CN104167755B - Method for determining commutation failure area caused by single-phase short circuit - Google Patents

Abstract

The invention provides a method for determining a phase change failure area caused by a single-phase short circuit. In particular to a method for determining a commutation failure area caused by single-phase short circuit based on a positive and negative zero sequence impedance matrix. The method comprises the steps of calculating the positive and negative zero sequence self-impedance of a transformer substation to be researched in an electric power system and the positive and negative zero sequence mutual impedance between the transformer substation and each inversion station, calculating the ratio of the sum of the positive and negative zero sequence mutual impedance to the sum of the positive and negative zero sequence self-impedance, and judging whether the single-phase short circuit of the transformer substation possibly causes the phase commutation failure of a direct current inversion station according to the calculated ratio; through scanning all substations to be researched and all inversion stations, a single-phase short-circuit fault area which possibly causes multi-circuit direct-current commutation failure is obtained, and reference is provided for researching the influence of the single-phase short-circuit fault of the alternating-current system on the direct-current system and arrangement of a power grid operation mode.

Description

A kind of method determining that single-phase short circuit causes commutation failure region

Technical field

The present invention proposes a kind of method determining that single-phase short circuit causes commutation failure region, and particularly a kind of method determining commutation failure region that single-phase short circuit causes based on positive and negative zero sequence impedance matrix, belongs to Power System Analysis technical field.

Background technology

Along with the development of power system, electrical network occurs in that AC/DC parallel is run, multiple-circuit line concentrates the new features such as feed-in, and ac and dc systems is closely connected, and is interweaved, and stability characteristic (quality) is complicated.Analyze influencing each other of AC system and straight-flow system, be Electric Power Network Planning, run in a very important problem.

Commutation failure is the modal fault of direct current transportation inverter.In actual motion, most of commutation failures are that the voltage disturbance caused by AC network fault causes.In multi-feed HVDC system, receiving end AC system subregion fault may cause multiple-circuit line transmission of electricity inverter generation commutation failure, causes dc power to decline, and then affects the stability of whole electrical network.

South electric network research institute is through carrying out deep research to commutation failure, propose a kind of simplex criteria judging direct-flow inverter commutation failure: in the electromechanical transient simulation programs such as BPA, DC Model owing to adopting is quasi-stationary model, for the judgement of commutation failure with simulate not accurate enough, simplex criteria can be adopted to carry out the judgement of commutation failure, different faults point in AC system arranges AC three-phase or single-phase earthing fault, as instant of failure DC inversion side change of current busbar voltage drops into the 90% of normal operating voltage value, then think this direct current generation commutation failure.

According to this criterion, in order to determine the single-phase earthing fault region being likely to cause multiple-circuit line generation commutation failure, all adopt electromechanical transient simulation software that each possible website is carried out fault simulation at present, obtain the voltage of each Inverter Station change of current bus of fault moment, whether the voltage according to instant of failure change of current bus drops into normal value less than 90% judges whether this current conversion station commutation failure occurs, so that it is determined that be likely to cause the single-phase earthing fault region of multiple-circuit line generation commutation failure.But, this computational methods need to each be likely to cause commutation failure carry out fault simulation at website, workload is big, the calculating time is long, use inconvenience, it is therefore desirable to propose a kind of simple and quick computational methods to determine the single-phase earthing fault region being likely to cause multiple-circuit line generation commutation failure, as the reference that straight-flow system impact and power system operating mode are arranged by assessment AC system.

Summary of the invention

The purpose of the present invention is to propose to a kind of method determining that single-phase short circuit causes commutation failure region, the method definition is clear, computational methods are simple, explicit physical meaning, the single-phase earthing fault region being likely to cause multiple-circuit line commutation failure can be determined easily and fast, provide reference for research AC system single-phase earthing fault to the impact of straight-flow system and the arrangement of power system operating mode.

The technical scheme is that

Present invention determine that the method that single-phase short circuit causes commutation failure region, comprise the following steps:

1) with alternating current-direct current electrical network for object of study, it is determined that DC inversion station to be studied is with probably due to fault in ac transmission system causes the transformer station of direct-current commutation failure, and wherein, there is M place in transformer station to be studied, and there is N place at DC inversion station；

2) the positive and negative zero sequence impedance matrix of alternating current-direct current electrical network to be studied is calculated, including positive sequence impedance matrix Z₁, negative sequence impedance matrix Z₂With zero sequence impedance matrix Z₀；

3) according to positive and negative zero sequence impedance matrix, calculate i-th transformer station to be studied positive and negative zero sequence self-impedance and Z_ii, i=1,2 ... M；

4) according to positive and negative zero sequence impedance matrix, calculate positive and negative zero sequence mutual impedance between jth Inverter Station and i-th transformer station and Z_ij, j=1,2 ... N；

5) calculate positive and negative zero sequence mutual impedance and with positive and negative zero sequence self-impedance and ratio k_ij, according to ratio k_ijSize, it is judged that i-th transformer station occur single-phase earthing fault whether be likely to cause jth Inverter Station generation commutation failure；

6) repeat step 4), step 5), until j=N, i place of record transformer station generation single-phase short circuit is likely to cause the Inverter Station number of commutation failure to be L_i；

7) repeat step 3), step 4), step 5), step 6), until i=M, obtain may result in K and go back to the single-phase earthing fault region of direct-current commutation failure, K=0,1,2 ... M.

Described step 3) in,

Z_ii=Z_ii-1+Z_ii-2+Z_ii-0(1)

In formula: Z_ii-1For the positive sequence self-impedance at i place of transformer station, Z_ii-2For the negative phase-sequence self-impedance at i place of transformer station, Z_ii-0For the zero sequence self-impedance at i place of transformer station, Z_iiFor the sum of the positive and negative zero sequence self-impedance at i place of transformer station,

Described step 4) in,

Z_ij=Z_ij-1+Z_ij-2+Z_ij-0(2)

In formula: Z_ij-1For the positive sequence mutual impedance between transformer station i and Inverter Station j, Z_ij-2For the negative phase-sequence mutual impedance between transformer station i and Inverter Station j, Z_ij-0For the zero sequence mutual impedance between transformer station i and Inverter Station j, Z_ijThe sum of the positive and negative zero sequence mutual impedance between transformer station i and Inverter Station j.

Described step 5) in,

$k_{\mathrm{ij}}=\left|\frac{z_{\mathrm{ij}}}{z_{\mathrm{ii}}}\right|---\left(3\right)$

If k_ij> 0.1, then it is assumed that i place of transformer station occurs single-phase short circuit to be likely to cause Inverter Station j that commutation failure occurs.

The present invention is a kind of method determining commutation failure region that single-phase short circuit causes based on positive and negative zero sequence impedance matrix.By the positive and negative zero sequence mutual impedance between positive and negative zero sequence self-impedance and transformer station and each Inverter Station of transformer station to be studied in calculating power system, calculate positive and negative zero sequence mutual impedance and with positive and negative zero sequence self-impedance and ratio, occur whether single-phase short circuit is likely to cause DC inversion station that commutation failure occurs according to this transformer station of the ratio in judgement tried to achieve；By the scanning to the transformer station required study and all Inverter Station, the single-phase earthing fault region being likely to cause multiple-circuit line commutation failure can be determined easily and fast, provide reference for research AC system single-phase earthing fault to the impact of straight-flow system and the arrangement of power system operating mode.The method determining commutation failure region that single-phase short circuit causes based on positive and negative zero sequence impedance matrix that the present invention proposes, definition is clear, and computational methods are simple, explicit physical meaning.

Accompanying drawing explanation

Fig. 1 is the flow chart of the present invention, and Fig. 2 is that in specific embodiment, the rich big mode of south electric network may result in 5 times direct currents the single-phase earthing fault region of commutation failure occurs simultaneously.

Specific embodiment

Present invention determine that the method that single-phase short circuit causes commutation failure region, comprise the following steps:

1) with alternating current-direct current electrical network for object of study, it is determined that DC inversion station to be studied is with probably due to fault in ac transmission system causes the transformer station of direct-current commutation failure, and wherein, there is M place in transformer station to be studied, and there is N place at DC inversion station；

2) the positive and negative zero sequence impedance matrix of alternating current-direct current electrical network to be studied is calculated, including positive sequence impedance matrix Z₁, negative sequence impedance matrix Z₂With zero sequence impedance matrix Z₀；

3) according to positive and negative zero sequence impedance matrix, calculate i-th transformer station to be studied positive and negative zero sequence self-impedance and Z_ii, i=1,2 ... M；

4) according to positive and negative zero sequence impedance matrix, calculate positive and negative zero sequence mutual impedance between jth Inverter Station and i-th transformer station and Z_ij, j=1,2 ... N；

5) calculate positive and negative zero sequence mutual impedance and with positive and negative zero sequence self-impedance and ratio k_ij, according to ratio k_ijSize, it is judged that i-th transformer station occur single-phase earthing fault whether be likely to cause jth Inverter Station generation commutation failure；

6) repeat step 4), step 5), until j=N, i place of record transformer station generation single-phase short circuit is likely to cause the Inverter Station number of commutation failure to be L_i；

7) repeat step 3), step 4), step 5), step 6), until i=M, obtain may result in K and go back to the single-phase earthing fault region of direct-current commutation failure, K=0,1,2 ... M.

Described step 3) in,

Z_ii=Z_ii-1+Z_ii-2+Z_ii-0(1)

In formula: Z_ii-1For the positive sequence self-impedance at i place of transformer station, Z_ii-2For the negative phase-sequence self-impedance at i place of transformer station, Z_ii-0For the zero sequence self-impedance at i place of transformer station, Z_iiFor the sum of the positive and negative zero sequence self-impedance at i place of transformer station,

Described step 4) in,

Z_ij=Z_ij-1+Z_ij-2+Z_ij-0(2)

In formula: Z_ij-1For the positive sequence mutual impedance between transformer station i and Inverter Station j, Z_ij-2For the negative phase-sequence mutual impedance between transformer station i and Inverter Station j, Z_ij-0For the zero sequence mutual impedance between transformer station i and Inverter Station j, Z_ijThe sum of the positive and negative zero sequence mutual impedance between transformer station i and Inverter Station j.

Described step 5) in,

$k_{\mathrm{ij}}=\left|\frac{z_{\mathrm{ij}}}{z_{\mathrm{ii}}}\right|---\left(3\right)$

If k_ij> 0.1, then it is assumed that i place of transformer station occurs single-phase short circuit to be likely to cause Inverter Station j that commutation failure occurs.

When unbalanced faults such as electric power networks generation single-phase short circuits, the value of each transportation load in system to be obtained, it is necessary to consider negative phase-sequence and zero-sequence network.The network equation of electric power networks positive negative zero three sequence is:

$\left\{\begin{array}{c}{U}_1=Z_1{I}_1\\ U_2=Z_2{I}_2\\ U_0=Z_0{I}_0\end{array}\right.---\left(4\right)$

In formula: U₁、U₂、U₀Respectively the positive sequence voltage of network is vectorial, negative sequence voltage vector, residual voltage are vectorial, I₁、I₂、I₀Respectively the forward-order current of network is vectorial, negative-sequence current vector, zero-sequence current are vectorial, Z₁、Z₂、Z₀Respectively the positive sequence impedance matrix of network, negative sequence impedance matrix, zero sequence impedance matrix.

Occur A phase single-phase short circuit to illustrate for website i place.

Time properly functioning (not breaking down), system three-phase symmetrical, the injection current vector of negative phase-sequence and zero-sequence network is 0, the expression formula such as formula (5) of each node A phase voltage of network:

U_A=U₁+U₂+U₀=Z₁I₁+Z₂I₂+Z₀I₀=Z₁I₁(5)

In formula: U_AFor network A phase voltage vector.

If there is single-phase short circuit at website i place, be equivalent to add the positive and negative zero sequence injection current of short circuit current size at website i place, and the injection current of positive negative zero three sequence is equal, the injection current of all the other websites is constant, network impedance matrix is constant, according to the linear relationship between node voltage and injection current, the variable quantity of each node A phase voltage of network is:

ΔU_A=Δ U₁+ΔU₂+ΔU₀=Z₁ΔI₁+Z₂ΔI₂+Z₀ΔI₀=(Z₁+Z₂+Z₀)ΔI₁

(6)ΔI₁=[0,0,0 ..., Δ I_1i... 0,0]^T(7)

In formula: Δ U_AFor the variable quantity of each node A phase voltage of network, Δ U₁、ΔU₂、ΔU₀Respectively positive sequence voltage variable quantity, negative sequence voltage variable quantity, residual voltage variable quantity, Δ I₁、ΔI₂、ΔI₀Respectively forward-order current variable quantity, negative-sequence current variable quantity, zero-sequence current variable quantity, Δ I_1iPositive sequence injection current variable quantity for website i place.

Can be obtained by formula (6), formula (7):

ΔU_Ai=(Z_ii-1+Z_ii-2+Z_ii-0)ΔI_1i(8)

ΔU_Aj=(Z_ij-1+Z_ij-2+Z_ij-0)ΔI_1i

In formula: Δ U_AiFor the A phase voltage variable quantity at website i place, Δ U_AjA phase voltage variable quantity for Inverter Station j place.

Employing perunit value is calculated, and before fault, the voltage of each website is it is believed that equal to perunit value 1, A phase single-phase short circuit occurs at website i place, and A phase voltage drops to 0, A phase voltage variation delta U_Ai=1.Can be obtained by formula (8):

$\frac{{\mathrm{\ΔU}}_{\mathrm{Aj}}}{{\mathrm{\ΔU}}_{\mathrm{Ai}}}={\mathrm{\ΔU}}_{\mathrm{Aj}}=\frac{(Z_{\mathrm{ii}-1}+Z_{\mathrm{ii}-2}+Z_{\mathrm{ii}-0}){\mathrm{\ΔI}}_{1i}}{(Z_{\mathrm{ij}-1}+Z_{\mathrm{ij}-2}+Z_{\mathrm{ij}-0}){\mathrm{\ΔI}}_{1i}}=\frac{Z_{\mathrm{ii}-1}+Z_{\mathrm{ii}-2}+Z_{\mathrm{ii}-0}}{Z_{\mathrm{ij}-1}+Z_{\mathrm{ij}-2}+Z_{\mathrm{ij}-0}}=k_{\mathrm{ij}}---\left(9\right)$

Can be obtained by formula (9), the A phase voltage variation delta U at Inverter Station j place_AjValue and positive and negative zero sequence mutual impedance and with positive and negative zero sequence self-impedance and ratio k_ijEqual, therefore, it can use k_ijSize judge whether Inverter Station j commutation failure occurs, if k_ij> 0.1, then be the A phase voltage landing Δ U at Inverter Station j place_AjMore than 10%, it is believed that commutation failure occurs Inverter Station j.

By the examples below the present invention is done further supplementary notes:

South electric network has 5 go back tos direct current feed-in Guangdong simultaneously for 2012, starts direct current, Chu Sui direct current including city, river direct current, Tianguang HVDC, Xingan's direct current, height.According to south electric network rich big mode data in 2012, calculate whether 50, Guangdong Power Grid domestic current conversion station near region 500kV plant stand outlet generation single-phase earthing fault can cause each direct current generation commutation failure.

Single-phase short circuit occurring for Boluo station, tries to achieve the positive sequence between the positive sequence at Boluo station, negative phase-sequence, zero sequence self-impedance and Boluo station and each Inverter Station, negative phase-sequence, zero sequence mutual impedance, and try to achieve three-phase self-impedance and three sequence mutual impedance and corresponding ratio, result is listed in table 1.

By the result of calculation of table 1 it can be seen that the ratio of three sequence mutual impedance between Boluo station and each Inverter Station and Boluo station three sequence self-impedance is all higher than 0.1, it is believed that Boluo station occurs single-phase short circuit to may result in 5 times direct currents and commutation failure occurs simultaneously.

The computational methods of other each websites are similar, detailed result of calculation is in Table 2, and according to result of calculation, depicts the fault zone figure being likely to cause 5 times direct currents that commutation failure occurs simultaneously, ranging for of seeing that black line in accompanying drawing 2, figure surrounds is likely to cause 5 times direct currents that the fault zone of commutation failure occurs simultaneously.

Table rich big mode 500kV Boluo station single-phase earthing fault in 12012 causes direct-current commutation failure computer chart

Table rich big mode Guangdong 500kV plant stand single-phase earthing fault in 22012 causes direct-current commutation failure computer chart

Claims (3)

1. the method determining that single-phase short circuit causes commutation failure region, it is characterised in that comprise the following steps:

1) with alternating current-direct current electrical network for object of study, it is determined that DC inversion station to be studied is with probably due to fault in ac transmission system causes the transformer station of direct-current commutation failure, and wherein, there is M place in transformer station to be studied, and there is N place at DC inversion station；

2) the positive and negative zero sequence impedance matrix of alternating current-direct current electrical network to be studied is calculated, including positive sequence impedance matrix Z₁, negative sequence impedance matrix Z₂With zero sequence impedance matrix Z₀；

3) according to positive and negative zero sequence impedance matrix, calculate i-th transformer station to be studied positive and negative zero sequence self-impedance and Z_ii, i=1,2 ... M；

4) according to positive and negative zero sequence impedance matrix, calculate positive and negative zero sequence mutual impedance between jth Inverter Station and i-th transformer station and Z_ij, j=1,2 ... N；

5) calculate positive and negative zero sequence mutual impedance and with positive and negative zero sequence self-impedance and ratio k_ij, according to ratio k_ijSize, it is judged that i-th transformer station occur single-phase earthing fault whether be likely to cause jth Inverter Station generation commutation failure；

6) repeat step 4), step 5), until j=N, i place of record transformer station generation single-phase short circuit is likely to cause the Inverter Station number of commutation failure to be L_i；

7) repeat step 3), step 4), step 5), step 6), until i=M, obtain may result in K and go back to the single-phase earthing fault region of direct-current commutation failure, K=0,1,2 ... M；

Above-mentioned steps 5) described in the determination single-phase short circuit method that causes commutation failure region,

If k_ij> 0.1, then it is assumed that i place of transformer station occurs single-phase short circuit to be likely to cause Inverter Station j that commutation failure occurs.

2. the method determining that single-phase short circuit causes commutation failure region according to claim 1, it is characterised in that described step 3) in,

Z_ii=Z_ii-1+Z_ii-2+Z_ii-0(1)

In formula: Z_ii-1For the positive sequence self-impedance at i place of transformer station, Z_ii-2For the negative phase-sequence self-impedance at i place of transformer station, Z_ii-0For the zero sequence self-impedance at i place of transformer station, Z_iiSum for the positive and negative zero sequence self-impedance at i place of transformer station.

3. the method determining that single-phase short circuit causes commutation failure region according to claim 1, it is characterised in that described step 4) in,

Z_ij=Z_ij-1+Z_ij-2+Z_ij-0(2)

In formula: Z_ij-1For the positive sequence mutual impedance between transformer station i and Inverter Station j, Z_ij-2For the negative phase-sequence mutual impedance between transformer station i and Inverter Station j, Z_ij-0For the zero sequence mutual impedance between transformer station i and Inverter Station j, Z_ijThe sum of the positive and negative zero sequence mutual impedance between transformer station i and Inverter Station j.