Nanrui Jibao PCS9613C microcomputer protection device

Nanrui Jibao PCS9613C microcomputer protection device

Identification of abnormal situations in differential circuits

The device categorizes abnormal situations in the differential circuit into three types: differential current abnormal alarm, instantaneous CT disconnection alarm, and delayed CT disconnection alarm.

Abnormal differential current alarm

When either of the following two conditions is met, the device will delay by 10 seconds and issue a differential current abnormal alarm signal, which also serves as a protective device

Set the self-test function of the AC sampling circuit.

1. Any differential current greater than the differential current alarm threshold

2. The negative sequence differential flow is greater than the threshold value (this criterion is not used when using two-phase CT on site), as shown in the following equation:

I d 2>a+b * I d _1st.max formula 1-7

among which

I d 2 is negative sequence differential current

I d_1st.max is the fundamental value in the three-phase differential current

A is a fixed threshold value, b is a certain proportional coefficient

The differential current alarm setting should avoid differential current caused by inconsistent CT characteristics during normal operation or other reasons that may occur during operation

The difference in quality.

Attention: The setting value of differential current alarm should be smaller than the setting value of differential starting current, generally between the differential current and normal operation

Between the minimum differential starting current settings; The smaller its value, the more sensitive it is.

CT disconnection

At the moment of CT disconnection, the starting element and differential relay on the disconnected side may act, but the starting element on the opposite side does not act and will not move to this location

Send differential protection action signals on the side to ensure that the longitudinal differential does not malfunction. After a delay, the non disconnected side reports a "differential current alarm" and is disconnected from the CT

Handle it the same way.

When a fault or system disturbance occurs due to CT disconnection or differential current alarm, causing the starting element to operate, if the control word [CT disconnection locking differential] is set to

If set as "1", the current differential protection will be locked; If the control word [CT disconnection locking differential] is set to "0" and the phase difference current is greater than

Differential current setting value] (setting value), still open current differential protection.

The device includes two types of CT disconnection alarms: instantaneous CT disconnection alarm and delayed CT disconnection alarm.

1) Instantaneous CT disconnection alarm. When the differential protection is activated, if the following conditions are met simultaneously, an alarm signal will be sent after a delay of 200ms:

A. No bus PT disconnection alarm occurs, no low voltage or negative sequence voltage;

B. The phase current is greater than 0.2In and there is no current in either phase (when the control word [two-phase CT] is activated, only A and C phases are judged to have no current).

2) Delayed CT disconnection alarm. When the phase current value is greater than 4 times the A-phase or C-phase current, and the phase current value is greater than 0.2In

Send an alarm signal with a delay of 10 seconds.

Attention: Whether the abnormality of the differential circuit causes the activation of differential protection or not, it indicates that there is a problem with the differential circuit or the fixed value

It should be given equal attention.

L channel longitudinal code

To improve the reliability of the digital channel line protection device, the PCS-9613D device has added adjustable local and opposite side longitudinal protection

Link code. There are two fixed value items in the PCS-9613D protection setting: "local longitudinal code" and "opposite longitudinal code", both ranging from 0 to 65535

The setting of the code should ensure that the protection devices running on the entire network have different longitudinal codes on the local side and the opposite side during normal operation,

And it should be different from the longitudinal code of another set of protection devices on this line, and should also be different from the longitudinal code of other line protection devices (which can be used during protection verification)

Chapter 3 PCS-9613D Line Fiber Longitudinal Differential Protection Device

Nanjing Nanrui Jibao Electric Co., Ltd. 65

Same setting, indicating self looping mode.

The protection device determines the master-slave mode of the device through the fixed values of the local longitudinal code and the opposite longitudinal code in this device. If the local longitudinal code

If the union code is greater than or equal to the longitudinal union code on the opposite side, it indicates that the local side is the master, otherwise it is the slave.

The protection device includes the fixed value of the local longitudinal code in the data frame sent to the opposite side and transmits it to the opposite side protection device. For dual channel

Protection device, when the longitudinal code received by the channel is inconsistent with the longitudinal code set on the opposite side, exits differential protection and reports "longitudinal code connected"

Received error "and" abnormal fiber channel "alarms. The "longitudinal code reception error" has a delay of 100ms and a 1-second spread alarm.

Nanrui Jibao PCS9613C microcomputer protection device

PCS-9613D is a line optical fiber longitudinal cable suitable for non directly grounded systems or low resistance grounded systems with voltage levels below 110kV

Differential and current protection and measurement devices can be installed in groups or on-site in the switchgear.

Protection configuration

Ratio differential protection

Timed overcurrent protection with directional compound voltage locking function

Zero sequence current protection

L Overcurrent acceleration protection

Zero sequence acceleration protection

Low frequency load shedding protection

Automatic reclosing function

Overload protection

Low current grounding line selection

Independent operating circuit