JP3132011B2 - Harmonic filter equipment protection 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 harmonic filter equipment protection relay provided for protecting a harmonic filter equipment.

[0002]

2. Description of the Related Art In a place where a large amount of harmonic current is generated as represented by a frequency conversion station, a harmonic filter facility is installed in parallel with the ground in order to absorb the harmonic current.

[0003] Harmonic filter equipment is a combination of a dedicated filter for removing a single frequency and a dual-purpose filter for simultaneously removing a plurality of harmonics. The eleventh and thirteenth harmonics are respectively removed by dedicated filters, and higher harmonics are removed by the combined filter. The n-th (n = 5, 11, 13)
The shunt for flowing the next harmonic is an n-th shunt (a dedicated filter is provided in this shunt), and the shunt for flowing higher harmonics collectively is an HP shunt (this shunt is A combined filter is provided).

[0004] One of the accidents in this harmonic filter equipment
One is a failure of a capacitor element and a reactor element constituting the harmonic filter equipment. There are several methods for detecting these faults, including a method for detecting impedance.However, the same-phase fundamental wave difference current between shunts focusing on the fundamental wave current flowing constantly in each shunt is considered. The detection method is adopted as an excellent method. The reason why the same phase is determined here is that the same phase does not depend on the imbalance of the phase voltages. In addition, the impedance method has a disadvantage that it is affected by frequency fluctuation.

FIG. 5 shows a circuit diagram of a conventional analog protection relay for detecting the same-phase fundamental wave difference current (see Nissin Electric Technical Report Vol. 23, No. 2 (1978, 4)). In the figure, there are four high-frequency shunts: a fifth shunt 5L, an eleventh shunt 11L, a thirteenth shunt 13L, and an HP shunt HPL, and a protection relay for monitoring a difference current between the shunts is illustrated. Have been. Hereinafter, the fifth
Although the protection relay for monitoring the difference current between the shunt 5L and the eleventh shunt 11L will be described, the operation of the protection relay for monitoring the difference current between the other shunts is similar to the operation of this protection relay. Therefore, the description is omitted.

As shown in FIG. 5, a filter circuit including a capacitor C5, a reactor L5, a resistor R5 and the like is provided in the fifth shunt 5L, and a capacitor C5 is provided in the eleventh shunt 11L.
11, a filter circuit comprising a reactor L11, a resistor R11, etc. is installed, and current transformers CT1, CT2, CT3 and CT4, CT5, which detect currents i5, i11 flowing through the respective shunts 5L, 11L.
CT6 is installed. Current transformers CT1 and CT
5 are connected to each other through compensating current transformers CCT1 and CCT2, and are connected to the current transformers CT1 and CT5.
, And the difference current Δi of the current corrected by the compensation current transformers CCT1 and CCT2 is obtained. Compensating current transformer CCT1, CC
T2 is for correcting a difference in the rated value of the fundamental wave between the shunts at the time of the initial adjustment. This difference current Δi is absorbed by the fifth harmonic pass filter F5 and the eleventh harmonic pass filter F11, and only the remaining fundamental wave component is introduced to the shunt fault detection relays 5A and 11B.

The shunt fault detection relay 5A is a relay that detects an increase in the current flowing through the fifth shunt based on an increase in the difference current Δi with reference to the current i5 flowing through the fifth shunt (ipol). The shunt fault detection relay 11B is a relay that detects an increase in the current flowing through the eleventh shunt based on a decrease in the difference current Δi based on the current i11 flowing through the eleventh shunt.

If the protection relay is configured as described above, it is possible to perform a protection operation against a typical accident such as a single-shunt element failure and a two-shunt same-phase element failure. For example, when the impedance decreases due to a failure of the capacitor of the fifth shunt, the fundamental wave current passing through the fifth shunt increases, and the fifth shunt side difference current between the fifth to eleventh shunts increases. The relay 5A operates and the relay 5B provided between the HP and the fifth shunt operates due to an increase in the fifth shunt current difference between the HP and the fifth shunt. Can be put out.

Further, when an element failure of the capacitor in the same phase of the two shunts, for example, a failure of the capacitor in the same phase of the fifth shunt or the HP shunt occurs, the current in the fifth shunt or the HP shunt is reduced. In order to increase, the relay 5A operates due to the increase of the fifth shunt side difference current between the fifth to eleventh shunts,
Since the relay HPB operates due to an increase in the HP shunt side difference current between the 13th and HP shunts, a trip command can be issued under this condition.

Further, if a ground fault or disconnection fault of a single shunt occurs, for example, a ground fault installed in the conductor of the reactor L5 of the fifth shunt or a disconnection of the resistor R5 occurs, the fifth shunt current becomes Decreases, equivalently, the eleventh shunt side difference current between the fifth to eleventh shunts increases, the relay 11B operates, and H
The HP shunt current difference between the P-fifth shunt increases and the relay H
Since the PA operates, a trip command can be issued according to this condition.

[0011]

However, in the case of the above-described capacitor internal element failure, the current in the failure shunt increases. However, in the case of a ground fault or disconnection failure, as will be understood from the above description, the other components are different. The current in the path increased only equivalently, and the decrease in current could not be directly detected. Therefore, there is a confusion that the relay on the faulty shunt does not operate and the relay on the faultless shunt operates.

Therefore, according to the present invention, a digital relay system is employed in protecting a harmonic filter equipment by detecting a same-phase fundamental wave difference current between shunts, and a capacitor internal element of the harmonic filter equipment is protected. In addition to the faults of the above, not only the ground fault fault in the harmonic filter equipment, the disconnection fault, or the fault in which the current decreases due to the short-circuit, the ground fault or the disconnection of the secondary side of the current transformer which is the current detecting means in the relay. It is an object of the present invention to provide a protection relay for a harmonic filter equipment capable of reliably detecting and responding to a faulty shunt.

[0013]

In order to achieve the above object, a harmonic filter equipment protection relay according to the present invention comprises a current detecting means for detecting a current flowing into each shunt, and a current detected by the current detecting means. A fundamental wave extracting means for obtaining a fundamental wave current value based on the shunt, and a fundamental wave current value of the shunt calculated by the fundamental wave extracting means and a basic wave of another shunt.
Wave current to the ratio of the fundamental wave current rating of both shunts.
A first determining means for determining an increase in the current flowing through the shunt from a change in a difference current from a value obtained by multiplying the shunt by the number of the shunts calculated by the fundamental wave extracting means .
The fundamental wave current value and the fundamental wave current values of the other shunts are
A second determining means for determining a decrease in the current flowing through the shunt from a change in a difference current from a value multiplied by a coefficient corresponding to a ratio of the main wave current rated value, and a determination output from the first determining means. A first trip command output means for outputting a trip command signal, and a second trip command output means for outputting a trip command signal based on the judgment output of the second judgment means. The command output means and the second trip command output means both perform timed operations,
The judgment value for the judgment by the first judgment means is set smaller than the judgment value of the second judgment means, and the operation time of the first trip instruction output means is shorter than that of the second trip instruction output means. It is set longer than the operation time.

[0014]

According to the harmonic filter equipment protection relay having the above configuration, first, the current flowing into each shunt of the harmonic filter equipment is detected, and the fundamental wave component is extracted by the fundamental wave extracting means. Then, a difference current between the currents flowing between the respective shunts is obtained based on the fundamental wave extracted by each fundamental wave extracting means.

Further, an increase in the shunt current is detected by the first determining means, and a decrease in the shunt current is detected by the second determining means. This makes it possible to directly detect a fault shunt even for a fault whose current decreases, such as a ground fault or a disconnection fault. In this case, for a fault in which the current increases, such as a capacitor element fault, the second determination means provided in the non-fault shunt detects a decrease in the current in the shunt, and as in the case of a ground fault / disconnection fault, For a failure in which the current decreases, the first determination means provided in the non-failure shunt may detect an increase in the shunt current.

However, the first trip command output means and the second trip command output means are operated in a timed manner,
The judgment value for the judgment by the first judgment means is made smaller than that of the second judgment means, and the operation time of the first trip command output means is made longer than the operation time of the second trip instruction output means. By increasing the length (see FIG. 2, which shows the operating range of the protection relay of the present invention. A change in the rated value of the fundamental wave current is used as a determination value that becomes the operation sensitivity of the first determination means and the second determination means. The rate of change is indicated by Pc and Pg, the operation time of the first trip command output means is indicated by Tc, and the operation time of the second trip command output means is indicated by Tg.) For failures such as internal element failures where the current increases, the first determination means first detects the increase in current with high sensitivity and for a long time, and detects failures where the current decreases like a ground fault or disconnection failure. On the other hand, by the second determination means, Since the decrease in the current is detected in a short time, the risk of double detection as described above can be avoided.

The reason why the operation sensitivity and the operation time are changed is that, in the case of the above-described disconnection fault and ground fault, the fault current increases depending on the fault location, and the fault must be detected in a short time in order to prevent the spread of the fault. On the other hand, the capacitor internal element of the shunt is composed of a number of small-capacitance capacitor elements connected in series and parallel, and a failure (short-circuit failure) of one of the elements has a small decrease in impedance, so that the current is small. This is because the increase is small, and detection must be performed with high sensitivity, and operation must be performed for a long time to avoid the influence of unnecessary operation due to a system transient.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows the fifth shunt 5L, the eleventh shunt 11L, and the first shunt 11L.
Filter circuit 2 connected to 3L shunt 13L and HP shunt HPL
It is a circuit diagram of protection relay which protects a-2d and each filter circuit 2a-2d.

Each of the filter circuits 2a to 2d is a series circuit including a capacitor, a reactor, a resistor, and the like. The current flowing through the filter circuits 2a to 2d is
a to 3d, and each of the fundamental wave extraction circuits 1a
To 1d. The fundamental wave extraction circuits 1a to 1d each include a harmonic attenuation filter 11a for attenuating a harmonic component of a current.
１１11d and a time corresponding to one cycle of the fundamental wave are equally divided at regular time intervals (in this embodiment, equally divided into 12; more or less may be used). Sampling circuits 12a to 12d
And effective value calculating circuits 13a to 13d for performing a square root calculation using a value obtained by adding a square value of the sampling value to a time corresponding to one cycle to each sampling value obtained by the sampling circuits 12a to 12d. Have.

The fundamental wave components obtained by the fundamental wave extracting circuits 1a to 1d are input to a judging circuit 4 (which operates as a difference current calculating means and a judging means). The increase / decrease of the difference current of the fundamental wave component is determined according to a determination formula (described later). The output of the decision circuit 4 is processed by a logic circuit 5 (corresponding to a trip command output means), and a trip command signal is output from the logic circuit 5 according to a certain standard.

Hereinafter, the operation of the protection relay will be described.
The sample value im sampled at each time by the sampling circuits 12a to 12d
3a to 13d are processed. RMS calculation circuit 13
Briefly describing the arithmetic processing method using a to 13d, at a certain point in time, two of past sampling values i0 to i11
The sum of the powers is taken, multiplied by 1/12 and the square root is taken. That is, it is calculated by the equation (1).

[0022]

(Equation 1)

Using the effective value calculation of the above equation (1), when the current contains a large amount of the fundamental wave component and does not contain much harmonic components, the magnitude I1 of the fundamental wave can be accurately calculated by the effective value calculation. It is well known that the approximation can be made (for example, if only the fundamental wave and the fifth harmonic exist, and the fundamental wave I1 = 100 and the fifth harmonic I5 = 3, the effective value is 100.0450, which is almost the fundamental wave component. This is because equation (1) can be regarded as an arithmetic expression that approximately extracts the magnitude of the fundamental component of the current.

By this calculation, the fundamental wave component can be calculated using the values in the past one cycle. Less than,
The fundamental wave component flowing through each shunt obtained in this way is indicated as I ⁽ⁱ⁾ (i = 5, 11, 13, HP). The fundamental wave component flowing through each shunt obtained in this way is input to the determination circuit 4.

FIG. 3 is a configuration diagram of the determination circuit 4. The fundamental wave output I ⁽⁵⁾ of the fifth shunt is supplied to the first determination circuit 41, respectively.
a, enters the second judgment circuit 42a, and in both judgment circuits,
Fundamental output I of the 11-minute passage ^(11), fundamental output I ⁽¹³⁾ of the first 13 minutes path is compared judged fundamental output I of the HP shunt ^(HP). In this case, the determination formula in the first determination circuit 41a is:
The rated value of the fundamental wave current in the j-th shunt (j = 5,11,13, HP) is represented by Inj, and by using r5j = In5 / Inj, I ⁽⁵⁾ -r5jI ^(j) is calculated as ΔI5j (j = 11,13, HP), then ΔI5j ≧ In5 × Pc / 100. Here, In5 is the fundamental wave current rating value in the fifth shunt as described above, and Pc is a value (%) corresponding to the rate of change of the fundamental wave current rating value for element failure determination. For example, assuming that Pc = 5%, the above-described determination formula indicates that the current of the fifth shunt has increased by 5% or more of the rated value of the fundamental wave current of the fifth shunt with reference to the current of the jth shunt. It represents.

The result of the judgment by the first judgment circuit 41a is obtained for each of j = 11, j = 13 and j = HP, so that a total of three judgment signals are output.
A signal representing the respective determination results ↑ 5 _11, ↑ 5 _13, displayed in ↑ 5 _HP. Further, the determination formula in the second determination circuit 42a is as follows: ΔI5j ≦ −In5 × Pg / 100 (j = 11,13, HP). Here, Pg is a value (%) corresponding to the rate of change of the rated value of the fundamental wave current for detecting a ground fault / disconnection, and Pg> P
c has been selected. For example, assuming that Pg = 10%, the above-mentioned determination formula indicates that the current of the fifth shunt is reduced by 10% or more of the rated value of the fundamental wave current of the fifth shunt with reference to the current of the jth shunt. Express.

The results of the determination by the second determination circuit 42a are also obtained for j = 11, j = 13, and j = HP, so that a total of three determination signals are output. Signals representing the results of each judgment are displayed as ↓ 5 _11, ↓ 5 ₁₃ , ↓ 5 _HP . The above description is for the first determination circuit 41a and the second determination circuit 42a for determining the current of the fifth shunt, but the fundamental wave output of the eleventh shunt and the fundamental wave of the thirteenth shunt Output 13, when determining the fundamental wave output of the HP shunt,
A first determination circuit and a second determination circuit are provided, respectively (not shown). The operation equation of each determination circuit can be expressed in the same manner as in the above case, and thus the description is omitted. Each judgment _{result, ↑ 11 5, ↑ 11 13} , ↑ 11 HP, ↓ 11 5, ↓
_{11 13, ↓ 11 HP, ↑} 13 5, ↑ 13 11, ↑ 13 HP, ↓
_{13 5, ↓ 13 11, ↓} 13 HP, ↑ HP 5, ↑ HP 11, ↑
HP ₁₃ , ↓ HP ₅ , ↓ HP ₁₁ , ↓ HP ₁₃ .

FIG. 4 is a detailed diagram of the logic circuit 5, and FIG.
The combination of the circuit shown in FIG. 7A and the circuit shown in FIG. Each decision signal ↑ 5 ₁₁ obtained first determination result, ↑ 5 _13, ↑ 5 _HP, as shown in FIG. 4 (a), ↑ 5 ₁₁ with ↑ 5 _13, ↑ 5 ₁₃ with ↑ 5 _HP, ↑ 5 _HP and ↑
5 ₁₃ Three pairs since each AND circuits 50a, 5
1a, 52a, and AND circuits 50a, 51a,
The output of 52a enters an OR circuit 53a,
The signal output from a is output to the outside as a capacitor internal element failure detection signal through a timed circuit 54a having a timed Tc. Also, other determination signal _{↑ 11 5, ↑ 11 13,} ↑ 11
_{HP, ↑ 13 5, ↑ 13} 11, ↑ 13 HP, ↑ HP 5, ↑ HP
₁₁ and ΔHP ₁₃ are also AND circuits 50b to 52b, 50
c to 52c, 50d to 52d, and an OR circuit 53b to
53d, which is output to the outside as a capacitor internal element failure detection signal through timed circuits 54b to 54d. As a result, from the four timed circuits 54a to 54d, the fifth shunt capacitor internal element failure detection signal, the eleventh shunt capacitor internal element failure detection signal, the thirteenth shunt capacitor internal element failure detection signal, the HP shunt capacitor internal An element failure detection signal is obtained.

Further, the determination signal ↓ 5 ₁₁ obtained the second determination result, ↓ 5 _13, ↓ 5 _HP also as shown in FIG. 4 (b), ↓ 5
₁₁ ↓ 5 _13, ↓ 5 ₁₃ and ↓ 5 _HP, ↓ 5 _HP and ↓ 5 ₁₃ three pairs since each AND circuits 55a, 56a, 57a
And the output of each of the AND circuits 55a, 56a and 57a enters an OR circuit 58a, and a signal output from the OR circuit 58a is externally transmitted through a time limit circuit 59a having a time limit Tg to a ground fault / disconnection fault detection signal in the filter equipment. Is output as Also, other determination signal _{↓ 11 5, ↓ 11 13,} ↓ 1
_{1 HP, ↓ 13 5, ↓} 13 11, ↓ 13 HP, ↓ HP 5, ↓ H
P _11, ↓ HP ₁₃ similarly AND circuit 55b~57b, 5
5c-57c, 55d-57d, and OR circuit 58b
To 58d, and output to the outside through the time limit circuits 59b to 59d as a ground fault / disconnection failure detection signal in the filter equipment. As a result, from the four timed circuits 59a to 59d, the fifth shunt ground fault / disconnection fault detection signal, the eleventh shunt ground fault / disconnection fault detection signal, the thirteenth shunt ground fault / disconnection fault detection signal, and the HP shunt ground fault, respectively.・ A disconnection failure detection signal is obtained.

The operation of the above logic circuit will be described. First, when a capacitor internal element of one shunt (i.e., shunt) fails, the determination signal 回路 i from the first determination circuit 41a of that shunt. _j (j ≠ i) comes out three, so A of that shunt
The ND circuit always operates, and the output of the OR circuit appears. Therefore, if the output continues for the time Tc or more, an output can be output from the timed circuit.

[0031] In this case, the second decision circuit 42a of another shunt also be issued an operation determination signal ↓ j _i, but since the AND circuit of the other of the shunt does not work, to issue an erroneous signal There is no. In addition, a ground fault of one shunt (referred to as i shunt)
In the case of a disconnection failure, since three determination signals ↓ i _j (j ≠ i) are output from the second determination circuit 42a of the shunt, the AND circuit always operates and the output of the OR circuit appears. Therefore, if the output continues for the time Tg or more, the output of the timed circuit can be output. At this time, the first determination circuit 41a of another shunt
Also it is to issue an operation determination signal ↑ j _i, since the AND circuit is not operating, the never give an erroneous signal is the same as above.

Next, in the event of a simultaneous failure of the capacitor internal elements of the two shunts (referred to as the i-th shunt and the j-th shunt), the first determination circuit of the i-th shunt determines the determination signal _{ i _k (k} i, k ≠ j), the AND circuit operates and the output of the OR circuit appears. Also, the judgment signal ↑ j is output from the first judgment circuit of the j-th shunt.
_{Since two k} (k ≠ j, k ≠ i) appear, the AND circuit of the shunt operates and the output of the OR circuit appears. Therefore, both the capacitor internal element failure detection signal of the i-th shunt and the capacitor internal element failure detection signal of the j-th shunt are output, and it is understood that the capacitor internal element failure of both the shunts.

It should be noted that the judgment signal ↓ k _{i is} also output from the second judgment circuit.
(k ≠ i, k ≠ j) and ↓ k _j (k ≠ i, k ≠ j)
Two AND circuits of shunts other than i and j work, and a ground fault / disconnection signal of a shunt other than i and j is output. Is set to be larger than Pc, the capacitor internal element failure detection signal appears first. Therefore, there is no possibility of being determined to be ground fault / disconnection.

Next, when there is a ground fault or disconnection fault in the second shunt (the ith shunt and the jth shunt), the judgment signal ↓ _ik (k ≠) is sent from the second judgment circuit of the ith shunt. i, k ≠ j) appears twice, so A
The ND circuit always operates, and the output of the OR circuit appears. Also, the judgment signal ↓ j _k (k か ら) is sent from the second judgment circuit of the j-th shunt.
j, k ≠ i), the AND circuit of the shunt always operates, and the output of the OR circuit appears. Therefore, both the ground fault and disconnection fault detection signal of the first shunt and the ground fault and disconnection fault detection signal of the jth shunt are output, and it is understood that there is a ground fault and disconnection fault of both shunts. At this time, the judgment signals ↑ k _i (k ≠ i, k ≠ j) and ↑ k _j (k ≠ i, k ≠ j) are also output from the first judgment circuit, and the shunts other than i, j Two AND circuits operate to generate a capacitor internal element failure signal in a shunt other than i and j. However, the time Tg for detecting a ground fault / disconnection is set shorter than the time Tc for detecting a capacitor internal element failure. Therefore, a ground fault / disconnection detection signal appears first, and it is not determined that a capacitor internal element failure has occurred.

Tables 1 to 4 summarize the above results in a table. Table 1 shows the case of the capacitor internal element failure of one shunt, Table 2 shows the case of capacitor internal element failure of the two shunt, Table 3 shows the case of ground fault / disconnection failure of the one shunt, and Table 4 shows the case of the two branch shunt. Shows the case of ground fault or disconnection fault. In the table, ◎ indicates the judgment output of the judgment circuit, X indicates the non-judgment output of the judgment circuit, and ○ indicates the judgment output of the judgment circuit. As described above, Pg> P
Since c and Tg <Tc, the case where it does not actually appear as an output is shown. In Tables 1 to 4, the one-shunt failure is the fifth shunt only and the two-shunt failure is the fifth shunt.
Although the case between the shunt and the eleventh shunt is shown, failures in other shunts can be considered in exactly the same way.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4]

The present invention is not limited to the above embodiment. For example, a fundamental component may be obtained by a Fourier integration method instead of performing an effective value operation. Various other design changes can be made without departing from the scope of the present invention.

[0041]

As described above, according to the harmonic filter equipment protection relay of the present invention, the current flowing into each shunt of the harmonic filter equipment is detected, and the fundamental wave component is obtained. By separately determining the increase and decrease of the flowing current in the form of the difference from the current of the other shunt, and applying different judgment values and time limits to each, failure of the capacitor internal element, ground fault in the filter equipment -It is possible to realize a protection relay that responds accurately to any failure such as disconnection.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a specific configuration of a harmonic filter equipment protection relay.

FIG. 2 is a graph showing an operation area of a harmonic filter equipment protection relay.

FIG. 3 is a block diagram illustrating an internal configuration of a determination circuit.

FIG. 4 is a circuit diagram showing an internal configuration of a logic circuit.

FIG. 5 is a circuit diagram showing a conventional analog type harmonic filter equipment protection relay.

[Description of Signs] 1a-1d Fundamental Wave Extraction Circuit 2a-2d Filter 3a-3d Current Transformer 4 Judgment Circuit 5 Logic Circuit 11a-11d Harmonic Attenuation Circuit 12a-12d Sampling Circuit 13a-13d Effective Value Operation Circuit 41a First Judgment circuit 41b Second judgment circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02H 7/00 H02J 3/01

Claims (1)

(57) [Claims] 1. A relay for protecting a harmonic filter equipment by detecting a same-phase fundamental difference current between harmonic shunts of a harmonic filter equipment, wherein a current flowing into each shunt is detected. Current detection means, fundamental wave extraction means for obtaining a fundamental wave current value based on the detection current of the current detection means, provided in each shunt, and the fundamental wave current value of the shunt calculated by the fundamental wave extraction means , The fundamental current value of the other shunts
Multiplied by a coefficient corresponding to the ratio of the fundamental current rating of both shunts
First determining means for determining an increase in the current flowing through the shunt based on a change in the difference current from the shunt current, and a fundamental wave current of the shunt calculated in the shunt calculated by the fundamental wave extracting means. Values and fundamental current values of other shunts
Multiplied by a coefficient corresponding to the ratio of the fundamental current rating of both shunts
A second determining means for determining a decrease in the current flowing through the shunt from a change in a difference current between the first and second trips, and a first trip command output for outputting a trip command signal based on a decision output of the first determining means. Means and a second trip command output means for outputting a trip command signal based on the judgment output of the second judgment means, wherein both the first trip command output means and the second trip command output means are timed. A determination value for the determination by the first determination means is set to be smaller than a determination value of the second determination means; A harmonic filter equipment protection relay, wherein the operation time is set longer than the operation time of the trip command output means.