CN103887782A - Hybrid type flux coupling superconduction fault current limiter and current limitation method - Google Patents

Abstract

The invention relates to a hybrid type flux coupling superconduction fault current limiter and current limitation method. According to the hybrid type flux coupling superconduction fault current limiter, a primary side winding coil of a coupling transformer and a high-speed switch are connected and are connected into an MOA zinc oxide resistor disc, a secondary side winding coil is connected with a superconduction current limiting material in series, and then the primary side winding coil and the secondary primary side winding coil are connected in an anti-parallel mode and then are connected into a main loop of a power system. When the power system operates normally, the high-speed switch is switched on; when the power system short-circuits, the high-speed switch is controlled to be triggered and switched off, the flux locking characteristic of the coupling transformer is relieved, the superconduction material is switched to be at the high resistance state as the through-flow of the superconduction material is larger than a set critical current, and at the moment, the current limiter carries out fault current limitation in an inductance-resistance hybrid mode. The hybrid type flux coupling superconduction fault current limiter is simple in structure and rapid in response, exchange losses generated when the superconduction current limiting material operates normally are reduced, and system economical efficiency of current limiting equipment is improved.

Description

A kind of mixed type magnetic flux Coupled Superconducting fault current limiter and current-limiting method

Technical field

The present invention relates to electric power system and automatic field, especially relate to a kind of mixed type magnetic flux Coupled Superconducting fault current limiter and current-limiting method.

Background technology

Along with social prosperity, economic progress, as the power industry of national basis industry also with swift and violent impetus development.Capacity of power unit, station capacity, city and commercial power load are increasing, add the further increasing of user to power supply supportability, power supply quality and reliability requirement, make electrical network to developing more on a large scale, and nationwide integrated power grid is interconnected progressively to be formed.In fact, electric power system scale develop rapidly and the application of internetwork-ing technology has increased system transmission capacity on the one hand, improve the flexibility of system operation, also greatly strengthened on the other hand the complexity of himself, and the original damping characteristic of system, frequency characteristic may all can be affected, this also makes modern power systems be faced with a series of new contradiction and problems.Wherein, the sharply increase of short circuit current level, has brought great hidden danger to the safe operation of electrical network.

Excessive short circuit current will cause following serious consequence: 1) produce high-energy electric arc, damage element; 2) impact electric equipment around, cause decline its useful life; 3) cause the overheated even fusing of conductor, and destroy its insulation system; 4) affect electric energy dynamic mass, system voltage significantly declines, and causes customer power supply to be destroyed; 5) power system operation stability is subject to vibration fluctuation, when serious, brings whole system to disintegrate; 6) communication line in power circuit is caused to electromagnetic interference; 7) jeopardize personal safety.

Along with electrical network development, fault current constantly increases, and the simple raising circuit breaker breaking capacity that relies on is unrealistic, and the one, from technology and economic angle, rupturing capacity can not improve always.Although at present foreign department point producer can produce breaking current and reach the circuit breaker of 80kA, actual usage quantity is considerably less, and security reliability is also more difficult to get guarantee; The 2nd, when improving rupturing capacity, also mean that equipment manufacturing cost will rise, the circuit breaker cost of 80kA is about 1.8 times of 63kA circuit breaker, also will relate in addition transformation or change existing other auxiliary equipment, and total infusion of financial resources will be larger.A large amount of scrap builds also can affect production run, and the economic loss causing is thus also considerable.

For alleviating the dynamic mass of the burden of the various electric equipments such as circuit breaker, the operation stability that improves electric power system, the security reliability that ensures customer power supply and enhancing electric energy, the technical concept of fault current limiter has been proposed, this equipment presents Low ESR in the time that system is normally moved, and symbolizes high impedance and carry out current limliting operation in the time of the system failure.

The overall development direction of current fault current limiter is based on new material and in conjunction with relevant control technology, according to the difference of application material, roughly can be divided into again two classes: a class is to select conventional material, the version of this type of flow restricter and current limliting mechanism have their own characteristics each, for example change the current transfer type of current path based on switch on and off, adopt the series compensation type of string benefit technology, utilize the mode of resonance of resonance principle and the solid-state version of dependence flexible AC transmission technology etc.; Another kind of is to use new material, and it represents that type is to choose the superconductive current limiter of superconductor.

Summary of the invention

The present invention solves the existing technical problem of prior art; Provide a kind of simple in structure, response rapidly, short circuit current can be limited in certain level rapidly, and the introducing of coupling transformer contributes to the present invention to apply in voltage levels electric power system, and be conducive to reduce the A.C.power loss of superconducting current-limiting material in the time of normal operation, promote a kind of mixed type magnetic flux Coupled Superconducting fault current limiter of the system economy of current limiter.

Above-mentioned technical problem of the present invention is mainly solved by following technical proposals:

A kind of mixed type magnetic flux Coupled Superconducting fault current limiter, it is characterized in that the MOA zinc oxide resistance sheet on the high-speed switch that comprises coupling transformer, connects with the first side winding coil of coupling transformer, the first side winding coil that is connected in parallel on coupling transformer, the superconducting current-limiting material of connecting with the secondary side winding coil of coupling transformer; After being reverse parallel connection, coupling transformer first and second side winding coil accesses electric power system major loop.

At above-mentioned a kind of mixed type magnetic flux Coupled Superconducting fault current limiter, the material of described coupling transformer first side winding coil and secondary side winding coil is common coiling material, and superconducting current-limiting material is high-temperature superconductor.

At above-mentioned a kind of mixed type magnetic flux Coupled Superconducting fault current limiter, described high-speed switch is electromagnetic switch or power electronics solid-state switch.

A kind of mixed type magnetic flux Coupled Superconducting failure current limit method, is characterized in that, based on to give a definition: U _s, Z _s, Z _loadrepresent respectively equivalent voltage source voltage, line impedance and load impedance.L ₁, L ₂, R _moaself-induction and the MOA ZnO resistors sheet resistor of indication transformer first siding ring W1 and second siding ring W2 respectively, R _sFCLfor high-temperature superconductor resistance quench situation resistance, M be coupling transformer once, second siding ring mutual inductance.

Concrete operation method is as follows: in the time that electric power system major loop does not break down, and high-speed switch closure; In the time that electric power system major loop breaks down, disconnect high-speed switch, the first and second coil decoupling zero of magnetic flux coupling transformer, primary side inductance coil L ₁produce high pressure, exceed MOA zinc oxide resistance sheet R _moacritical voltage, R _moareduce fast, with first siding ring L ₁form discharge loop, first siding ring L ₁overvoltage is suppressed fast, high-temperature superconductor resistance overcurrent quench R _sFCL>0; Now, magnetic flux coupling transformer secondary side L ₂lead resistance R with mistake _sFCLseries connection access main loop, suppresses fault current fast; After failure removal, high-speed switch closure, magnetic flux coupling transformer recovers lockout feature, high-temperature superconductor resistance R _sFCLrecover superconducting state, fault current limiter recovers normal operation.

The present invention is in the time that electric power system normally moves, and high-speed switch is in closure state, in view of the magnetic flux of coupling transformer is offset the group effect that (locking) characteristic and superconductor present low resistive state, flow restricter on main loop without impact; When system is short-circuited after fault, control high-speed switch and trigger disconnection (MOA resistor disc is in order to suppress possible switching overvoltage), the magnetic flux lockout feature of coupling transformer will be removed, and superconductor is greater than critical current to be set and be switched to high-impedance state because it is through-flow, now flow restricter presents the hybrid composition of inductance-resistance and carries out failure current limit operation.

Therefore, tool of the present invention has the following advantages: simple in structure, response rapidly, short circuit current can be limited in certain level rapidly, and the introducing of coupling transformer contributes to the present invention to apply in voltage levels electric power system, and be conducive to reduce the A.C.power loss of superconducting current-limiting material in the time of normal operation, promote the system economy of current limiter.

Brief description of the drawings

Fig. 1 is the topology diagram that the present invention is applied to electric power system.

Fig. 2 is the equivalent circuit diagram that the present invention is applied to electric power system.

Fig. 3 is superconducting current-limiting material R in exemplary application of the present invention _sFCLresistance switching characteristic, abscissa is time t(s), ordinate is superconduction resistance R _sFCL(Ω).

Fig. 4 is main circuit current i under failure condition in exemplary application of the present invention _soscillogram, abscissa is time t(s), ordinate is current i _s(A); Dotted line is for there being fault current limiter, solid line fault-free demand limiter.

Fig. 5 is the magnetic flux coupling transformer first and second side current waveform of AC system of the present invention, and abscissa is time t(s), ordinate is the current i TRV(A that magnetic flux coupling transformer first and second effluent is crossed).

Embodiment

Below by embodiment, and by reference to the accompanying drawings, technical scheme of the present invention is described in further detail.

Embodiment:

As shown in Figure 1, the present invention, mainly by the control to high-speed switch closure state, offsets the conversion of (locking) characteristic and the low high-impedance state of superconductor based on magnetic flux, realizes the operation of inductance-resistance-type mixing current limiting.

MOA zinc oxide resistance sheet on the high-speed switch that the present invention includes coupling transformer, connect with the first side winding coil of coupling transformer, the first side winding coil that is connected in parallel on coupling transformer, the superconducting current-limiting material of connecting with the secondary side winding coil of coupling transformer; After being reverse parallel connection, coupling transformer first and second side winding coil accesses electric power system major loop.

Wherein, the material of coupling transformer first side winding coil and secondary side winding coil is common coiling material, and superconducting current-limiting material is high-temperature superconductor; High-speed switch is electromagnetic switch or power electronics solid-state switch.

Based on the equivalent electric circuit relation of magnetic flux coupling transformer and superconduction resistance, the isoboles that the present invention is applied to AC electric power systems as shown in Figure 2, U _s, Z _s, Z _loadrepresent respectively equivalent voltage source voltage, line impedance and load impedance.L ₁, L ₂, R _moaself-induction and the MOA ZnO resistors sheet resistor of indication transformer first siding ring W1 and second siding ring W2 respectively, R _sFCLfor high-temperature superconductor resistance quench situation resistance, M be coupling transformer once, second siding ring mutual inductance.

System is normally moved, controllable switch S 1 closure state, R _moabe high-impedance state and be equivalent to open circuit, R _sFCLbe low resistance state and be equivalent to short circuit, according to drawing shown in Fig. 2, the equiva lent impedance of mixed type magnetic flux Coupled Superconducting fault current limiter:

$\begin{array}{c}{Z}_{\mathrm{CT}}=\mathrm{j\&omega;}[({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA0000490151550000022.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+M)//(L_2+M)-M]\\ =\mathrm{j\&omega;}(L_1{L}_2-M^2)/({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA0000490151550000022.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L_2+2M)\end{array}---\left(1\right)$

Coupling transformer no-load voltage ratio, both sides coil coupling rate are expressed as equation (1) can be expressed as: Z _cT=j ω L ₂(1-k ²) n ²/ (n ²+ 2kn+1), if k levels off to or equals 0 in equation, transformer coupled rate k can be approximated to be 1, Z _cT≈ 0, therefore under normal circumstances, mixed type magnetic flux Coupled Superconducting fault current limiter presents Low ESR, on system without impact.

Under failure condition, controllable switch S 1 quick-speed turning on-off, the first and second coil decoupling zero of magnetic flux coupling transformer, primary side inductance coil L ₁produce high pressure, exceed MOA zinc oxide resistance sheet R _moacritical voltage, R _moareduce fast, with first siding ring L ₁form discharge loop, first siding ring L ₁overvoltage is suppressed fast, and high-temperature superconductor resistance overcurrent quench R _sFCL>0.Therefore, the resistance value of mixed type magnetic flux Coupled Superconducting Fault Current Limiting Device is:

$\begin{array}{c}{Z}_{\mathrm{SFCL}}=[\stackrel{\&CenterDot;}{I_2^{\&prime;}}(R_{\mathrm{YBCO}}+\mathrm{j\&omega;}{L}_2)-\stackrel{\&CenterDot;}{{\mathrm{<figure-callout\; id="1"\; label="I"\; filenames="HDA0000490151550000022.png"\; state="\{\{state\}\}">I</figure-callout>}}_1^{\&prime;}}\mathrm{j\&omega;M}]/\stackrel{\&CenterDot;}{I_2^{\&prime;}}\\ =R_{\mathrm{YBCO}}+\mathrm{j\&omega;}{L}_2-\stackrel{\&CenterDot;}{I_1^{\&prime;}}\mathrm{j\&omega;M}/\stackrel{\&CenterDot;}{I_2^{\&prime;}}\end{array}---\left(2\right)$

with

represent respectively coupling transformer failure condition next, second siding ring size of current, can be expressed as:

$\stackrel{\&CenterDot;}{I_1^{\&prime;}}/\stackrel{\&CenterDot;}{I_2^{\&prime;}}=\mathrm{j\&omega;M}/(\mathrm{j\&omega;}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA0000490151550000022.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+R_{\mathrm{moa}})---\left(3\right)$

Based on (1), (2), (3) equation and

mixed type magnetic flux Coupled Superconducting Fault Current Limiting Device equivalent impedance: Z _sFCL=[R _yBCO+ j ω L ₂+ (kn ω L ₂) ²/ (R _moa+ n ²j ω L ₂)], due to coupling transformer first siding ring discharge loop resistance R _moa>>n ²ω L ₂so, the impedance Z under mixed type magnetic flux Coupled Superconducting Fault Current Limiting Device failure condition _sFCL≈ j ω L ₂+ R _sFCL.

In this example, magnetic flux coupling transformer one, two lateral coils are selected common coiling material, and controllable switch S 1 is electronic power switch, and superconduction resistance is high-temperature superconductor resistance YBCO, and the AC power of main loop is ideal voltage source.Structural parameters are as follows: U _s=380sin ω tV; Magnetic flux coupling transformer self-induction of loop, mutual inductance: L ₁=L ₂=4mH, M=3.96mH; Superconduction resistance quench resistance: R _sFCL=2 Ω; Line impedance: Z ₁=(1+3j) Ω; Load impedance: Z ₂=15+2j Ω; MOA zinc oxide resistance sheet low resistance state resistance: R _moa=2 Ω; Power frequency f=50Hz.

Figure 3 shows that the resistance characteristic of superconduction resistance, resistance is 0, t under normal circumstances ₀moment is short-circuited, and superconduction resistance quench, plays metering function to fault current, t ₁moment failure removal, superconduction resistance starts to recover superconducting state, t ₂moment is recovered superconducting state, and superconduction resistance size can be carried out given according to system actual conditions: R _sFCL=Rm.

Figure 4 shows that under failure condition, main circuit breaker CB cut-offs before circuit, AC system has or not the current waveform figure in mixed type magnetic flux Coupled Superconducting Fault Current Limiting Device situation.Within 0～1s time, AC electric power systems is normally moved, within 1s～1.5s time, and the AC electric power systems fault that is short-circuited.Solid line indicates without current-limiting apparatus AC system current i _s, dotted line represents current limiting device AC system current i _s.In this example, the normal running current peak value of system is 22.6A, when fault, as nothing, current-limiting apparatus is installed, and shown in solid line, current peak first cycle after short circuit rises to rapidly 145.5A; As system is installed current-limiting apparatus, when fault, to control controllable switch S 1 and cut-off, restriction system fault current shown in dotted line, can be suppressed at 69A left and right the peak value of system failure electric current in first cycle after fault occurs, and current limitation effect is obvious.

Figure 5 shows that magnetic flux coupling transformer first and second coil current oscillogram, when 1s, controllable switch S 1 disconnects, and coupling transformer primary side and system are cut-off.Solid line represents magnetic flux coupling transformer primary side current, and dotted line represents secondary side current, and under failure condition, fault current flows to fault point by coupling flux transformer secondary side and high-temperature superconductor resistance.

Specific embodiment described herein is only to the explanation for example of the present invention's spirit.Those skilled in the art can make various amendments or supplement or adopt similar mode to substitute described specific embodiment, but can't depart from spirit of the present invention or surmount the defined scope of appended claims.

Claims (4)

1. a mixed type magnetic flux Coupled Superconducting fault current limiter, it is characterized in that the MOA zinc oxide resistance sheet on the high-speed switch that comprises coupling transformer, connects with the first side winding coil of coupling transformer, the first side winding coil that is connected in parallel on coupling transformer, the superconducting current-limiting material of connecting with the secondary side winding coil of coupling transformer; After being reverse parallel connection, coupling transformer first and second side winding coil accesses electric power system major loop.

2. a kind of mixed type magnetic flux Coupled Superconducting fault current limiter according to claim 1, is characterized in that, the material of described coupling transformer first side winding coil and secondary side winding coil is common coiling material, and superconducting current-limiting material is high-temperature superconductor.

3. a kind of mixed type magnetic flux Coupled Superconducting fault current limiter according to claim 1, is characterized in that, described high-speed switch is electromagnetic switch or power electronics solid-state switch.

4. a mixed type magnetic flux Coupled Superconducting failure current limit method, is characterized in that, based on to give a definition: U _s, Z _s, Z _loadrepresent respectively equivalent voltage source voltage, line impedance and load impedance, L ₁, L ₂, R _moaself-induction and the MOA ZnO resistors sheet resistor of indication transformer first siding ring W1 and second siding ring W2 respectively, R _sFCLfor high-temperature superconductor resistance quench situation resistance, M be coupling transformer once, second siding ring mutual inductance;

Concrete operation method is as follows: in the time that electric power system major loop does not break down, and high-speed switch closure; In the time that electric power system major loop breaks down, disconnect high-speed switch, the first and second coil decoupling zero of magnetic flux coupling transformer, primary side inductance coil L ₁produce high pressure, exceed MOA zinc oxide resistance sheet R _moacritical voltage, R _moareduce fast, with first siding ring L ₁form discharge loop, first siding ring L ₁overvoltage is suppressed fast, high-temperature superconductor resistance overcurrent quench R _sFCL>0; Now, magnetic flux coupling transformer secondary side L ₂lead resistance R with mistake _sFCLseries connection access main loop, suppresses fault current fast; After failure removal, high-speed switch closure, magnetic flux coupling transformer recovers couple state, high-temperature superconductor resistance R _sFCLrecover superconducting state, fault current limiter recovers normal operation.

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