CN101316033A

CN101316033A - High-capacity direct current de-icing device

Info

Publication number: CN101316033A
Application number: CNA2008100479595A
Authority: CN
Inventors: 李澍森; 吴夕科; 陈晓燕; 石延辉; 左文霞; 程军照; 李敏; 桂朋林
Original assignee: 国网武汉高压研究院
Priority date: 2008-06-11
Filing date: 2008-06-11
Publication date: 2008-12-03

Abstract

The invention provides a large-capacity DC thawing apparatus, comprising a rectifier transformer, six-pulse rectifier, measurement and control units, a DC voltage and current transformer TV and TA, a DC smoothing reactor, a balancing reactor, an AC voltage transformer TVa, an AC current transformer TAa and a central control system; the large-capacity DC thawing apparatus has N six-pulse rectifiers with identical parameters; N measurement and control units respectively provide triggering pulses for each six-pulse rectifier; the input terminal of the DC thawing apparatus is provided with the AC voltage transformer TVa and AC current transformer TAa and the output terminal thereof is connected with the central control system; the output anodes of the N six-pulse rectifiers are directly connected in parallel by the smoothing reactor and connected with one end of the transmission line to be thawed and the output cathode thereof is connected with the other end of the transmission line to be thawed in parallel by N tap balance reactors. By adopting the parallel running technique of the rectifier, the problems of the large-capacity DC thawing apparatus such as large current, high voltage and large capacity are solved.

Description

A kind of high-capacity direct current de-icing device

Technical field

The ice-melt equipment that belongs to electric power transmission line.

Background technology

Transmission line icing in the winter time is one of major natural disasters of electric power system.The power failure that causes because of icing, even damage sequence such as grid disconnection is very serious usually, the repair difficulty is big, the cycle is long.For solving the difficult problem of this serious threat safe operation of power system, countries in the world have all been dropped into great manpower and materials and have been studied.The deicing of current power transmission circuit mainly contains methods such as heating power deicing, mechanical deicing, passive deicing.Because of ultra-high-tension power transmission line is erected between field, wilderness, the high and steep mountains mostly,, with regard to present technical merit, adopt the Mechanical Method deicing to be difficult to reach the purpose of timely deicing in case produce icing.Therefore thermal ice-melting is still feasible common method at present.

Thermal ice-melting adopt the AC and DC electric current all can, but on implementing very big difference is arranged.Adopt the prior art and the deficiency thereof of AC and DC electric current thermal ice-melting as follows:

1, " three-phase shortcircuit ice-melting method "

" three-phase shortcircuit ice-melting method " is with an end three-phase shortcircuit ground connection of DC ice-melting, applies suitable ice-melt power supply at the other end, by bigger short circuit current heating wires, makes it to reach the temperature of ice-melt.Three-phase shortcircuit ice-melting method principle is shown in Fig. 1, if ice-melt voltage is U _R, the three phase line parallel impedance is Z _L, ice melting current I then _R:

$I_{R} = \frac{U_{R}}{Z_{L}}$

Ice melting current I _RMust therefore must select suitable ice-melt voltage greater than the critical icing electric current of transmission line less than the safe current of circuit.Suitable ice-melt power supply promptly must be provided.In electrical network, have only two kinds of approach that the ice-melt power supply is provided.

(1) generating set by generator and energizing apparatus, adopts zero up-flow way to provide direct current to line ice-melting.The existing problem of this method is need be at corresponding circuit link ice-melt special equipment, the wiring of Iterim Change generator excited system, ice-melt preliminary preparation amount is big, real-time and rapidity are relatively poor, and in being only applicable to, short-range line ice-melting.

(2) system power supply promptly selects suitable electric pressure as the ice-melt power supply in transformer station.Because U _RRestriction, obtain the I of suitable size _R, can only manage to change Z _L, method commonly used is that some transmission lines are connected in series, to reach desired Z _LTherefore the three-phase shortcircuit ice-melting method often needs many circuits of stopping transport, although some circuit does not need ice-melt, many circuits is stopped transport, and causes unnecessary loss of outage.

Mainly also there is following drawback in the three-phase shortcircuit ice-melting method:

(1) implements the three-phase shortcircuit ice-melt, need to comprise that overhead transmission line stops in all ice-melt loops of DC ice-melting, the ice-melt power supply is provided by system usually, so can only take to impact the combined floodgate mode, standbyly may destroy system stability when not enough in that system voltage is lower, idle.

(2) ice-melt preliminary preparation amount is very big, and a plurality of departments such as the guarantor that needs to dispatch, moves, continues cooperate, and influence ordinary production;

(3) three-phase shortcircuit ice-melt power consumption is big, and the required electric weight of ice-melt is usually all more than tens thousand of kWh.

(4) this method is only feasible to 220kV and following electric pressure circuit, because the ice-melt power supply is difficult to solve, can't implement substantially 500kV and above circuit, promptly makes the ice-melt power supply with the low voltage grade, and the DC ice-melting of is too short; Adopt voltage levels, need system that huge reactive power is provided.For example to 4 * LGJ300,4 * LGJ400, three kinds of 500kV of 4 * LGJ500 lead commonly used, apply different brackets voltage, satisfy under the minimum ice melting current condition, length and the calculating of required reactive power that institute can DC ice-melting the results are shown in table 1;

Table 1 line length and required reactive capability

Annotate: the minimum ice melting current of above-mentioned three kinds of 500kV circuits is got 2.8kA, 3.2kA, 4.0kA respectively;

Calculating shows, uses 35kV, 220kV system as the ice-melt power supply, but the longest 25km, the 169km of being no more than respectively of DC ice-melting; And make the ice-melt power supply with the 500kV system, and line length can meet the demands substantially, but needs system that 2000Mvar is provided above reactive power, and general transformer station can't provide so huge idle deposit.

In sum, the three-phase shortcircuit ice-melting method can't satisfy 500kV transmission line ice-melt needs, and lower electric pressure ice-melt is also had problems.Research, calculating show, adopt the DC ice melting technology then can overcome above drawback.

2, " DC ice melting method "

Because the 500kV circuit adopts bundle conductor, the distributed capacitance of circuit is big, and D.C. resistance has only about 10% of AC impedance, and during the ac short circuit ice-melt, the ice-melt power supply need provide a large amount of idle line chargings that are used for, and the part that acts on resistance heating is relatively very little.Therefore to obtain onesize ice-melt power, adopt the required power supply capacity of direct current ice-melt much smaller.

For example, generally in 100km, lead commonly used has LGJ300, LGJ400,2 * LGJ300,2 * LGJ400 to the 220kV transmission line length; Special have 2 * LGJ630; The 500kV transmission line length generally in 400km, is used conductors on quad bundled, i.e. 4 * LGJ300,4 * LGJ400,4 * LGJ500 always.Extrapolate DC ice melting power and voltage by experimental result, see Table 2.Ice-melt loop resistance R wherein _L=1.5 * R _d* L (during DC ice melting, being in series with another again after circuit two is in parallel); Ice melting current: _d=I _d* R _d, ice-melt power: P _d=U _d* I _dCan get by calculating, analyzing, consider certain nargin, satisfy the DC de-icing device of 500kV and following transmission line ice-melt requirement, its electric current is not less than 5kA, and voltage should be about 60kV, so capacity is not less than 300MW.

Table 2 ice-melt power and voltage (the ring temperature :-16 ℃, wind speed 3.5m/S)

Annotate: the D.C. resistance invar core difference of each model lead is variant, gets maximum wherein

The DC ice melting key problem in technology is the development of high voltage, high power DC power source and rationally utilizes.Direct current power source is rectifier in essence, utilizes power electronic technology design, manufacturing heavy-duty rectifier to be not difficult according to reason, but is used for line ice-melting, because the restriction of device parameters, its electric current can't reach desired level.By above analysis, calculating as can be known, satisfy the DC de-icing device of 500kV and following transmission line ice-melt requirement, its basic parameter is:

300MW/60kV/5kA(1)

Even use thyristor (5 inches silicon chips) in DC transmission engineering (HVDC), its rated current is 3kA, and the capacity limit of therefore present 500kV DC transmission engineering is in 3000MW; And 6 inches silicon chips that ultra high voltage HVDC engineering will adopt, its rated current also can only reach 4～4.5kA, all can not satisfy the requirement to electric current of DC de-icing device.

Summary of the invention

The objective of the invention is to overcome the deficiency of existing de-icing technology, a kind of high-capacity direct current de-icing device is provided, adopt the parallel running technology of rectifier, solve big electric current, high voltage, high-capacity direct current de-icing device problem.

Technical scheme of the present invention is: a kind of high-capacity direct current de-icing device is characterized in that: comprise rectifier transformer, six pulse rectifiers, measurement and control unit, direct voltage, current transformer TV, TA, dc flat-wave reactor, interphase reactor, AC voltage transformer TV _a, AC current transformer TA _aAnd central control system;

It has N six pulse rectifiers that parameter is identical, N is more than or equal to 2, N measurement and control unit gathered the signal of direct voltage, current transformer TV, TA simultaneously alone for each six pulse rectifier provides trigger impulse, analyzes, calculates voltage, the current value of the output of six pulse rectifiers; The input of DC de-icing device is furnished with AC voltage transformer TV _a, AC current transformer TA _a, its output connects central control system, is used to detect voltage, electric current, the meritorious parameters such as reactive power, harmonic wave that reach of DC de-icing device AC side; The identical six pulse rectifier output cathodes of N parameter are received an end for the treatment of ice-thawing electric transmission line after by the direct parallel connection of smoothing reactor; Its negative pole is parallel-connected to by N tap interphase reactor and treats the ice-thawing electric transmission line other end.

Aforesaid high-capacity direct current de-icing device is characterized in that: six pulse rectifiers adopt high-power thyristor or directly adopt the converter valve of HVDC.

Aforesaid high-capacity direct current de-icing device is characterized in that: the wiring of rectifier transformer is followed successively by Y/Y _-12, the Y/ Δ _-12Y/Y _-11, the Y/ Δ _-11..., rectifier transformer is designed to different connection groups, makes the former and deputy polygonal voltage of rectifier transformer form different phase shift, thereby makes per two six pulse rectifiers constitute 12 pulse rectifiers, per 4 constitute 24 pulse rectifiers ..., to reduce the harmonic current of AC side; According to six different pulse rectifier platform numbers, promptly different umber of pulses, the characteristic harmonics frequency n that produces in the rectifier transformer high-pressure side:

N=k * p ± 1 k-umber of pulse; P=1,2,3 ....

Aforesaid high-capacity direct current de-icing device, it is characterized in that: the bank of filters of each six pulse rectifier AC side installing tuningly is made of 2～3 groups of double tunnings or three, its parameter needs according to the quantity N of six pulse rectifiers and the characteristic harmonics number of times decision that produced, the harmonic current that produces with filtering six pulse rectifiers to greatest extent.

Aforesaid high-capacity direct current de-icing device is characterized in that: the trigger angle of each six pulse rectifier satisfies following formula:

α ₁＝α ₂＝α ₃＝......＝α _N

Advantage of the present invention and beneficial effect: (1) can be met the demands by existing thyristor; (2) according to the circuit of different electric pressures, different length, do not drop into and count on the same stage, to adapt to the demand of different line ice-meltings; (3) capacity and electric current can be expanded arbitrarily; (4) adopt modularization, standardization, container type moveable structure, be convenient to transportation and move, can satisfy different local ice-melt demands.

Description of drawings

Fig. 1 is the three-phase shortcircuit ice-melting method schematic diagram of prior art.

Fig. 2, six pulse rectifier circuit diagrams of the embodiment of the invention.

Fig. 3, high-capacity direct current de-icing device schematic diagram of the present invention.

Fig. 4 is a measurement and control unit theory diagram among Fig. 3.

Fig. 5 is the central control system theory diagram among Fig. 3.

Fig. 6, the HVDC current conversion station winding diagram of prior art.

Fig. 7, two single bridge parallel connections of the HVDC current conversion station of the embodiment of the invention.

Fig. 8 is Fig. 7 embodiment---two rectifiers are formed the high-capacity direct current de-icing device schematic diagram.

Embodiment

The explanation of mark among Fig. 3: 1.-rectifier transformer, 2.-six pulse rectifier, 3.-measurement and control unit, 4.-direct voltage, current transformer TV, TA, 5.-dc flat-wave reactor, 6.-interphase reactor, 7.-AC voltage transformer TV _a, 8. AC current transformer TA _a, 9.-central control system, 10.-bank of filters.

Referring to Fig. 3.Embodiment of the present invention is: a kind of high-capacity direct current de-icing device is characterized in that: comprise rectifier transformer 1., six pulse rectifiers 2., measurement and control unit 3., direct voltage, current transformer TV, TA 4., dc flat-wave reactor 5., interphase reactor 6., AC voltage transformer TV _a7., AC current transformer TA _a8. with central control system 9.;

2. it have six identical pulse rectifiers of N parameter, N is more than or equal to 2,2. 3. N measurement and control unit provide trigger impulse for each six pulse rectifier alone, gather direct voltage, current transformer TV, TA signal 4. simultaneously, analyze, calculate voltage, current value that 2. six pulse rectifiers are exported; The input of DC de-icing device is furnished with AC voltage transformer TV _a7., AC current transformer TA _a8., its output connects central control system, is used to detect voltage, electric current, the meritorious parameters such as reactive power, harmonic wave that reach of DC de-icing device AC side; 5. identical six pulse rectifiers of N parameter 2. output cathode directly receive an end for the treatment of ice-thawing electric transmission line after the parallel connection by smoothing reactor; 6. its negative pole is parallel-connected to by N tap interphase reactor and treats the ice-thawing electric transmission line other end.(treat ice-thawing electric transmission line two is in parallel be in series with another again).

2. 3. measurement and control unit provide trigger impulse to each six pulse rectifier, and 9. central control system receives voltage, the current value that 3. each measurement and control unit transmits, and coordinates the unified operation 2. of each six pulse rectifier.

Six pulse controlled rectification circuits for resistive load, are the thyristor angle of flow as if α as shown in Figure 2, and rectifier transformer secondary side line voltage is U ₂, dc voltage is U _d:

$U_{d} = \frac{3 \sqrt{2}}{π} U_{2} \cos α = 1.35 U_{2} \cos α - - - (3)$

With N six pulse rectifier parallel runnings (Fig. 3), the output voltage of each rectifier is respectively:

$U_{d 1} = \frac{3 \sqrt{2}}{π} U_{21} \cos α_{1}$

$U_{d 12} = \frac{3 \sqrt{2}}{π} U_{22} \cos α_{2}, N = 1,2,3 . . . . . ., - - - (4)$

……

$U_{d 1 N} = \frac{3 \sqrt{2}}{π} U_{2 N} \cos α_{N}$

N the 2. direct current outlet side parallel connection of six pulse rectifiers that parameter is identical, output current is single N times, six pulse rectifiers adopt high-power thyristor (or directly adopt HVDC converter valve), so the power of deicing device and electric current are easy to reach the requirement of (1) formula.

The voltage U that 3. 9. central control system transmit by each measurement and control unit of real-time reception _Di, electric current I _Di, judge that according to (5), (6) formula whether the difference of voltage, electric current and mean value that 2. each six pulse rectifier is exported is less than ε _U, ε _I, and in time provide control signal, regulate each six pulse rectifiers output 2., reduce the circulation of each six pulse rectifier between 2. as far as possible; 6. interphase reactor plays each 2. effect of output voltage, current imbalance of six pulse rectifiers of balance.

(1) each rectifier output voltage equilibrium criterion:

${\overset{&OverBar;}{U}}_{d} = \frac{U_{d 1} + U_{d 2} + \cdot \cdot \cdot + U_{dN}}{N}, U_{di} - {\overset{&OverBar;}{U}}_{d} \leq ϵ_{U} - - - (5)$

(2) each rectifier output current equilibrium criterion:

${\overset{&OverBar;}{I}}_{d} = \frac{I_{d 1} + I_{d 2} + \cdot \cdot \cdot + I_{dN}}{N}, I_{di} - {\overset{&OverBar;}{I}}_{d} \leq ϵ_{I} - - - (6)$

High-capacity direct current de-icing device in the present embodiment, the wiring 1. of its rectifier transformer is followed successively by Y/Y _-12, the Y/ Δ _-12Y/Y _-11, the Y/ Δ _-11..., 1. rectifier transformer is designed to different connection groups, make the 1. former and deputy polygonal voltage of rectifier transformer form different phase shift, thereby 2. per two six pulse rectifiers constitutes 12 pulse rectifiers, per 4 constitute 24 pulse rectifiers ..., to reduce the harmonic current of AC side; According to six different pulse rectifiers platform number 2., promptly different umber of pulses, in the 1. characteristic harmonics frequency n that produces of high-pressure side of rectifier transformer:

N=k * p ± 1 k-umber of pulse; P=1,2,3 ...(7)

High-capacity direct current de-icing device in the embodiment of the invention, 10. each six pulse rectifier 2. AC side install bank of filters, 10. bank of filters tuningly is made of 2～3 groups of double tunnings or three, its parameter needs according to six pulse rectifiers quantity N 2. and the characteristic harmonics number of times decision that is produced, the harmonic current that 2. produces with filtering six pulse rectifiers to greatest extent.

High-capacity direct current de-icing device in the embodiment of the invention is characterized in that: each six pulse rectifiers trigger angle 2. satisfies following formula:

α ₁＝α ₂＝α ₃＝......＝α _N

Referring to Fig. 4.3. measurement and control unit in the embodiment of the invention is made up of digital signal processor DSP, ROM, RAM, FPGA etc., is responsible for control, the data acquisition 2. of six pulse rectifiers, computing, processing, communication and management; 4. after the signal that is transmitted by direct voltage, current transformer TV, TA enters TV, the preliminary treatment of TA input buffer cell, deliver to overvoltage, over-current detection and protection loop and A/D converter A/D, calculate voltage, the current value that 2. six pulse rectifiers are exported by DSP, show in real time, and be uploaded to central control system 9.; In a single day 3. measurement and control unit finds faults such as overvoltage, overcurrent, block six pulse rectifiers immediately 2., and 9. report to the police to central control system; Generally provide zero cross signal by the A phase voltage, the trigger impulse by zero passage detection and trigger angle control loop generation Rack send trigger generator, 2. provides trigger impulse through the photoelectricity isolated loop for six pulse rectifiers.Trigger angle α can be provided with by measurement and control unit is 3. local, is then 9. provided by central control system during many operations, makes that each six pulse rectifiers trigger angle 2. is in full accord; Show and 2. operation control unit can be adjusted, be provided with and show six pulse rectifiers running state information 2. six pulse rectifiers; Measurement and control unit 3. by the communication interface loop to 9. Data transmission and receive control command of central control system.

Referring to Fig. 5.9. central control system is made up of industrial computer, communication interface, overvoltage, mistake current control protection module, alternating voltage, current transformer interface module, voltage, current harmonics detection module.Major function: (1) 2. sends unified trigger angle control signal to each six pulse rectifier; (2) receive overvoltage, over current fault signal and voltage, the current data that 2. each six pulse rectifier is uploaded; (3) detect AC side voltage, electric current, the meritorious parameters such as reactive power, harmonic wave that reach; (4) sending fault-signal to transformer station is used for reporting to the police or tripping operation.

Referring to Fig. 6.Existing HVDC current conversion station, basic wiring are formed 12 pulse rectifiers by two the 6 single bridges of pulse as shown in Figure 6, two single bridge series connection.

Referring to Fig. 7.Two then exportable electric currents of single bridge parallel connection of existing HVDC current conversion station are doubled, use as high-capacity direct current de-icing device of the present invention.

Referring to Fig. 8.Fig. 8 is the physical circuit form of Fig. 7, and 2. DC de-icing device constitutes 12 pulse rectifiers by 2 six identical pulse rectifiers of parameter, and 6. the negative pole that 2. 2 six pulse rectifiers are exported connects by interphase reactor; 1. rectifier transformer is that three circle formula Y/Y/ Δs connect transformers, so DC de-icing device produces n=12p ± 1, promptly 11,13,23,25 ..., inferior characteristic harmonics.

Six pulse rectifiers parameter 2.: 150MW/60kV/2.5kA, the simulation result of DC de-icing device is listed in table 3.By regulating six pulse rectifiers trigger angle 2., the output voltage of control device, the size of electric current; (differing 1 °) two six pulse rectifiers voltages 2. are equal substantially when two six pulse rectifiers trigger angle 2. is inconsistent, and it is bigger that electric current then differs, α ₁=50 °, α ₂In the time of=51 °, I _D1=2.00A, I _D2=1.17A, both differ 1.7 times, and therefore each six pulse rectifiers trigger angle 2. is consistent as far as possible.

The simulation result of table 3 DC de-icing device

Claims

1, a kind of high-capacity direct current de-icing device is characterized in that: comprise rectifier transformer, six pulse rectifiers, measurement and control unit, direct voltage, current transformer TV, TA, dc flat-wave reactor, interphase reactor, AC voltage transformer TV _a, AC current transformer TA _aAnd central control system;

2, high-capacity direct current de-icing device as claimed in claim 1 is characterized in that: six pulse rectifiers adopt high-power thyristor or directly adopt the converter valve of HVDC.

3, high-capacity direct current de-icing device as claimed in claim 1 is characterized in that: the wiring of rectifier transformer is followed successively by Y/Y _-12, the Y/ Δ _-12Y/Y _-11, the Y/ Δ _-11..., rectifier transformer is designed to different connection groups, makes the former and deputy polygonal voltage of rectifier transformer form different phase shift, thereby makes per two six pulse rectifiers constitute 12 pulse rectifiers, per 4 constitute 24 pulse rectifiers ..., to reduce the harmonic current of AC side; According to six different pulse rectifier platform numbers, promptly different umber of pulses, the characteristic harmonics frequency n that produces in the rectifier transformer high-pressure side:

N=k * p ± 1 k-umber of pulse; P=1,2,3 ....

4, as claim 1 or 3 described high-capacity direct current de-icing devices, it is characterized in that: the bank of filters of each six pulse rectifier AC side installing tuningly is made of 2～3 groups of double tunnings or three, its parameter needs according to the quantity N of six pulse rectifiers and the characteristic harmonics number of times decision that produced, the harmonic current that produces with filtering six pulse rectifiers to greatest extent.

5, as claim 1 or 3 described high-capacity direct current de-icing devices, it is characterized in that: the trigger angle of each six pulse rectifier satisfies following formula: α ₁=α ₂=α ₃=...=α _N

6, high-capacity direct current de-icing device as claimed in claim 4 is characterized in that: the trigger angle of each six pulse rectifier satisfies following formula: α ₁=α ₂=α ₃=...=α _N