Reflections on electrodynamics teaching for physics majors.
Dynamics electromagnetic phenomena's classical dynamics theory. Also known as classical electrodynamics, electrodynamics is its abbreviation. It studies the basic properties and motion laws of electromagnetic field and the interaction between electromagnetic field and charged matter.
First, the basic concepts of curriculum teaching
First, in teaching, we should respect the subjectivity of teachers' learning and the leading role of teachers' teaching, and give full play to teachers' blindness, automaticity and creativity. Second,? Electrodynamics? This course is a professional basic course. The arrangement of teaching content not only allows teachers to learn the basic knowledge, practice and ideas of this course, but also has a personality and characteristic relationship with other physics branches. In view of this feature, teachers should pay attention to guiding the abstract thinking of Mr. Similar in teaching. Thirdly, teaching should emphasize the exploratory teaching method, change the traditional teaching form, integrate information technology and electrodynamics course to the maximum extent, optimize the teaching process by using various ancient educational technologies, popularize teaching methods such as enlightenment, exploration, discussion and small manufacturing, and cultivate Mr. Wang's innovative ideas and concepts.
Second, in the teaching of this course, we should do the following.
1. Teaching content should be integrated with practice.
? Electrodynamics? As a specialized course, it is a basic practical course for physics majors in normal universities. In teaching, teachers are required to master the basic knowledge, basic reality and basic principles of the course, so that teachers can deepen their understanding of what they have learned, have a deeper understanding of the practical use value of electrodynamics, achieve the purpose of applying what they have learned, and improve their ability to analyze and process results.
2. Pay attention to the subjectivity and collective cultivation of teachers' learning.
Pay attention to the teaching reform in Tong 134 and 20 16, and pay special attention to teachers' learning subject status from curriculum design to evaluation, so as to give full play to teachers' enthusiasm and tap their learning potential. Mr. Wang is required to make a preliminary analysis of the electrodynamics results in consumption and life in order to improve Mr. Wang's analysis results and processing ability. In the practical study of electrodynamics, we should use mathematical tools to deal with grades, so that teachers can see the close relationship between mathematics and physics and cultivate their ability to deal with physical grades with mathematical tools. To cultivate Mr. Wang's self-study ability, it is important not to teach content, but to teach Mr. Wang learning methods. We should pay full attention to the collective differences in Mr. Wang's interests, specialties and foundations, teach students in accordance with their aptitude, determine the learning objectives and evaluation methods according to these differences, and put forward corresponding teaching suggestions. Curriculum norms provide choices and space for teaching and learning in curriculum design, teaching scheme, scheme formulation, content selection and teaching evaluation.
3. Use various ancient educational skills to optimize teaching links.
Make full use of ancient teaching skills, carry forward the disadvantages of information-based teaching, strengthen Mr. Wang's interest in learning, further strengthen the knowledge points he needs to master, broaden his knowledge, strengthen his theoretical operation skills, cultivate superstitious ways of thinking, and let Mr. Wang master them better? Electrodynamics? The superstitious methods involved in curriculum knowledge are ineffective in improving students' ability to discover, analyze and deal with grades.
4. Have good experimental conditions and fully guarantee the quality of demonstration and theoretical training.
Encourage Mr. Wang to carry out scientific research theory training and participate in various scientific and technological competitions. In the experimental class and theoretical training, we should pay attention to cultivating Mr. Wang's logical thinking and innovative thinking, and make full use of innovative platforms such as physics and electronic competitions to promote the teaching of electrodynamics.
Third, the exploration of curriculum learning strategies
First, for? Electrodynamics? This is the characteristic of practical basic courses. Teacher Wang must insist on previewing before class, and unconsciously present his achievements during the previewing process. Inquiry-based classroom teaching method is mainly used in classroom teaching, that is, each class highlights a theme, and the relevant theoretical knowledge is explained and explained in depth. Each theme is interacted by teachers and students in various ways, so that teachers can understand and deal with the results of teachers' questions in time and enhance students' interest in learning. Second, combine traditional blackboard writing, electronic courseware, network and video teaching skills. For example, the combination of in-class teaching and extracurricular discussion and manufacturing, the combination of basic practice teaching and cutting-edge lectures, and the combination of basic practice and scientific research theory training. Third, encourage Mr. Gu to participate in scientific research theory training and various scientific and technological competitions. Cultivate diversified practical talents, so as to cultivate practical, compound and skilled talents, enhance the unemployment ability of graduates and complete the expected purpose of capital courses. Fourthly, electrodynamics is also a theoretical course, and its research object is the material form different from the real thing, which has general characteristics. In order to prevent the mathematicization of course teaching, we will make full use of the disadvantages of contemporary information technology, for example, using video teaching materials to strengthen teachers' rational views and starting ability. Third, pay attention to cultivating Mr. Wang's logical thinking, creative thinking ability and quality in experimental classes and theoretical training, and fully develop Mr. Wang's physical thinking and physical exploration ability.
Fourthly, the exploration of course teaching methods.
In the teaching of this course, we should pay attention to the combination of electrodynamics practice and theory, respect Mr. Wang's subjectivity in learning, arrange and guide self-study reasonably, and cultivate Mr. Wang's self-study ability. Strengthen the counseling of answering questions before and after class, and pay attention to the cultivation of Mr. Wang's talent, so that teachers can explore ideas and initially cultivate scientific research ideas after understanding and understanding the fundamental reality of electrodynamics and mastering the research law of electrodynamics principles.
1.？ Bilateral reaction? teaching method
How did this teaching method come about? Self-study and? Reaction? It consists of two parts, focusing on the teacher's self-study under the guidance of the teacher and the teacher's focused explanation stopped by the information he replied, which made the teacher's talent lose his temper in repeated training. ? Self-study and? Reaction? It shows the training process of mutual contact, cooperation and interaction between teachers.
2. Pay attention to the results and start the class discussion.
It is suggested that classroom teaching should follow the standards of superstition, subjectivity and development, adopt the group discussion method with Mr. as the main body, start with the results, stimulate Mr.' s interest in learning, and let Mr. explore and apply practical knowledge to deal with actual results; We can also design discussions or think about the achievements encountered in the scientific research tasks of the teaching and research section, and inspire teachers to analyze and discuss the achievements of electrodynamics, learn and stabilize the knowledge of electrodynamics, develop thinking and cultivate scientific research ideas.
3. Advocate learning-oriented teaching methods.
Under the guidance of the teacher, the teacher stopped self-study and self-practice. Teachers regard teachers' cognitive activities in the teaching process as the main body of teaching activities, so that teachers can automatically acquire knowledge and develop their respective talents, thus achieving the foundation of fully developing teachers' automaticity, infiltrating teachers' correct guidance, and making all teaching parties do their best and get their places.
4. Carry out extra-curricular theoretical activities.
In extracurricular theoretical training, we should pay attention to cultivating Mr. Wang's logical thinking, innovative thinking ability and quality. Encourage and guide talented teachers to enter scientific research theory training and participate in various scientific and technological competitions. Integrate the course essays written by Mr. Wang into the whole teaching process, and select high-quality projects to enter the scientific research theory training. Make full use of innovative platforms such as physics and electronic competitions, promote electrodynamics teaching, cultivate practical, compound and skilled talents, and enhance graduates' employability. ? Electrodynamics? As an exploratory course, teachers' participation should be emphasized in classroom teaching, so that they can automatically get superstitious conclusions instead of taking the initiative. Interactive thinking makes teachers feel that electrodynamics is thought-provoking and easy to get started. ? Electrodynamics? Other branches of physics? Personality? And then what? Features? The relationship. In order to arouse teachers' interest in learning, we can often adopt the way of classroom discussion, in which teachers ask questions and discuss them under the guidance of teachers to draw correct conclusions. Due to anatomy? Electrodynamics? We should use general ideas, so we should make full use of multimedia in classroom teaching, and try our best to match images and colors, so that teachers can establish a correct physical image. Attention? Information technology? With what? Electrodynamics? The ineffective integration of courses is of great ideal significance to the optimization of teaching process, the learning effect of Mr. Progressive's professional knowledge, his information technology ability, his cooperative understanding and the cultivation of innovative bodies. At the same time, the teaching practice can be applied to the cultivation of innovative theoretical talents, as well as various competitions such as physics and electronics.
References:
[1] Exploration on the teaching reform of electrodynamics in Feng physics major [J]. Wisdom, 20 14, (19).
[2] Kevin Z, Lv Yan. Discussion on the establishment of electrodynamics network teaching platform [J]. Journal of Shenyang Normal University (Natural Superstition Edition), 2013,31(4): 531-534.
[3] Liu Jia. "Electromagnetism" and "Electrodynamics" Curriculum System Reform [J]. Science and Technology Information, 20 13, (1 1): 44.
[4] Bear and land. Right? Electrodynamics? Exploration of Curriculum Reform [J]. Basic Liberal Arts Education, 2003, (6): 72-75.
[5] Fu,,,. Discussion on learning methods based on electrodynamics teaching reform [J]. Journal of tonghua normal University, 2009,30.
Physical Fusion System of Power Information (Physics II)
With the rapid development of embedded system, computer technology and network communication technology, it is possible to build smart grid in the future. The construction of Power Information Physical Fusion System (CPPS) based on cyber-physical systems (CPS) technology provides a new idea for the realization of smart grid in the future. This paper makes a preliminary study and analysis of CPPS platform, and introduces the application of synchronous PMU technology, open communication network and distributed control in CPPS.
Keywords CPPS；; Synchronous PMU open communication; distributed control
introduce
Driven by the energy crisis, the pressure of environmental protection and the increasing demand of users for power quality, contemporary power systems can no longer meet the development needs of society, and smart grid has become the development direction of future power systems. The reasons for the development of smart grid mainly include the following aspects:
1) Distributed Generation (DG) connected to the power grid leads to system stability problems. Due to a large number of DG access, the power grid has become an active network with bidirectional flow of fault current and operating power, which increases the complexity and fragility of the system. Therefore, it is urgent to develop smart grid to solve the problem of system stability caused by a large number of DG connected to the grid.
2) Power users' requirements for power quality (QoS) are constantly improving. Short-term power outages in modern society will also bring huge economic losses to high-tech industries, and large-scale power outages in recent years have brought incalculable economic losses to society. Therefore, it is urgent to build a powerful self-healing smart grid to provide high-quality power services.
The main structure of the paper is as follows: 1 Part introduces the development of cyber-physical systems (CPS) technology in recent years and the relationship between CPS and smart grid; The second part introduces the hardware platform model of Information Physical Power System (CPPS). The third part introduces the phasor measurement unit (PMU) technology. The fourth part makes a preliminary analysis of the open communication network of CPPS; The fifth part briefly introduces the distributed control technology of CPPS; Finally, the sixth part summarizes the full text.
Relationship between 1 CPS and Smart Grid
The development of CPS technology benefits from the rapid development of embedded system technology, computer technology and network communication technology in recent years, and its ultimate goal is to control the physical world anytime and anywhere. CPS realizes the environmental perception of the physical world by embedding a large number of wireless sensors, realizes the safe, timely and reliable communication in the system through a high-performance and open communication network, and realizes the goal of autonomous coordination and remote precise control through a high-precision and reliable data processing system [1].
CPS technology has been preliminarily studied and applied in warehousing and logistics, autonomous navigation vehicles, unmanned aerial vehicles, intelligent traffic management, intelligent buildings, smart power grids and other fields [2].
The concept of information physical power system (CPPS) can be obtained by introducing CPS technology into smart grid. In order to analyze the relationship between CPPS and smart grid, the concept of smart grid is briefly reviewed. At present, there are many concepts about smart grid, and no consensus has been reached. Martin Hauske, a senior power expert of IBM China Company, believes that smart grid has three meanings: one is to use sensors to monitor the operation of key equipment in power generation, transmission, distribution and power supply in real time; Then the obtained data are transmitted, collected and integrated through the network system; Finally, through the analysis and mining of real-time data, the purpose of optimal management of the whole power system operation is achieved [3-4].
From the introduction of CPS and smart grid, it can be seen that CPS and smart grid are similar in concept, and both emphasize the use of frontier communication technology and high-end control technology to enhance the environmental awareness and control ability of the system. Therefore, CPPS based on CPS provides a new way to promote the deep integration of power primary system and power information system, and finally realize the construction of a complete smart grid.
Hardware platform architecture of the second generation CPPS
Based on the problem of system stability caused by the widespread access of distributed energy to the power grid and the overall goal of building a strong and self-healing smart grid, building a safe, stable and reliable smart grid has become an important direction of power system research in the future, and it is also the main content of CPPS research.
Traditional power system monitoring methods mainly include SCADA/EMS system based on power system steady-state monitoring and various fault recorders based on electromagnetic transient process monitoring. Protection control methods mainly include centralized control based on SCADA master station and local control based on installation of protection control devices [5]. The local control mode is easy to realize and the response speed is fast. However, due to the limited information used and the imperfect control performance, it is impossible to predict and solve the unknown faults of the system, and it is even more impossible to act accurately for the repeated response faults of the power system. Centralized control mode can optimize the control performance of the system by using the global information of the system, but it has huge calculation data, many communication links and slow response speed of the system. Moreover, the existing SCADA system mainly analyzes the steady state of the power system and cannot effectively control the dynamic operation of the power system.
In view of the shortage of current power system monitoring means, in order to build a powerful self-healing smart grid in the future, it is necessary to establish a corresponding wide-area protection real-time dynamic monitoring system, and the hardware platform of CPPS is established on this basis.
The six-layer architecture of CPPS hardware platform is shown in figure 1, which mainly includes physical layer (primary power equipment), sensor driver layer (synchronous PMU) and distributed control layer (intelligent terminal unit STU, intelligent electronic equipment IED, etc. ), process control layer (control substation PLC), advanced optimization control layer (SCADA master station control center) and information layer (open communication network).
Among them, the underlying physical layer refers to the primary equipment of the power system, such as power plants, transmission and distribution networks, etc. The sensing drive layer is mainly used to monitor the dynamic operation parameters of power system in real time, including current, voltage and phase angle. Synchronous PMU is widely used in CPPS. The decentralized control layer mainly includes STU/IED, which provides a feedback control loop for decentralized local control of wide-area protection. The process control layer mainly refers to the control substations of hub power plants and substations, and is an important part of CPPS. By collecting data information of multiple measuring nodes, a system-level control loop is established and corresponding control decisions are made. Advanced optimization control layer refers to the main control station of dispatching center, which mainly provides artificial auxiliary optimization control for the dynamic operation of power system. The top information layer is the open communication network of smart grid. Please note that the information layer is not a single layer, but covers all layers of CPPS, providing safe, timely and reliable communication for the internal components of CPPS.
The hardware platform model of CPPS is given above, but the realization of CPPS in power system involves many technical problems. Here, the synchronous PMU, open communication network and distributed control of CPPS are briefly introduced.
3 synchronous PMU measurement technology
Synchronous PMU is the foundation of CPPS construction, which provides rich measurement data for dynamic monitoring of CPPS wide-area protection. Synchronous PMU device mainly measures and outputs synchronous phasor in power system. Installation points include large power plants, tie lines, important load connection points and control systems such as HVDC and SVC. The measured data include three-phase voltage, three-phase current, switching value, excitation current, excitation voltage, excitation signal, valve opening signal, AGC, AVC, PSS and generator control. The measured data can be used to analyze the stability margin of the system and provide a basis for the dynamic control of the power system.
The hardware structure block diagram of synchronous PMU is shown in Figure 2.
Among them, the GPS receiving module will be accurate to? The second pulse within 1 microsecond sends the timing pulse and the standard time signal to the A/D converter and CPU unit as the standard time source for data acquisition and vector calculation. After filtering, shaping and A/D conversion, the three-phase current and voltage measured by voltage and current transformer are sent to CPU unit for discrete Fourier calculation, and the synchronous phasor is obtained and then output. Note that in addition to measuring the terminal voltage, current and excitation voltage and current, the generator PMU also needs to connect the key phase pulse signal to measure the generator power angle [7].
4 CPPS open communication network
On the basis of ensuring safe, timely and reliable communication, CPPS open communication network should make the system highly open, support plug and play of automation equipment and application software, and support the combination of decentralized control and centralized control. For the established open communication network, it is necessary to analyze the real-time communication, network security and reliability.
4. Application of1IEC 61850 Standard
As a new generation network communication standard, IEC 6 1850 standard is applied to smart substations, which supports plug-and-play and interoperability of devices and makes smart substations highly open. Therefore, it is the best choice to adopt IEC 6 1850 as the communication standard of CPPS communication network.
The core technologies of IEC 6 1850 [9] include object-oriented modeling technology, XML technology, software reuse technology, embedded operating system technology and high-speed Ethernet technology.
4.2 Communication Network Configuration and Analysis
The network configuration of CPPS open communication network refers to the three-layer dual-network structure configuration of smart substation, and a three-layer communication network of CPPS is constructed, as shown in Figure 3.
Among them, the bottom layer is a large number of PMU and STU/IED located in power plants, substations and important loads, which are responsible for collecting real-time information and performing protection and control functions respectively. The middle layer is the control sub-station (process control unit PLC), and each control sub-station is connected with multiple PMU's and STU/IED's to complete the system-level protection control of this partition, and upload the data to the SCADA master station control center as required. The control center of SCADA master station receives the data uploaded by each control substation, and sends the control information to each control substation after processing, thus realizing the wide-area protection control function of CPPS. Note that all layers of equipment are embedded with GPS to achieve accurate time synchronization and ensure data sampling synchronization of the whole system.
Distributed control mechanism of 5 CPPS
In order to build a powerful self-healing smart grid, a new control mechanism must be adopted to establish a reliable power control system. The document [10- 1 1] proposes to establish a time-space coordinated blackout defense framework and three lines of defense for the power system, which lays a good foundation for realizing wide-area dynamic protection control of smart grid.
Compared with the traditional centralized control mode of SCADA master station, decentralized control (DC) of power system refers to a multi-computer system, that is, multiple computers (including PLC control substation and STU/IED, etc. ) is used to control different devices and objects (such as generators, loads, protective devices, etc.). ), each subsystem forms an independent subsystem, which is connected with each other through the communication network to complete the task of coordinated distribution. What are the core features of distributed control? Decentralized control and centralized management? . Based on the three defense lines of power system and the distributed control technology, a three-layer control architecture of CPPS is established, as shown in Figure 4.
Among them, the distributed control layer mainly takes control measures in the initial stage of failure (slow interruption stage), and its control goal should be to ensure the stability of the system without serious failure and prevent the spread of failure. The process control layer is a wide-area emergency control measure when the system has a serious fault (the initial stage of cascade collapse), which needs to pay a high price. Usually, for a specific fault that may make the system unstable, it is necessary to switch the non-fault equipment to ensure the stability of the system. The wide-area emergency control measures should be implemented immediately after the fault is determined, and the later the control measures are implemented, the worse the control effect will be. The optimal control layer is a control measure that the first two layers of control refuse to operate or have insufficient control, but fail to achieve the control effect. At the same time, after detecting various unstable phenomena, it usually needs multiple rounds of load shedding and oscillation decoupling. In the power recovery stage, there should be an adaptive black start and self-healing control scheme.
6 conclusion
The CPS method is introduced into the power system, and the CPPS model platform is established, which provides a new idea for establishing a powerful self-healing smart grid. In this paper, the synchronous PMU measurement technology, open communication network technology and distributed control technology of CPPS are briefly introduced.
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