, when the center point of step-out is outside the b end, voltage 4 is the minimum, and high sensitivity can be obtained by using voltage v4.

FIG. 6 is a block diagram showing the signal processing of the relay 8. The voltage calculation processing unit 81 inputs the bus voltage V3 and the line current ■, and outputs the voltage (corrected voltage amount) as the voltage (V, -IZ7) at the other end. Calculate. The average voltage processing section 82 calculates all the average voltages of the own end and the opposite end.

The output voltage V4 and the bus voltage Vj are inputted, and the average value voltage vh is outputted. The minimum voltage calculation unit 83 calculates the voltage v
, , v4. A selection process is performed on the minimum voltage among vh. The voltage change rate calculation section 84 receives the input from the minimum voltage calculation section 83 and sends out the operating output of the relay by comparing it with a set value.

〔Effect of the invention〕

As described above, according to the present invention, the protection calculation is performed using the minimum voltage among the self-end voltage, the voltage at the farthest end of the protection interval, and the voltage at the intermediate point, so that a protection connection with high reliability and high sensitivity can be achieved. This has the advantage of being an electric method.

[Brief explanation of drawings]

Figure 1 is a simulated power system diagram, Figure 2 is the voltage distribution diagram of Figure 1, Figure 3 is a simulated power system diagram explaining the present invention, Figures 4 and 5. is a vector diagram of the present invention, and FIG. 6 is a configuration diagram showing signal processing of the relay. 1.2...Back power supply 3,4゛ A end, B end bus bar
5.6...Current transformer, transformer 8...Relay 81...
・Voltage calculation processing section 82... Average voltage processing section 83...
・Minimum N1 pressure calculation unit 84... Voltage change rate calculation unit 8
6... Judgment Processing Department Agent Masuo Oiwa Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Continued from page 1 [Phase] Inventor Akiyoshi Honma

Claims (2)

[Claims] (1) A central processing unit that reads alternating current amount data detected at a predetermined sampling period from the power system to be protected, performs predetermined arithmetic processing on the voltage amount of the data, and outputs a determination command for protecting the power system. In the protective relay method, the central processing unit corrects the read voltage amount to a voltage amount from the simultaneously read current amount and a first setting value set in advance, and makes the correction voltage amount. A protective relay system comprising: a determination processing section that outputs a full determination command for protecting the power system when the magnitude of the voltage amount is less than a preset second set value. (2) Provide a voltage calculation processing unit that calculates the voltage at the other end by inputting all of the voltage amount and the amount of current, and calculates the average voltage of the own end and the other end by inputting the voltage and voltage amount of the other end. A minimum voltage calculation unit is provided which has a voltage processing unit and calculates the minimum voltage by inputting the average voltage, the opposite end voltage, and the own end voltage, and the voltage change is input from the minimum voltage calculation unit and sends out a determination processing signal. 2. The protective relay system according to claim 1, further comprising a ratio calculating section.