In the field of renewable energy power generation, wind power has always been a leader in the industry. At present, the installed capacity of wind power in China has reached 26.68 million kilowatts, and cumulative power generation has reached 51.6 billion kwh. China has planned to further develop wind power, and it is expected that wind power will be generated in 2020. Will reach at least 150 million kilowatts of installed capacity, strive to achieve 300 million and 500 million kilowatts in 2030 and 2050, when the wind power generation will account for 10% and 20% of the total power generation.
Europe is the home of global wind power. Even in the hardest-hit region of the financial crisis, Europe increased wind power capacity by 577 MW in 2009, an increase of 54% from 373 MW in 2008. According to the European Wind Energy Association, Europe will Build 10 offshore wind farms, increase 10 million watts, equivalent to an increase of 75% over the installed capacity in 2009.
The natural wind power that drives the turbines to generate electrical energy does not pollute the air. It can be regarded as a clean energy source. Compared with other clean energy sources, wind power is currently the most widely used renewable energy source and has been widely used in European countries. .
Offshore wind farms will be the mainstream trend
Zhang Songgang: The grid-connected bottleneck of large-scale wind power generation requires the development of a smart grid.
From the perspective of wind power grid prices, it is also cheaper than other new energy sources. Generally, the price of thermal power grids is around 0.3 yuan/kWh, while the wind power grid price is 0.51 yuan/kWh to 0.61 yuan/kWh, which is more than solar power generation. Close to traditional electricity prices. The approachable price is also the reason why wind power has been greatly promoted by various governments. At present, the investment cost of a wind farm is converted to about 8,000 yuan/kilowatt per kilowatt, accounting for 70%~75 of the total cost of wind farm investment. The cost per kilowatt of wind turbines in % has been declining since 2007 (early 2007: RMB 6,700/kW; in 2008: around RMB 6,300; by the end of 2009: RMB 5,000/kW), with an average of RMB 100/kWh per month. About the decline.
Zhang Songgang, ADI's technical business manager, said that in the future, with the improvement of wind power technology, wind turbines will become cheaper and more efficient. With the increase of single capacity of wind turbines, the same installed capacity will require a smaller number of turbines. The input costs of infrastructure, and thus save the cost of wind power.
Among various new energy sources, the technology of wind power generation is relatively mature and the degree of industrialization is relatively high. Xu Haoping, vice president of Jiaxing Star Semiconductor Co., Ltd., said that the height of wind power towers will continue to increase. Increasing the height of wind towers can capture more More wind resources increase the amount of power generated, and the cost of increasing the height of wind towers is cheaper than the cost of large-capacity wind turbines. With the increase of towers, the length of wind turbine blades is also increasing. “The ability to capture wind energy is stronger. The requirements for paddle materials are also getting higher and higher." Xu Haoping added.
Xu Haoping: The wind farm is gradually developing from inland to offshore.
The biggest controversy surrounding wind power generation is that the wind farm area is unacceptable for cities with high land prices. As a result, most of the wind farms have been built in the sparsely populated northwest region. However, densely populated coastal cities are the sources of energy consumption. Large-scale, wind farms are far away from the power load center, which poses a certain obstacle to the transmission of wind power and access to the power grid. Offshore wind power development is not only close to coastal cities, but wind resources are superior to inland and do not occupy land resources.
Zhang Songgang said that offshore wind power has risen quietly and will become an important form of energy. During the Shanghai World Expo, the Shanghai Donghai Bridge offshore wind farm has been successfully put into use.
“The wind farm is gradually developing from the inland and continental coasts to the sea. At present, offshore wind farms have become a hot spot for the development of wind power in the world.†Xu Haoping pointed out, “This is mainly due to the abundance of offshore wind resources, and the installation of larger single-capacity units. It's easier to achieve than land."
Intelligent and dynamic control of wind power system
Although construction of wind farms is in full swing all over the world, wind power generation is a low-density energy source, characterized by instability and randomness, which makes wind power design face many challenges.
“The utilization of wind energy ultimately depends on the realization of the grid connection to the grid, and the main requirement for grid connection is that the output frequency, voltage and phase should be kept consistent with the grid,†Xu Haoping explained. This requirement is under constant wind speed and wind power. It is relatively easy to realize, but the reality is that wind speed and wind power are constantly changing. Therefore, how to convert the variable wind power into stable electric energy is the key link of wind power generation system. “In the early days of wind power, variable pitch and gearbox were used. Technology to achieve, but today's mainstream technology is dominated by intelligent control technology."
Lu Lei: The main challenge for wind power generation comes from the dynamic control of wind power systems.
Lu Lei, an Asian business area manager at ADI Processor-DS, believes that the main challenge for wind power generation comes from the dynamic control of wind power systems. Since the wind changes all the time, in order to maximize the use of wind energy and improve the efficiency of wind power generation, it is necessary to implement real-time wind power generation systems. control.
Lu Lei said: “For power generation systems, the task of most system designs is to implement real-time control algorithms, so most control systems use high-performance processors or DSPs, and the DSPs used in them must be able to meet a range of requirements.â€
He said that ADI's floating-point processor is particularly suitable for dealing with the complexity of wind power control algorithms. The SHARC floating-point processor as the core algorithm processor provides a feasible solution for the industry to meet the needs of designing wind power systems. All key requirements. In addition to addressing these challenges, the SHARC processor also allows developers to divide internal memory into data and program memory in a very flexible manner, allowing the application to adapt to future changes in requirements without hardware changes.
In addition, he also mentioned that speed is also a critical factor for real-time processing operations that must be performed in 100 microseconds or less. In addition, the necessary condition for wind power systems is sufficient processor memory to avoid processing. Delayed wait states. "In addition, the internal memory can reduce the number of external devices, which can minimize the EMI problems in the circuit board design." Lu Lei stressed.
In addition, Zhang Songgang also mentioned that cost and price factors are also one of the main obstacles to the growth of wind power. “One of the biggest bottlenecks in wind power development is one-time huge investment, unit cost is higher than thermal power, and high hydropower.†In addition, long-term maintenance is also a The burden is not small. Zhang Songgang pointed out that wind power generation is also constrained by other factors in the actual development process. For example, wind farm construction must comprehensively consider factors such as traffic, geology, environmental protection, and grid connection conditions.
Smart grid is expected to break the wind power bottleneck
Wind power plays a key role in improving the energy structure and improving the utilization of multiple types of composite energy. However, wind power generation, especially large-scale wind power generation, will bring great impact to the traditional grid once it is realized.
Wind power itself is an intermittent and uncontrollable energy source. After being integrated into the traditional power grid, the entire energy system must be adjusted accordingly. As the capacity of the wind power unit increases, the peak-to-valley difference of power generation also gradually increases, giving power generation dispatch and grid security. Cause greater impact.
Zhang Songgang analyzes that, first of all, because the driving force of wind power is not controllable, the power generated by power generation is volatile and intermittent. When the scale of wind power generation is connected to a certain degree, it will change the trend distribution of the power grid, and the traditional network power flow control will undergo major changes. It will directly affect the stability of the power grid. Second, due to the uncertainty of wind power generation, the power of the power grid is deteriorating due to the fluctuation of wind power.
“Wind power generation and solar power generation will also have islanding effects. The use of traditional power grid protection and monitoring and control equipment will not meet the requirements. Newer types of power grid protection and control equipment are needed; wind power generation also requires more energy storage equipment to join the power grid.†Zhang Songgang emphasized that traditional grids are difficult to meet the need for large-scale grid-connected wind power generation, and the development of smart grids will be very urgent.
The dilemma of grid-connected wind power generation has caused most of the wind power facilities to stop operating during the peak period of wind power generation at night. Traditional power grids lack the capacity for digestion and transportation to waste a lot of energy. Wind farms occupy a large amount of land resources, so most of them are currently in China. The wind farm was built in a remote area. Xu Haoping pointed out that the regional power distribution network at wind power plants was lagging behind, which caused certain difficulties in wind power grid connection.
The smart grid can effectively optimize the grid scheduling, rationally configure the power transmission, and enhance the ability of the grid to resist failure. Therefore, the smart grid is considered as a breakthrough to break the wind power bottleneck.
Obviously, the smart grid has more compatibility than the traditional grid, paving the way for the dispatch and deployment of wind power. Zhang Songgang pointed out that the smart grid will increase more energy storage links, more rationally allocate energy consumption and regulate the flow of electricity. More power electronic devices are introduced to improve power quality, and power supply balance between supply and demand is better adjusted according to different user needs, and the use of high-intelligence and networked protection and control devices are gradually promoted and used to ease wind power grid interconnection. Bring problems and increase the use of green energy in the entire power grid.
Xu Haoping believes that in the coming years, the smart grid needs to be strengthened in terms of standardization, automation and interaction, making it a truly Internet in the power industry.
Wind farm lightning protection solution
Thunder can be divided into direct lightning and induced lightning. Direct lightning has too much energy. Generally, only the earth can undertake it. Therefore, it is generally only possible to use the lightning needle to protect electronic equipment exposed in the wild. For wind farms, despite the wind tower, The use of metal shell, but for safety reasons, it is best to use lightning or lightning rod.
At present, there are suppliers of lightning conductors in the industry, such as Ailida, Durmeissen and Shenzhen Thunder. In addition to owning the brand's lead wire, Thunder also represents the two leading lightning conductor products.
Wind farm room lightning protection scheme is almost the same as that of the base station. The main lightning protection target is an electronic device that may be affected by induction lightning coming from the power line, such as an inverter. This is generally used by MOV (varistor) and GDT ( The combination of lightning arresters for gas discharge tubes. Currently the main MOV suppliers in the industry are Littelfuse, TDK-EPC, Tyco Electronics, Hefei Yushun Electrical Technology, GDT suppliers are mainly Tyco Electronics, TDK-EPC, DEHN, OBO, Shenzhen Penang Electronics, Shenzhen Tianshun and Thunder are agents of DEHN lightning arrester.
Whether it is to protect AC 110V/220V switching power supply or 48V DC switching power supply, the traditional lightning protection solution is: the first level lightning protection adopts GDT, and the second level lightning protection adopts MOV.
The main reasons why MOV is widely used in the industry are the advantages of large inrush current, fast response time, and low cost. However, it is well known that MOV has technically been unable to break through the bottleneck. MOV has good insulation resistance before being impacted. That is, the leakage current is very low; but when subjected to the impact of the induced lightning, the varistor will be degraded, leading to a decrease in the insulation resistance and an increase in the leakage current. As the external impact increases, this leakage current will increase and cause the circuit board to burn. Bad or even short circuit fire.
At present, the industry has adopted two methods to solve this problem. One is to encapsulate varistors, but this is a method of pursuing a temporary solution, and the other is a method of stringing fuses. However, this method has a contradiction. : If a fuse with a smaller current is used to prevent a smaller leakage current, the through-flow rate will also decrease. Otherwise, a large lightning current will burn the low-current fuse. If a fuse with a larger current is used to increase the through-current, At this time, a slightly smaller leakage current will still burn out other components of the circuit board, and even a varistor will burn out the fuse and it will not work.
Although ceramic GDT is slower than MOV, it is a kind of switching device. When it is struck by lightning, it can rapidly expel the amplified current, but its conduction voltage drop after being struck by lightning is very low, generally only about 10V, if it is directly connected with MOV. At the two ends of the circuit to be protected, the ceramic GDT will always be in a conducting state, which means that there is a freewheeling problem in the industry.
In order to solve the freewheeling problem of the GDT and the leakage current of the MOV, the current methods used in the AC switching power supply industry are: a first-level GDT is connected in series with one MOV; a second-stage is connected with two MOVs in series; GDT to the ground not only solves the current leakage problem when the second-level MOV is struck by lightning, but also effectively solves the first-stage GDT freewheeling and MOV leakage problems.
If it is a 48V DC switching power supply, the lightning protection solution can be further simplified. The first stage can still use the GDT series connection MOV method. The second stage can use a MOV to further reduce the lightning strike voltage, but a TVS diode can also be used. Alternatives.
If it can effectively increase the on-voltage of the GDT, then there is no need to use a clamp-type MOV, that is, you can remove the first-stage bulky MOV. Fortunately, Shenzhen Penang Electronics recently took the lead in the industry. This point. They technically broke through the bottleneck of this problem, developed a free-wheeling ceramic gas discharge tube named BH601, it will increase the value of the conduction voltage above 60V, which can be directly used in the 48V DC power supply Lightning protection.
Compared with traditional varistor solutions, the BH601 not only fundamentally solves the problem of leakage current, but also the structural characteristics of the ceramic GDT determines that it can be easily achieved in the flow level. The BH601 has a maximum inrush current of up to 20 kA. The resistance exceeds 1G ohms, the response time is less than 200ns, and the size is only 8.3×24.8mm.
"The BH601 is the industry's first truly non-freewheeling GDT, and it has now passed Huawei's rigorous laboratory tests," said Ye Yuming, the head of Penang Electronic FAE.
Penang Electronics is a private enterprise specializing in SMD Ceramics GDT in Shenzhen. At present, there are mainly three series of products. The first is the BS series miniaturized SMD GDT. The maximum inrush current reaches 500A, and the minimum size is already 1,206. Ye Yuming stated: " The 1206 is the smallest size SMD GDT currently available in the industry. The monthly shipments of the GDT series have reached 2-3 KK.
The second is the BS series of semiconductor discharge tube TSS, a new package line into the mass production at the end of July this year, the current monthly shipments in more than 4KK. The third is the BV series TVS TVS.
At present, the product quality and performance of Penang Electronics is quite close to TDK-EPC. For example, the highest performance of TDK-EPC GDT is: maximum impact current 100KA, impact breakdown voltage 5.5KV, insulation resistance 1G ohm, parasitic capacitance 0.5pF; Penang electronic GDT's highest performance is: the maximum impact resistance current 20KA, impact breakdown voltage 7.5KV, insulation resistance is greater than 1G ohms, parasitic capacitance is less than 0.6pF.