Views:8 Author:Site Editor Publish Time: 2015-08-07 Origin:Site
Xushuang Sun ; Feng Zhou
(Tongling Tongfei Technology Co.,Ltd., Tongling , 244000)
2 special capacitor selection in the field of new energy
New energy is also called “the unconventional energy”, refers to the various forms of energy except the traditional energy, such as solar energy, heat energy, wind energy, ocean energy, biomass energy and fusion energy these newly developed, actively researching, or energy available to promote. In new energy and new energy vehicles, smart grid and other fields, the special capacitor mainly use as a new energy, smart grid control system, power management system, power supply and DC AC inverter switching system. Now, our country energetically advocate using wind energy, solar energy, which is a clean energy, due to the rapid growth of installed capacity, it will led to the demand of the inverter, among which special capacitor occupies the important position, in wind power products, special capacitor is mainly used in three aspects:
A, high pressure absorption
B, filtering energy storage (DC - LINK, DC - DC conversion)
C, interconnection of anti-jamming. As shown in figure 1.
Figure 1 :Capacitor in the use of wind power generation system
The demand of wind power capacitor device is larger, the capacitor module is set between the windmills and inverter, when the wind increases gradually, it can absorb capacity, and has the effect of buffer memory; When power suddenly stop, you can use the energy stored in the capacitor, smoothly supply the power to the inverter.
That means capacity of the equipment is small when breeze, use capacitor supply power; Instead, generating capacity of the equipment will be more than (1 kw), the provisions of the inverter capacity when strong wind, at this time capacitor electric storage is available to avoid wasteful.
In photovoltaic systems, the power of photovoltaic array is direct current (dc), however, many load need ac power, such as transformer and motor. DC power supply system has significant limitations, like not easy to transform voltage, load application scope is also limited. Except the special load, the inverter is all in required to transform DC into alternating current. The function of inverter is converting DC to AC, rectifying process for "reverse", so called "inverter". The literature  points out that the demand of photovoltaic inverter capacitor mainly has the following kinds:
A, power within 10 kw mainly use MKP capacitor, such as 0.33 u F / 1200 VDC; 0.47 u F / 1000 VDC; 1 u F / 850 VDC;
safety capacitance Y2 type: 1nF/250VAC、2.2nF/250VAC、4.7nF/250VAC、10nF/250VAC；
safety capacitance X2 type: 1μF/275VAC、3.3μF/275VAC、4.7μ F/275VAC；
B, power of 10-100 - kw mainly use capacitor: MKP DC - Link capacity: 10-100 - u F / 500 v - 1000 VDC;
MKP capacitor: 0.33, 0.47, 0.68, 1, 2, 3, 4 u F / 1200 VDC; Filter capacitor: 10, 20, 30, 40, 50, 60, 100 u F / 850 VDC;
C, power of 100 kw or more, the mainly use capacitor: MKP DC - Link capacity: 100-1000 - u F / 800 V - 900 VDC;
Among which the common use: 420μ F/800VDC、510μ F/800VDC、730μ F/800VDC and 145μ F/900VDC、205μ F/900VDC、1500μ F/900VDC；
MKP capacitor: 0.47, 0.68, 1, 2, 3, 4 u F / 1200 VDC;
Filter capacitor: 50、60、100μ F/800VDC、3×60μ F/450VDC、3×100μ F/450VDC、3×200μ F/450VDC；
Mainly special capacitors used in railway traffic: VVF car in each group with 12 pieces of capacity about 6000 u F / 1000 VDC capacitor (6 car in each group, 3 cars with traction function, among which each car has two groups, each group with two large capacitors); Metro vehicle sivs auxiliary power use special capacitor in the capacity of 1800 u F, aims to adjust 750 VDC to 380 VAC through the inverter.
There are a larger develop space for capacitor industry during the "twelfth five-year", special capacitor has begun to enter high-end market, from the point of sales, capacitor main producers focused on Japan, China and Taiwan, our country has become the second only to Japan's production power, the matching new energy of special capacitor, power inverter capacitor, power frequency capacitor, the auto electronic capacitor has been the development key. In order to meet the needs of emerging industry, high frequency, large capacity, high current, low impedance, high voltage, high dv/dt characteristics is the development direction.
The Literature  pointed out that in recent years, the special metallized film capacitor developed by some foreign manufacturers have been in mass production and put on the market. Although there are many capacitor manufacturers in China, in terms of the beginning technology and production, the quality can't compared with some foreign manufacturers’ products, the quality difference and market share is mainly as follows:
1) the abroad development and market conditions of this type capacitor:
now the foreign advanced manufacturers such as ABB, ICAR, GE, METAR, the main characteristic of these company's capacitors is in a constant volume and constant voltage, the size and weight are only half of domestic capacitors, the service life ensure to 20 years. Now the METAR, ICAR company has developed the 500000 v high voltage parallel capacitor and put into use, now occupy 95% of domestic market.
2) the development and domestic market conditions of this type capacitor:
Now the size and weight of capacitors produced by domestic manufacturer is much larger and heavier for the same capacitor type than foreign products, the service life is from 5 to 10 years.
The domestic demand for the metallized film high voltage parallel capacitor, high frequency pulse capacitor, DC high voltage capacitor is growing, and basically rely on imports, Developing special capacitor in batch production, will have a strong market competitiveness.