Abstract: Mainly studied has developed the new energy and the renewable energy source key technologies, proposed the electric power electron transformation, the electrical energy saved, the electrical energy management and the electrical energy quality control in the new energy power supply system’s key role. Discusses several kind of electrical energy mix power supply to generate electricity and to disperse the power supply way emphatically, as well as the integration power supply system’s power source transforms, questions and so on intelligent management and safety control, and foresees the new energy power supply system’s application perspective.
Key word: Electric power electron and electric drive; Electrical energy transformation; Energy management system management system; Electrical energy quality control
0 introductions
The energy supports one of modern civilization social development main material bases, along with the traditional mineral energy, like resources and so on petroleum, coal day-by-day exhaustions, the energy question becomes the important issue which the human society universal attention the focal point and must solve.
In order to solve the present shortage of energy problem, various countries to develop and use the new energy to throw in the massive manpower and the physical resource conduct the research. In 1981 the United Nations held the world new and renewable sources of energy international conference, proposed that take the new technology and the new material as the foundation, develops the new renewable energy source to substitute for the resources to be limited, pollution of the environment’s fossil energy, maintains the sustainable development and the protection ecological environment.
The new and renewable sources of energy has the influential role similarly in our country social economy sustainable development, is our country energy development important content and the constituent. In 2005 the tenth Standing Committee of the National People’s Congress 14th conference adopted “the People’s Republic of China Renewable energy source Law” officially, lists as the energy development renewable energy source’s development use the first domain, thus has established our country renewable energy source enterprise plan and the development legal base, in 2006 promulgates the national medium and long-term technological progress summary and “25″ the technological progress plan proposed explicitly the national energy research and the developmental strategy, integrate this aspect’s research high technology and new technology projects and so on national 863 plans to give the key support.
Because the solar energy, the wind energy, the hydro energy, the sea can, the biomass energy, the geothermal energy and so on non-fossil class energy belong to the procedural energy, not only may regenerate, and does not have the pollution or the low pollution cleanly, the reserves are huge. Therefore, domestic and foreign in new energy development and use aspect, the wind power generation, the solar cell and the fuel cell and so on takes the current electrical engineering important research area and the development direction, and has made the important progress and the achievement. The domestic and foreign many scientists predicted that along with the fossil energy time’s end and the new civilization’s arrival, in next dozens of years the solar energy, the wind energy and so on renewable clean energy will become the world one kind of important energy. Therefore, the new and renewable sources of energy’s development use, is a merit in contemporary, the advantage in the century new enterprise. But, the new energy’s application still had many problems to need to study and the solution.
This article main elaboration power transducer in the new energy power supply system’s key role, the electric power electron converter technique and the modern Chinese Journal of Power Sources’s fusion, studies several electrical energy mix power supply way, the discussion integration power supply system’s power source transforms, questions and so on intelligent management and safety control, will provide the scientific basis and the technical support for the future new energy power supply system’s application.
1 new energy electricity generation way
1.1 wind power generations
At present, the wind power generation already became the wind energy use the main form, receives various countries to take seriously, moreover the development speed is quickest. The wind power generation usually has 3 movement ways:
(1) independent movement way, usually is a small wind-driven generator provides the electric power to household or several households, it uses the accumulator cell to gather energy, guaranteed is calm when using electricity;
(2) wind power generation the union power supply way which (for example diesel engine electricity generation) unifies with other electricity generation strength type, to the transportation inconvenient outlying mountain village, the offshore islands, or the vast territory with a sparse population prairie pasture raises the power supply;
(3) incorporation wind power generation movement way, installs in has the electrical network and the wind power fruitful in resources area, is frequently a wind field installs several dozens even several hundred wind-driven generators, this is the wind power generation main development strength approaches.
The wind generator set works when the different wind speed condition, its generator outputs the voltage peak-to-peak value and the frequency are the change, therefore needs to dispose the electric power electron power transformer, trades the class control through the power transformer, enables the output voltage to achieve the constant pressure permanent frequency the request. The power transformer and wind-driven generator’s system integration has two kind of plans: Direct output wind-power system and double-fed wind-driven generator system. Figure 1 has given two kind of wind-power system’s structure.
1.2 solar electrical energy generations
Developed from the 1950s first practical silicon solar cell successfully, the solar energy optoelectronic technology has had been through repeatedly half century’s development. At present occupied the mainstream the solar cell was still the silicon solar cell, it divided the monocrystalline silicon solar cell, the polycrystalline silicon solar cell (the general name crystalline silicon solar cell) and the amorphous silicon solar cell.
Typical solar energy power supply system structure as shown in Figure 2, through solar cell array’s electro-optical transformation, transforms the solar energy the electrical energy, the direct-current phonograph which the solar cell will output by the power transformer changes into the power source form which again the user needs. According to the user request, the power transformer may choose the direct-current chopper to carry on the DC/DC transformation, or uses the invertor to carry on the DC/DC transformation. In addition, the power transducer should also include the accumulator system, by is balanced uses electricity the demand. When the Dangyang light is sufficient, by the solar cell power supply, simultaneously approaches the battery charging; When the night or the sunlight are scarce, supplies power by the accumulator cell. Converter circuit structure as shown in Figure 2.
1.3 fuel cells
The fuel cell will be one kind will store up in the fuel and the oxidant chemical energy, will transform directly as the electrical energy installment. When continuously from outside to fuel cell fuel feed and oxidant, it may generate electricity continuously. Based on the electrolyte difference, the fuel cell divides into alkalinity fuel cell (AFC), phosphoric acid fuel cell (PAFC), fusing carbonate fuel cell (MCFC), the solid oxide compound fuel cell (S0FC) and proton exchange membrane fuel cell (PEMFC) and so on. The fuel cell the Garnot cycle limit, the energy conversion efficiency is not been high, and has purely, does not have the pollution, the low noise, the modular structure, the high power ratio, may characteristics and so on building block and continuous working.
Fuel cell generating system’s structure as shown in Figure 3, the system through the power transducer which is composed of the direct-current chopper and the invertor, causes fuel cell’s output voltage and the user’s needs matches.
2 key technologies
The key question which needs to solve using the new energy electricity generation is the electrical energy transformation, the electrical energy saves, the electrical energy management and the electrical energy quality control. Its core is uses the electric power electronic technology, the automatic control technology, the computer technology and the artificial intelligence technology and so on, specially above technical integration and fusion. But, forms for a long time the discipline system and the profession division of vertical, becomes restricts one of the new energy electrical power system widespread application and development main bottlenecks. Therefore, needs specially through the discipline overlapping research, the development and the new energy generating set necessary electric power electron power transformer, forms the product through the system integration, by convenient user.
2.1 electrical energy transformations
It is well known, the new energy electrical power system’s common characteristic is needs to carry on the power source to transform, namely causes the electrical energy which the generating set outputs at formally with the existing current collector’s request through the electric power transducer to match, satisfies the user in the quality the demand. How uses the electric power electronic switching component structure appropriate electric power transducer solves the above question basic outlet. Figure 4 gave one to use the multi-level inversion analysis situs constitution the combined three-phase AC power source.
Because in the new energy electrical power system the electrical energy transformation is mainly relies on the DC/DC transformation and AC/DC transforms two ways, therefore, raises the variable current efficiency and the power density appears especially important. The soft switch technology is decreases the switching loss, to enhance the current density and the transfer efficiency effective measure, therefore needs to develop based on the soft switch’s converter.
2.2 electrical energy storage
Because energy and so on solar energy, wind energy are big the natural environment and climatic conditions’ influence, has the instability and the uncertainty. In order to improve the power source quality, should establish the stored energy installment in the new energy generating system, so when the exterior energy is sufficient stores up the unnecessary electrical energy, but when energy insufficiency provides the electrical energy. For instance: The wind-driven generator may through the inductance energy storer memory wind energy, improve the electrical network power supply quality. Besides stored energy ways and so on traditional accumulator cell and inductance, the modern stored energy installment has super ways and so on electric capacity and flywheel.
Compares with the electrolysis electric capacity, the super electric capacity electroplates the two-layer electrode stored energy which using the carbon the surface produces, has the very high power density and the substantive energy density. Now, the super electric capacity power density may reach as high as 20kw/kg, the charging and discharging time each is 0.1~100 minute. In the past several years, these components have applied in the expense electron, the industry and the automobile and so on many domains.
The flywheel stored energy is the use high speed revolving flywheel inertia memory electrical energy. If with the wind-driven generator union, may when the wind speed is very high, drives the flywheel to revolve high speed; When the wind speed reduces, the flywheel actuates the generator output electrical energy. How current reduces flywheel’s friction loss is raises the stored energy efficiency the key, causes the flywheel revolution axis aerosol using the magnetic suspension technology in the space is one kind of effective solution stably. Estimated that the flywheel stored energy installment in domains and so on national defense, electric power, transportation will have the application prospect.
2.3 electrical energy management
The power source management system management system (PMS) technology is raises the power source efficiency and the system reliable new method. PMS the intelligent control and the management thought introduction electrical power system, from the electricity generation, the power distribution and uses electricity and so on each level, carries on the assignment, the monitor, the control, the management and the safekeeping of security to the electrical energy and so on. Its major function includes:
(1) electrical energy assignment;
(2) optimized control;
(3) condition monitor;
(4) failure diagnosis;
(5) fault-tolerant control.
Realizes the above function core technologies is: Computer technology, like database, network service, field bus and so on; Automatic control technology, like process monitoring, optimized algorithm, fault-tolerant control and so on; Artificial intelligence, like pattern recognition, expert system, fuzzy logic, neural network, genetic algorithm and so on. Specially more importantly these technical fusion, including each kind of technical interior own fusion, as well as between each kind of technical fusion.
For example: The overall system may use the network control, adopts three network architectures: The first floor uses the field bus and realizes the real-time control, the data acquisition and the correspondence based on the DSP embedded controller; The intermediate level realizes functions and so on system’s condition examination, data storage, trend analysis and malfunction alert through the distributed computer supervisory system; The upper formation uses artificial intelligence technology construction intelligence PMS, realizes the load predict that the electrical energy assignment, the system optimization and the energy management. In the power source management system management system (PMS) aspect, will have the breakthrough in the intelligent optimization and the safety control.
2.4 electrical energy quality control
In recent years, along with the massive misalignment primary device’s use, specially the electric power electron converter’s widespread application, caused the electrical network power factor to reduce with questions and so on harmonic distortion. How to govern “the electric power environmental damage”, enhances important topic which the electrical energy quality becomes current urgent needs to solve. The electrical energy quality control’s main research content is:
(1) power source overtone examination and the parsing technique overtone’s survey and the analysis realize the overtone government prerequisite, the accurate harmonic measure and the analysis can provide the good basis for the overtone government. Since proposed that fast Fournier transformation algorithm (FFT), then obtained the widespread application based on Fourier transformation’s harmonic measure. However based on Fourier transformation harmonic measure request complete cycle synchronization sampling, will otherwise have the frequency spectrum divulging phenomenon and the stockade effect. Therefore, how to reduce the measuring error which caused because of the synchronized deviation to become the focal point which the numerous scholars paid attention.
(2) electrical energy quality control and the management include: Power factor adjustment and filter design. As a result of traditional passive filter volume and weight ultra big, Japan must aim at the different frequency to carry on the design, the power factor adjusts the (PFC) technology is enhances the power factor and reduces the overtone pollution the important way. In recent years, active power factor adjustment technology (APFC) has become the electric power electron domain the research hot spot. Already from the electric circuit topology, the control policy developed to the integrated module, first makes the progress in the single-phase PFC electric circuit aspect. For instance: May use in DC/DC basic transfer networks and so on Buck, Boost, Buck-boost, Cuk special-purpose or the general PFC controller. Present research key in three-phase PFC control technology, for instance: The single switch, the multi-switches as well as rise to close the three-phase PFC electric circuit’s development softly. Specially, the soft switch technology and the PFC technology’s fusion is the development new tendency. Although, the PFC product receives the power at present the limit, but applies in the distributional new energy generating system is actually the important opportunity.
3 trends of development
3.1 mix power supply system
The new energy will take the electrical power system future development direction is: Uses several kind of new energy electricity generation way composition mix power supply system, the mix power supply system may choose the wind power generation and the solar cell combination, or solar energy and fuel cell combination, may also three combine in together. Another mixed mode is, the use fuel cell’s production’s waste gas or the quantity of heat, lead the generator composition mix electrical power system. Shown in Figure 5 for the mix generating system structure.
In the mix power supply system’s research, mainly studies the solar energy, the wind power as well as the fuel cell system’s incorporation power technology. Through the incorporation output voltage electric current’s control plan’s optimization, enables the output performance using the electric current pre-estimate principle to have the enhancement; Obtains the maximum efficiency; Causes the output current lock following network voltage phase through the software phase-lock; And has functions and so on protection and monitoring, guaranteed drafts the light to bend down the incorporation electricity generation safe operation.
3.2 distributional power sources
Figure 6 is by the mix electric power facility constitution distributional electrical power system. This distributional power supply way will be the future electrical power system development direction. This kind of distributional power source, may achieve the energy conservation and the environmental protection goal.
4 conclusions
In summary, new energy electrical power system, although had already made the breakthrough progress, but, must become the happy ideal the reality, realizes its widespread commercial use also to have many questions truly to urgently await to be solved. This already needs in basic subject domain and so on physics, chemistry, material union attacks, by to further raise the energy transfer efficiency and to reduce the cost; The history to needs more importantly in engineering technology domain cooperation research and so on electricity, electron, control and information, realizes between each kind of electrical energy the convenient effective transformation, the memory, the transmission, the use and the management. Therefore, breaks down the discipline boundary, through the system integration and the technical fusion, we can certainly electricity clothing each kind idle difficult, will welcome the new energy to benefit humanity’s bright tomorrow.
