JPS607884B2 - Inspection method of ratio differential relay device - Google Patents

Description

[Detailed description of the invention] The present invention relates to an inspection method for a ratio differential relay system.

Here, a bus protection relay system layer will be described as an example of a relay system that employs a current differential method.

Busbars at power generation and substations have a significant impact on other systems in the event of an accident, so a busbar protection relay layer is installed. There are various methods for the bus protection relay layer, such as a current differential method and a voltage differential method. Here, the current differential method related to the present invention will be explained. As shown in FIGS. 1 and 2, a plurality of power transmission lines L, . . . Ln are connected to the bus bar in a concentrated manner. Therefore, for example, if an accident occurs at the accident point F in Fig. 1, all the transmission lines connected to the bus bus will be affected, so the short circuit breaker CB,~n is tripped at high speed. There is a need. As can be seen in Figures 1 and 2, in the case of a busbar accident, to the busbar, IF=
Zipn flows in, but in the case of an accident outside the busbar (Fig. 2), 21Fn=0. In this way, the current differential bus protection relay system attempts to discriminate between an internal fault and an external fault based on the magnitude of the vector sum current ZIFn of all lines.
Its operating principle is shown in FIG. As shown in Figure 3,
Current transformer (CT,, CT2, CT3...CTn)
Assuming that the secondary circuit is integrated and the current of the differential circuit is used as the operating force, in the case of an internal fault, a current proportional to the current at the fault point flows to the operating coil OC, which operates, and in the case of an external fault, the current transformer (hereinafter referred to as C
It is called T. ) Current only circulates between them and does not flow through the operating coil OC, so it does not operate. However, in this method, when an external fault occurs, the error current based on the difference in CT characteristics is
There is a risk that it will flow to the operating coil OC and cause malfunction. In order to prevent this, it is common to add a suppression coil RC as shown in FIG. 3 to provide a suppressing effect and to create a ratio characteristic as shown in FIG. 5. However, in the same figure, 1 is the inflow current, 12 is the outflow current, 5 is the ratio characteristic, and 6 is 1,
=12 is shown. The shaded area is the operating castle. FIG. 4 shows a bus protection relay layer in which the circuit currents are suppressed by the scalar sum and operated by the vector sum, based on the above-mentioned concept. The CT secondary circuit current of each line is taken into the input circuit 1 by an auxiliary current transformer GCT with a gap, and is converted into two sets of voltages proportional to the input current. A set of voltages are connected in series (added) with alternating current amounts, and a vector sum k is obtained in the full-wave rectifier circuit 42. IZIFnf is calculated. The other set consists of individual full-wave rectifier circuits 4.
1, each is rectified and then connected in series (added) to calculate a scalar sum kr2lIFnl. Therefore, the former is proportional to the vector sum of all line currents 21Fn, and the latter is
Scalar sum〆l Proportional to IFnl. In the determination circuit 3 in the protective relay 2, IZIFnl, which is obtained by rectifying 21Fn, is used as the operating force, and 2fIFnl is used as the suppressing force for comparison.

! 21Fn amount-krZ! Operates when IFnf and K.

Here K is a small value corresponding to the bias voltage,
If this is ignored, the operating condition equation can be expressed as Nojima Ryojik.

. In an internal accident, it operates as IZIFnl>k2fIFnl, and in an external accident, it operates as "121Fnl《k2lIFnl.
1 and becomes inoperable. As described above, the current differential bus protection relay layer has a ratio characteristic as shown in FIG. 5 to prevent malfunction due to CT error in the event of an external fault. The present invention relates to a method for checking whether there is any deviation in this ratio characteristic.

In order to manage this ratio characteristic, in Figure 6, a?
Each input device was inspected by externally applying inspection signals corresponding to points b, c, and d. An example of this conventional technique is shown in FIG. In the same figure, IA, IB...IN
is an input circuit having the same configuration as the one explained as symbol 1 in Fig. 4, and its output terminals R,,R2 output a scalar quantity corresponding to the input, and 0,,02 output a vector quantity. be done. The protective relay 2 has a contact point F with the vector sum as the operating force and the scalar quantity as the suppressing force. Gives a relay output via b. Furthermore, F. b is a contact related to inspection, which prevents relay output from being provided by the output of the protective relay 2 during inspection. F. A is a contact that closes only during inspection, and the output of the protective relay 2 during inspection drives the auxiliary relay Ft to display and output the inspection results. Input circuit IA, IB...IN
In addition to each line current, an inspection signal is applied from an inspection power supply G to the line. In this inspection method, input circuit iA is used as a reference, inspection signals corresponding to a and b in FIG. 6 are applied to this input circuit to evaluate its validity, and then input circuit IA and other input circuits such as IB The ratio characteristics at points c and d in FIG. 6 are monitored by simultaneously applying inspection signals of opposite polarity to both of them. That is, first, contacts T and Fa are closed and a check current is applied to the input circuit IA.

Here, when no inspection signal is applied and there is no accident on the bus bar to be protected, the vector sum Z1n derived to the protective relay 2 is zero, and the protective relay 2 does not provide an operational output. When a check signal is applied by closing Fa, T, the vector sum becomes 21n0. If the inspection current at the tap position of the contact Fa is selected to be on the operating side of the ratio difference characteristic 5 as shown in Figure 6a, the protective vertical electrical device 2 will give an operating output and the "auxiliary relay The inspection result is displayed by Ft. Next, inspection is performed by closing T and Fb. However, the inspection signal given by closing Fb is set to the non-operating side as shown in Fig. 6b. The input circuit IA is checked in this order, and only in the former case, if an operational output is provided, the input circuit IA is judged to be normal.
Next, the input circuit IB is inspected on the premise that the input circuit IA is normal.

At this time, open contacts F and T to input circuit IA and apply a check current, and contact F to input circuit IB.
C and L are closed and a check current is applied. Here, the inspection terminals ■-■ and ◎-◎ are connected so that the inspection current of the input circuit IA and the inspection current of the input circuit IB have opposite polarities. Therefore, if the inspection current to the input circuit IA simulates the inflow current 1 to the bus bar to be protected, then the inspection current to the input circuit IA simulates the outflow current 12 from the bus bar. . And li,! Since the vector sum (operating force) of the protective relay 2 before inspection is zero, the characteristic of the protective relay 2 at this time is shown at point c in FIG. 6. Since point c is on the action side,
If the protective relay 2 is normal, it gives an operating output. Next F
Close Fd with respect to Fc while keeping cd, T, , T2 closed. The characteristic at this time is as shown in FIG. 6d, and the protective relay 2 does not operate. In this way, the input circuit IB is determined to be normal if the protective relay 2 gives an operating output when a test current corresponding to point c is applied, and does not provide an operating output when a test current corresponding to point d is applied. At this time, it can be determined that the input circuit IA is also normal.In other words, if you only check points a and b for the input circuit IA, you will not be able to see that the ratio differential characteristic 5 has changed to 7 or 8. Although it cannot be confirmed, the fact that a correct result was obtained when the inspection current was applied to input circuits IA and IB at the same time is only because input circuit IA operated correctly.The following also applies to each input circuit that has not been inspected. Perform the inspection by applying the inspection current corresponding to points c and d using the input circuit IA as a reference (opening T and Fcd).

In addition, the fact that there is no output from the protective relay 2 when inspecting point c means that the original ratio differential characteristic 5 has changed as shown in 8, and it means that there is an output from the protective relay 2 when inspecting point d. means that 5 has changed to 7. It is also possible to inspect the ratio difference characteristic using this conventional inspection method.

However, it has the following problems. 1. There are many inspection steps and the equipment becomes complicated.

......points a, b or c for one input circuit,
In order to inspect point d, inspections are required twice each, and when the number of CTs (number of input circuits) is large as in the case of a bus bar, the number of inspections becomes extremely large. Further, the circuits for switching each contact are complicated, and the inspection equipment is large-scale. 2. Unable to detect minute changes such as aging.

...In this method, it is monitored that an operating output is given when the motor is on the operating side for characteristic 5, and no operating output is given when it is on the non-operating side.In order to make the inspection more reliable, It is necessary to set inspection points c and d appropriately apart from characteristic 5. For this reason, minute changes in characteristics 5 such as aging cannot be detected. In view of the above, it is an object of the present invention to provide an inspection method that can detect the Year of the Year change using a simple device.

According to the present invention, a check current such that the vector sum becomes zero is released from the outside, and an abnormality is determined when the vector sum of the output currents obtained from each input circuit does not become zero. FIG. 8 shows an embodiment of the present invention, in which vector quantities derived from terminals ○, 102 of each input circuit IA, IB, . . . , and scalar quantities derived from terminals R, -R2. teeth,
All of the signals are applied to a protective relay 2 (not shown) to perform a protective operation.

In the present invention, a vector sum is obtained from the vector quantities of each terminal 0 and 102, and this is introduced into the operation quantity comparison RT' of the inspection circuit T. Furthermore, in order to inspect the circuit that generates the scalar amount appearing at the terminals R, -R2, a resistor R is provided, and the vector voltage across the resistor R is derived between the terminals T, -T2. Then, the vector sum is calculated by the suppression amount comparison circuit OT.
to be introduced. In RT and OT, an input circuit abnormal output is given when the introduced vector sum is not zero. On the other hand, a check current is applied from the check power source G by first closing the contacts T, , T2. At this time, since the total sum of the inspection currents is considered to be zero, naturally the vector sum input to OT and RT is also zero, and RT and OT do not give an input circuit abnormal output. If it does not become zero, it is considered that the input circuit is abnormal. Looking at the operation amount deriving side of the input circuits IA, IB...IN, the voltage value derived across the resistor R changes due to a change in the value of the impedance of the resistor R or the winding, and the vector sum becomes zero. Regarding the suppression amount deriving circuit of the input circuit, the voltage across the resistor R changes due to changes in the impedance value of the winding, deterioration of the characteristics of the rectifier circuit 41, changes in the impedance of the load circuit, etc., and the vector sum becomes zero. Therefore, if deterioration occurs in the input circuits IA, IB,...IN due to aging, etc., the vector sum will not become zero, and an abnormal input circuit output will be given upon inspection.Therefore, inspection should be performed as appropriate. In this case, it is possible to detect an abnormality at an early stage before the characteristic change of the ratio differential characteristic 5 shown in Fig. 6 progresses.In the case of the embodiment shown in Fig. 8, after input is applied to the input circuits IA and IB, Inspection is performed by applying inputs to circuit IA and other input circuits, such as IN.
According to this method, it is possible to determine the abnormal input circuit, but if there is no need to determine the abnormal location and it is sufficient to know that an abnormality has occurred in the protective relay system as a whole, then the input circuit It is sufficient to apply the inspection current to all of them at the same time, and it is sufficient if consideration is given so that the sum of the inspection currents becomes zero. It should be noted that the comparison circuits RT and OT are composed of a rectifier circuit and a comparator, and only need to provide an output when the rectifier output is not zero.

Further, the resistor R added on the suppression side may be placed at a location where a vector quantity appears, and the vector quantity changes under the influence of impedance changes in the circuit.
According to the present invention, the inspection device can be simple and even minute changes in ratio characteristics can be detected.

This invention is, so to speak, a signal on characteristic 6 in FIG.
2.0) is given and inspected. Here, a description will be given of why the configuration of the present invention allows estimation of whether or not the ratio characteristic is above characteristic 5 in FIG. 6. For ease of explanation, FIG. 1 is simplified and represented using two terminals, and this is expressed as the above-mentioned determination formula k.

l21Fnl-kr2lIFnl and K... {1', vector sum l21Fnl=lI
F, -1F2l=lp,-IF2
■Scalar sum ZIIFnl=lIF, quantity 10fIF2l=IF, 10IF2'3}, ko121Fnl-kr2! IFn! =k.

(IF, 1F2) - kr (IF, 10IF2) 2K...
・'4-' Therefore, if we find this for IF2, F
225 trunk loan/F2-k.

(, -mine r/k.) 3aIFl-b--[5] However, a: Curve b Three cores Therefore, if this is represented on a graph, it will be a straight line with slope a and grain b.

This characteristic is shown in FIG. Here, regarding the input circuit of the line LI in FIG. 1, the input is IF, and the output k.

, IF, and kr, IF,, Assuming that the input circuit of line L2 is lp2 and the outputs are k, 21F2 and kr21F2, when normal, the constant is k.

,, k. 2, kr1'kr2 is k.

=k. ,=k. 2, kr=kr,=kr2・river
On the shelf, it becomes like equation '5).

Therefore, the inspection signal where the sum of the alternating current amounts to zero, IF, = -
When applying IP2, k.

, IF, tenk. 21F2=k.

(IF, 10 IF2) = o [7} kr, IF, 10 kr21
F2 = kr (IF, 10 IF2) = 0 (8) It is normal, but for example, k due to a hardware failure. , sheep k. 2, or kr, sheep kr2...'9', the slope a of the L equation (■) is the value a in normal conditions.

From this, it becomes aF at the time of abnormality. In other words, since the nostalgia changes from the normal value, the characteristics shown in 7 and 8 in Figure 6 are as follows.
At this time, according to the formula {91, k., sheep k.2 or kr
・Sheep kr2, therefore, the formula {7) and {shoe mare do not hold.

That is, in order to be above characteristic 5 in FIG. 6, the formula {7
}, '8} must hold true. Therefore the expression '
If inspected under conditions 7' and 81, abnormalities will be detected (7 and 8 in Figure 6).
state). Although the above explanation has been made using a busbar protection relay as an example, the present invention is applicable to any device that employs a ratio differential method. Brief explanation of the drawings Figures 1, 2, 3, and 4 are diagrams for explaining the bus protection relay system, and Figures 5 and 6 are diagrams for explaining the ratio differential characteristics. FIG. 7 is a diagram for explaining a conventional inspection method for a ratio differential relay, and FIG. 8 is a diagram showing an embodiment of the present invention.

1...Input circuit, 2...Protective relay, T,,L,Tn,
Fcd, Fa, Fb, Fc, Fd...Contact, RT,
OT...comparison circuit.

Tsutomu Figure 1 Mustard 2 Figure 3 Figure 4 Chrysanthemum illustration Chrysanthemum 5 Little brother picture Figure 8

Claims (1)

[Claims] 1. A plurality of current transformers that detect the current of the line connected to the protected part, an input circuit provided for each current transformer and inputting the secondary current, which calculates a vector quantity according to the input. an input circuit consisting of a first circuit that outputs and a second circuit that outputs a scalar amount obtained by rectifying the input; an output sum of the first circuit among the plurality of input circuits and a second circuit; In a ratio differential relay device comprising a relay that provides an operating output according to the difference between the sum of the outputs of the input circuit and the input circuit, A ratio differential relay device characterized in that it is equipped with an inspection circuit that applies an abnormal output when the sum of the output of the first circuit or the sum of the amount of alternating current before rectification of the second circuit is not zero. inspection method.