JPH0424935B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a protective relay device for protecting an electric power system. [Prior Art] A step-out protection relay device that detects whether the system oscillation is a stable oscillation or a step-out when an accident occurs in a power system and oscillations occur in the system after the accident is cleared will be described below. FIG. 1 is a power system diagram schematically showing a power system, where 1 indicates a back power source at the a end and 2 indicates a back power source at the b end. 3,
4 is a bus bar at the A end and B end, respectively; 5 and 6 are current transformers that introduce current to protective relays (hereinafter referred to as relays) 9 and 10; 7 and 8 are transformers that introduce voltage to the relays 9 and 10; 11 indicates a power transmission line. When the phase angle θ of current and voltage is measured at end a and b, active power P = VI _cps θ, reactive power Q = VI _sio
It is determined by θ. The active power P and reactive power Q are the second
As shown in the figure, it changes when the phase difference angle φ between the power supplies 1 and 2 at both ends changes, and the active power P is φ = 90°, and the reactive power Q
has a maximum value at φ=180°, and becomes equal at point A in the figure. Further, when the horizontal axis is the active power P and the vertical axis is the reactive power Q, the P and Q trajectories become circles as shown in FIG. 3, and the point A in the figure indicates φ=90°. Generally, power systems are operated with a phase difference angle of 90° or less.
If the phase angle exceeds 90°, synchronization will occur. In other words, to detect step-out, the effective power P is determined by the voltage and current at the power supply terminal.
It is a good idea to calculate the reactive power Q and detect that the P and Q trajectories exceed 90°. As mentioned above, step-out detection is performed using the P-Q locus.
It would be good to detect when the angle exceeds 90°, but the center point of the step-out cannot be detected in this state. In addition, with conventional equipment, the voltage phase φ at both ends is compared and the phase φ
= 180°, we could make an internal determination, but this could not be done at around phase φ = 90°, that is, at the time of predicting step-out. [Summary of the Invention] In view of the problems of the prior art as described above, the present invention provides a protection joint that can accurately detect the center point of a step-out at the time of predicting the step-out and perform optimal system separation of the step-out. The purpose is to provide electrical equipment. [Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 4 to 7. FIG. 7 shows a block diagram for calculating the amount of electricity according to the present invention. 4a and 5a are the voltage and current input as the amount of electricity from the a end of the system, and 7a is the input amount of electricity 4
_8a is the active _power at each time.
A second calculation unit 9a that creates a string generated from the trajectory of P _a and reactive power Q _a determines a change in the direction of the string,
A determination unit that outputs a change pattern 91a of string quadrant data; 10a is a change pattern 9 of string quadrant data;
1a and a pattern determination processing section that inputs the output of the change pattern data section 11a on the other end side, 11a is a change pattern data section that sends string quadrant data at the other end relay 10, and 12 is a section detection section of the center point of out-of-step. This shows the overall judgment data section that outputs data. P when there is an out-of-step center point between ends a and b
-Q locus is as shown in Figure 4, if it is on the back power source 1 side of the a end, it is as shown in Figure 5, and as shown in Figure 5 if it is on the back power source 1 side of the b end
If it is on the side, it will be as shown in Figure 6. 4, 5, and 6. A shows the locus at the a end, and C shows the locus at the b end. Note that in FIGS. 4, 5, and 6, A represents a point at φ=90°, and B represents a point at 180°. When the P-Q locus is moving from the origin to point A in FIG. 4A, it is assumed that the locus is moving in the direction of the first quadrant. The direction from point A to point B is the direction of the second quadrant. Similarly, in FIG. 4B, the direction from the origin to point A is the direction of the second quadrant, and the direction from point A to point B is the direction of the first quadrant. In FIG. 5A, the direction changes from the direction of the fourth quadrant to the direction of the third quadrant. These quadrant directions are treated as quadrant vectors, and these quadrant vectors [1→2], [2
→1], [4→3], [3→4] changes occur φ
= 90°. Now, in the a-end relay shown in Fig. 1, a change in quadrant vector [1→2] as shown in Fig. 4-A occurs, and the quadrant vector transmitted from the b-end relay changes from quadrant vector [2→1]. ], it is determined that the out-of-sync center point is inside, and when the quadrant vector of the b-end relay is quadrant vector [3→4], it is determined that the out-of-sync center point is outside the b-end. These combination judgments are obtained in the comprehensive judgment data section 12, and are as shown in Table 1 below.

〔Effect of the invention〕

As described above, according to the present invention, since the quadrant vectors or their change patterns at the own end and the opposite end are compared to determine whether the center point of the step-out is inside or outside,
It is possible to determine whether the center point of the step-out is inside or outside at the time of predicting the step-out, and it is possible to perform optimal system separation, thereby providing a protective relay device that can contribute to stable operation of the power system.

[Brief explanation of drawings]

Figure 1 is a simulated power system diagram, Figure 2 is a characteristic diagram of active power P and reactive power Q with respect to the phase difference angle at end a and b, and Figure 3 is a characteristic diagram of active power P and reactive power Q.
The locus diagrams, Figures 4, 5, and 6 show the active power P.
Explanatory diagram illustrating the locus of reactive power Q and reactive power Q, seventh
The figure is a configuration diagram of a protective relay device illustrating an embodiment of the present invention. 1, 2... Back power supply, 3, 4... Bus bar, 5, 6
...transformer, 7,8...transformer, 9...a-end relay, 10...other-end relay, 11...power transmission line, 7a
...First calculation section, 8a...Second calculation section, 9a...
Determination unit, 10a... Pattern determination processing unit, 11a
...Change pattern data section, 12...Comprehensive judgment data section.

Claims (1)

[Claims] 1. A first calculation unit that calculates active power and reactive power from voltage and current signals introduced from the a-side of the power system, a second calculation unit that creates a chord generated from the locus of this active power and reactive power, and a determination unit that determines a change in the direction of the string and outputs a change pattern of string quadrant data; a change pattern data unit that transmits string quadrant data at the opposite end, which is the b end of the power system; A pattern determination process that compares the change pattern of the string quadrant data outputted from the change pattern data section with the change pattern of the string quadrant data outputted from the change pattern data section to detect whether the center point of the step-out is within the protection zone or outside the zone. A protective relay device comprising a general determination data section that inputs the determination signal from the pattern determination processing section and outputs section detection data of the center point of synchronization.