CN106340863A - Protection method for adaptive instantaneous current quick tripping - Google Patents

Abstract

The invention provides a protection method for adaptive instantaneous current quick tripping. The method comprises: a current current value of a power supply line is read; a current value, read at last time, of the power supply line is subtracted from the read current current value of the power supply line to obtain a fault current component; according to the fault current component, whether starting of a sudden change of a current occurs is determined; a fault type is determined; whether a practically measured current is larger than a short-current calculation value at the tail end of the line is determined; and a tripping signal is sent and the like. The method has the following effects: although the short-circuit current at the tail end of the line and the short-circuit current at any point of the line change simultaneously with the change of the reactance of the system, the short-circuit current at any point of the line is larger than or equal to the short-circuit current at the tail end of the line all the time. On the basis of the adaptive change, the sensitivity of the protection device is improved; and the complete protection range of the overall line is realized. The protection device can cut off the fault instantaneously. Compared with the traditional instantaneous current quick-tripping way, the provided method enables protection to be improved essentially.

Description

A kind of guard method of self adaptation transient current quick-break

Technical field

The invention belongs to power line protection technical field, more particularly to a kind of protection of self adaptation transient current quick-break Method.

Background technology

In power system, traditional transient current fast tripping protection setting valve will be matched with next stage quick-break electric current, by In it without the time limit, the therefore protection seting value of the current quick-breaking adjacent lines outlet three-phase under maximum operational mode that will stagger is short The electric current of protection device installation place is flow through during road.When in non-maximum operational mode or minimum operational mode, the scope protected To diminish, it could even be possible to the situation that protection domain is zero occurs.The protection domain of transient current quick-break is subject to system operation mode Impact is very big, is a very serious defect.

Fig. 1 is a kind of existing power system electrical primary wiring diagram, now taking system shown in Figure 1 as a example illustrates:

Calculate the short circuit current in b busbar short-circuit for this system:

Three short circuit current under maximum operational mode:

$i_{k1}^{\left(3\right)}=\frac{e_s}{\sqrt{3}\×(x_{s1\max }+x_{1ab})}=\frac{37000}{\sqrt{3}\×(5+8)}=1643a$

Line to line fault electric current:

$i_{k1}^{\left(2\right)}=\frac{\sqrt{3}}{2}\×i_{k1}^{\left(3\right)}=0.87\×1643=1429a$

Three short circuit current under minimum operational mode:

$i_{k1}^{\left(3\right)}=\frac{e_s}{\sqrt{3}\×(x_{s1\min }+x_{1ab})}=\frac{37000}{\sqrt{3}\×(10+8)}=1187a$

Line to line fault electric current:

$i_{k1}^{\left(2\right)}=\frac{\sqrt{3}}{2}\×i_{k1}^{\left(3\right)}=0.87\×1187=1033a$

From result of calculation, for the short circuit current staggering under maximum operational mode at b bus, protection seting value needs It is greater than 1643a (three-phase shortcircuit) and 1429a (line to line fault), and the short circuit current at b bus under minimum operational mode is far little In above numerical value, therefore under system minimum operational mode, current fault-clearing protective relays will be difficult to effective action.

Content of the invention

In order to solve the above problems, it is an object of the invention to provide a kind of protection side of self adaptation transient current quick-break Method.

In order to achieve the above object, the guard method of the self adaptation transient current quick-break that the present invention provides includes holding in order The following step of row:

Step 1) current sample: described current sample is the circulating sampling of each cycle for supply line's electric current In unitary sampling, using line current transformer read supply line present current value；

Step 2) calculate fault current component: the power supply that the present current value last time of this supply line reading reads Current value=the fault current component of circuit；

Step 3) judge whether that jump-value of current starts according to above-mentioned fault current component: above-mentioned fault current is divided The protection seting value measuring the current supply line short circuit current being calculated in real time with this moment microcomputer is compared, if above-mentioned fault Current component is more than or equal to the protection seting value of current supply line short circuit current, judges that jump-value of current starts, under One step execution step 5), otherwise next step execution step 4)；

Step 4) normal operation program: terminate this circular flow, return and wait subsequent cycle to run；

Step 5) determine fault type；Failure classes are carried out according to a, b, c three-phase electricity flow valuve that line current transformer records Type judges, if meeting ia+ic=-ib or ia+ib+ic=0, for three phase short circuit fault, otherwise for two-phase short-circuit fault；

Step 6) judge whether measured current is more than the calculation of short-circuit current value of line end: by above-mentioned steps 1) obtain The present current value of supply line is compared with the calculation of short-circuit current value of line end, if the current flow of supply line Value is more than the calculation of short-circuit current value of line end, next step execution step 7), otherwise next step execution step 4)；

Step 7) send trip signal: tripping line switching, disengagement failure line power.

The guard method of the self adaptation transient current quick-break that the present invention provides has the effect that

Although the short circuit current of any point change with system reactance simultaneously on the short circuit current of line end and circuit Change and change, but on circuit, the short circuit current of arbitrfary point is always greater than or is equal to the short circuit current that line end calculates, this Adaptive change, so that the sensitivity of protection device is improved it is achieved that the protection domain of total track length 100%, is protected Protection unit can instantaneously excise fault, and more traditional instantaneous quick-break current protection has the lifting of matter.

Brief description

Fig. 1 is a kind of existing power system electrical primary wiring diagram.

The guard method flow chart of the self adaptation transient current quick-break that Fig. 2 provides for the present invention.

Specific embodiment

The guard method of the self adaptation transient current quick-break with specific embodiment, the present invention being provided below in conjunction with the accompanying drawings is entered Row describes in detail.

As shown in figure 1, in order that protection domain can include a, b supply line total length, using b busbar short-circuit electric current as guarantor Shield setting valve.This protection seting value is to change with the change of the method for operation, also different because of the difference of short-circuit-type, for this Microcomputer Calculation system reactance value xs1 must be utilized in real time, calculate short-circuit current value at b bus further according to system reactance value xs1, This value is the protection seting value of current supply line short circuit current.By the current supply line calculating in real time short circuit current Protection seting value is stored in a certain region of ram random access memory, then measures supply line in real time using line current transformer Present current value, then calculate fault current component, afterwards by the fault current component of synchronization and above-mentioned current confession The protection seting value of electric line short circuit current is compared, if current failure current component is more than or equal to this moment microcomputer meter The protection seting value of the supply line's short circuit current calculating, you can be judged as that this short circuit occurs in ab supply line region, so Determine fault type afterwards, finally according to the supply line measuring in real time present current value whether more than the short circuit of line end Current calculation value is deciding whether to send trip signal.

As shown in Fig. 2 the guard method of the self adaptation transient current quick-break of present invention offer includes executing down in order Row step:

Step 1) current sample: described current sample is the circulating sampling of each cycle for supply line's electric current In unitary sampling, using line current transformer read supply line present current value；

Step 2) calculate fault current component: the power supply that the present current value last time of this supply line reading reads Current value=the fault current component of circuit；

Step 3) judge whether that jump-value of current starts according to above-mentioned fault current component: above-mentioned fault current is divided The protection seting value measuring the current supply line short circuit current being calculated in real time with this moment microcomputer is compared, if above-mentioned fault Current component is more than or equal to the protection seting value of current supply line short circuit current, judges that jump-value of current starts, under One step execution step 5), otherwise next step execution step 4)；

Step 4) normal operation program: terminate this circular flow, return and wait subsequent cycle to run；

Step 5) determine fault type；Failure classes are carried out according to a, b, c three-phase electricity flow valuve that line current transformer records Type judges, if meeting ia+ic=-ib or ia+ib+ic=0, for three phase short circuit fault, otherwise for two-phase short-circuit fault；

Step 6) judge whether measured current is more than the calculation of short-circuit current value of line end: by above-mentioned steps 1) obtain The present current value of supply line is compared with the calculation of short-circuit current value of line end, if the current flow of supply line Value is more than the calculation of short-circuit current value of line end, next step execution step 7), otherwise next step execution step 4)；

Step 7) send trip signal: tripping line switching, disengagement failure line power.

Claims (1)

1. a kind of guard method of self adaptation transient current quick-break it is characterised in that: described self adaptation transient current quick-break Guard method includes the following step executing in order:

Step 1) current sample: described current sample is in the circulating sampling for each cycle of supply line's electric current Unitary sampling, reads the present current value of supply line using line current transformer；

Step 2) calculate fault current component: the supply line that the present current value last time of this supply line reading reads Current value=fault current component；

Step 3) judge whether to occur jump-value of current according to above-mentioned fault current component and start: by above-mentioned fault current component with The protection seting value of the current supply line short circuit current that this moment microcomputer calculates in real time is compared, if above-mentioned fault current Component is more than or equal to the protection seting value of current supply line short circuit current, judges that jump-value of current starts, next step Execution step 5), otherwise next step execution step 4)；

Step 4) normal operation program: terminate this circular flow, return and wait subsequent cycle to run；

Step 5) determine fault type；Carry out fault type according to a, b, c three-phase electricity flow valuve that line current transformer records to sentence Disconnected, if meeting ia+ic=-ib or ia+ib+ic=0, for three phase short circuit fault, otherwise for two-phase short-circuit fault；

Step 6) judge measured current whether more than the calculation of short-circuit current value of line end: by above-mentioned steps 1) power supply that obtains The present current value of circuit is compared with the calculation of short-circuit current value of line end, if the present current value of supply line is big In the calculation of short-circuit current value of line end, next step execution step 7), otherwise next step execution step 4)；

Step 7) send trip signal: tripping line switching, disengagement failure line power.