Voltage support capacitance module
Technical field
The present invention relates to a kind of voltage support capacitance module, more particularly, relate to a kind of by aluminium electrolytic capacitor and film capacitor mix use the direct voltage of wind electric converter is carried out to the voltage support capacitance module of voltage support.
Background technology
Along with the pay attention to day by day of country to wind energy development, wind power generation has obtained developing rapidly, and installed capacity increases day by day, and the problem in useful life of wind-driven generator also more and more receives publicity.The current transformer of wind-driven generator is the core that power conversion is controlled, in its hardcore IGBT power model, for the direct current support capacitor that the direct voltage of wind-driven generator output (through over commutation) is supported, be one of critical piece affecting useful life.
Wind electric converter DC bus need to adopt voltage support electric capacity (following, referred to as Support Capacitor) to carry out energy storage, voltage support etc., to meet the normal operation functional requirement of current transformer.The voltage support here refers to and suppresses ripple voltage and direct voltage is remained on to a certain degree.Conventionally, DC support electric capacity can be selected alminium electrolytic condenser or metal film electric capacity.
General aluminium electrolytic capacitor because of the highest nominal magnitude of voltage of its materials limitations be 500-600V, therefore high withstand voltage in order to obtain, aluminium electrolytic capacitor needs series connection.But due to aluminium electrolytic capacitor initial charge and leakage current diversity ratio larger, being connected while using must special all pressure of considering electric capacity, otherwise capacitor is easily blasted or the accident such as leakage.In addition,, in order to prevent the capacitor overvoltage of series connection, need to leave more voltage margin.Each capacitor of while series arm need to add grading resistor all presses, but grading resistor is many, exists damage risk, has increased the unreliability of system.
On the other hand, in order to obtain high capacitance, need again Parallel-connected Capacitor, but electric capacity quantity in parallel is more, equalizer circuit is also just more, and the consistency of the leakage current of electric capacity and capacitance coupling is better.But ,Bing joint conference causes the busbar design that whole alminium electrolytic condenser group volume is large and needs are complicated.In addition, the aluminium electrolytic capacitor module that parallel connection is as shown in Figure 1 connected afterwards also has following shortcoming: 1) life-span short, General Life is under normal temperature, to work 5 years; 2) be not easy to store, under general normal temperature, storing 2-3 just needs electric capacity to activate, otherwise electric capacity is withstand voltage and capacitance can reduce, and leakage current can increase.
Film capacitor has advantages of as follows: bear high effective value electric current power (can reach 1A/uF), can bear double rated voltage overvoltage, can bear reverse voltage, bear high peak current, long service life (can reach 10-20), can store for a long time etc.But, because the dielectric loss of film capacitor is little, thereby cause it cannot make large capacity.Fig. 2 is the diagram of the support capacitance module of based thin film capacitor in prior art.
Therefore, for solve above shortcomings in prior art, need to provide can extend support capacitance module useful life, reduce electric capacity quantity, reduce module volume and improve the support capacitance module of the utilance of capacitor.
Summary of the invention
In order to solve the above-mentioned problems in the prior art, the invention provides a kind of support capacitance module that uses aluminium electrolytic capacitor and film capacitor that mixes.
A kind of for direct voltage being carried out to the voltage support capacitance module of voltage support, comprise: flexible lamp container module, comprise the first flexible lamp container unit and the second flexible lamp container unit, wherein, positive pole and the other end that one end of the first flexible lamp container unit is connected to described direct voltage are connected to ground connection, one end of the second flexible lamp container unit is connected to ground connection, and the other end is connected to the negative pole of described direct voltage, fixed capacitor module, comprise the first fixed capacitor unit and the second fixed capacitor unit, wherein, positive pole and the other end that one end of the first fixed capacitor unit is connected to described direct voltage are connected to ground connection, one end of the second fixed capacitor unit is connected to ground connection, the other end is connected to the negative pole of described direct voltage, wherein, each in the first flexible lamp container unit and the second flexible lamp container unit comprises K the aluminium electrolytic capacitor group being connected in series, each electrolytic capacitor group comprises L aluminium electrolytic capacitor and the resistor being connected in parallel, each in the first fixed capacitor unit and the second fixed capacitor unit comprises M the film capacitor group being connected in series, each film capacitor group comprises N film capacitor and the resistor being connected in parallel, wherein, K, L, M and N are not less than 1 integer.
Described direct voltage is the direct voltage after over commutation to wind-driven generator output.
When the rated voltage of described voltage support capacitance module is 1200V, when rated current is 150A, the aluminium electrolytic capacitor that aluminium electrolytic capacitor is 400V/6800uf, film capacitor is the film capacitor of 1200V/128uf, and K equals 2, L and equals 1, M equals 1, N and equals 2.
As the rated voltage 1150V of described voltage support capacitance module, when rated current is 300A, the aluminium electrolytic capacitor that aluminium electrolytic capacitor is 400V/6800uf, film capacitor is the film capacitor of 1200V/220uf, and K equals 2, L and equals 1, M equals 1, N and equals 6.
Described wind-driven generator is 1.5MW wind-driven generator.
Described flexible lamp container module is releasably attached to described voltage support capacitance module.
Support capacitance module provided by the invention, not only can extend support capacitance module useful life, reduce electric capacity quantity, reduce module volume, and can improve the utilance of capacitor.
Accompanying drawing explanation
By the description of embodiment being carried out below in conjunction with accompanying drawing, these and/or other aspect of the present invention and advantage will become clear and be easier to and understand, wherein:
Fig. 1 is according to the diagram of the support capacitance module based on aluminium electrolytic capacitor of prior art;
Fig. 2 is according to the diagram of the support capacitance module of the based thin film capacitor of prior art;
Fig. 3 is according to the diagram of the support capacitance module of exemplary embodiment of the present invention.
Embodiment
Now the embodiment of the present invention is described in detail, in the accompanying drawings, wherein, identical label represents same parts to its example shown all the time.
Support capacitance module for 1.5MW current transformer of wind-driven generator, technical scheme of the present invention is applied to the mixing type of attachment of alminium electrolytic condenser and thin-film capacitor the wind-powered electricity generation converter system (for example 1.5MW current transformer of wind-driven generator) of DC bus neutral earthing, wherein by four alminium electrolytic condensers, be composed in series flexible lamp container module, by four thin-film capacitors two two strings, form fixed capacitor module, flexible lamp container module is mainly used in filtering and voltage support, and fixed capacitor module is mainly used in supporting ripple current.Flexible lamp container module is removably attached to described support capacitance module, is therefore convenient to flexible lamp container module to change.
Below, in conjunction with Fig. 3, describe the support capacitance module according to exemplary embodiment of the present invention, wherein, Fig. 3 is according to the diagram of the support capacitance module of exemplary embodiment of the present invention.
As shown in Figure 3, according to the support capacitance module 100 of exemplary embodiment of the present invention, comprise the flexible lamp container module with aluminium electrolytic capacitor and the fixed capacitor module with film capacitor.Specifically, support capacitance module comprises having the flexible lamp container module of the first flexible lamp container unit 110 and the second flexible lamp container unit 120 and have the first fixed capacitor unit 130 and the fixed capacitor module of the second fixed capacitor unit 140.
One end of the first flexible lamp container unit 110 is connected to the positive pole (following, to be called for short anodal) of direct voltage, and the other end is connected to ground connection.One end of the second flexible lamp container unit 120 is connected to ground connection, and the other end is connected to the negative pole (following, to be called for short negative pole) of direct voltage.One end of the first fixed capacitor unit 130 is connected to positive pole, and the other end is connected to ground connection.One end of the second fixed capacitor unit 140 is connected to ground connection, and the other end is connected to negative pole.
The first flexible lamp container unit 110 and the second flexible lamp container unit 120 are symmetrical with ground nodes,, each in the first flexible lamp container unit 110 and the second flexible lamp container unit 120 comprises K the aluminium electrolytic capacitor group being connected in series, and each electrolytic capacitor group comprises L aluminium electrolytic capacitor and the resistor being connected in parallel, and K and L are not less than 1 integer here.In Fig. 3, K is that 2, L is 1.
Similarly, the first fixed capacitor unit 130 and the second fixed capacitor unit 140 are symmetrical with ground nodes,, each in the first fixed capacitor unit 130 and the second fixed capacitor unit 140 comprises M the film capacitor group being connected in series, and each film capacitor group comprises N film capacitor and the resistor being connected in parallel, and M and N are not less than 1 positive integer here.In Fig. 3, M is that 1, N is 2.
For the situation that needs rated voltage 1150V/ rated current 150A, the electric capacity needing is
Wherein, U
ripplefor the ripple voltage allowing, I
rmsfor the effective current under 2KHz.
Under 2KHz frequency, the capacitor C needing is about 6800uf, and considers the I of every uf of aluminium electrolytic capacitor
rmsfor 22mA/uf.If while all using aluminium electrolytic capacitor, for the aluminium electrolytic capacitor of 16 400V/6800uf, by 4, in parallel form one group and connect 4 this group and form capacitance module (as shown in Figure 1).
If used according to the hybrid plan of aluminium electrolytic capacitor of the present invention and film capacitor, and while using the aluminium electrolytic capacitor of 400V/6800uf, in order to support 1150V and to consider enough remainings, to use 4 aluminium electrolytic capacitors (as shown in Figure 3), the effective current that flows through aluminium electrolytic capacitor is:
And for film capacitor, I
film=150-I
electrolysis=113 (A)=C * 0.22A/uf.
The total capacity that can release fixed capacitor unit according to above-mentioned formula is 514uf, and the capacitor of 514uf can be formed by 2 film capacitors capacitance group forming in parallel by connecting 2 groups by the film capacitor of 1200V/128uf.
In addition,, for the situation of rated voltage 1150V/300A, if all use alminium electrolytic condenser, for the aluminium electrolytic capacitor of 32 400V/6800uf, need to carry out one group of 8 formation in parallel and connect 4 this group forming capacitance module.When using according to hybrid plan of the present invention, 4 the 400V/6800uf aluminium electrolytic capacitors of need to connecting, need to 12 film capacitors of one group of 6 formation in parallel 2 this group of forms of connecting, that is, need 16 capacitors altogether.
Therefore, than the situation of whole use aluminium electrolytic capacitors, alminium electrolytic condenser and thin-film capacitor are mixed to the quantity that situation about using can reduce capacitor, thereby reduce volume.
For the useful life of support capacitance module, due to 1/5 to 1/4 of useful life (being generally 20 years) that is generally film capacitor useful life (being generally 4-5) of aluminium electrolytic capacitor.Therefore, than the support capacitance module of whole use aluminium electrolytic capacitors that are 4-5 in useful life as above.Movable capacitance module owing to consisting of the dismountable aluminium electrolytic capacitor of periodic replacement, according to reaching 20 years the useful life of support capacitance module of the present invention, has therefore extended the useful life of whole support capacitance module.
According to support capacitance module of the present invention, the movable capacitance module forming due to the aluminium electrolytic capacitor by the low life-span is to be removably attached to support capacitance module, is therefore convenient to the maintenance to support capacitance module.
Although represented and described some embodiments of the present invention, it should be appreciated by those skilled in the art that in the situation that do not depart from principle of the present invention and the spirit that is limited its scope by claim and equivalent thereof, can modify to these embodiment.