JPS5843402Y2 - Hogokeiden Sochi - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a power system protection relay device that protects power systems such as power transmission lines, busbars, and power equipment.

Although this invention can be applied to various power system protection relay devices, a case where it is applied to a busbar protection relay device will be described here.

Recently, with the increase in the scale of power systems, the charging capacity of the line and the capacity of the compensation reactor have increased, and the current passing through the current transformer (hereinafter abbreviated as CT) in the event of an external single-line ground fault has also increased, causing the excitation of the CT. Conventional bus protection relay devices that utilize residual differential differentials could cause malfunctions due to only current errors.

Therefore, recently, zero-sequence voltage (hereinafter referred to as V
This is an effective component detection joint that uses only the in-phase components of the zero-phase current (hereinafter abbreviated as 0) and the zero-phase current (hereinafter abbreviated as There is a tendency to adopt electric methods.

The explanation will be given below according to the figures.

Figure 1 is a normal busbar configuration diagram, in which 1 is the busbar to be protected, 2 is the charging capacity, 3L 32 is a compensation reactor, 11 to 15 are each line connected to the busbar, and 21 to 25 are each line. This is a CT installed on a railway line, and the output currents of these CTs are differentially connected, and a relay element (not shown) is operated by the differential current IQ flowing here.

Reference numeral 20 indicates a neutral point grounding resistance, and FO indicates a bus line external to line ground fault point.

When a failure occurs at the FO point, for example, the charging current IC
= j2100A Reactor current IT = -j1800A Neutral point resistance current IR = Assuming 40OA, limiting current I F = I C + I L + I R = j2100-j
1800+400=400+j300.

Therefore, lIF+=50OA. on the other hand,! Depending on the voltage phase at the time of generation, a total of 18 from reactance 31, 32
If a DC component with a peak value of 00r2A is generated and the external fault generating terminal is completely saturated due to the excessive DC component or residual magnetic flux due to an external failure of the bus bar, 1800. An error differential input terminal ID as shown in FIG. 2, in which an AC component of 50 OA is superimposed on an attenuated DC component having a peak value of 2 A, enters the bus residual differential relay element.

Due to this error current, not only simple differential relay elements but also relay elements that respond to the effective component of IO with respect to VO may malfunction depending on the balance between the DC component decay time constant and the relay element operating speed. There is a possibility that

Conventionally, a circuit such as that shown in FIG. 3 was used to avoid malfunctions when DC components are superimposed.

In Figure 3, 71 is the IO differential manual transformation transformer, 61.6
2 is a diode, 3 and 4 are positive and negative effective component derivators each having functions such as sampling and sampling hold circuits, 41.42 is a human power detection element that outputs when input continues for a predetermined time, 51 is an AND element, 6 is a relay element, 8 is a transformer for introducing VO, and 9 is a VO phase or vector output device. In the effective component derivators 3 and 4, the positive component is calculated based on the VO phase or the output from the vector output device 9, respectively. The half wave and the effective part of the negative half wave are derived.

Therefore, a waveform diagram in this method is shown in FIG. 4.

In Figure 4, VO comes as a sine wave, so
If the effective component deriver 3 samples the positive half-wave of IO at the positive peak of VO, and the effective component deriver 4 samples the negative half-wave of IO at the negative peak, in the case of Fig. 4, the DC component is sampled. Since the waveform rises in the positive direction, only the positive side effective component deriver 3 responds, and the relay element 6 outputs the output from the positive side and negative side effective component derivers 3 and 4. Since the relay element 6 will not operate unless it is continuously input to the detection element 4L42 for a predetermined period of time, the relay element 6 can avoid malfunction in this case.

Also, since the AC component error decreases as the DC component attenuates,
By the time the DC component disappears, both the positive side and negative side effective component derivators 3 and 4 are already in a non-operating state, so there is no problem.

However, if the second harmonic (0°) appears as shown in Fig. 5, and the phase force of this harmonic changes with time, at a certain moment the positive side effective component deriver 3 At the next moment, an error input is input to the negative side effective component deriving device 4, and if this state continues, the relay element 6 easily malfunctions due to the harmonic error dynamic force.

This invention attempts to eliminate this inconvenience, and its purpose is to obtain a power system protection relay device that is not affected by the DC component and harmonic components contained in the fault current at the time of a system failure. .

An embodiment of this invention will be described below with reference to FIG. 6.

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

In FIG. 6, 72 is a current transformer, 10 is a harmonic filter that passes only the fundamental wave, and 100 is a sampling and sampling hold circuit for deriving the effective IO component for VO of the fundamental wave that has passed through this filter 10. The effective component deriving device 52 is an AND element, which drives the relay element 6 only when all three effective component deriving devices 3.4.

A sampling output with a phase shift of 90 degrees is output from the vector output device 9 by human input due to the zero-phase voltage vO generated due to a system failure, and appears in the CT differential circuit.

As mentioned in Fig. 3, the effective component in the differential zero-sequence current ■0 is derived by the effective component derivators 3 and 4, respectively.
Derive the effective component of the negative wave.

In FIG. 6, in addition to the effective component derivators 3 and 4, a fundamental wave is obtained through a harmonic filter 10 that extracts only the fundamental component from the differential zero-sequence current IO, and the effective component for VO in this fundamental wave is A circuit is added that detects with the effective component deriving device 100 that the value is greater than a certain set value, and outputs an output to the AND element 52 when the human power detection element 34 receives human power continuously for a predetermined period of time.

Therefore, only when all effective component derivators 3, 4, and 100 output operating signals, the AND element 52 outputs an output to drive the relay element 6.

Therefore, according to this invention, when a DC component is superimposed when a fault occurs, the effective component derivers 3 and 4 prevent malfunction, and when harmonics are included, the effective component deriver 100 prevents malfunction, so that no fault condition can occur. Accurate operation can be expected even when

Furthermore, because the purpose of the so-called power system protection relay device that protects the power system is very public, and the range of influence that can be affected by malfunction is wide, there is a strong demand for reliable operation, especially among protective relay devices. be done.

Therefore, the effect of being able to prevent malfunctions caused by harmonics is extremely significant in the power system protection relay device.

Moreover, in order to prevent malfunctions caused by harmonics, it is only necessary to add new components to the components that have made up the existing device, and there is no need to make any complete changes; Since the parts include a fundamental wave filter and a third effective component deriving device, the above two types of protection operations can be prevented with a simple configuration.

[Brief explanation of the drawing]

Fig. 1 is a normal bus bar configuration diagram, Fig. 2 is a transient current waveform diagram when a fault occurs, Fig. 3 is a circuit diagram showing a conventional protective relay device, and Fig. 4 is a diagram for explaining its operating state. Waveform diagram, 5th
The figure is a waveform diagram for explaining the disadvantages of the conventional device, and FIG. 6 is a circuit diagram showing an embodiment of this invention. In the figure, IO is current, VO is voltage, 61.62 is a diode, 3 and 4 are first . 2nd effective component detector, 10 is a filter, 100 is a 3rd effective component detector, 4L 42,
43 is a human force detection element, 52 is an AND element, and 6 is a relay element. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] a first effective component deriver that detects an effective component of current relative to the voltage when the voltage is in positive polarity and derives an output based on the effective component; and an effective component of current relative to the voltage when the voltage is in negative polarity; A second step that detects and derives an output based on the effective component.
a filter that derives the fundamental wave of the current; a third effective component deriver that detects the effective component of the fundamental wave with respect to the voltage and derives an output based on the effective component;
Each human power detection element that takes the output of each of the effective component derivators above as human power and outputs when the human power continues for a predetermined time, an AND element that takes the output of each input detection element as input, and a relay that responds to the output of this AND element. A power system protection relay device characterized by being equipped with an element.