JPH049013B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD OF THE INVENTION The present invention relates to a protective relay device (hereinafter abbreviated as relay) for protecting an electric power system.

[Prior art]

A conventional device of this type is shown in FIG. The figure shows a simulated system diagram of the power system, where 1 indicates the back power source at the a end and 2 indicates the back power source at the b end.
Reference numerals 3 and 4 indicate busbars at ends A and B, respectively, 5 a transformer that introduces voltage to the relay 8, and 7 a power transmission line. As described above, the conventional device used only the voltage at the relay installation point for calculations, so in Figure 2, which shows the voltage distribution diagram at the fault point in the power system, the fault point (center point of step-out) in the power system When F is far away or when the rear power source is close, the voltage at the relay installation point does not drop much, resulting in disadvantages such as the relay's sensitivity becoming extremely poor or the relay becoming inoperable.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional devices as described above, and it supplies a correction value to the voltage at the relay installation point based on the current at the relay installation point and the preset impedance of the power transmission line. Input the resulting voltage at the opposite end and the voltage at the own end to calculate the average voltage, input the voltage at the relay installation point, the voltage at the opposite end, and the average voltage to the judgment processing section to determine the relay sensitivity. The purpose is to provide a protective relay device that improves the

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 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, and 3 and 4 are
are the busbars at the a and b ends, 5 and 6 are the currents in the relay 8,
Shows current transformers and transformers that introduce voltage. FIG. 6 is a configuration diagram showing the signal processing circuit of the relay 8, in which 81 is a voltage calculation processing section that calculates the voltage at the other end, 82 is an average voltage processing section that calculates the average voltage of the own end and the other end, 83, 84, and 85 are first, second, and third voltage change rate calculation units that calculate the voltage change rate, and 85A is the output of the first, second, and third voltage change rate calculation units 83, 84, and 85. This is an OR circuit with inputs. 86 is a voltage change rate calculation unit 83, 8
4, 85 and an OR circuit 85A. The voltage calculation processing unit 81 inputs the bus voltage V ₃ and the line current I, and calculates the output voltage V ₄ (corrected voltage amount) as the voltage at the other end (V ₃ −IZl). In order to calculate the average voltage of the own end and the opposite end, the average voltage processing section 82 inputs the output voltage V ₄ and the bus voltage V ₃ and outputs the average value voltage Vh. 1st, 2nd,
The third voltage change rate calculation units 83, 84, and 85 measure the voltage change rates _dV3 /dt, _dV4 /dt, and dVh/dt for each of the input voltages _V3 , _V4 , and Vh, Sends output based on comparison with set value. The OR circuit 85A generates an output signal that operates the relay when the outputs of the voltage change rate calculating sections 83, 84, and 85 are supplied. Next, the operation of this embodiment will be explained with reference to the vector diagrams of FIGS. 4 and 5. Now, when the back power source 1 and the back power source 2 are out of synchronization and the phase difference angle becomes 90 degrees apart, the vector diagram shown in FIG. 4 will be obtained. However, the center point of step-out is between ends a and b. The voltages V ₁ , V ₂ , V ₃ , and V ₄ shown in FIG.
These are voltage vectors of the back power source 1, back power source 2, bus bar 3, and bus bar 4 shown in the figure. Current I is a current flowing from bus bar 3 to bus bar 4, and Zl is a preset power transmission line impedance. Transmission line 7 is almost L
, the current I is the voltage as shown in Figure 4.
It is perpendicular to the vector connecting V ₁ and voltage V ₂ . As is clear from the figure, in order to obtain the voltage of the bus 4 at the bus 3, it is preferable to calculate the relationship between the voltage V ₃ , the transmission line impedance Zl, and the current I. Also, the average voltage is calculated as (V ₃ + V ₄ ) x 1/2 = Vh, and the voltage change rate is calculated as dV ₃ /dt, dV ₄ /dt, and dVh / dt. The largest voltage change rate value is compared with a preset set value, and when it is larger than the set value, a protection command is output. As shown in Figure 4, when the center point of step-out is between busbars 3 and 4, the voltage change rate dVh/dt is the highest among the voltage change rates dV ₃ /dt, dV ₄ /dt, and dVh/dt. growing. In other words, even if the center point of the step-out is close to one of the busbars, the maximum voltage change rate is at the center point, so it is clear that the sensitivity is the highest when comparing the voltage change rate dVh/dt and the set value. . Next, as shown in the vector diagram in Fig. 5, if the center point of step-out is outside the b end, the voltage change rate dV ₄ /dt becomes maximum, and by comparing the voltage change rate dV ₄ /dt and the set value, High sensitivity can be obtained.

【Effect of the invention】

As described above, according to the present invention, the protection calculation is performed using the minimum rate of change of the voltage among the self-end voltage, the farthest end voltage of the protection interval, and the voltage at the intermediate point, so it is highly reliable. This has the effect of providing a highly sensitive protective relay device.

[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... Bus bar at end a, b end, 5, 6... Current transformer, transformer, 8... Relay, 81... Voltage calculation processing unit, 82... Average Voltage processing section, 83, 84, 85... Voltage change rate calculation section, 85A... OR circuit, 86... Judgment processing section.

Claims (1)

[Claims] 1. The voltage and current output from the transformer that introduces the voltage and the current transformer that introduces the current at the relay installation point, and the preset impedance of the transmission line that connects the own end and the other end, a voltage calculation processing section that calculates the voltage of the transformer, and an average voltage processing section that calculates the average voltage of the own end and the opposite end by inputting the voltage output from the transformer and the voltage output from the voltage calculation processing section. Then, the voltage change rate of the voltage output from the transformer, the voltage output from the voltage calculation processing section, and the average voltage output from the average voltage processing section is calculated, and when the rate of change is greater than a set value, the power system is protected. protection comprising a judgment processing section configured with a plurality of voltage change rate calculation sections that output protection outputs and an OR circuit that outputs a relay operation signal when outputs are supplied from these voltage change rate calculation sections. Relay device.