JPH069429B2 - Digital ground fault bus protection relay - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a digital ground fault busbar protective relay device for protecting a busbar of a high resistance grounding power system, and is particularly applied to a cable system.

[Prior Art] FIG. 4 is a circuit diagram showing a conventional busbar protection device disclosed in, for example, Japanese Patent Publication No. 50-27574.
(1) is a bus, (3-1) to (3-n) is CT, (14) is PT, (15-1)
~ (15-n) is an input device, (16) (17) is a transformer, (18) is a resistor, (19) is a rectifier circuit, (20) is a busbar protection relay, (21) is a zero-phase current (hereinafter, _Io or _Io current) Effective component differential amount derivation circuit, (22) is _Io effective component suppression amount derivation circuit, (23)
Is a level detection circuit.

Next, the operation will be described. _Io current is derived from the residual circuits of CT (3-1) to (3-n) installed on all lines connected to the busbar (1), and this is input to input devices (15-1) to (15-n). ),
The transformer (16) creates the amount of operation, and the transformer (17), the resistor (18), and the rectifier circuit (19) create the amount of suppression. All line input devices (15-1) to (1
The output of the transformer (16) of (5-n) is vector-combined to obtain a differential amount, and the outputs of the rectifier circuits (19) are connected in parallel to each other to obtain I _{o of} each line.
The maximum value of the suppression amount proportional to the current is obtained. With the above configuration, when the bus (1) has an external accident, the differential amount is zero or a minute amount proportional to the CT error, and the suppression amount is an amount proportional to the fault current. On the other hand, in the case of an internal bus fault, the differential amount is proportional to the fault current, and the suppression amount is proportional to the maximum value of the line fault currents flowing into the bus. The busbar protection relay (20) is a relay based on the ratio differential principle, which introduces the differential amount and the suppression amount to detect a busbar accident, but the cable system is connected to the transmission line connected to the busbar (1). If so, the normal ratio differential relay has a drawback that reliable operation cannot be expected in the event of an internal accident. This will be described with reference to FIG.
When the cable transmission line is connected to the busbar (1) and the charging capacity (24) is large, a neutral point, a reactor (hereinafter referred to as NGL) (26), is usually provided to compensate for this. If a one-line ground fault occurs on the bus (1) in this system, CT (3-1), (3-
The 2) flow charging people flow jI _C, CT (3-3) in the neutral point resistor (hereinafter, referred to as NGR.) (25) of the current _{I N} and NGL (2
Will be the combined value I _N -jI _L current -JI _L 6) flows, a fifth corresponding to the output circuit of the rectifier circuit of FIG. 4 (19)
Suppressing the output I _R of the maximum value suppression derivation circuit of Fig. (27) I _N -j
The amount is proportional to I _L , and the differential output I of the differential amount deriving circuit (28) of FIG. 5 corresponding to the transformer (6) output circuit of FIG.
_D is the case of _I N _-jI L + _{2jI C} next to _{I L = 2I C I D =} I N. As is clear from the above description, if the amount of suppression by the reactive currents I _C and I _L becomes large, the ratio differential relay (29) becomes inoperable due to an internal bus accident. As a countermeasure against the above reactive current, the conventional device shown in FIG.
The busbar protection relay (20) is based on the I _O effective ratio differential principle. That is, in FIG. 4, the input devices (15-1) to (15-
suppressing the output E _R and bus (1) connected to the third order from the obtained zero-phase voltage of the PT of n) (hereinafter, referred to as V _O or V _O voltage.) The I _O active component suppression Ryoshirube circuit (22 ), And the differential output I _D
And V _O voltage are introduced into the I _O effective component differential amount deriving circuit (21),
To derive the V _O voltage and phase inhibiting amount E _RN and the differential amount E _DN of,
_{E DN -η R E RN K O} ( where η _{R, K O} is constant) at the level detection circuit (23) is adapted to determine.

FIG. 6 shows another conventional embodiment. (1-1) (1-2) are busbars
(101) ~ (1n), (201) ~ (2n) is a disconnecting switch, (14-1) (14-2) is P
T (101x) ~ (1nx), (201x) ~ (2nx) are disconnectors (101) ~ (1
n), (201) ~ (2n) auxiliary relay contact closes when operating. (20-1) is a busbar protection relay that protects busbar 1 (1-1) (hereinafter referred to as 87A), (20-2) is a busbar protection relay that protects busbar 2 (1-2) (hereinafter referred to as 87B) ) And the input device (1
5-1) to (15-n) and 87A (20-1), 87B (20-2) have the same structure and principle as those in FIG. The example of FIG. 6 shows a well-known protection system called a split system for protecting a double bus, in which each line connected to the bus is connected to a disconnecting switch (101), (201)-(1).
n) (2n) according to the selected state of bus 1 (1-1) or bus 2 (1-2), the output of the input device (15-1) ~ (15-n) contacts (101x) ( 2
Switch from 01x) to (1nx) (2nx) 87A (20-1) Bus 1 (1-1)
Introduced the output of the input device of all lines connected to, 87B (20-
In 2), the input device outputs of all the lines connected to the bus 2 (1-2) are introduced.

[Problems to be solved by the invention]

Since the conventional busbar protection device is configured as described above, an input device for each line and a busbar protection relay for each busbar are required, the amount of hardware is large, and the double busbar protection shown in FIG. 6 is required. Since many disconnector auxiliary relay contacts are used,
There are problems that contact failure is likely to occur and the number of wires in the device is large.

The present invention has been made to solve the above-mentioned problems, and a digital relay using a microprocessor, which is expected to develop more and more in the future, is used to process the conventional _IO effective current ratio differential principle by software. The purpose of the present invention is to obtain a digital type ground fault bus protection relay device that can obtain a high-performance relay with no characteristic deterioration and can easily perform software processing on the disconnector switching conditions.

[Means for solving problems]

The digital ground fault bus protection relay device according to the present invention derives an effective component current from the I _O current of each line by a digital relay, and sets the maximum value or scalar sum thereof as the suppression amount | I _R | Difference of the effective component of the sum of I _O current vector of
_{As D} | | I _D | -η _R | I _R |> 0 (η _R is a constant)
And a second element for discriminating the I _O current vector sum level of each line, and operated under the AND condition of the first element and the second element. In addition, in double bus protection, a disconnecting switch condition for selecting a bus is introduced into the digital relay, and IO current data of each line is selected according to the ON-OFF condition of the disconnecting switch, and the above first element and Two element operations are performed.

[Action]

Since the digital busbar protection relay device according to the present invention performs the ratio differential operation with the IO active current of each line, an unnecessary suppression amount is not generated by the reactive current of the cable system, and the double busbar protection is performed. Since the CT secondary IO current of each line is not directly switched by the disconnect switch auxiliary relay contact, the number of contacts is reduced and contact failure is reduced.

〔Example〕

In FIG. 1 showing an embodiment of the present invention, CT (3-1)
~ (3-n) secondary current is input transformer with cap (4-1) ~ (4
-n) converts the voltage, and the tertiary voltage of PT (14) is introduced into the digital relay (5) via the input transformer (4-a). In the case of a double busbar The disconnecting switch (101) (201)… (1n) (2n) is opened / closed by a digital relay (5) via its auxiliary relay contact (101x) (201x)… (1nx) (2nx). ) Has been introduced. Input transformer (4-1)
Each of the secondary outputs of (4-n) and (4-a) passes through a filter (6) and a sample-hold device (hereinafter referred to as S / H) (7).
At the same time, sample the instantaneous value of analog quantity at a constant interval. The multiplexer (8) sequentially switches the output of each S / H (7), converts the analog quantity into a digital quantity by the analog-digital converter (9), and stores it in the memory (12). The open / closed state of the disconnecting switch for the double bus is taken in from the digital input circuit (10), stored in the memory (12), and the CPU (13) performs the selection calculation of the digital current amount, and the output of the relay calculation result is digital. The output circuit (11) outputs it to the outside.

FIG. 2 shows the operation principle of the digital ground fault bus protection relay device having the above-mentioned configuration. In FIG. 2, inputs I _{1 to} In are digital quantities proportional to the secondary current instantaneous values of CT (3-1) to (3-n) in FIG. 1, respectively, and input VO is the tertiary of PT (14). It is a digital value proportional to the instantaneous value of VO voltage.
Figure memory (12) Temporarily stored. The arithmetic processing blocks (101) to (108) show the contents to be calculated by the CPU (13) according to the program written in the memory (12), and the block (101) shows the IO effective of each line CT secondary current. The calculation block for deriving the minute, the block (102) is a differential amount I _D
, A block (103) is a calculation block for deriving the suppression amount, (104) is a calculation block for deriving the IO effective component of the differential amount I _D , and a block (105) is a calculation block for ratio differential determination. A block (106) is a block for calculating an amplitude value, a block (107) is a block for determining a differential level, and (108) is a logical product operation circuit. The details of the calculation will be described below. The block (101) is current data I _{1 to} I
Up to n, the IO effective component derivation calculation is performed for each current data, and the calculation will be as follows if the IO effective component of the current data In is calculated.

Current data In at time t, respectively Vo data Vo I _nt, if _{V ot V ot = V O sinωt} ...... (1) Formula _{I nt = I n sin (ωt} + θn) ...... (2) equation However, .theta.n Is the phase angle between Vo and I _n , and current data I _n and Vo data 90 ° before time t is I
_nt -90 °, if V _ot -90 ° V _ot -90 ° = Vosin (ωt-90 °) = Vocosωt ...... (3) formula I _nt -90 ° _{= I n sin (ωt + θn} -90 °) = _{I n cos (ωt + θn)} ...... (4) equation (1) to (4) and _{V ot · I nt + V ot} -90 ° · I _nt -90 ° _{= Vo · I n cosθn ...... (} 5) from equation equation A product value of the Vo voltage amplitude value Vo and the effective component amplitude value I _n cos θn of the Io current (where θn is the phase angle of the Vo current and the In current) irrespective of the time t can be obtained.

Next, block (102) is a differential amount deriving operation to full line partial addition operation the current data I _lt ~I _nt of time t. Now, if the addition result (differential amount) is I _Dt The block (104) is an _Io effective component deriving operation of the differential amount I _D , and the method of deriving the _Io effective component may be the same operation as the equations (1) to (5).

A = V _ot I _Dt + V _ot −90 ° I _Dt −90 ° = V _o I _D cos θ (7) Equation (7) Next, the block (103) is the suppression amount derivation operation and the block (10) is used.
Current data _I 1 for each line derived by 1) ~I _n of _{I o} active current in proportion to _V o _{I n cosθn} (where n =. 1 to
The maximum value | B | of the absolute values of n) is selected, and for example, an operation of comparing two data in magnitude may be sequentially executed.

The block (105) calculates the ratio differential principle of the relay. The absolute value | A | of the differential amount expressed by the equation (7) and the absolute value | B | Perform the operation of.

, And therefore _{| A | -η R | B |} > 0 is _V o (| I _DN | _-η
R | V _RN |)> 0 and eventually | I _DN | −η _R | I
_RN |)> 0 is discriminated, which is a ratio differential operation by the effective current of I _o .

The block (106) is the amplitude value calculation of the differential amount I _D , and the vector calculation method, the area method, and the like are well known, and therefore the description thereof is omitted here. A block (107) is a comparison calculation of the calculation result of the amplitude value of the differential amount I _D and a constant K _o that determines the operation value, and the ratio differential calculation result and the differential level determination of the block (105) both operate. When this happens, the relay output by the AND operation circuit (108) is output.

In addition, in the above embodiment, the single busbar protection is used, but it can be applied to the double busbar protection, and this embodiment is shown in FIG.
FIG. 3 is a bus bar 1 (1-1) corresponding to FIG. 6 showing a conventional example.
And the bus 2 (1-2) are protected by one digital relay, and the currents I _{1 to} In are CT (3-1) to (3-n) in FIG.
The V _o voltage data V _OA and V _OB are PT (14-1) and (14-
2) introduced, LS ON-OFF data (101x) ~ (1nx), (201
x) to (2nx) are the disconnectors (101) to (1n) and (201) to (2n) of FIG.
In the ON-OFF state of FIG. 1, the inputs to the digital relay are the currents I _{1 to} In shown in FIG. 1, the input transformers (4-1) to (4-n), and the Vo voltage V. _OA and V _OB are introduced from the input transformer (4-a) in FIG. 1 and the input transformer for the bus 2 (not shown), and LS ON-OFF data (101x) to (1nx), (201
x) to (2nx) are introduced into DI (10) of digital relay (5).
In FIG. 3, a block (109) is an LS selection calculation block and corresponds to the secondary output switching circuit of the conventional input devices (15-1) to (15-n) shown in FIG. 6, for example, the disconnector (101). Is ON and the disconnector (201) is OFF, the LS ON-OFF data (101x) is “1” (O
N) and (201x) are set to “0” (OFF), and the current data I ₁ is calculated so as to be extracted for the bus 1 (1-1). Block (11
Reference numerals 0) and (111) respectively represent current data groups selected for the bus 2 (1-2) for the bus 1 (1-1). Blocks (112), (113)
Shows the calculation of the busbar 1 (1-1) protection relay and the busbar 2 (1-2) protection relay, respectively, which is equivalent to the conventional Fig. 87A, 87B, and is the calculation of the blocks (112), (113). The contents are the same as in FIG. Further, in the above embodiment is of a maximum value introduced block (103) of FIG. 2, but the block (101) of each current Io active component V _o I _n cosθn similar as the absolute value sum (scalar sum inhibition) The effect can be obtained. Further, the block (102) in FIG. 2 derives the differential amount by digital calculation, but in the case of the single bus configuration, the input transformer (4-
A tertiary coil may be provided in 1) to (4-n), and the output may be introduced into the digital relay (5) as an analog composite differential.

〔The invention's effect〕

As described above, according to the present invention, the I _o current of each line and the V _o voltage of the bus are introduced into the digital relay, the I _o effective current for each line is calculated, and this is used as the suppression amount. As a result, unnecessary suppression power due to reactive current is eliminated, and _Io current switching of each line necessary for double bus protection can be performed by introducing LS ON-OFF information of each line to a digital relay and performing digital arithmetic processing. , Wiring inside the device can be simplified,
Factors for contact failure can be reduced, and high performance and high reliability can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram according to one embodiment of the present invention, FIG. 2 is the same operation principle diagram, FIG. 3 is an operation principle diagram showing another embodiment of the present invention, and FIG. 4 is a conventional configuration diagram, FIG. 5 is a supplementary explanatory view for explaining the reason why the principle of I _o effective current ratio differential is required in the conventional and the present invention, and FIG. 6 is another configuration diagram of the conventional. In the figure, (6) is a filter, (7) is a sample and hold device, (8) is a multipressor, (9) is an A / D converter, and (10).
Is a digital input, (12) is a memory, (13) is a microprocessor, (101) is an _Io effective component deriving means for each current, (102) is a differential amount deriving means, (103) is a maximum value deriving means, (104) is an I _o effective component derivation means of I _D , (105) is a ratio calculation derivation means, (107)
Is a differential level determination means, and (108) is an AND element. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A zero-phase current of each line derived from a current transformer installed in each line connected to a bus and a zero-phase voltage derived from an instrument transformer connected to the bus at the same time, sampled at the same intervals, in the digital form locations絡母line protective relay device having means for converting digital quantity, instantaneous values I _nt proportional to the zero-phase current of the respective line at time t, by an electrical angle of the time t Instantaneous value data _Int- 90 ° proportional to the zero-phase current of each line at a time 90 ° earlier,
Instantaneous value data V proportional to the zero-phase voltage at time t
_ot , instantaneous value data V _ot −90 ° proportional to the zero-phase voltage at a time 90 ° before the time t in electrical angle is introduced, and based on these data, the differential amount I _Dt = Σ at the time t
_Int and the differential amount at time t-90 ° I _Dt −90 ° = ΣI _nt
-90 ° and calculated data A = V _ot · I _Dt + V _ot −90 °
First computing means for computing I _Dt -90 °, | V _ot · I _nt +
V _ot −90 ° · _Int −90 ° | maximum value in the calculated data, or second calculated means for calculating the calculated data B of the respective scalar sums, data calculated by the first and second calculating means To | A | −η _R | B |> 0 (where η _R is a constant)
The first element for determining the difference, I _Dt ² + (I _Dt −90 °) ² −K
_A second element for determining ₀ > 0, and the first and second elements
A digital ground fault bus protection relay device, which generates an operation output when both elements of the operation are determined to be operation.