JP3204693B2 - Balanced relay - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balanced relay capable of detecting an unbalanced state of two electric quantities with high accuracy.

[0002]

2. Description of the Related Art In a balanced relay that responds to the difference between two electric quantities A and B, when the nominal values (rated values) of the electric quantities A and B are equal to the nominal value (rated value) of the input converter, the two are equal. Detecting an unbalanced state by differential operation A _R -B _R has been conventionally performed.

[0003]

However, the quantity of electricity A, B
And the input converter have an apparent imbalance. For this reason, there has been a problem that a relay that requires high accuracy unnecessarily responds due to the apparent unbalance. Also, to eliminate this error,
For example, in a voltage balance relay, the balance between two input values was adjusted by the volume at the start of operation, but it was difficult to make accurate adjustments, and the above error could not be completely canceled when the input voltage fluctuated. There was a problem. Also, the first input and the second input
The ratio A ₀ / B ₀ of the period amounts A ₀ and B _{0 is} defined as a balance operation coefficient.
Correcting means for multiplying the second input and correcting the second input
A first input and a second input corrected by the correction means
Unbalance detection that detects an unbalanced state based on the difference from the correction value
Means for solving the above problems by providing
Although a balanced relay is conceivable, two
The detection error is small enough when the volume is correlated
There was no problem.

An object of the present invention is to correctly detect an unbalanced state without responding to the unbalanced portion at the beginning of operation and when the nominal values of the electric quantities A and B and the nominal value of the input converter are not equal. To provide a balanced relay that can be used.

[0005]

[0006]

SUMMARY OF THE INVENTION The present invention relates to
A balanced relay responsive to the difference between the two electric quantity is, the initial amount of the first and second inputs A ₀ and B
_{From 0} , 2B ₀ / (A ₀ + B ₀ ), 2A ₀ / (A ₀ + B
₀ ) is used as the balance operation coefficient, 2B ₀ / (A ₀ + B ₀ ) is multiplied by the first input, 2A ₀ / (A ₀ + B ₀ ) is multiplied by the second input, and the first and second inputs are obtained. And a correction means for correcting the difference between the first and second inputs corrected by the correction means, and an unbalance detection means for detecting an unbalanced state.

[0007]

[0008]

[Action] In the equilibrium relay according to claim 1, the initial amount of A
₀ and B ₀ , 2B ₀ / (A ₀ + B ₀ ) and 2A ₀ /
(A ₀ + B ₀ ) is obtained as a balance operation coefficient.
Then, the former coefficient is multiplied by the first input A _R , and the latter coefficient is multiplied by the second input B _R , the difference is obtained, and the unbalanced state is detected from the difference.

Here, the effectiveness of the balanced relay will be analyzed.

The following two quantities are defined, where A and B represent two quantities of electricity introduced into the balancing relay.

A _n : Nominal value of electric quantity A B _n : Nominal value of electric quantity B ε _a : Error of electric quantity A ε _b : Error of electric quantity B K _n : Introduce electric quantity A to the balanced relay Conversion factor nominal value of the input converter (for example, CT: the first-order quadratic ratio of PT) L _n : the conversion factor nominal value of the input converter with respect to the electric quantity B δ _k : the input converter of the electric quantity A error [delta] _l: now the input transducer electrical quantity B error, and the electrical quantity a which displacement ΔA occurs. If there is some correlation between the electric quantities A and B, it is assumed that the displacement of the electric quantity A affects the electric quantity B, and the electric quantity B also has a displacement ΔB.

At this time, the input to the balance relay is given by the following equation.

[0013]

(Equation 1)

[0014] Two electric quantity A, the nominal value A _n of B, B _n equals the conversion factor nominal value Kn of the input transducers, are equal Nn, further A, even though there is no displacement in B, simple differential in operation _{a R -B R, ε a,} ε b, δ k, the differential amount of the apparent by errors such as [delta] _l (unbalanced) would occur.
Therefore, in order to cancel this imbalance, the following equation 2
Two differential operation methods are considered.

[0015]

(Equation 2)

Here, A _R0 and B _R0 are initial inputs of the electric quantities A and B to the balanced relay, and are represented by the following equations.

[0017]

(Equation 3)

If there is no displacement, the differential operation result of the equations (3) and (4) is clearly 0, and ε _a , ε _b ,
The apparent imbalance due to δ _k and δ _l is canceled.

Next, the equations (3) and (4) will be analyzed in detail.

First, the differential operation method 1 shown in equation (3)
Check out.

Using equations (1), (2), (5) and (6),

[0022]

(Equation 4)

## EQU1 ## Here, the approximation is ε _a δ _k << 1
by.

Next, the operation calculation method 2 shown in equation (4) will be examined.

Equation (4) can be transformed into the following equation.

[0026]

(Equation 5)

Using the same approximation method as described above, (5),
The following equations (9) and (10) are obtained from the equation (6).

[0028]

(Equation 6)

When ε << 1, 1 / (1 + ε) ≒ 1−ε
Using equations (9), (10) and (7),

[0030]

(Equation 7)

Using the relationship α + β = 1,

[0032]

(Equation 8)

Is obtained. In the equations (7) and (10), the last term on the right side is a detection error term.

At this stage, it can be said that there is no difference between the two methods regarding the detection error.

The nominal values A _n ,
Nominal conversion coefficient values K _n , L _{n of the} input converter, where B _n are equal
Are equal, the equations (7) and (11) are as follows.
Here, the relationship of α + β = 1 is used.

[0036]

(Equation 9)

A voltage balanced relay that responds to the difference between the terminal voltages of the first and second capacitors is just this example.

In this example, it will be further analyzed how the expressions (12) and (13) become.

The rated capacitance of the first and second capacitors is C, and the manufacturing errors of the first and second capacitors are ΔF and ΔR. Now, assuming that a capacitance change of ΔC has occurred in the preceding capacitor, the terminal voltages of the preceding and succeeding capacitors are as follows corresponding to the two electric quantities A and B.

[0040]

(Equation 10)

Similarly, using the approximation method,

[0042]

[Equation 11]

Is as follows. Here, E is a voltage applied before and after the capacitor. Therefore, the nominal values, errors, and displacements of the electric quantities A and B have the following correspondence relationships, respectively.

[0044]

(Equation 12)

From this, the expressions (12) and (13) are

[0046]

(Equation 13)

Thus, it can be understood that the detection error is further reduced in the differential operation method 2.

[0048] From the above analysis, differential relay of the present invention is not to be responding to the initial unbalanced component, correctly to detect the unbalance amount, the detection error is generally in the two balanced relays There is no difference. However, when the capacitors are cascade-connected and the nominal value is equal and there is a correlation between the two quantities, as in the case of a voltage balancing relay that detects the failure of the capacitor, the detection error of the method 2 is smaller. There is an advantage that it becomes.

[0049]

FIG. 1 is a circuit diagram of a voltage balancing relay on which the present invention is based . In this example , a voltage balancing relay for detecting an internal element failure of a capacitor in a phase adjustment facility is shown. In the figure, the portion within the two-dot chain line is the voltage balancing relay portion. Phase modifying equipment is connected to the tertiary winding of the transformer T through the circuit breaker CB, phase modifying equipment is disconnector SW, series-connected two pairs of capacitor C _F, composed of C _R and series reactor L Have been. The capacitor C _F, discharge coil DC each having a secondary winding is connected to the C _R,
A voltage balance relay is connected to the secondary windings of the two discharge coils DC.

Reference numerals 18f and 18r provided on the input side of the voltage balancing relay are auxiliary transformers for insulation. 13
Is a balance calculation coefficient calculator for calculating a balance calculation coefficient K;
Means for multiplying the equilibrium calculation coefficient K to the output voltage V _F of the auxiliary transformer 18f, 16 are unbalanced value calculating means for obtaining a difference component of output voltage V _R the value obtained by multiplying the equilibrium calculation coefficient. The level judging means 17 is an unbalance detecting means for judging an unbalanced state and outputting a trip when the obtained unbalanced value exceeds a predetermined set value.

FIG. 2 is a flow chart showing a schematic operation of the voltage balancing relay shown in FIG.

First, at the start of operation, the initial voltages V _F0 , V
_R0 is read (n1). Subsequently, the balance calculation coefficient K is calculated as V _R0 /
_Calculate with V _F0 and store it. Then, read the front end voltage V _F and the rear stage voltage V _R after the start of operation, the absolute value of the difference with the correction is performed by multiplying the equilibrium passage coefficient K V _F (n3 → n4). Then, it is determined whether or not this value is equal to or greater than a predetermined set value Vs (n5). If it is less than the set value Vs, the processing of the above steps n3 to n5 is repeated, and if it is more than the set value Vs, a detection signal is output (trip output is performed) (n6).

FIG. 3 shows an embodiment of the present invention.

In the configuration, the difference from the voltage balanced relay shown in FIG.
The two balance calculation coefficients K _F and K _R are calculated, and the auxiliary transformer 18 is calculated.
in that a multiplier 15 for correcting the output voltage V _R of r. That is, in the equilibrium calculation coefficient calculation unit 13,
From K _F = 2V _R0 / (V _F0 + V _R0 ) K _R = 2V _F0 / (V _F0 + V _R0 ), two balance calculation coefficients K _F and K _R are calculated and given to the multiplication means 14 and 15, respectively. In multiplying means 14 and 15, the coefficients K _F, by multiplying respectively the K _R output voltage V _F, the V _R, and outputs the result to the imbalance value calculating unit 16.
The unbalance value calculating means 16 calculates a difference component between the two multiplication results, and the level determining means 17 determines whether the calculated unbalance value exceeds a predetermined set value.

FIG. 4 shows the operation of the voltage balancing relay of the embodiment shown in FIG.

In the above-described embodiment, the voltage is exemplified as the quantity of electricity. However, the present invention is not limited to the voltage, but may be a current, a phase, or the like.
It can be applied to other electric quantities.

[0057]

According to the present invention, in a balanced relay which responds to a difference between two electric quantities, it responds to an apparent imbalance caused by an error of an electric quantity or an error of an input converter. No, highly accurate operation can be performed. In addition, there is an advantage that no adjustment work is required, such as the necessity of balancing adjustment using a volume or the like which has been conventionally used. Furthermore , there is an advantage that the error becomes smaller when two electric quantities are dependent on each other, such as in a balanced relay used as a protection device of a phase adjustment facility.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a voltage balancing relay according to the premise of the present invention and a phase adjustment facility using the same.

FIG. 2 is a flowchart showing an operation of the voltage balancing relay.

FIG. 3 shows an embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of the embodiment.

[Explanation of symbols]

 13-Balance calculation coefficient calculation unit 14, 15-Multiplication means 16-Unbalance value calculation means 17-Level determination means (Unbalance detection means)

Continuation of front page (72) Inventor Takafumi Maeda 1-3-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Tokyo Electric Power Company (56) References JP-A-56-117536 (JP, A) JP-A-57-186916 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02H 3/02 H02H 3/28

Claims (1)

(57) [Claims] 1. A balanced relay responsive to the difference between two mutually correlated electrical quantities, wherein 2B ₀ / (A ₀₎ from initial quantities A ₀ and B _{0 of a} first input and a second input. + B
₀ ), 2A ₀ / (A ₀ + B ₀ ) as balance calculation coefficients.
Multiply 2B ₀ / (A ₀ + B ₀ ) by the first input to obtain 2A ₀ /
Correction means for multiplying (A ₀ + B ₀ ) by the second input to correct the first and second inputs, and imbalance due to a difference between the correction values of the first and second inputs corrected by the correction means And an unbalance detection means for detecting a state.