JPH05137232A - Protective relay having function for switching instrument transformer - Google Patents

Abstract

PURPOSE:To sustain continuity of secondary voltage even at the time of switching secondary voltage of an instrument transformer. CONSTITUTION:Secondary voltages VA, VB of an instrument transformer are converted, at an A/D converting section 21, into digital information. The digital information and 'ON', 'OFF' information of line switches 6a-6n, 7a-7n are then processed at a processing section 24. The processing section 24 contains first and second instrument transformer switching processing sections 24a, 24b and a protective relay arithmetic processing section 24c for processing the information. According to the constitution, secondary voltage can be switched without intermission keeping its continuity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective relay device having an instrument transformer switching function.

[0002]

2. Description of the Related Art FIG. 8 is an explanatory view of the configuration of an instrument transformer switching device. In FIG. 8, buses 1 and 2 are connected by line switches 3 and 5 and a bus breaker 4. Also,
Line switch group 6a connected in series between the buses 1 and 2
6n and 7a to 7n are connected. Line switch group 6
Branch lines 9a to 9n are connected to common connection points 8a to 8n of a to 6n and 7a to 7n. Breakers 10a to 10n and current transformers 11a to 11n are provided on the branch lines 9a to 9n.

Reference numerals 12 and 13 are transformers for measuring instruments, and the secondary voltages V _A and V _{B of the} transformers 12 and 13 are the changing transformers for measuring instruments 1
Given to 4. Further, "ON" of the line switch group 6a~6n and 7a~7n This switch 14, "OFF" information is given, instrument transformer switch with this information and the secondary voltage V _A and V _B Reference numeral 14 denotes a protection relay (not shown) operation information V of the branch lines 9a to 9n by a switching processing circuit described later.
to output _a ~V _n.

Next, the switching processing circuit of the instrument transformer switching device 14 will be described. This circuit has two types, an uninterruptible switching processing circuit and an uninterruptible switching processing circuit. The former circuit is shown in FIG.
And the latter circuit is shown in FIG.
First, the switching processing circuit shown in FIG. 9 will be described. The circuit shown in FIG. 9 is connected to the bus bar 1 during switching, and is connected to the transformer 1 for an instrument.
Secondary voltage V _A of 2 and transformer 1 for instrument connected to bus 2
The secondary voltage V _B of 3 is once switched in parallel, and then switched.
In FIG. 9, the operation output of the AC undervoltage relay 27A is given to the inhibit input terminal of the AND circuit A ₁ .
The line switch 6 is connected to the other input terminal of the AND circuit A _1.
The "on" information for a is given. The output information of the AND circuit A ₁ is given to the set terminal S of the flip-flop FF ₁ .

The "OFF" information of the line switch 6a is applied to the first input terminal of the AND circuit A ₂ , and the output information of the output terminal Q of the flip-flop FF ₂ is applied to the second input terminal. When AND circuit A ₂ satisfies both information,
Inverts the output of the flip-flop FF ₁ gives output information to the reset terminal R of the flip-flop FF _1. The AND circuit A ₃ sends the operation information V _a to the output via the OR circuit OR when the AND condition is satisfied by the output voltage V _A and the output information of the output terminal Q of the flip-flop FF ₁ .

Similarly, the AND circuit A ₄ flip-flops FF when the AND condition is satisfied by the operation output of the AC undervoltage relay 27B and the "ON" information of the line switch 7a.
₂ is set. Further, in the AND circuit A ₅ , the flip-flop FF ₂ is reset when the AND condition is satisfied by the “OFF” information of the line switch 7b and the output information of the flip-flop FF ₁ . The output information of the flip-flop FF ₂ and the secondary voltage V _B are input to the AND circuit A ₆ , and when the AND condition is satisfied, the operation information V _a is sent to the output via the OR circuit OR.

FIG. 10 is a time chart of the uninterruptible switching processing circuit described above. During switching from FIG. 10, the secondary voltages V _A and V _B of the instrument transformers 12 and 13 are added and output. , Can be switched without power failure.

Next, the switching processing circuit shown in FIG. 11 will be described. The circuit shown in FIG. 11 is designed so that the secondary voltage of the instrument transformer that has been used up to now, for example, V _B is disconnected and then V _A is applied to switch the circuit. AND circuit A which takes the AND condition of the "ON" information of the line switch 6a and the "OFF" information of the line switch 7a
₇ , output information of AND circuit A ₁ and flip-flop FF
An AND circuit A ₈ with an inhibit terminal that takes the AND condition of the output information of ₂ and a timer T ₁ are provided, and the AND circuit A ₂ is provided.
The output information of the AND circuit A ₄ is given to the second input terminal of the. Although this circuit is for the secondary voltage V _A , the circuit for the secondary voltage V _B is similarly constructed.

FIG. 12 is a time chart of the above-described power failure switching processing circuit. During switching from FIG. 12, the secondary voltages V _A and V _B of the instrument transformers 12 and 13 are kept for a fixed time and the switching device 14 is operated.
No longer appears in the output. That is, the operation information V _a disappears, whereby the protective relay operates and the lines 9a-9
n will be a power outage.

[0010]

[Problem to be Solved by the Invention] Transformer 1 for instrument
4, when switching from one bus bar currently used to the other bus line, there are the uninterruptible switching system (the one shown in FIG. 9) and the power failure switching system (the one shown in FIG. 11) as described above.
In the former method, there is no unnecessary operation of each relay due to loss of the suppression voltage, so there is no need to lock the trip circuit when switching. Therefore, although the device can be simplified, the secondary voltage is doubled because the secondary voltages V _A and V _{B of} the instrument transformers 12 and 13 are added, which causes a so-called reverse up phenomenon. have.

Further, in the latter method, since the secondary voltage is not added, the reverse up phenomenon does not occur, but since the suppression voltage is lost due to the switching, it is necessary to lock the trip circuit or the like. For this reason, the device becomes complicated, and the reliability is lowered due to routing of a trip circuit or the like.

Further, since the instrument transformer switching device and the protective relay device are separate devices, the hardware cost is increased and the reliability of the protective relay device is reduced.

The present invention has been made in view of the above circumstances, and is intended to maintain the continuity of the secondary voltage even when the secondary voltage of the instrument transformer is switched, and to prevent disconnection of the instrument transformer. An object of the present invention is to provide a protective relay device having an instrument transformer switching function that can switch to a sound instrument transformer even when a failure occurs.

[0014]

In order to achieve the above-mentioned object, the present invention connects two bus bars with a bus bar breaker and a line switch group connected in series, and a line switch group connected in series. In a power transmission system in which branch lines are respectively drawn from the common connection points of the above, each of the bus bars is provided with an instrument transformer, and the secondary voltage of these instrument transformers and the current flowing in the branch line are digitalized by an analog-digital converter. The information is converted into information and supplied to the common bus, and the "ON" and "OFF" information of the line switch group and the "ON" information of the busbar breaker are supplied to the digital input section, and the output information of the digital input section is supplied. Is supplied to the common bus, and the processing unit connected to the common bus uses both information from the analog-digital conversion unit and the digital input unit. Performs arithmetic processing of switching processing and protection relay dexterity transformer, in which the processing outputs of the protection relay and so as to delivered from the digital output unit.

[0015]

The digital information of the secondary voltage of the instrument transformer and the current flowing in the branch line, which are input to the analog-digital conversion section, and the "ON" and "OFF" information of the line switch output from the digital input section. Etc. are processed by the processing unit.
In the processing unit, the secondary voltage of the instrument transformer is processed so as to be switched continuously without being interrupted, and when one of the instrument transformers fails, the other instrument transformer is also switched. The switching process is performed without interrupting the secondary voltage. In addition to this, the processing unit also performs arithmetic processing of the protective relay,
The result is sent from the digital output section.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 21 is an analog-digital conversion unit (A / D conversion unit), and this A / D conversion unit 21 is composed of a sampling hold S / H, a multiplexer MPX and an A / D converter, and is an instrument transformer. (12 and 13 shown in FIG. 8) secondary voltages V _A and V _B and branch lines (FIG. 8)
The analog information of the current I flowing in 9a to 9n) is converted into digital information and supplied to the common bus 22. Reference numeral 23 is a digital input section.
Line switches 3, 5, 6a to 6n, 7a to 7n shown in
"ON" and "OFF" information of the above and "ON" information of the busbar breaker 4 are given. The digital input unit 23 sends the input information to the common bus 22. Common bus 22
The above-mentioned two pieces of information that have flowed to the processing section 24 are taken into the processing section 24, where switching processing of the instrument transformer is performed. The processing unit 24 includes a first and second instrument switching processing unit 24a, the details of which will be described later.
24b and a protective relay arithmetic processing unit 24c. Reference numeral 25 denotes a digital output unit, which sends the output information of the protective relay processed by the processing unit 24.

FIG. 2 is a logic circuit diagram of the first instrument switching processing section 24a. In FIG. 2, AND circuits A _{21 to} A ₂₄ have inhibit terminals, and a line is provided to the inhibit terminals of the AND circuit A _21. The "ON" information of the switch 6a is given, and the line switch 6a "OFF" information is given to the other terminals. FF ₂₁ ~FF ₂₃ is a flip-flop, to the set terminal S of the flip-flop FF ₂₁ given the "ON" information of the line switch 6a, the flip-flop FF
₂₁ is set. The output of the AND circuit A ₂₁ is given to the reset terminal R of the flip-flop FF _21, thereby the flip-flop FF ₂₁ is reset. Similarly, the flip-flop FF ₂₂ is set by the "ON" information of the line switch 7a and reset by the output of the AND circuit A ₂₂ .

The output from the output terminal Q of the flip-flop FF ₂₁ sets the flip-flop FF _3, and the output is sent from the output terminal Q thereof. This output is given to one input terminal of the AND circuit A ₂₅ . When the secondary voltage V _A is applied to the other input terminal of the AND circuit A ₂₅ and the AND condition is satisfied, the operation information V _{a is} output to the output of the OR circuit OR.
Is sent. The flip-flop FF ₂₃ is an AND circuit A.
Reset at ₂₃ outputs. The AND circuit A ₂₄ outputs the operation information V _a via the OR circuit OR when the secondary voltage V _B and the output of the flip-flop FF ₃ are exhausted.
This operation information V _a is continuously transmitted as described later.

FIG. 3 is a time chart of the logic circuit diagram shown in FIG. 2. From FIG. 3, the logic circuit shows a sampling time Δ.
When operating at t, the operation information V _a is the secondary voltage V _B to V
Even if switched to _A , normally V _B = V _A , so that the operation is continuously performed. Therefore, operation information V _a will not be as discontinuous (intermittent).

FIG. 4 shows a second instrument transformer switching processing section 24.
In the logic circuit diagram of b, OR is an OR circuit and A is A in FIG.
N is an AND circuit, NA is a NAND circuit, T ₁ and T ₂ are timers, FF is a flip-flop, and IN is a knot circuit. In FIG. 4, when a disconnection occurs in the instrument transformer 12, or when an abnormality occurs in the _VA intake section of the analog-digital conversion section 21, the logic circuit diagram of FIG. 4 shows the time shown in FIG. Works like a chart. That is, in FIG. 5, when a disconnection occurs at the time point a in the figure, the sound side transformer 13 is switched to the sound side transformer 13 after the time T ₁ (time point opening) of the timer T ₁ . After that, when the disconnection is restored (time point c), the time is changed to the instrument transformer 12 after T ₂ time (time point d) of the timer T ₂ . Note that the LS bridge in FIG. 4 refers to a state in which the line switch 6a is "on" and the line switch 7a is "on". Further, V _Aa , V _Ab , and V _Ac represent V _A in three-phase representation, and the same V _Ba , V _Bb , and V _Bc represent V _B in three-phase representation.

FIG. 6 shows an example in which a process combining the first and second instrument transformer switching processing units 24a and 24b is applied to the relay input of the line selection relay device.
7 is an AC undervoltage relay, 44S is a short-circuit distance relay, 5
0G is a ground fault overcurrent relay, 50S is a short circuit selection relay, 5
0SA is a short circuit overcurrent relay for 50S, 51 is an AC overcurrent relay, 51G is a ground fault overcurrent relay, 64 is a ground fault overvoltage relay, and 67G is a ground fault direction relay. Also,
_{(A) I a, I b} , I c and I _o is current transformer 8 11
(b) I _a , I _b , I representing each phase of the information from a
Similarly, _c and I _o represent the information from the current transformer 11b in each phase. (A) Bus 1 is the first with respect to line 9a
After the processing of the instrument transformer switching processing unit 24a,
It is determined that the bus is connected to the bus 1. (B) The busbar 1 is the line 9b that has been processed by the first instrument transformer conversion processing unit 24a, and is determined to be connected to the busbar 1. In FIG. 6, (V _Aa , V _Ab , V _Ac ) and (V _Ba , V _Bb , V _Bc ) are the voltages processed by the second instrument transformer switching processing unit 24b.

In the above relay, if there is no PT disconnection or abnormality of the analog / digital converter 21, the first instrument transformer switching processor 24a processes (1) 44S,
(1) The working voltage of 67 G is applied to the line switch 6 on the line 9a.
a, 7a connected bus voltage, (2) 44S,
(2) The working voltage of 67G is the voltage of the bus bar similarly connected to the line 9b, and (1) 50S and (1) 50G are the line 9
It is the voltage of the bus bar connected to a. However, PT
When the disconnection or the abnormality of the analog / digital conversion unit 21 occurs, the voltage on the normal side is used by the processing of the processing unit 24b. In addition, 64MA, 27A, 64G _O A, 64
BA is the voltage (V _Aa , V _Ab , after processing by the processing unit 24b.
V _Ac ), 64 MB, 27 B, 64 G _O B, 64
BB also uses voltages (V _Ba , V _Bb , V _Bc ).

FIG. 7 is an explanatory view of the configuration of the protection relay arithmetic processing section 24c, which describes the main protection relay of the line selection relay device. AN is an AND circuit, OR is an OR circuit,
T is a timer. In FIG. 7, when (1) 50S and (1) 50SA operate, the AND condition is satisfied and the output for tripping the circuit breaker 10a of the line 9a is sent from the digital output unit 25. (A) When the bus 1 is established by the processing of the processing unit 24a, (1) 50G
64G _O A, 64mA operates with and 27A becomes inoperative, the AND condition is satisfied, interrupted line 9a device 1
Trip 0a. If not established, (1) 5
0G, 64G _O B, 64MB operation, 27A is to trip a circuit breaker 10a becomes inoperative. However, 43-
50 use, 10a input, 10b input, BP non-operation, CBF
(Breaker non-operation protection) non-operation, adjacent line trip (10
In the case of a trip, a 10b trip command and in the case of 10b trip, 10a trip command), the condition without command is the final AND condition. (2) 50S, (2) 5
The 0G trip sequence is similar, tripping 10b.

[0024]

As described above, according to the present invention,
The continuity of the secondary voltage can be maintained even when the secondary voltage of the instrument transformer is switched, and the secondary voltage of the instrument transformer on the sound side is not interrupted even when the instrument transformer is disconnected. Since it can be switched, high functionality and high reliability can be maintained. Further, since the instrument transformer switching device and the protective relay device can be configured by the same device, the amount of hardware can be reduced and the reliability of the protective relay device can be increased.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the present invention,

FIG. 2 is a logic circuit diagram of a first instrument transformer conversion processing unit;

FIG. 3 is a time chart of FIG.

FIG. 4 is a logic circuit diagram of a second instrument transformer switching processing unit;

5 is a time chart of FIG.

FIG. 6 is an explanatory diagram of a configuration of a line selection relay device,

FIG. 7 is an explanatory diagram of a configuration of an arithmetic processing unit of a protective relay;

FIG. 8 is a configuration explanatory view showing a conventional example,

FIG. 9 is a logic circuit diagram in uninterruptible switching processing,

10 is a time chart of FIG.

FIG. 11 is a logic circuit diagram in power failure switching processing,

FIG. 12 is a time chart of FIG.

[Explanation of symbols]

 21 ... Analog-digital conversion part 22 ... Common bus 23 ... Digital input part 24 ... Processing part 24a, 24b ... First and second instrument transformer switching process part 24c ... Protective relay arithmetic processing part 25 ... Digital output part.

Claims (1)

[Claims] 1. A power transmission system in which two busbars are connected by a busbar breaker and a line switch group connected in series, and branch lines are drawn from common connection points of the line switch groups connected in series, respectively. Each of the busbars is provided with an instrument transformer, and the secondary voltage of the instrument transformer and the current flowing through the branch line are converted into digital information by an analog-digital converter and supplied to a common bus, and the line switch group is also provided. "ON", "OFF" information and "ON" information of the busbar breaker are supplied to the digital input section, output information of the digital input section is supplied to the common bus, and processing connected to the common bus is performed. Section performs switching processing of the instrument transformer and arithmetic processing of the protective relay by using both information from the analog-digital conversion section and the digital input section. , Protective relay device with a instrument transformer switching function, characterized in that the processing output of the protective relay to be sent from the digital output unit.