JPH04213A - Digital bus protective relay - Google Patents

Abstract

PURPOSE:To facilitate countermeasure to electrical noise and adjusting work by providing a plurality of input boards and a main relay board, operating the input signal from bus side digitally and transmitting to the main relay board for the purpose of data processing. CONSTITUTION:A protective relay comprises a main relay board 200 and a plurality of input boards 101, 102,... connected therewith. Auxiliary contacts ALS1, ALS2 indicating the states of an auxiliary current transformer ACT and disconnectors LS1, LS2 are arranged in the input detection unit 101A of the input board 101. A data processing unit 101B comprises an analog filter AF, an A/D converter A/D, a microprocessor MPU1 and the like, and transmits data to the main relay board 200. The main relay board 200 comprises a plurality of microprocessors MPU2 and the like, and produces a trip signal for a circuit breaker. Consequently, countermeasure against noise can be taken advantageously and the length of wiring in the board can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a digital bus protection relay that includes a plurality of input boards connected to a bus and a main relay board that performs protection calculations.

(Prior art) A busbar protection relay inputs current from a large number of terminals to determine whether or not there is an accident within the protected area. It consists of a front input panel. For electromagnetic protection relays and analog protection relays that use electronic components such as transistors, each input panel contains inputs for 6 terminals, and the number of panels on this input panel is equal to the number of terminals in the protection system. The decision will be made accordingly.

In recent digital protection relays using microprocessors, due to the miniaturization of component parts, the input panel accommodates, for example, 12 terminals per panel.

Normally, terminals such as transformers and power transmission lines are connected to the busbar, but the number of input terminals of the busbar protection relay increases or decreases due to changes in the system configuration or new additions. Parts that change the hardware configuration due to an increase or decrease in the number of terminals are generally housed in the input board, and common hardware is often housed in the main relay board. Against this background, the busbar protection relay needs to have a configuration that can easily accommodate the addition of hardware inputs and input panels due to the addition of terminals, etc.

On the other hand, the bus bar, which is the object of protection of this type of relay, has a configuration that differs depending on the scale of the system, but it is made up of at least two sections divided by a circuit breaker.

Hereinafter, as shown in FIG. 2, the first and second bus lines B, , B
The explanation will be continued on the premise that the circuit breaker 2 is connected by a bus-tie circuit breaker CB. To connect a transformer, power transmission line, etc. to a busbar with this type of configuration, the third
As shown in the figure, both buses B□ and B2 are connected to each other via disconnectors LS□Y, LS2□ and LSI2°LS, □. These disconnectors LS1□, LS2. or LS□
2. LS2□ is 2 connected in series under normal operating conditions.
One of the two is in a connected (shorted) state and the other is in a non-connected (open) state.

For example, regarding disconnectors LSI□, LS, □, L
Assuming that LS2□ is short-circuited, LS2□ is open, and the transformer is connected to the first bus B, the operation of bus B□ will be stopped due to a system fault occurring on this bus B or the need for maintenance. When doing so, short-circuit one disconnector LS2□ and disconnect the other
S1□ is opened and the transformer is connected to the second bus B2 side.

Such bus bar protection relays include a first bus bar division protection relay that protects the first bus bar B, a second bus division protection relay that protects the second bus bar B2, and the first and second bus bar B1. B
It consists of a collective bus protection relay including 2. The type of protection relay is a so-called differential relay that adds the currents of all terminals within the protection range to determine whether or not there is an accident within the protection range.

The current input to this dividing differential relay is taken from a current transformer CT installed between the circuit breaker CB1 and the power transmission line (or transformer), as shown in Fig. Use disconnector LS1 (LS□0.LS
,, ), LSI (LSEyo.

It is determined by the open/closed state of LS2□).

In conventional analog protection relays, the auxiliary contacts of disconnector LS and LS2 are connected in series to the output side of current transformer CT for switching, but digital protection relays improve hardware reliability and reduce costs. etc., the disconnector LS1. The contact of LS2 is taken in via the digital signal input section DI, and this input is switched and used by software.

Specifically, the digital protection relay as described above needs to have the following configuration.

In other words, as shown in Fig. 5, the terminal current flows from the secondary side of the main current transformer MCT directly connected to the grid through a cross-sectional area of 5.5 s.
q (5.5 m") of electric wire is used to connect to the external line terminal block of the input panel, and the cross-sectional area is 2 sq (21 m") inside the input panel.
2) The electric wire of the above thickness is connected to the unit of the auxiliary current transformer ACT via the test terminal TT. This auxiliary current transformer ACT not only insulates equipment inside the protective relay panel and equipment outside the panel with high withstand voltage, but also has the role of removing electrical noise and converting the signal level in VA units to the weak electric signal level of the internal equipment. ing.

Then, the weak electric signal on the secondary side of the auxiliary current transformer ACT is transmitted to the main relay board. In an analog type busbar protection relay, the signals are synthesized by an electrical synthesis circuit via the auxiliary contacts of the above-mentioned disconnector and then transmitted to the main relay board (the specific method is not covered by the present invention). 6) On the other hand, with digital protection relays, each terminal current is synthesized by software, so it is necessary to capture all the terminal currents.

Normally, signals on the secondary side of the auxiliary current transformer ACT are transmitted through a connector using a shielded cable.

Further, as shown in FIG. 5, for example, a disconnector LSi□.

The contacts of LS and , are insulated with a photocoupler PC if necessary, and after contact amplification (driving an auxiliary relay with multiple contacts with one contact to increase the number of contacts) is performed and converted into an electrical signal. , connect to the main relay board. In order to ensure reliability, the contact point of this disconnector is as shown in Figure 5.
A combination of a contact and a b contact is supplied as one set.

On the other hand, the hardware of the output circuit that trips the circuit breaker must not be too large in terms of circuit scale, and
They are housed in the main relay panel because it is preferable to install them all at once from the point of view of maintenance.

In this way, except for the output circuit, it is desirable that hardware whose configuration changes depending on an increase or decrease in the number of terminals has a configuration that can independently handle increases or decreases for each terminal. Here, the fifth
HW in the figure is hardware specific to one input terminal, and most of this size is occupied by part A in Figure 5, and the circuits after the analog filter AF and digital signal input section DI are electronic. It is made up of circuits and is usually relatively small. For this reason, generally, the input panel and the main relay panel are separated between the auxiliary current transformer ACT and the analog filter AF, and the two are electrically connected.

In addition, in FIG. 5, SH is a sample hold circuit,
MPX is a multiplexer, A/D is an A/D converter, BU
S is the system bus, MPU is the microprocessor, I/
F indicates a transmission interface, respectively.

(Problems to be Solved by the Invention) The conventional digital bus protection relay shown in FIG. 5 has the following drawbacks.

(1) Since weak electric wires are connected at the switchboard, sufficient electrical noise countermeasures must be taken.

(2) When adding input terminals, it is necessary to add analog filters AF and digital signal input terminals DI in the main relay board, and the main relay board lacks versatility.

(3) The number of cables connecting power distribution II (input panel, main relay panel) to transmit AC input, disconnector status signals, etc. increases, resulting in higher costs and complexity, and noise countermeasures are also more complicated. become.

(4) Adjustment of the level and phase of the electrical signal is performed by the analog filter AF, which is an electronic circuit, but the AC signal is input from the input panel and adjustment is made on the main relay panel side where the analog filter AF is installed. The work is complicated because it spans both boards.

Moreover, the various drawbacks mentioned above become more apparent when the input panel and the main relay panel are installed apart from each other.

The present invention has been made to solve the above problems,
The purpose of this is to make it resistant to electrical noise and add hardware to accommodate the addition of input terminals.

The purpose of the present invention is to provide a digital bus protection relay that allows most of the changes to be made within the input panel, prevents an increase in the number of cables between distribution panels, and facilitates adjustment work.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a plurality of input panels connected to a bus to be protected via a main current transformer, and digital signals transmitted from these input panels. and a main relay board that performs protection calculations based on data, and the input board is a data processing unit that processes the input signal from the bus side as a digital signal and transmits the resulting digital data to the main relay board. It is equipped with the following.

(Function) According to the present invention, a data processing unit which has a function between the analog filter AF and the microprocessor MPU shown in FIG. 5 and transmits digital data to the main relay board is provided in the input board, so that the input terminal Most of the hardware addition/change processing associated with expansion or modification can be carried out within the input panel, with the exception of the output circuit.

This eliminates the need for additional changes to the hardware configuration within the main relay panel, and enables the realization of a bus protection relay that is resistant to electrical noise by digitally transmitting data between switchboards.
Additionally, testing and adjustment work can be performed only on the input panel side.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a schematic configuration of a digital busbar protection relay according to this embodiment, and this protection relay includes a main relay panel 200 and a plurality of input panels 10 connected to it.
1.102. An outfit consisting of... In addition, the first
In the figure, only one input panel 101 is shown for convenience.

First, the connection state between the bus bar and the input panel 101 will be explained.
There are disconnectors LS on the first and second bus lines B□ and B2.

LS2 is connected, and a circuit breaker CB is connected to the connection point between the two.
A power transmission line, a transformer, etc. (not shown) are connected thereto, and a main current transformer MCT is also connected thereto. The secondary side of the main current transformer MCT is the input detection unit 10 of the input panel 101.
1A, and an auxiliary current transformer ACT is connected.

On the other hand, the auxiliary contact AL indicates the status of the disconnector LS□, LS.
S1. ALS2 is also provided in the input detection unit 1olA, and the secondary side of the auxiliary current transformer ACT is connected to the input panel 10.
The analog filter AP in the data processing unit 101B of No. 1 and the auxiliary contact ALS□.

ALS2 is connected to the digital signal input section DI to detect the operational status of the bus B and B2, respectively.

Here, the data processing unit 101B is a unit that can execute data processing from the analog filter AF to the microprocessor MPU in FIG. 5, and as is clear from FIG. It has an A/D converter, a microprocessor MPU, and a system bus BUS□, as well as a transmission interface I/F□ for transmitting digital data to the main relay board 200. In addition,
For convenience, illustration of the sample and hold circuit on the output side of the analog filter AF is omitted.

On the other hand, the main relay board 200 includes a plurality of transmission interfaces I/F2 connected to the transmission interface I/F1 of the plurality of input boards, a microprocessor MPU,
, a system bus Bus2, and a digital signal output unit DO that outputs a circuit breaker trip signal.

Therefore, the data processing unit 10 in this embodiment
1B performs the following processing.

(1) The analog filter AF removes harmonic components and DC components from the AC input, and the A/D converter A/D performs analog/digital conversion.

(2) Open/closed states of disconnectors L Sl and L B2, that is, bus line B1. The operational status of B2 is indicated by the auxiliary contact ALS1. ALS2
The state of the circuit breaker CB is detected as a contact signal, and the state of the circuit breaker CB is detected by the contact signal and stored as a digital value by the digital signal input section DI.

(3) The disconnector LS in (2) above determines whether the power transmission line or transformer (not shown) is connected to the first bus B□ or the second bus B2 based on the status signal of LS2. Judgment is made by the processor MPU.

(4) AC inputs of the terminals connected to the first bus line B1 and the second bus line B2 are vector-added by the microprocessor MPU.

(5) The vector sum current of all terminals is calculated by the microprocessor M
Obtained from PU1.

(6) Current value (instantaneous value) of each terminal and (4) and (5) above
As a result of the calculation, the state signals of the circuit breaker CB and the disconnectors LS□ and LS2 are transmitted to the main relay board 200 via the transmission interface I/F□ in the form of digital signals.

The other main relay panel 200 performs protection calculations based on digital data from a plurality of input panels via a plurality of transmission interfaces E/F2, and outputs a circuit breaker trip signal from a digital signal output section DO as necessary. This is to protect the intended busbar.

Note that in the above configuration, a procedure for adding an input terminal will be explained. Here, it is assumed that space is already secured in the input panel 101 to accommodate devices for 12 terminals.

First, in the input panel 101, equipment required for adding terminals (test terminals, auxiliary current transformers, analog filters, sample and hold circuits, contact input parts, etc.) is mounted,
Connect each device. Next, the data processing unit 10
Processing associated with the addition of terminals, such as changing (adding) software in the microprocessor MPU, etc., is performed on the functions of 1B. In addition.

In this case, it is naturally necessary to add an output circuit, but the explanation will be omitted since it is not directly related to the present invention.

(Effects of the Invention) As described above, according to the present invention, regardless of whether input terminals are added or newly installed, the wiring for the AC input section is internal wiring only in the input panel, so the electrical noise resistance is comparatively low. The target size may be small, which is advantageous in terms of noise countermeasures.

Furthermore, the length of the wiring within the board may be relatively short, so costs can be reduced.

Furthermore, since the number of connection cables between panels does not change unless an input panel is added, work can be done without having to do with other equipment. There are also management issues.

Although the work is done at the level of the entire substation, etc., in the present invention, the work can be limited to the addition of the protection relay itself.

In addition, since tests after connecting additional equipment can be performed inside the input panel, tests and adjustments can be easily performed even when the main relay panel is remote.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention, and FIG.
The figure is an explanatory diagram of the connection status of the bus bar, Figures 3 and 4 are explanatory diagrams of the connection status of the bus bar and power transmission line, etc., and Figure 5 is the hardware configuration for one terminal in a conventional digital bus bar protection relay. It is a diagram. 101.102... Input panel 101A... Kugata detection unit 101B... Data processing unit 200... Main relay panel B work, B2... Bus bar L
S□, LS2...Disconnector ALS,, ALS,...Disconnector auxiliary contact CB...Breaker MCT...Main current transformer ACT...Auxiliary current transformer AF...Analog filter A /D... A/D converter DI... Digital signal input unit MPU1. MPU2...Microprocessor I/F unit, I/F...Transmission interface DO...Digital signal output section

Claims (1)

[Claims] The input panel includes a plurality of input panels connected to the bus to be protected via main current transformers, and a main relay panel that performs protection calculations based on digital data transmitted from these input panels. A digital bus protection relay comprising a data processing unit that processes an input signal from the bus side as a digital signal and transmits the resulting digital data to the main relay board.