CN102904227A - Six-sequence component-based double circuit lines on same pole phase difference protection method - Google Patents

Abstract

The invention belongs to the field of relay protection of a power system, and relates to a six-sequence component-based double circuit lines on same pole phase difference protection method. The method comprises the following steps of: (1) acquiring six currents on each side of double-circuit lines by using current transformers at the protective installation positions on m and n sides of a circuit; (2) converting the six currents on each side of the double-circuit lines into six sequence current components by six-sequence transformation; (3) respectively subtracting corresponding sequence component a week before a fault from the same positive sequence components on the two sides to obtain respective same positive sequence fault components; (4) constructing composite currents by using the same positive sequence fault components, reverse positive sequence components and the same negative sequence components of the six sequence current components, and respectively solving the phase angles of the composite currents on the two sides; and (5) setting a phase difference protection action angle as Phi OP, determining that an internal fault exists if the absolute value of the difference between the phase angles of composite currents on the two sides of the circuit is smaller than the action angle, and otherwise, judging to be an external fault. By the method, a fault, particularly a cross-line fault, can be judged very well; and the method is easy to implement.

Description

A kind of double-circuit line on same pole phase-comparison protection method based on six order components

Technical field

The present invention relates to the relaying protection field of electric power system, be specifically related to a kind of new method of the double-circuit line on same pole phase-comparison protection based on six order components.

Background technology

On the double-circuit line on same pole road of 220kV and above, protection configuration generally with differential current as the first main protection, the vertical connection of direction or distance is as the second main protection, the syllogic distance protection is protected in support ^[1]But the differential current protection of double-circuit line on same pole needs to compare respectively the two ends current amplitude on six circuits, and the active channel number is more, makes its possibility increasing that reduces reliability because of channel failure, and expensive.As the direction of the second main protection or be subjected to the impact of power system oscillation apart from pilot protection, the ability of reaction transition resistance is subjected to the impact of the factors such as earth point position, fault preload electric current when earth fault.

Vertical connection current phase differential protecting is the current phase at protected circuit two ends relatively, and is irrelevant with the amplitude of fault current, not affected by power system oscillation, can allow larger transition resistance, and formation is simple, reliable operation.The vertical phase-comparison protection of three phase line adopts recombination current

As the operating current of protection, with the criterion that the phase angle difference of both sides operating current is moved as protection, its advantage is that three-phase current is considered as a whole, saves propagation ducts.When double-circuit line on same pole was regarded as two three phase lines, this principle can be directly used on the double-circuit line on same pole road as the second main protection, but the cross line fault of double-circuit line on same pole is difficult to correct judgement ^[2,3]

Therefore, be necessary to propose a kind of new guard method, the second main protection as the double-circuit line on same pole road can reduce active channel quantity, can improve again the discriminating power to fault type.

List of references

[1] He Jiali, Song Congju, Power System Relay Protection (enlarged edition), Beijing: China Electric Power Publishing House, 2007.

[2] Ge Yaozhong, novel relaying protection and fault localization philosophy and technique, publishing house of Xi'an Communications University, 1996

[3] stratagem, Zhang Yanxia, Yang Gang. the research of Phase Comparison Criterion of Operating Component in Phase Differential High Frequency Protection, electric power network technique, 2006,30(4): 55-59

[4] Zhang Yanxia, Wang Yan, 5 bodyguards, etc., based on the Six-phase power systems Fault Phase Selection of six order component methods, Automation of Electric Systems, 2009,33 (24): 1-5

Summary of the invention

The objective of the invention is to overcome the above-mentioned deficiency of prior art, a kind of phase-comparison protection method for double-circuit line on same pole is provided, under various fault types, can judge better fault, particularly cross line fault, and be easy to realize.Technical scheme of the present invention is as follows:

A kind of double-circuit line on same pole phase-comparison protection method based on six order components comprises the following steps:

(1) current transformer by circuit m, protection installation place, n both sides gathers six electric currents of the every side of double loop;

(2) be six order current components with six electric currents of the every side of double loop by six order shift conversion respectively:

With

Be respectively the same zero-sequence component of m side, same positive sequence component, same negative sequence component, anti-zero-sequence component, anyway order component and anti-negative sequence component;

With

Be respectively the same zero-sequence component of n side, same positive sequence component, same negative sequence component, anti-zero-sequence component, anyway order component and anti-negative sequence component;

(3) to the same positive sequence component of m

Same positive sequence component with the n both sides

Deduct respectively fault this order component corresponding to the last week, obtain same positive sequence fault component

(4) utilize

With

The recombination current of the m side that consists of respectively Recombination current with the n side

Try to achieve respectively the phase angle of both sides recombination current;

(5) operating angle of establishing phase-comparison protection is

If the absolute value of the difference of the phase angle of circuit both sides recombination current less than Then be judged to be internal fault, otherwise be judged to external fault.

As preferred implementation,

L is protected circuit length, unit: km; K _F1Get 2～4, K _T2Get 19～21.

Beneficial effect of the present invention is as follows:

1, the phase-comparison protection new method of double-circuit line on same pole is considered six electric currents of double-circuit line on same pole as a whole, is not subjected to the impact of system oscillation, has saved number of channels, improves protection reliability, has simplified the configuration of protection.

2, new method is not affected by load current, and the anti-resistance ability of crossing is strong, affected by capacitance current little.

3, the new method operating principle is simply clear and definite, is easy to realize in Microcomputer Protection;

Description of drawings

Fig. 1 double loop system schematic.

Embodiment

The impedance matrix of complete transposition double loop as shown in Figure 1 is full battle array, finds the solution difficulty.Six order conversion ^[2]Essence be the alternate mutual inductance of mutual inductance and single loop line between the line of decoupling zero double loop.Utilize first the P matrix of formula (1) that each phasor of complete transposition double loop is carried out conversion, its essence is six phase currents are divided into two parts: three with vector (amount of passing through represents with T) and three contravariant vectors (circulation represents with F).Because three with 120 ° of vectorial electric current mutual deviations, the induced potential that produces in the contravariant vector loop is cancelled each other, and the induced potential that the loop is measured in three each leisures of the oppositely amount of passing through electric current that have the loop of one's own is in the same way also cancelled out each other, therefore same, contravariant vector has not had mutual inductance between the loop, thus double-circuit line being decoupled into two independently three-phase systems---three-phase is with vectorial system and three-phase contravariant vector system, finished mutual inductance decoupling zero between the line of double loop, six order components after the decoupling zero and double loop current-voltage correlation are expressed with formula (2), as seen there is mutual inductance between three-phase each phase with vectorial system, also there is mutual inductance between each phase of three-phase contravariant vector system, but with not had mutual inductance between vectorial system and the contravariant vector system.

$P=\left[\begin{array}{cccccc}1& 0& 0& 1& 0& 0\\ 0& 1& 0& 0& 1& 0\\ 0& 0& 1& 0& 0& 1\\ 1& 0& 0& -1& 0& 0\\ 0& 1& 0& 0& -1& 0\\ 0& 0& 1& 0& 0& -1\end{array}\right]---\left(1\right)$

$\left[\begin{array}{c}{\stackrel{\·}{U}}_{\mathrm{mnTA}}\\ {\stackrel{\·}{U}}_{\mathrm{mnTB}}\\ {\stackrel{\·}{U}}_{\mathrm{mnTC}}\\ {\stackrel{\·}{U}}_{\mathrm{mnFA}}\\ {\stackrel{\·}{U}}_{\mathrm{mnFB}}\\ {\stackrel{\·}{U}}_{\mathrm{mnFC}}\end{array}\right]=\left[\begin{array}{cccccc}{Z}_S+Z_M^{\′}& Z_M+Z_M^{\′}& Z_M+Z_M^{\′}& & & \\ Z_M+Z_M^{\′}& Z_S+Z_M^{\′}& Z_M+Z_M^{\′}& & 0& \\ & & & & & \\ & & & Z_S-Z_M^{\′}& Z_M-Z_M^{\′}& Z_M-Z_M^{\′}\\ & 0& & Z_M-Z_M^{\′}& Z_S-Z_M^{\′}& Z_M-Z_M^{\′}\\ & & & Z_M-Z_M^{\′}& Z_M-Z_M^{\′}& Z_S-Z_M^{\′}\end{array}\right]\·\left[\begin{array}{c}{\stackrel{\·}{I}}_{\mathrm{mnTA}}\\ {\stackrel{\·}{I}}_{\mathrm{mnTB}}\\ {\stackrel{\·}{I}}_{\mathrm{mnTC}}\\ {\stackrel{\·}{I}}_{\mathrm{mnFA}}\\ {\stackrel{\·}{I}}_{\mathrm{mnFB}}\\ {\stackrel{\·}{I}}_{\mathrm{mnFC}}\end{array}\right]---\left(2\right)$

In the formula, T ₀, T ₁And T ₂Represent respectively same zero sequence, with positive sequence with the negative phase-sequence amount; F ₀, F ₁And F ₂Represent respectively anti-zero sequence, anyway order and anti-negative phase-sequence amount.

In order to eliminate with the separately mutual inductance between the three-phase in vectorial system and the contravariant vector system, more same, anti-phase amount to be utilized respectively the symmetrical component transformation matrix S of formula (3) to carry out conversion, thereby formed six order component types (4).

$S=\left[\begin{array}{cccccc}1& 1& 1& 0& 0& 0\\ 0& a& a^2& 0& 0& 0\\ 0& a^2& a& 0& 0& 0\\ 0& 0& 0& 1& 1& 1\\ 0& 0& 0& 1& a& a^2\\ 0& 0& 0& 1& a^2& a\end{array}\right]---\left(3\right)$

Wherein, a=e ^{J2 π/3}

$\left[\begin{array}{c}{\stackrel{\·}{U}}_{\mathrm{mnT}0}\\ {\stackrel{\·}{U}}_{\mathrm{mnF}0}\\ {\stackrel{\·}{U}}_{\mathrm{mnT}1}\\ {\stackrel{\·}{U}}_{\mathrm{mnF}1}\\ {\stackrel{\·}{U}}_{\mathrm{mnT}2}\\ {\stackrel{\·}{U}}_{\mathrm{mnF}2}\end{array}\right]=\left[\begin{array}{cccccc}{Z}_{T0}& & & & & \\ & Z_{F0}& & & & \\ & & Z_{T1}& & & \\ & & & Z_{F1}& & \\ & & & & Z_{T2}& \\ & & & & & Z_{F2}\end{array}\right]\·\left[\begin{array}{c}{\stackrel{\·}{I}}_{\mathrm{mnT}0}\\ {\stackrel{\·}{I}}_{\mathrm{mnF}0}\\ {\stackrel{\·}{I}}_{\mathrm{mnT}1}\\ {\stackrel{\·}{I}}_{\mathrm{mnF}1}\\ {\stackrel{\·}{I}}_{\mathrm{mnT}2}\\ {\stackrel{\·}{I}}_{\mathrm{mnF}2}\end{array}\right]---\left(4\right)$

With above-mentioned two kinds of conversion processes altogether, just obtain the final transform matrix M of double loop decoupling zero.

$M=\left[\begin{array}{cccccc}1& 1& 1& 1& 1& 1\\ 1& 1& a^2& a^2& a& a\\ 1& 1& a& a& a^2& a^2\\ 1& -1& 1& -1& 1& -1\\ 1& -1& a^2& -a^2& a& -a\\ 1& -1& a& -a& a^2& -a^2\end{array}\right]---\left(5\right)$

The below analyzes the six order component fault signatures of summing up the double-circuit line on same pole system.

When single loop line three-phase fault such as IABC occur in the double-circuit line on same pole of Fig. 1, because can there be positive sequence amount (1 order amount) in two loop lines three-phase symmetrical separately, and uneven between two loop lines, contravariant vector (F vector) can appear.Therefore, exist in the electric current during this fault

And satisfy the fault point

All the other faults of single loop line since the balance of every loop line itself be broken, also balance no longer between line, thus in the fault current together, each order amount of contravariant vector all exists.

When occuring with famous prime minister's cross line fault such as IAIIAG or IBCIIBCG, balance still between double loop is so only exist with vector namely in the fault current

With

Non-two-phase of the same name, three-phase, four mutually with five cross line faults mutually, all exist with each order amount of, contravariant vector.

When six phase faults occurs when, single loop line internal balance, also balance between double loop is so only exist in the fault current

By above analysis as can be known, All faults that can the reaction double loop line,

Key reaction is with famous prime minister's cross line fault,

The single loop line three-phase fault of key reaction.Therefore, suitable compound as long as the three carries out, just can sensitively react all types of faults.In order to eliminate the impact of load current, adopt

Fault component

Will The recombination current that consists of is as the operating current of phase-comparison protection, namely The phase bit motion that compares the operating current at double loop M, N two ends.Therefore, the vertical phase-comparison protection operating criterion of double-circuit line on same pole is expressed as

Wherein

Be the operating angle of phase-comparison protection, get according to conventional setting principle

L is protected circuit length, km.

When preventing fault

With

Cancel out each other, guarantee the reliability of operating current, adopt following formula as the principle of selecting the K value.

$|K_{F1}{\stackrel{\·}{I}}_{F1}+K_{T2}{\stackrel{\·}{I}}_{T2}|\≥1.5\left|\mathrm{\Δ}{\stackrel{\·}{I}}_{T1}\right|---\left(7\right)$

Namely $|K_{F1}{\stackrel{\·}{I}}_{F1}+K_{T2}{\stackrel{\·}{I}}_{T2}|-1.5\left|\mathrm{\Δ}{\stackrel{\·}{I}}_{T1}\right|\≥0$

In the double loop complete transposition situation,

Ignore the resistance in the impedance, Z in the real system _F0/ Z _T0≈ 6.Operating criterion expression formula when obtaining various fault is thus listed among the table 1-1.

The various fault type K of table 1-1 double loop value is selected

Tab?1-1?The?selection?of?K?value?over?a?variety?of?double?transmission?lines?fault?patterns

Listed criterion satisfies formula (7) in the table in order to make, suggestion K _T2Get 19～21, K _F1Get 2～4.This value can both make the recombination current of output non-vanishing in the time of can guaranteeing various fault in theory, the various faults of correct response, and action message.

Guard method of the present invention can be summarized as follows:

1, protective device utilizes order component transformation formula and full-cycle DFT to calculate six order components of both sides electric current by the electric current that the CT of transmission line m side and n side gathers the circuit both sides;

2, use

The load current that deducts normal operation obtains fault component

3, will The recombination current that consists of then is judged to be internal fault if equation is set up, otherwise is judged to external fault as the operating current substitution Judgment formula (6) of phase-comparison protection.

Claims (3)

1. the double-circuit line on same pole phase-comparison protection method based on six order components comprises the following steps:

(1) current transformer by circuit m, protection installation place, n both sides gathers six electric currents of the every side of double loop;

(2) be six order current components with six electric currents of the every side of double loop by six order shift conversion respectively:

With Be respectively the same zero-sequence component of m side, same positive sequence component, same negative sequence component, anti-zero-sequence component, anyway order component and anti-negative sequence component; With

Be respectively the same zero-sequence component of n side, same positive sequence component, same negative sequence component, anti-zero-sequence component, anyway order component and anti-negative sequence component;

(3) to the same positive sequence component of m

Same positive sequence component with the n both sides Deduct respectively fault this order component corresponding to the last week, obtain same positive sequence fault component

(4) utilize With

The recombination current of the m side that consists of respectively

Recombination current with the n side

Try to achieve respectively the phase angle of both sides recombination current;

(5) operating angle of establishing phase-comparison protection is

If the absolute value of the difference of the phase angle of circuit both sides recombination current less than

Then be judged to be internal fault, otherwise be judged to external fault.

2. the double-circuit line on same pole phase-comparison protection method based on six order components according to claim 1 is characterized in that,

L is protected circuit length, unit: km.

3. the double-circuit line on same pole phase-comparison protection method based on six order components according to claim 1 is characterized in that K _F1Get 2～4, K _T2Get 19～21.

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