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Digital directional relay

A relay and digital technology, which is applied in the field of digital directional relays, can solve the problems of unbalanced reverse-phase components, zero-phase components, low sensitivity of directional relays, and malfunctions, etc.

Inactive Publication Date: 2003-08-13
KK TOSHIBA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0012] However, when multiple lines are erected together in the same tower, and zero-phase circulating current flows between the lines, or when one of the three phases is temporarily missing during the single-phase reclosing no-voltage time, although it does not actually occur in the power system Fault, but there are unbalanced components such as reverse phase components or zero phase components
In such a case, when using the power of the unbalanced component to calculate the fault judgment, there is a possibility that the sensitivity of the direction relay will become low or malfunction.

Method used

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no. 1 Embodiment

[0041] FIG. 2 is a block diagram of a first embodiment showing the functions of the calculation circuit 109 described above in the form of a plurality of calculation units. In Fig. 2, 110 is a digital filter. The digital filter 110 filters the input digital data V and I, and outputs v and I respectively to the calculation units 111 and 112 described later.

[0042] 111 is a voltage anti-phase component calculation unit. This voltage reverse-phase component calculating section 111 obtains the voltage reverse-phase component using, for example, the following equation (4).

[0043] 3V 2m =V Am +V B(m·8) +V C(m·4) (4)

[0044] In the formula, m is the sample value at the present moment, and a value is taken every 30° below, therefore, m·4 means the value before 120°.

[0045] 112 is a current anti-phase component calculation unit. The current reverse-phase component calculation unit 112 obtains the current reverse-phase component using, for example, the f...

no. 2 Embodiment

[0080] Figure 6 It is a block diagram of the second embodiment, which shows the functions of the calculation circuit 109 in the form of a plurality of calculation units.

[0081] The digital directional relay of the second embodiment obtains the reverse-phase unbalanced impedance from the reverse-phase-changing component current and the reverse-phase-changing component voltage, and determines the direction of the fault based on the value of the reverse-phase unbalanced impedance. In addition, various functions of the digital filter 110 to the current anti-phase change component calculation unit 115 are the same as those in the first embodiment shown in FIG. 2 , and their descriptions are omitted.

[0082] The impedance in the anti-phase unbalanced impedance can be used by I m (ΔV 2 / ΔI 2 ) to find out. The reverse phase unbalance component existing in the power system under normal conditions can be canceled by using the reverse phase unbalanced impedance obtained from the...

no. 3 Embodiment

[0099] Figure 8 It is a block diagram of the third embodiment, which shows the functions of the calculation circuit 109 in the form of a plurality of calculation units.

[0100] In the third embodiment, the digital filter 110 to the current reverse phase change component calculation unit 115 are the same as those in the first embodiment shown in FIG. 2 . And the absolute value calculation unit 120 and the inner product calculation unit 121 and Figure 6 The second embodiment shown is the same, and the description thereof is omitted.

[0101] Front failure determination means 131 determines the front failure based on the calculation results of absolute value calculation means 120 and inner product calculation means 121 and the establishment of determination formula (19) described later. Rear failure determination unit 132 determines a rear failure based on the calculation results of absolute value calculation unit 120 and inner product calculation unit 121 and the establishm...

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Abstract

A digital directional relay converts a voltage value and a current value of a power system into digital voltage data and digital current data by periodic sampling and determines a direction of a fault using the digital voltage data and the digital current data. In the digital directional relay, a variation in unbalanced component voltage (114, 142) and a variation in unbalanced component current (115, 143) are computed using both voltage data at a reference point in time and voltage data at a point in time elapsed from the reference point in time by a given sampling interval and using both current data at reference time and current data at time elapsed from the reference time by a given sampling interval, respectively. A relationship in phase between these variations is obtained to determine whether a forward fault or a reverse fault occurs (116, 117).

Description

technical field [0001] The invention relates to a digital directional relay for judging the direction of a fault by using the change components of the unbalanced component electric quantity such as the reverse phase change component or the zero phase change component. Background technique [0002] It is known to determine the direction of a fault in a power system by using a directional relay using a reverse-phase component power quantity or a zero-phase component power quantity, as described on page 54 of Electric Cooperative Research Vol. 37 No. 1. [0003] When implementing a digital reverse-phase relay, it is assumed that the sample values ​​of the voltage and current of the power system obtained at a certain sampling interval are V m , I m . In this way, the anti-phase components of the voltage and current can be obtained by the following equations (1) (2). [0004] 3V 2m =V am +V b(m·8) +V c(m·4) (1) [0005] 3I 2m =I am +I b(m·8) +I c(m·4...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H3/08H02H3/38H02H3/44
CPCH02H3/081H02H3/385H02H3/26
Inventor 加濑高弘天羽秀也园部泰孝
Owner KK TOSHIBA
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