CN103762570A - Grid line relay protection method applicable to double line faults - Google Patents

Abstract

The invention relates to a grid line relay protection method applicable to double line faults. According to the method, when a grid topology structure changes after double line fault tripping occurs on a grid, a grid branch admittance matrix and a grid node incidence matrix do not need to be amended, and then the variable quantity of current flowing through each line after the grid double line fault tripping occurs can be calculated directly, so that the calculation time is short, the protection action speed is high and is higher than of a line backup protection algorithm based on the local amount decision, the line can be reliably locked before a line overload relay protection faulty operation, other faulty lines can be isolated rapidly in a tripping mode, and the operation safety and stability of the grid are improved.

Description

A kind of power network line relay protecting method that is applicable to dual line fault

Technical field

The present invention relates to Relay Protection Technology in Power System field, more particularly, relate to a kind of power network line relay protecting method that is applicable to dual line fault.

Background technology

The task of relaying protection is fault and the irregular operating state of reflection protected element, according to function, can be divided into main protection and backup protection.Wherein the task of excision protected element fault fast is only being undertaken in main protection, is not substantially subject to the impact of system operation mode.Along with the application of optical-fibre channel, high pressure, extra high voltage system main protection technology based on Two-Terminal Electrical Quantities are ripe day by day.And the task of doing the backup protection far away of adjacent electric component is also being undertaken in backup protection, owing to existing the possibility of transforming plant DC power-fail, this responsibility is to cancel.The information of protection installation place is only reacted in existing electrical network backup protection, is subject to the impact of power network topology annexation and operational mode.For guaranteeing its reliability, have to be configured and adjust according to the harshest situation; For guaranteeing its selectivity, have to sacrifice rapidity and the sensitivity of backup protection.Because electric network composition is increasingly sophisticated, just cause following potential safety hazard simultaneously:

1) backup protection matching relationship complexity, operate time is long.When serious, likely do not meet the desired critical clearing time of stability of power system, and then become large power grid security hidden danger.

2) backup protection configuration is large with the difficulty of adjusting, and can not follow the tracks of the variation of power system operation mode, even may occur protecting mismatch or under-sensitive situation.

3) backup protection can not be distinguished the trend transfer causing after internal fault and failure removal, and this likely causes the backup protection cascading trip in heavy load situation.

In the accident of having a power failure on a large scale, although just occurred that electric power system backup protection, according to design principle correct operation, objectively but accelerated the phenomenon of system crash.Therefore the backup protection system for damping of, considering electrical network global information is studied extremely urgent.

In recent years, the drawing-in system information in backup protection that appears as of wide area synchronized measurement system (WAMS) provides possibility.WAMS mono-is the electric phasor that can synchronously obtain in the whole network, has realized the monitoring of dynamic process of electrical power system; The 2nd, the renewal speed of measurement amount was tapered to a few tens of milliseconds by several seconds, for realizing dynamic process of electrical power system control, created condition, make the design of carrying out backup protection from the angle of electrical network total optimization become possibility.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, a kind of power network line relay protecting method that is applicable to dual line fault is provided.Whether the method can occur effectively to identify All other routes in dual circuit fault trip situation at electrical network and break down; can be by reliable circuit locking before regular link overload protective relaying maloperation is done; can, by other faulty line fast trip isolation, improve safe operation of electric network stability.

Technical scheme of the present invention is as follows:

A power network line relay protecting method that is applicable to dual line fault, comprises following sequential steps:

1) wide area backup protection system utilizes the existing WAMS of electrical network to realize the synchro measure of the each transformer substation voltage of electrical network, electric current phasor, and Real-time Obtaining synchronized data, if after the circuit breaker tripping at circuit i and circuit j two ends, enter step 2);

Wherein, i=1 ..., n; J=1 ..., n; Circuit i and circuit j are different circuits; N is power network line sum;

2) n between each line current of wide area backup protection system-computed electrical network × n dimension incidence matrices ζ=YA ^t(AYA ^t) ^-1a;

Wherein, Y is grid branch admittance matrix; A is grid nodes incidence matrices;

3) variable quantity of circuit k current flowing after the circuit breaker tripping at wide area backup protection system-computed circuit i and circuit j two ends ${\stackrel{\·}{\mathrm{\ΔI}}}_k=\frac{{\mathrm{\ζ}}_{\mathrm{ki}}+{\mathrm{\ζ}}_{\mathrm{ji}}{\mathrm{\ζ}}_{\mathrm{kj}}}{1-{\mathrm{\ζ}}_{\mathrm{ij}}{\mathrm{\ζ}}_{\mathrm{ji}}}{\stackrel{\·}{I}}_i+\frac{{\mathrm{\ζ}}_{\mathrm{kj}}+{\mathrm{\ζ}}_{\mathrm{ij}}{\mathrm{\ζ}}_{\mathrm{ki}}}{1-{\mathrm{\ζ}}_{\mathrm{ji}}{\mathrm{\ζ}}_{\mathrm{ij}}}{\stackrel{\·}{I}}_j;$

Wherein, ζ _kifor the capable i column element of k of incidence matrices ζ; ζ _kjfor the capable j column element of k of incidence matrices ζ; ζ _ijfor the capable j column element of i of incidence matrices ζ; ζ _jifor the capable i column element of j of incidence matrices ζ; Circuit k and circuit j are different circuits; Circuit k and circuit i are different circuits; K=1 ..., n;

for the circuit breaker at circuit i and circuit j two ends is not before tripping, WAMS measures the electric current flowing through on circuit i;

for the circuit breaker at circuit i and circuit j two ends is not before tripping, WAMS measures the electric current flowing through on circuit j;

4) wide area backup protection system judgement whether set up, if set up, judge that circuit k breaks down, send action trip signal, the circuit breaker at tripping circuit k two ends; If

set up, judge that circuit k is normal, to the circuit breaker at circuit k two ends, send block signal;

Wherein, I _setfor setting current threshold value;

after circuit breaker tripping for circuit i and circuit j two ends, WAMS measures the electric current that circuit k flows through;

for the circuit breaker at circuit i and circuit j two ends is not before tripping, WAMS measures the electric current that circuit k flows through.

Beneficial effect of the present invention is as follows:

Voltage, electric current phasor that first the inventive method utilizes the each transformer station of electrical network existing WAMS synchro measure electrical network, obtain synchronized data; If there is dual circuit fault trip in electrical network; incidence matrices between each line current of wide area backup protection system-computed electrical network; utilize the incidence matrices between each line current of electrical network to calculate the current change quantity that each line flows of electrical network crossed, then utilize the line current variable quantity calculating and the line current variable quantity that actual measurement obtains to form relaying protection criterion.The inventive method is when after dual circuit fault trip occurs electrical network, topological structure of electric changes; without revising grid branch admittance matrix, grid nodes incidence matrices, just can directly calculate each the current change quantity that line flows is crossed after the dual circuit fault trip of electrical network; computing time is short; protection quick action; faster than the existing line backup protection algorithm based on this locality amount decision-making; can be by reliable circuit locking before circuit overload protective relaying maloperation is done; can, by other faulty line fast trip isolation, improve safe operation of electric network stability.

Accompanying drawing explanation

Fig. 1 is the flow chart of method of the present invention.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in further detail.

Fig. 1 is the application power network line relay protecting method flow chart that is applicable to dual line fault of the present invention.In the present embodiment, voltage, electric current phasor that wide area backup protection system is utilized the each transformer station of electrical network existing WAMS synchro measure electrical network, obtain synchronized data.

If after the circuit breaker tripping at circuit i and circuit j two ends, the n × n dimension incidence matrices ζ=YA between each line current of wide area backup protection system-computed electrical network ^t(AYA ^t) ^-1a; Wherein, Y is grid branch admittance matrix; A is grid nodes incidence matrices; I=1 ..., n; J=1 ..., n; Circuit i and circuit j are different circuits; N is power network line sum.

The variable quantity of circuit k current flowing after the circuit breaker tripping at wide area backup protection system-computed circuit i and circuit j two ends

wherein, ζ _kifor the capable i column element of k of incidence matrices ζ; ζ _kjfor the capable j column element of k of incidence matrices ζ; ζ _ijfor the capable j column element of i of incidence matrices ζ; ζ _jifor the capable i column element of j of incidence matrices ζ; Circuit k and circuit j are different circuits; Circuit k and circuit i are different circuits; K=1 ..., n; for the circuit breaker at circuit i and circuit j two ends is not before tripping, WAMS measures the electric current flowing through on circuit i;

for the circuit breaker at circuit i and circuit j two ends is not before tripping, WAMS measures the electric current flowing through on circuit j.

The judgement of wide area backup protection system whether set up, if set up, judge that circuit k breaks down, send action trip signal, the circuit breaker at tripping circuit k two ends.

The judgement of wide area backup protection system

whether set up, if set up, judge that circuit k is normal, to the circuit breaker at circuit k two ends, send block signal; Wherein, I _setfor setting current threshold value;

after circuit breaker tripping for circuit i and circuit j two ends, WAMS measures the electric current that circuit k flows through;

for the circuit breaker at circuit i and circuit j two ends is not before tripping, WAMS measures the electric current that circuit k flows through.

The inventive method is when after dual circuit fault trip occurs electrical network, topological structure of electric changes; without revising grid branch admittance matrix, grid nodes incidence matrices, just can directly calculate each the current change quantity that line flows is crossed after the dual circuit fault trip of electrical network; computing time is short; protection quick action; faster than the existing line backup protection algorithm based on this locality amount decision-making; can be by reliable circuit locking before circuit overload protective relaying maloperation is done; can, by other faulty line fast trip isolation, improve safe operation of electric network stability.

Above-described embodiment is only for the present invention is described, and not as limitation of the invention.As long as according to technical spirit of the present invention, to above-described embodiment change, modification etc. all will drop in the scope of claim of the present invention.

Claims (1)

1. a power network line relay protecting method that is applicable to dual line fault, is characterized in that, comprises following sequential steps:

1) wide area backup protection system utilizes the existing WAMS of electrical network to realize the synchro measure of the each transformer substation voltage of electrical network, electric current phasor, and Real-time Obtaining synchronized data, if after the circuit breaker tripping at circuit i and circuit j two ends, enter step 2);

Wherein, i=1 ..., n; J=1 ..., n; Circuit i and circuit j are different circuits; N is power network line sum;

2) n between each line current of wide area backup protection system-computed electrical network × n dimension incidence matrices ζ=YA ^t(AYA ^t) ^-1a;

Wherein, Y is grid branch admittance matrix; A is grid nodes incidence matrices;

3) variable quantity of circuit k current flowing after the circuit breaker tripping at wide area backup protection system-computed circuit i and circuit j two ends ${\stackrel{\·}{\mathrm{\ΔI}}}_k=\frac{{\mathrm{\ζ}}_{\mathrm{ki}}+{\mathrm{\ζ}}_{\mathrm{ji}}{\mathrm{\ζ}}_{\mathrm{kj}}}{1-{\mathrm{\ζ}}_{\mathrm{ij}}{\mathrm{\ζ}}_{\mathrm{ji}}}{\stackrel{\·}{I}}_i+\frac{{\mathrm{\ζ}}_{\mathrm{kj}}+{\mathrm{\ζ}}_{\mathrm{ij}}{\mathrm{\ζ}}_{\mathrm{ki}}}{1-{\mathrm{\ζ}}_{\mathrm{ji}}{\mathrm{\ζ}}_{\mathrm{ij}}}{\stackrel{\·}{I}}_j;$

Wherein, ζ _kifor the capable i column element of k of incidence matrices ζ; ζ _kjfor the capable j column element of k of incidence matrices ζ; ζ _ijfor the capable j column element of i of incidence matrices ζ; ζ _jifor the capable i column element of j of incidence matrices ζ; Circuit k and circuit j are different circuits; Circuit k and circuit i are different circuits; K=1 ..., n; for the circuit breaker at circuit i and circuit j two ends is not before tripping, WAMS measures the electric current flowing through on circuit i;

for the circuit breaker at circuit i and circuit j two ends is not before tripping, WAMS measures the electric current flowing through on circuit j;

4) wide area backup protection system judgement whether set up, if set up, judge that circuit k breaks down, send action trip signal, the circuit breaker at tripping circuit k two ends; If

set up, judge that circuit k is normal, to the circuit breaker at circuit k two ends, send block signal;

Wherein, I _setfor setting current threshold value;

after circuit breaker tripping for circuit i and circuit j two ends, WAMS measures the electric current that circuit k flows through;

for the circuit breaker at circuit i and circuit j two ends is not before tripping, WAMS measures the electric current that circuit k flows through.

Images