CN100444493C - Adaptive earthing distance relay - Google Patents

Abstract

The present invention relates to the technology of the distance protection of an earth fault of a high-voltage transmission line, which belongs to a self-adapting earth impedance relay. The present invention is a self-adapting impedance relay which is towards an earth direction and is formed by the method that the negative sequence voltage Um2 for protecting the installation point after a fault happens serves as the polarization quantity. The relay of the present invention not only has a strong transition resistance capability, but also has the advantage of negative sequence component protection; the present invention is a self-adapting earth impedance relay with very good combination performance. According to the result of the MATLAB simulation analysis, the relay can be testified that the relay has excellent acting performance and has the strong self-adapting capability for the earth resistance on a 500KV super high voltage line.

Description

A kind of adaptive earthing impedance relay

Technical field

The present invention relates to ultra-high-tension power transmission line earth fault distance protection technology.

Background technology

Single phase ground fault is the principal mode of high-voltage fence fault, and other fault also is to be formed by the single phase ground fault development mostly.Therefore, the performance that improves the impedance ground relay is for reducing the loss that electric network fault causes, safe, the stability that improve operation of power networks have significance.How to overcome transition resistance to the influence of protection zone, how the directivity of safety action is the major issue that the impedance ground relay need solve.The research document of existing a lot of relevant impedance ground relays, these impedance ground relay performance are different, or very strong anti-transition resistance ability is arranged, but it is serious to surmount phenomenon; Or anti-transition resistance ability is not enough; Or the dead band arranged; Or it is non-directional.Tracing it to its cause, is because their dynamic action border can not be followed the variation of fault point false voltage fully with the variation of transition resistance.

Summary of the invention

The technical problem to be solved in the present invention is; defective at the prior art existence; propose a kind of adaptive earthing impedance relay, it has good adaptivity to transition resistance, the problem of anti-transition resistance ability when having impedance relay to the protection zone internal fault now to overcome.

Technical solution of the present invention is that described adaptive earthing impedance relay is: with the negative sequence voltage of protection installation place after the fault (m is A or B, C phase) constitutes the adaptive earthing impedance relay for amount of polarization.

Below the present invention made further specify.

Adaptive earthing impedance relay of the present invention has the good adaptivity of earth resistance, and its adaptive characteristic is analyzed as follows:

Unified employing double ended system model shown in Figure 1 is located at the K point through the transition resistance R during analysis _gSingle-phase earthing (this paper is example with the A phase fault all) has taken place, and rated current positive direction such as Fig. 1 show, during fault each fault amount as shown in Figures 2 and 3, Fig. 2 send electricity for M side direction N side, Fig. 3 gives for N side direction M side. Be the voltage before the fault phase A phase fault point failure,

Be the short circuit current of fault point,

With R _gDo to change counterclockwise along circular arc from the variation of 0～∞.

${\stackrel{\·}{I}}_{\mathrm{KA}}=\frac{3{\stackrel{\·}{U}}_{\mathrm{KA}\left[0\right]}}{3R_g+Z_{\mathrm{\Σ}1}+Z_{\mathrm{\Σ}2}+Z_{\mathrm{\Σ}0}}$

A phase bucking voltage

For

${{\stackrel{\·}{U}}^{\′}}_A={\stackrel{\·}{U}}_A-({\stackrel{\·}{I}}_A+k3{\stackrel{\·}{I}}_0)Z_{\mathrm{set}}$

$=3{\stackrel{\·}{I}}_{\mathrm{KA}2}{R}_g-({\stackrel{\·}{I}}_A+k3{\stackrel{\·}{I}}_0)Z_{\mathrm{set}}+({\stackrel{\·}{I}}_A+k3{\stackrel{\·}{I}}_0)Z_1{l}_k$

${\stackrel{\·}{I}}_A+k3{\stackrel{\·}{I}}_0={\stackrel{\·}{I}}_{\mathrm{loa}.A}+\mathrm{\α}{\stackrel{\·}{I}}_{\mathrm{KA}}$

In the formula,

Be M side A phase voltage;

A phase current and zero-sequence current for the M side;

Be fault point fault current negative sequence component;

Z _SetBe the impedance of adjusting; Penalty coefficient $k=\frac{z_0-z_1}{3z_1}$ (z ₀, z ₁: the unit positive sequence impedance of circuit, zero sequence impedance); Be A phase load electric current; α is and network configuration, a relevant coefficient of position of failure point.As can be seen from Fig. 2, no matter be to send electric side or be subjected to electric side, if with

Be on trip boundary (dynamic action border) that the side that lags behind is an active region, then during the internal fault of protection zone,

Always at active region, during the protection external area error,

Always at non-active region, Bao Hu operating characteristics just is not subjected to the influence of fault point transition resistance, load current like this, and also not being subjected to relay is to send electric side or be subjected to the influence of electric side, and its operation equation formula is

But measure in the protection installation place less than

Therefore to seek an energy from motion tracking

Variation and the amount that can measure.

Because the negative sequence voltage of protection installation place

For

${\stackrel{\·}{U}}_{A2}=-C_{2M}{Z}_{M2}{\stackrel{\·}{I}}_{\mathrm{KA}2}$

C _2MBe M side negative-sequence current distribution coefficient (can make real number handles), Z _M2Be the negative phase-sequence equivalent reactance of M side system, because the negative sequence impedance angle of each element of system is very big Therefore, the negative sequence voltage of available protection installation place-

Phase place replaces

R _g, constituting the impedance relay that negative sequence voltage polarizes, its operation equation formula is

Relay can be adjusted its trip boundary automatically according to transition resistance, therefore has extremely strong anti-transition resistance ability.If will make relay that transition resistance is had best self adaptation degree, can be with the negative phase-sequence polarizing voltage

According to Z _M2Impedance angle suitably phase shift of size (if

Then Reach angle θ≤5 °) realizes.While is owing to fault point negative sequence voltage maximum, so there is not the voltage " dead band " of action in relay.

About actuating of relay directional analysis.The operation equation of the adaptive earthing impedance relay of negative sequence voltage polarization is as follows:

Or:

Direction with fault current during analysis is the positive direction of electric current, and is easy for analyzing simultaneously, and establishing the circuit no-load condition under generation metallicity single-phase earthing and total system has identical preface impedance angle, and system wiring is seen Fig. 1

(1) positive direction K point single-phase earthing

${\stackrel{\·}{U}}_{\mathrm{OPA}}={\stackrel{\·}{U}}_A-({\stackrel{\·}{I}}_A+K3{\stackrel{\·}{I}}_0)Z_{\mathrm{set}}=({\stackrel{\·}{I}}_A+K3{\stackrel{\·}{I}}_0)(Z_m-Z_{\mathrm{set}})---\left(3\right)$

${\stackrel{\·}{U}}_{A2}=\frac{-C_1{Z}_{M1}}{Z_{\mathrm{\Σ}1}+Z_{\mathrm{\Σ}2}+Z_{\mathrm{\Σ}0}}{\stackrel{\·}{U}}_{\mathrm{KA}\left[0\right]}=\frac{-C_1{Z}_{M1}}{Z_{\mathrm{\Σ}1}+Z_{\mathrm{\Σ}2}+Z_{\mathrm{\Σ}0}}{\stackrel{\·}{E}}_{\mathrm{MA}}$

$=\frac{-C_1{Z}_{M1}}{Z_{\mathrm{\Σ}1}+Z_{\mathrm{\Σ}2}+Z_{\mathrm{\Σ}0}}\×({\stackrel{\·}{I}}_A+K3{\stackrel{\·}{I}}_0)\×(Z_m+Z_{M1})---\left(4\right)$

The operation equation formula that (3) (4) formula substitution formula (1) can be got the positive direction single-phase earthing is

Operating characteristics is an active region in the circle as shown in Figure 4.

(2) in the other direction during single-phase earthing

This moment short circuit current by

Z is provided _SetBe negative value.

Can getting in the other direction according to (5) formula, the operation equation formula of single-phase earthing is

Operating characteristics is an active region in the circle as shown in Figure 5.

By operating characteristics as seen, relay has clear and definite directivity to single phase ground fault.

As known from the above, the present invention is a kind of adaptive earthing impedance relay, and its characteristic compared with the prior art has:

When (1) in protection range earth fault taking place, the impedance ground relay of negative sequence voltage polarization has very strong anti-transition resistance ability, and this is that other polarizing voltage relay is incomparable;

(2) when earth fault took place in the protection exit, the negative sequence voltage polarized relay had the highest operating sensitivity, did not promptly have voltage action " dead band ", had solved " dead band " problem of conventional impedance ground relay;

(3) actuating of relay has clear and definite directivity, and this is that the relay of zero sequence reactance characteristic is not available;

(4) no matter relay is provided in a side of and send electric side and be subjected to the electric side can both correct operation;

Description of drawings

Fig. 1 is a both-end electric power system diagram;

Voltage phasor-diagram when Fig. 2 is A phase ground connection;

Voltage phasor-diagram when Fig. 3 is A phase ground connection;

Operating characteristics when Fig. 4 is positive direction ground connection;

Operating characteristics when Fig. 5 is opposite direction ground connection.

Embodiment

Carry out simulation calculation when adopting MATLAB software to the 500KV supertension line A phase ground connection of a long 300Km, wherein transmission line adopts distributed parameter model.System wiring as shown in Figure 1, simulation system parameters is as follows:

System parameters: Z _M=Z _N=5.74+j14.1 Ω

Line parameter circuit value: r ₁=0.02083 Ω/km, l ₁=0.8984mH/km, c ₁=0.0129MF/km

r ₀＝0.1148Ω/km，l ₀＝2.2886mH/km，c ₀＝0.00523MF/km。

60 ° of circuit both sides electrical source voltage phase differences, the district of adjusting is 85% of total track length.

The simulation calculation content: simultaneously to negative sequence voltage polarization (

) and present memory voltage commonly used polarization ( ), positive sequence voltage polarization (

) the operating characteristics of impedance ground relay carry out the phase bit emulator, calculate

Phase place.Relay is located at respectively and send electric side and be subjected to electric side; the fault point is chosen for protection outlet in the other direction, positive direction outlet, positive direction 150KM place, 4 points in the terminal 240KM place of nearly protection range; transition resistance changes to 300 Ω (step-length is 10 Ω) from 0, and the operating characteristics of relay is

Simulation calculation the results are shown in Table 1 (sending electric side) and table 2 (being subjected to electric side).

Table 1 send electric side

Table 1 (continuing)

Table 2 is subjected to electric side

Table 2 (continuing)

Claims (1)

1, a kind of adaptive earthing impedance relay is characterized in that, with the negative sequence voltage of protection installation place after the fault

For amount of polarization constitutes this adaptive earthing impedance relay, its operation equation formula is:

Wherein: m is A, B or C phase, Be A phase bucking voltage,

Be the negative phase-sequence polarizing voltage.

Images