20 1 1 year [Harbin Institute of Technology]
First, what is Industry-University-Research's cooperative innovation? explain
A: The advantages of Industry-University-Research's cooperative innovation are that resources can be shared and their advantages are complementary, which can save a lot of time and reduce risks. But it has a problem. The biggest problem is that economic disputes often occur in Industry-University-Research.
Example: Taking Guizhou Nanhai Electric Machinery Factory as an example, talk about the benefits and advantages of Industry-University-Research's cooperative innovation model. Guizhou Nanhai Electric Machinery Factory used to be a military enterprise, and its original product was not a metal handle. The military enterprise went bankrupt in 2002, and a new company was born from the original state-owned enterprise, which was registered and born in June 2002. This enterprise is a private enterprise with only 65,438+005 employees. Since its establishment in 2002, it has been innovating through the cooperation of Industry-University-Research. By 2008, its sales revenue reached 1. 1 100 million, earning 3 million US dollars, and its per capita output value reached 1 10,000. This is very data. Why has it changed from a frontier military enterprise and mineral enterprise to such an advanced enterprise with a very high per capita output value is mainly based on Industry-University-Research's cooperative innovation, that is to say,
One is to turn the factory into a training base of the school, that is, undergraduates and postgraduates from Guizhou University come to the enterprise to practice or engage in research work, and combine the core problems and technologies in the enterprise as their graduation thesis and research thesis for research, so that the key technologies and problems of the enterprise can be solved with the help of undergraduates and postgraduates from Guizhou University.
Second, enterprises send promising and important talents to universities for training.
Through these two modes, enterprises have developed rapidly. In other words, Industry-University-Research's innovations include:
1 Jedi survival; ② Introduction, digestion, absorption and innovation; ③ Open technology innovation.
Second, how to improve a person's innovation ability?
A: For a professional technician, whether he can enhance his innovation ability and succeed in his career depends not only on his professional quality and personal innovation ability, but also on his cooperation or collaboration ability, and on the innovation system arrangement and innovation culture of his institution.
In the atmosphere of lacking innovation culture, individual innovation ability cannot be fully exerted. Similarly, the probability of failure of an "innovator" without cooperative spirit is much higher than that of success. On the contrary, in a vibrant innovation organization and cultural atmosphere, an individual's innovation ability may be brought into full play.
Personal innovation ability includes: learning, observation, imagination, abstraction, analysis, analogy, modeling, presentation, cooperation, changing thinking dimension, changing cognitive mode and comprehensive thinking. Innovators can exercise at the same time in the following three ways to improve their innovation ability.
(1) Self-discipline. The self-training of professional and technical personnel around improving individual innovation ability refers to the training process of innovation ability with "I" as the behavior subject.
Professional and technical personnel have obtained considerable professional knowledge and skills through formal education and continuing education, but professional knowledge and skills are only the basis of personal innovation ability. Personal innovation ability is mainly reflected in the mastery and application of innovative thinking. Only by being familiar with the application of innovative thinking can we be familiar with using professional knowledge and skills to solve difficult problems and achieve innovative goals. Therefore, the self-discipline of professional and technical personnel is not only a process of constantly enriching their professional knowledge and skills, but also a process of learning and applying innovative thinking.
The biggest secret of learning and using innovative thinking lies in the collision, transplantation and reference of ideas, and in the change of thinking angle and even thinking mode. The inspiration for innovation often comes from the process of collision, transplantation and reference of ideas.
(2) Collaborative exercise. "Tempering in cooperation" refers to the process of cultivating innovative ability with "we" as the main body of behavior. In this process, the innovator improves his innovation ability by participating in organized innovation practice, but his thinking angle is no longer "I" but "we". It is difficult or even impossible for people with indifferent group consciousness to complete this training process. Therefore, a true innovator must always keep an open and inclusive mind, be good at expressing or expressing his own thoughts, ideas or opinions, be good at listening to others' opinions, and participate in discussions, research and actions.
(3) temper in learning. People pay more and more attention to the importance of learning. Innovation is an exploratory and practical activity, and personal innovation opportunities and practices are very limited. Therefore, learning the theories and methods summarized by experts and scholars and learning the innovative practice of others is an effective way to improve their own innovative ability. Learning successful innovation cases, especially those with similar learning and innovation environment, is very helpful to improve the innovation ability of individuals and teams. There are collective thinking and action characteristics of individuals and teams in innovation cases, and there are experiences and lessons of individuals and teams in innovation activities, which can be tried and learned from the perspectives of "me" and "us" respectively. This is the purpose of compiling this textbook.
3. What are the basic characteristics of the information age?
A: 1. The development characteristics of the information age or the law followed by the development of integrated circuits-Moore's Law.
The integration of chips (integrated circuits) doubles every 65,438+08 months. According to this rule, integrated circuits are constantly pursuing smaller and smaller scribe lines, faster and faster integrated circuit information processing speed, and colder integrated circuit power consumption.
2. Information inflation.
3. The development from using electrons as information carriers to using electrons and photons as information carriers.
4. Take the tube as the information carrier.
4. What are the challenges and opportunities facing the human energy crisis?
Answer: human energy: 1, renewable energy such as solar power generation, wind energy, hydropower and biomass energy. 2, new energy, 3, large advanced pressurized water reactor and high temperature gas cooled reactor nuclear power plant; 4, inertial confinement fusion ignition engineering.
The challenges facing the human energy crisis are:
Future energy security depends on the following four modes: 1, and tap the existing energy reserves. 2. Overseas mining. 3. Direct import. 4. Energy substitution technology. After analyzing these four schemes one by one, we feel that the selectivity of energy is more limited. First of all, not many people expect more from our existing reserves. Here we emphasize oil, which is also the focus of contradiction. In the next 20 years, China will have hundreds of millions of private cars, and its oil consumption will undoubtedly surpass that of the United States in the near future. According to the analysis of geology and mineral resources department, domestic mining can only meet the domestic demand of 1/3 at most, so it is very unrealistic to hope for the exploitation of domestic reserves. The international oil price continues to run in the bull market track, and the high oil price makes many market participants exclaim that the "energy crisis" is coming.
The opportunities of the energy crisis facing mankind are:
The energy crisis objectively encourages the capital market to fully tap the investment opportunities under the theme of the energy crisis, hoping to support the adjustment and optimization of the industrial structure and energy consumption structure of the whole society in China more efficiently with the help of the resource allocation function of the capital market. The energy crisis is not terrible. Facing the energy crisis, we need to improve investment opportunities in the fields of energy efficiency, energy conservation and emission reduction. Under the existing division of labor, population growth and economic development, especially the vigorous development of processing industry and manufacturing industry, need more effective energy. Improving energy efficiency is not only beneficial to the long-term development of the country, but also a great contribution to the world.
V. Experiences and opinions after learning this course.
A: The spirit of innovation is not innate, but gradually formed through acquired cultivation. To cultivate and stimulate creative motivation, the most fundamental thing is to have a strong sense of professionalism and social responsibility. Social spirit provides spiritual support and motivation for innovation by cultivating the innovative spirit that is transformed into the subject of social practice.
First of all, social spirit innovation. Public opinion is a powerful social psychological force. Correct public opinion will make individuals have enthusiasm for innovation, and good fashion habits will form strong psychological hints and guide social subjects to actively innovate and be brave in innovation. The spirit of innovation is the spiritual expression of people's innovative essence and the spiritual quality reflected in people's innovative activities. Cultivating innovative social spirit is of great significance to promoting innovation. The spirit of innovation is a spirit of doubt. Don't be superstitious about theory, authority, books and truth. The spirit of innovation is a critical spirit. Criticism is research, criticism is discussion, criticism is the confrontation, complementarity and interaction of ideas, and the integrity and promotion of ideas can be achieved through communication. The spirit of innovation is a scientific spirit. People are required to persist in seeking truth from facts in creative activities, respect objective laws, proceed from reality in everything, stress practical results, and unify subjective initiative with realistic possibilities. The spirit of innovation is a spirit of freedom.
Second, social mentality innovation. Mentality is character plus attitude. Personality is a person's unique and stable personality characteristics. Attitude is a person's psychological reaction to objective things, that is, the sum of a person's attitude and psychological state under the control of ideas. A good mentality is the basic condition for innovation, which should include a healthy psychological mechanism, a sound personality, a stable mood, a strong will and a broad mind. First of all, we should be full of passion and keep the mentality of seeking knowledge, innovation, change, innovation and victory. A positive attitude helps people overcome difficulties, see hope, maintain strong fighting spirit, give full play to their intelligence, enhance their psychological endurance, and adapt their thoughts and behaviors to the requirements of objective and actual changes. Let yourself form the habit of striving for perfection and use love and enthusiasm to play this habit. Positive passion can mobilize the great potential of the whole body and promote innovation. Secondly, to be indomitable, we must establish a persistent attitude, adjust self-control, increase patience and embrace everything with an open mind. No one in the world can reach the sky in one step, and repeated setbacks are the road signs on the road to success. The more frustrated and brave we are, the more successful we will be. We must make every effort to win, and the only way to succeed is perseverance.
Third, scientific theory innovation. Theoretical innovation is the forerunner of social development and change. The so-called theoretical innovation means that people give new meaning to theory through creative activities. It is a process of putting forward new ideas, theories and doctrines through creative thinking activities on the basis of sublating the original ideas and principles. From the perspective of theoretical innovation, we should dare to deny ourselves and surpass ourselves. The ancients were stronger than others and stronger than themselves. Therefore, it is an important way of theoretical innovation.
Based on the reality of China, the new central collective leadership headed by Hu Jintao put forward Scientific Outlook on Development with world outlook and methodological significance, which greatly enriched and developed the guiding ideology of China's modernization. Scientific Outlook on Development changed his ruling ideal from pursuing economic growth to paying attention to people themselves, putting people first, establishing people's all-round development as the fundamental goal of economic and social development, and taking the coordination and mutual promotion between people's all-round development and economic and social development as the value goal, which promoted a new realm of understanding. Human development and social development are based on each other and promote each other. There is no end to the development of society, and the all-round development of human beings should constantly open up a broad space. In today's world, all-round globalization in politics, economy and culture has linked the fate of all mankind. Human beings should not only exchange and cooperate under the same rules, but also face the threat of ecological deterioration, environmental pollution, terrorism and the shadow of war. The measure of social progress is the degree of people's freedom and liberation, and the all-round development of people is essentially the all-round improvement of people's quality, including the all-round development of people's cognitive ability, aesthetic ability, moral sentiment and practical ability. Theoretical innovation requires innovators to have high theoretical literacy and follow the inherent laws and principles of theoretical innovation. To achieve the unity of upholding truth and developing truth, emancipating the mind and seeking truth from facts, always bear in mind that mass practice is the source of theoretical innovation, and any theoretical innovation is the crystallization of comprehensive reference to the outstanding achievements of human civilization. We should be willing and dare to participate in various innovative practices, be good at summing up and improving in practice, keep pace with the times and never stop.
Homework problems of electrical engineering courses in continuing education
20 1 1 year [Harbin Institute of Technology]
1 1 What's the difference between an independent power supply system and a grid-connected power generation system in terms of structure and control?
A: The single-stage inverter system directly converts DC into AC. Its main disadvantages are: it needs high DC input, which increases the cost and reduces the reliability; There is no independent control operation for tracking the maximum power point, which reduces the overall output power of the system; The expansion of this structure is not flexible enough to meet the variability of DC input of photovoltaic array module. Therefore, when the DC input is low, it is considered to use AC transformer to boost the voltage, so as to obtain the standard AC voltage and frequency, and at the same time, the input and output can be electrically isolated.
Grid-connected photovoltaic power generation system generally consists of photovoltaic array module, inverter and controller. The inverter converts the electric energy generated by photovoltaic cells into sinusoidal current and merges it into the power grid; The controller controls the tracking of the maximum power point of the photovoltaic cell and the waveforms of the power and current of the inverter connected to the power grid, so that the power transmitted to the power grid is balanced with the maximum electric power generated by the photovoltaic array module. The controller is generally based on single chip microcomputer or digital signal processing chip. First of all, the stability and quality of load power supply need not be considered; Secondly, photovoltaic cells can always run at the maximum power point, because the large power grid receives all the electric energy generated by solar energy, the efficiency of solar power generation is improved; Thirdly, the energy storage link of the battery is omitted, which reduces the energy loss in the process of charging and discharging the battery, avoids the operation and maintenance cost caused by the existence of the battery, and also eliminates the secondary pollution caused by the disposal of waste batteries. The control of photovoltaic grid-connected power generation system is generally divided into two links: the first link obtains the system power point, that is, the working point of photovoltaic array module; The second link completes the tracking of photovoltaic inverter system to the power grid. At the same time, in order to ensure the safe and effective operation of photovoltaic inverter in grid-connected state, the system must have certain protection function and anti-islanding detection control function.
12 gives the structure of common grid-connected inverters and explains their switching control strategies.
Answer: * * * The inverter has three active modes, namely, phase control mode, phase shift control mode and PWM mode.
Under the phase control of 1), the switching frequency and loss of the device are low, but the phase of the output current is limited by the minimum inversion angle and cannot be adjusted at will;
2) Under the current mode phase-shifting control, the switching frequency of the device is low, the loss is low, and the phase of the output current is easy to control, but the output current is very harmonic; Under the voltage-type phase shift control, the switching frequency of the device is low, the loss is low, and the output current is related to the load, which is difficult to control.
3) Under the control of current-mode PWM, the switching frequency of the device is high and the loss is large. Although the phase of the output current is controllable, the harmonic is very large; Under the control of voltage source PWM, the device has high switching frequency and high loss, but the output current phase is controllable and the harmonic content is low, so it should be the most valuable grid-connected inverter.
The following table summarizes the control of phase-controlled inverter, phase-shifted inverter and PWM inverter.
Control mode phase control phase shift control PWM control
Current mode voltage mode voltage mode current mode
Commutation forced commutation forced commutation forced commutation forced commutation forced commutation power grid forced commutation
Current distortion THD 29.57% 30.66% 9.2% is lower than 5% 7 1. 16%.
The current phase is controllable (limited by the minimum reversal angle), controllable (easy), controllable (difficult), controllable (easy), controllable (easy).
The switching frequencies of the device are 50hz, 50hz, several khz and several KHz.
The switching loss of devices is low, low, low and high.
Control complexity is simple, simple, simple, relatively complex, relatively complex.
Control strategies applicable to grid-connected inverters in three situations:
1) For grid-connected inverter with L-type filter, current single-loop control is enough, but this structure is easily affected by external interference, such as grid voltage distortion, so voltage feedforward control is often introduced. In addition, under the same filtering effect, the inductance value selected by this filter is greater than other filtering methods;
2) Grid-connected inverter with LC filter is suitable for current double-loop control mode, the system is relatively stable, and it is suitable for independent/grid-connected dual-mode operation;
3) Grid-connected inverter system with LCL filter is suitable for double-loop control structure of capacitor current inner loop to obtain better performance. In addition, LCL filtering can better filter out higher harmonics and is suitable for high power occasions.
13 briefly describes the control problems and solutions of grid-connected power generation system.
The control methods of grid-connected inverter are divided into voltage control and current control. Voltage control is equivalent to equivalent inverter to voltage source. Through control, the phase and frequency of its output voltage are completely equal to the grid voltage, and the amplitude tracks the amplitude of the grid voltage, which is essentially equivalent to connecting two voltage sources in parallel.
To realize the grid-connected operation of photovoltaic power generation system, the following requirements need to be met: the output voltage is the same frequency and amplitude as the grid voltage, the output current is the same frequency and phase as the grid voltage (power factor is 1), and its output should also meet the power quality requirements of the grid. These all depend on the effective control strategy of inverter. The control of photovoltaic grid-connected power generation system is generally divided into two links: the first link obtains the system power point, that is, the working point of photovoltaic array module; The second link completes the tracking of photovoltaic inverter system to the power grid. At the same time, in order to ensure the safe and effective operation of photovoltaic inverter in grid-connected state, the system must have certain protection function and anti-islanding detection control function.
There are two main methods to control the working point of voltage array module: constant voltage tracking (CVT) and maximum power point tracking (MPPT).
CVT control is to determine the system power point by stabilizing the terminal voltage of photovoltaic array module at a certain value. Its advantages are simple control and good system stability. However, when the temperature changes greatly, the working point of photovoltaic array module will deviate from the maximum power point in CVT control mode.
MPPT is a widely used power point control strategy for photovoltaic array modules. It changes the working state of the system in real time and tracks the maximum working point of the array, thus realizing the maximum power output of the system. It is an autonomous optimization method with good dynamic performance, but its stability is not as good as CVT. Its common methods are "uphill" method, interference observation method, conductance increment method and so on.
At present, the research on MPPT mainly focuses on the realization of simple and stable control algorithms, such as optimal gradient method, fuzzy logic control method and neural network control method. All of them have achieved remarkable tracking control effect.
14 why do grid-connected inverters generally use filter circuits to couple with the power grid?
For grid-connected inverter with L-type filter, current single-loop control is enough, but this structure is easily affected by external interference, such as grid voltage distortion, so voltage feedforward control is often introduced. In addition, under the same filtering effect, the inductance value selected by this filter is greater than that of other filtering methods; Grid-connected inverter with LC filter is suitable for current double-loop control mode, and the system is relatively stable, which is suitable for independent/grid-connected dual-mode operation. Grid-connected inverter system with LCL filter is suitable for double-loop control structure of capacitor current inner loop to obtain better performance. In addition, LCL filtering can better filter out higher harmonics and is suitable for high power occasions.
What kind of structure and function do you think the ideal solar power generation system should have after learning this course?
A: The ideal solar power generation system is mainly composed of solar panels, controllers, inverters and energy storage units.
Solar photovoltaic power generation is a device that uses photovoltaic effect to convert it into electric energy. Solar cells are calibrated with voltage and current values. In sunny conditions, the nominal voltage of 50W module is 12V, and the current is about 3A. The photovoltaic system adopts series-parallel connection to obtain the required voltage and current values.
The controller adjusts the battery voltage by adjusting the input and output power of the system to prevent the battery from being overcharged by the solar array or discharged by the load. There are four basic types of controllers: bypass controller, series controller, multi-order controller and pulse controller.
Solar photovoltaic power generation system generates electricity during the day to charge the battery, and the battery supplies electricity to Volts at night. Battery investment accounts for about 20% of the whole solar photovoltaic system.
The main function of the inverter is to convert the direct current emitted by the solar cell array into the alternating current required by users. Inverter also has the function of automatic voltage regulation or manual voltage regulation to improve the power supply quality of photovoltaic power generation system. The battery storage system generates surplus power, which is used to supply power to the load when the solar array cannot work normally.
1, economy, the real cost consumption of off-grid solar power generation system is battery, so it is the best scheme to design the minimum battery capacity according to the load power in system design to save the use cost.
2. Maintenance-free. At present, the maintenance cost of solar power generation system is relatively high, that is, special maintenance personnel are needed to ensure the normal operation in the later period. Therefore, a fool-like control system is designed, which can directly investigate the problems in the system without professionals and has a high penetration rate.
3. The overall design of the system should be based on the use environment. At present, the cost of solar power generation system is still relatively high. The more functions, the better. The more functions, the greater the power consumption and the higher the cost. So try to design the system to meet the basic use conditions.
First, some problems in jewelry appreciation,
1, ruby identification characteristics (1) Crystallization habit: it belongs to cubic c