CN105445615A - Corrosion diagnosis method for transformer station grounding network - Google Patents

Abstract

The invention relates to a corrosion diagnosis method for a transformer station grounding network. The method is characterized by comprising the following steps of S1, according to the structure of an actual transformer station grounding network, establishing a simplified network circuit model for the structure of the actual transformer station grounding network; S2, based on the Tellegen's theorem, establishing a corrosion diagnosis equation set for the grounding network; S3, transporting the excitation current to the branch of the simplified network circuit model, conducting the data collection by a signal collection sensor, and transporting the collected data to a terminal processor; S4, solving out a solution for the corrosion diagnosis equation set based on the collected data through the iterative method; S5, comparing the solved result by the terminal processor so as to judge the corrosion failure state of the grounding network. According to the technical scheme of the invention, a quick and effective corrosion diagnosis method is provided for the current large-scale corrosion diagnosis of grounding networks in the prior art based on the diagnosing requirement of the excavation-free monitoring operation. Therefore, the method has a certain real significance on improving the safety and the reliability of the power system.

Description

A kind of grounding net of transformer substation corrosion diagnosis method

Technical field

The present invention relates to a kind of grounding net of transformer substation corrosion diagnosis method, especially relate to the corrosion diagnosis method of circuit ultimate principle and Tellegen.

Background technology

At present, there is problems such as running the time limit is long, earthing device defectiveness, the safe and stable operation of serious threat electric system in most of transformer station.Ground connection refers to the part of nodes of electrical system or the electrical connection between the current-carrying part of electric utility and the earth, it is the key device ensureing transformer station and power system security work, having the vital role of all pressure and earial drainage, is the key guaranteed the reliable and secure operation of system, ensure staff and electrical equipment safe operation.But grounded screen can cause the thinning and corrosion cracking of grounding body because of spontaneous corrosion or stray current corrosion, the resistivity of its degree and soil, salt content, the element such as water percentage and pH value are directly related; Special in there being stray current to exist, corrosion can be concentrated and be occurred in a certain position of grounded screen and make it that thinning and fracture occur at short notice.Net corrosion in grounded screen often causes or expansion accident, brings huge economic loss and bad social influence.

The research of grounded screen in recent years mainly concentrates on research, the grounding network anti-corrosion maintenance of ground net corrosion feature and corrosion mechanism and does not excavate ground net corrosion situation diagnostic monitoring.Actual grounded screen number of nodes is often beyond 100, and grounded screen area is large, electrical equipment and down conductor more, bring extreme difficulties to corrosion diagnosis.Most effective to the method adopting large piecemeal to measure in conjunction with fixed point during grounded screen tentative diagnosis, diagnosis effect is best, can improve diagnosis speed, reduce real work amount.For improving ground net corrosion protection effect, anti-corrosion earthing material need be used, as continuous casting copper Baogang and copper plated steel; Implement cathodic protection; Coated with conductive material is to isolate the corrosive medium such as electrolyte, dissolved oxygen DO, moisture in soil.

Transformer station has concentrated a large amount of important electrical, is the hinge in electrical network, ensures that the good earth of transformer station is the prerequisite of electric power netting safe running.Therefore, often or termly the situation of grounded screen being detected, and grounded screen situation is assessed, pinpoint the problems in advance to take corresponding measure, safeguarding that the safe and reliable operation of grounded screen is to ensureing that the reliability of electrical network has important practical significance.

Summary of the invention

Object of the present invention is exactly to improve diagnosis protective capability to grounded screen and a kind of grounding net of transformer substation corrosion diagnosis method based on Tellegen proposed.

The object of invention can be achieved through the following technical solutions:

A kind of grounding net of transformer substation corrosion diagnosis method, is characterized in that: comprise step as follows:

Step S1: according to the structure of actual grounding net of transformer substation, sets up the simplified network circuit model of actual substation grounding web frame;

Step S2: based on Tellegen, sets up corrosion diagnosis of grounding grid system of equations;

Step S3: to the branch road conveying exciting current of simplified network circuit model, carry out data acquisition by signals collecting sensor, and the data collected are flowed to terminal handler;

Step S4: the data separate alternative manner according to collecting solves corrosion diagnosis system of equations;

Step S5: utilize terminal handler to contrast the result after solving, thus judge the corrosion failure state of grounded screen.

Further: described step S2 sets up corrosion diagnosis of grounding grid system of equations, shown in specific as follows:

1) according to the simplified network circuit model set up, in conjunction with known exciting current (I ₀) and the branch node column voltage vector (U that collected by signals collecting sensor _b+1), then according to nodal analysis, the resistance of any two ends mouth can be obtained

R _ij＝U _b+1/I ₀

Thus draw the resistance delta of any two ends mouth

ΔR _ij＝R’ _ij-R _ij

i＝1,…,n；j＝1,…,n；b＝1,…,n；n＝1,2,3…。

2) according to Tellegen, then can show that the relational expression of branch resistance increment is

3) according to step 1) and step 2) resistance delta of network two-port that obtains and branch resistance increase

The relation of amount, can obtain a prescription journey:

……

i＝1,…,m；j＝1,…,m；k＝1,…,m；m＝1,2,3…。

Further again: shown in the alternative manner provided in described step S4 is specific as follows:

Step 1: read grounded screen topology data, electric data, calculates the magnitude of current I on branch road _k;

Step 2: selected part measured node, calculates R _ij, measure R ' _ij;

Step 3: the resistance delta Δ R of computational grid two-port _ij=R ' _ij-R _ij;

Step 4: arranging primary iterations (t) is 0, I ' _k=I _k;

Step 5: calculate Δ R according to diagnostic equation group ^(t) _k;

Step 6: enter step (G) when iterations (t) >=1, otherwise iterations (t) adds 1 gets back to step D);

Step 7: when | Δ R _k ^(t)-Δ R _k ^{(t-1) |}enter step (H) time < ε (ε is accuracy value), otherwise iterations (t) adds 1 gets back to step D);

Step 8: calculate I ^(t+1) _k.

Further again: utilize terminal handler to contrast the result after solving in described step S5, it is specifically as the I calculated ^(t+1) _kwith I under normal circumstances _kwhen differing by more than one times, then prove that this grounded screen branch road there occurs corrosion failure, thus send ground connection corrosion alarm.

Further again: the kind of the signals collecting sensor in described step S3 has voltage sensor, current sensor and electric resistance sensor.

The present invention can judge fault corrosion branch road fast and effectively, ensures the property safe and reliable to operation of electric system, has and simply, accurately, by on-the-spot service condition limit the advantages such as little, have certain realistic meaning.

Accompanying drawing explanation

Below in conjunction with the drawings and specific embodiments, the present invention is further detailed explanation.

The process flow diagram of alternative manner of Fig. 1 for adopting in step S4.

Embodiment

The invention provides a kind of grounding net of transformer substation corrosion diagnosis method, it is as follows that it comprises step:

Step S1: according to the structure of actual grounding net of transformer substation, sets up the simplified network circuit model of actual substation grounding web frame;

Step S2: based on Tellegen, sets up corrosion diagnosis of grounding grid system of equations;

Step S3: to the branch road conveying exciting current of simplified network circuit model, carry out data acquisition by signals collecting sensor, and the data collected are flowed to terminal handler;

Step S4: the data separate alternative manner according to collecting solves corrosion diagnosis system of equations;

Step S5: utilize terminal handler to contrast the result after solving, thus judge the corrosion failure state of grounded screen.

It is considered herein that the grounding grids be embedded in soil is connected and constitute resistor network, if ignore edphic factor impact, whole grounded screen can directly as the network of pure resistive.Utilize this characteristic of grounded screen, the present invention chooses fault parameter method of identification to carry out the identification of fault element.Fault parameter method of identification is according to the known topological structure of circuit network and parameter, responded by input stimulus and output, estimate all parameters of residue of network organization with certain algorithm, the last permission tolerance according to parameters determines a kind of fault recognition method of fault element in circuit network.After actual grounded screen has been constructed, the length of each section of grounding body, cross-sectional area and resistivity thereof have been definite value, and its measuring resistance numerical value can be considered definite value.When grounded screen puts into operation for many years, there is corrosion or fracture in grounding body, cause grounded screen branch resistance to be greater than standard value, it is identical that ground networks now can be considered as topological structure, and the small resistor network that branch resistance value is different.Grounded screen topological structure before corrosion and its branch resistance known, resistor network port resistive value can utilize Circuit theory to calculate; Grounded screen port resistive after corrosion can be measured through ground lead.Through comparison, the changing value of outbound port resistance at last, i.e. increment.

Above-mentioned step S2 sets up corrosion diagnosis of grounding grid system of equations, shown in specific as follows:

Step 1) in the present invention for convenience of the foundation of data input and corresponding system of equations, that does not consider cable bearer, underground cable can the natural grounding substance such as framework base apparatus of conducting metal crust, running water pipe or power distribution network.Suppose that point that the ground lead of testing resistance or voltage is connected with grounded screen is all at horizontal grounding net branch node place, ignores the environmental factor such as soil moisture, temperature.Suppose to comprise n+1 node, b bar branch road, the ground outlet of m bar, grounded screen can be simplified the small-sized ground connection networking of pure resistance become as shown in Figure 1.Fig. 1 is only example, and the simplification resistance network figure used is as the criterion to answer practical structures.

If select to add excitation current source between this network the i-th, j two-port, setting electric current is I ₀, do to give a definition based on Circuit theory: A is the network associate matrix of specifying reference mode; Y _bfor branch admittance matrix; Y _nfor bus admittance matrix; I _bfor branch current matrix; U _nfor node voltage column vector; U _bfor branch voltage column vector; I _nfor node activations electric current column vector (non-actuated node current is 0).

According to Circuit theory:

Y _n＝A·Y _b·A ^T

And denotable KVL and the KCL equation of incidence matrix A is:

AI _b＝0

U _b＝A′U _n

Can obtain:

Y _nU _n＝I _n

Can port resistive be obtained thus:

R _ij＝U _b+1/I ₀

I=1 ..., n; J=1 ..., n; B=1 ..., n; Wherein n is that propping up of lattice network model is counted.

Any N holds network, if can known whole network structure and branch resistance value, comprises excitation situation, then according to nodal analysis, can obtain the resistance of any two ends mouth.

Illustraton of model before grounded screen being corroded regards as one and comprises b+1 bar branch road, the resistor network N of n+1 node.Wherein, if b+1 article of branch resistance is in the directly connection of the i of ground outlet, j end.Now between the i-th, j, two ports, add a current known source, electric current is I ₀, then Nortons theorem obtains R _ij.

Model after grounded screen generation corrosion failure as network N ', still between its i, j two-port, add current source, its current value is similarly I ₀, can R ' be obtained _ij; Obvious, network N is identical with the topological structure of N '.

When branch road k has corrosion or fracture defect, its resistance R _kbecome R ' _k, namely

ΔR _k＝R’ _k-R _k

The now resistance R of the network port _ijbecome R ' _ij, that is:

ΔR _ij＝R’ _ij-R _ij

Step 2) by Tellegen, can draw:

Because the branch current value of b+1 article of two networks between i, j end is all I ₀, namely

Calculated by abbreviation,

Final

Step 3) just can obtain the resistance delta of network two-port and the relation of branch resistance increment thus, but now also cannot directly calculate branch resistance increment by two-port resistance delta, because each branch resistance has b variable, so one group of port resistive data must be measured and then obtain a prescription journey:

……

I=1 ..., m; J=1 ..., m; K=1 ..., m; Wherein, m is the two-port group number measured, I _kcan by R _kobtain.

Shown in the alternative manner provided in above-mentioned step S4 is specific as follows:

Step 1: read grounded screen topology data, electric data, calculates the magnitude of current I on branch road _k;

Step 2: selected part measured node, calculates R _ij, measure R ' _ij;

Step 3: the resistance delta Δ R of computational grid two-port _ij=R ' _ij-R _ij;

Step 4: arranging primary iterations (t) is 0, I ' _k=I _k;

Step 5: calculate Δ R according to diagnostic equation group ^(t) _k;

Step 6: enter step (G) when iterations (t) >=1, otherwise iterations (t) adds 1 gets back to step D);

Step 7: when | Δ R _k ^(t)-Δ R _k ^{(t-1) |}enter step (H) time < ε (ε is accuracy value), otherwise iterations (t) adds 1 gets back to step D);

Step 8: calculate I ^(t+1) _k.

Corrosion diagnosis equation is nonlinear equation, cannot direct solution.Using iterative method, if initial value I ' _k(0)=I _k, become system of linear equations.Due to m<b (equation number is less than unknown quantity number), system of equations owes fixed, still cannot direct solution, and the present invention uses least square method to solve.

The resistance R of the original topological structure of whole grounded screen and each branch road can be obtained according to the design of grounded screen _k, calculate I _{k (s)}; Choose a part of measured node and calculate resistance R between theoretical node _{ij (s)}(s=1 ~ m), for its port resistive of the node measurement selected R ' _{ij (s)}, and calculate port resistive increment Delta R _{ij (s)}=R ' _{ij (s)}-R _{ij (s)}.Initial value I ' is set _{k (s)}(0)=I _{k (s)}, utilize corrosion diagnosis equation to calculate Δ R _k ^(t) _(s)(t=0,1 ..., t is iterations).R ' _k ^(t)=R _k+ Δ R _k ^(t)if, t>=1 and | Δ R _k ^(t)-Δ R _k ^{(t-1) |}< ε (ε is accuracy value), reaching accuracy requirement can stop iteration, thinks R ' _k ^(t)for end product, otherwise continue iteration, until meet accuracy requirement, idiographic flow as shown in Figure 1.

Utilize terminal handler to contrast the result after solving in above-mentioned step S5, it is specifically as the I calculated ^(t+1) _kwith I under normal circumstances _kwhen differing by more than one times, then prove that this grounded screen branch road there occurs corrosion failure, thus send ground connection corrosion alarm.

The kind of the signals collecting sensor in above-mentioned step S3 has voltage sensor, current sensor and electric resistance sensor.

Claims (5)

1. a grounding net of transformer substation corrosion diagnosis method, is characterized in that: comprise step as follows:

Step S1: according to the structure of actual grounding net of transformer substation, sets up the simplified network circuit model of actual substation grounding web frame;

Step S2: based on Tellegen, sets up corrosion diagnosis of grounding grid system of equations;

Step S3: to the branch road conveying exciting current of simplified network circuit model, carry out data acquisition by signals collecting sensor, and the data collected are flowed to terminal handler;

Step S4: the data separate alternative manner according to collecting solves corrosion diagnosis system of equations;

Step S5: utilize terminal handler to contrast the result after solving, thus judge the corrosion failure state of grounded screen.

2. a kind of grounding net of transformer substation corrosion diagnosis method according to claim 1, is characterized in that: described step S2 sets up corrosion diagnosis of grounding grid system of equations, shown in specific as follows:

1) according to the simplified network circuit model set up, in conjunction with known exciting current (I ₀) and the branch node column voltage vector (U that collected by signals collecting sensor _b+1), then according to nodal analysis, the resistance of any two ends mouth can be obtained

R _ij＝U _b+1/I ₀

Thus draw the resistance delta of any two ends mouth

ΔR _ij＝R’ _ij-R _ij

i＝1,…,n；j＝1,…,n；b＝1,…,n

2) according to Tellegen, then can show that the relational expression of branch resistance increment is

${\mathrm{\&Delta;R}}_{ij}=\underset{k=1}{\overset{b}{\&Sigma;}}{\mathrm{\&Delta;R}}_k{I}_k^{\&prime;}{I}_k/{I_0}^2$

3) according to step 1) and step 2) resistance delta of network two-port that obtains and the relation of branch resistance increment, a prescription journey can be obtained:

${\mathrm{\&Delta;R}}_{ij\left(1\right)}=\underset{k=1}{\overset{b}{\&Sigma;}}{\mathrm{\&Delta;R}}_k{I}_{k\left(1\right)}^{\&prime;}{I}_{k\left(1\right)}/{I_0}^2$

${\mathrm{\&Delta;R}}_{ij\left(2\right)}=\underset{k=1}{\overset{b}{\&Sigma;}}{\mathrm{\&Delta;R}}_k{I}_{k\left(2\right)}^{\&prime;}{I}_{k\left(2\right)}/{I_0}^2$

……

${\mathrm{\&Delta;R}}_{ij\left(m\right)}=\underset{k=1}{\overset{b}{\&Sigma;}}{\mathrm{\&Delta;R}}_k{I}_{k\left(m\right)}^{\&prime;}{I}_{k\left(m\right)}/{I_0}^2$

i＝1,…,m；j＝1,…,m；k＝1,…,m。

3. a kind of grounding net of transformer substation corrosion diagnosis method according to claim 1, is characterized in that: shown in the alternative manner provided in described step S4 is specific as follows:

Step 1: read grounded screen topology data, electric data, calculates the magnitude of current I on branch road _k;

Step 2: selected part measured node, calculates R _ij, measure R ' _ij;

Step 3: the resistance delta Δ R of computational grid two-port _ij=R ' _ij-R _ij;

Step 4: arranging primary iterations (t) is 0, I ' _k=i _k;

Step 5: calculate Δ R according to diagnostic equation group ^(t) _k;

Step 6: enter step (G) when iterations (t) >=1, otherwise iterations (t) adds 1 gets back to step D);

Step 7: when | Δ R _k ^(t)-Δ R _k ^{(t-1) |}enter step (H) time < ε (ε is accuracy value), otherwise iterations (t) adds 1 gets back to step D);

Step 8: calculate I ^(t+1) _k.

4. a kind of grounding net of transformer substation corrosion diagnosis method according to claim 1, is characterized in that: utilize terminal handler to contrast the result after solving in described step S5, it is specifically as the I calculated ^(t+1) _kwith I under normal circumstances _kwhen differing by more than one times, then prove that this grounded screen branch road there occurs corrosion failure, thus send ground connection corrosion alarm.

5. a kind of grounding net of transformer substation corrosion diagnosis method according to claim 1, is characterized in that: the kind of the signals collecting sensor in described step S3 has voltage sensor, current sensor and electric resistance sensor.