As early as the beginning of this century, the concept of smart grid has been put forward, and through the development of wind and light, in China, smart grid has become a cause of wind and light. But what is the smart grid? Do you really understand? Please see the small series for you to come together.
As for what is a smart grid? Let's look at the authority definition first.
The United States is defined like this:
US Department of Energy "Grid2030": A fully automated power transmission network that monitors and controls each user and grid node, ensuring bidirectional flow of information and power between all nodes in the entire transmission and distribution process from the plant to the end user.
The domestic definition is as follows:
State Grid China Electric Power Research Institute: Based on the physical grid (based on China's smart grid with UHV grid as the backbone grid and a strong grid for the coordinated development of voltage grade grids), advanced sensing technology and communication are now available. A new type of grid formed by the high integration of technology, information technology, computer technology and control technology with the physical grid. It achieves reliable and economical users for the purpose of fully satisfying users' demand for electricity and optimizing resource allocation, ensuring the safety, reliability and economy of power supply, meeting environmental constraints, ensuring power quality, and adapting to the development of power market. Clean, interactive power supply and value-added services.
Is it boring and boring? Not to mention non-professionals, even professionals do not have much interest in watching.
At this time, I need to go out, I will try to explain the contents of these boring and unpopular in the easy-to-understand language.
Since it comes to smart grids, let’s first look at what the grid means.
The so-called power grid generally refers to the whole consisting of substation devices and transmission and distribution lines except for the power generation side.
Medium and high voltage substation devices are generally equipped with special substations, and low voltage substation units are also found everywhere.
Yes, you usually see the poles on the side of the road.
High-voltage pole tower seen by the urban-rural junction
Transformer box in the community
There are also substations hiding in the corner
They are all part of the grid. The power grid consists of three parts: substation, transmission and distribution.
Powertransforming refers to the process of changing a voltage from a low level to a high level (boost) or from a high level to a low level (buck) through a substation.
Power transmission refers to the process of transmitting electrical energy through a transmission line.
Power distribution (powerdistribuTIon) refers to the process of distributing electrical energy from a high-voltage transmission line to a user through power distribution and voltage transformation.
The electric energy is manufactured from the power plant, and is transformed into a high-voltage transmission line by substation, and then converted to a voltage drop to distribute power to each user.
The part of the high-voltage transmission is also called the main network, and the part of the low-voltage distribution is also called the distribution (electrical) network.
In addition, the generators, transformer boxes, and high-voltage wires we just mentioned, including various "switches" in the circuit - circuit breakers, contactors, disconnectors, knife gates, etc., are directly used to produce and transmit electrical energy. It is called "Primary Equipment".
Some people may ask, I usually see these, is there any other hidden part in the power grid?
That's right, that's the so-called "secondary device." The so-called secondary equipment (Secondary equipment) refers to the auxiliary equipment for monitoring, measuring, controlling, protecting and regulating the primary equipment in the power grid.
The secondary equipment includes an electric meter, a monitoring device, a relay protection device, a magnetic recorder, a direct current source, and the like.
Imagine launching a rocket. Then the rocket itself can be regarded as a similar "primary device", and the device that monitors the rocket's orbit, speed, and various parameters can be regarded as a similar "secondary device."
Ok, let's take a look at the grid. Let's take a look at what the smart grid is "smart" in.
User interaction, grid transparencyHow to understand user interaction? In the past, users could do almost anything about the grid: paying for electricity on time, or taking a few degrees of electricity on their mechanical aluminum-plated meters. Other than that, there really seems to be nothing to do.
So what about smart grids? Users will be an integral part of the power system. Encouraging and facilitating users to participate in their own operations and management is an important feature of the smart grid.
Comparison of old-fashioned electric meters and smart meters
For power supply companies, mastering the needs of users means better measuring the relationship between supply and demand. By counting the user's electricity consumption information, it is possible to understand the electricity consumption law of a region from the data analysis, such as what period of electricity is used, and when there is less electricity, and correspondingly, the energy-saving power generation and transmission in each region are formulated accordingly. Distribution plan. In addition, by adjusting the user's power consumption time, the power consumption efficiency of the grid terminal can be effectively improved, the peak filling valley is cut, the grid load curve is smoothed, and the load pressure of the power grid is reduced. The benefit of regulation is that reducing or diverting electricity demand during peak hours is the power company's efforts to minimize capital expenditures and operating expenses. As electricity costs decrease, electricity prices will naturally fall.
For users, electricity consumption is the same as mobile phone bills and can be selectively consumed. Users can choose different options to purchase power and choose electricity. For example, users can always know that during peak hours, the electricity price is high, and they can choose to use less electricity. When the electricity price is low during the low valley period, they can cooperate with the trial operation and remote control of intelligent electric appliances to select electricity during the low electricity price period.
Intelligent devices to realize the Internet of ThingsAs mentioned above, smart terminals such as smart home appliances and intelligent control devices will occupy a very important position in the smart grid. By using the power APP installed on the mobile phone, it is possible to remotely control the electric water heater, air conditioner, refrigerator, electric kettle and other electrical appliances, and it is easy to use electricity when the electricity price is cheap.
I might as well imagine it. When I go out in the winter, I can open the air conditioner in advance through the APP before going home. I can touch the warmth when I open the door... I want to burn a pot of water with half price before 6 o'clock in the morning, but I don’t want to get up so early. APP timing function ensures that the water is automatically completed before 6 o'clock... Through the APP, you can also know the power consumption of an electrical device for a certain period of time, just like querying the mobile phone traffic, so that the user can see at a glance about his own electricity account. .
A panoramic view of smart grid home users
The distribution power collection box in the smart grid is not just a one-way collection function in the past. They will bring their own WIFI and network functions. After collecting the user's power consumption information and data, they will send it to the power supply company through the network. Data terminal. The power supply company will classify and compare these data, and then tailor the power plan according to the actual situation of the user's electricity consumption, and send the notification through SMS and other forms.
For example, users can know which appliances in their homes are wasted by querying the real-time usage data of high-energy appliances. For example, if the TV is on but not seen, no one in the house can turn on the air conditioner and so on.
Smart grid panorama display from power plant to user
Measurement upgrade, big data eraThe old mechanical electric meters mentioned above are neither accurate nor easily stolen. In the era of smart grids, they will not only be replaced by digital meters, but the time interval between acquisitions will be greatly reduced. For example, the current smart meter may take 15 minutes to collect data, and in the ideal state of the smart grid, the interval between data collection may be as short as 1 second or even shorter. Similarly, in the transmission network, collecting various switching semaphores, telemetry information (voltage, current, phase, phase angle, active power, reactive power, and even transformer oil temperature, etc.), will also achieve real-time update, refresh rate It will also reach at least once per second. Such accurate data volume will greatly improve the reliability of the power grid, and can also effectively predict faults and quickly adjust.
Overview of various response times of power systems
As a result, the amount of data generated will be extremely impressive, and it is a real amount of “big dataâ€. For example, the collection of smart meters has been shortened from 15 minutes to 1 second, and the data of the electricity information collected by 10,000 smart meters has increased from 32.61 GB to 114.6 TB. And this amount of data is only a drop in the ocean for a highly developed smart grid in a big country.
So nowadays China's emerging power grid massive real-time data system, its core database mostly uses Hadoop's HDFS system, using distributed data storage and MapReduce computing model to store such huge data in real time. This is similar to Taobao's database. In addition to Hadoop's No-SQL database, a common relational database is also essential to assist.
Beijing's grid data distribution system (partial)
Self-predicting, self-healing, self-regulationBig data certainly has its own benefits. Through the big data platform with cloud computing technology, technicians can observe data such as power flow status, power load hot area, equipment fault high-incidence area and customer concentration area in the whole network in real time to realize a more intelligent power grid. Specific new concepts and technologies include the following:
1. Grid data visualization
In the smart grid, through the analysis of large data including scheduling, transmission and distribution, power generation and user information (these data are mostly real-time and highly information-integrated), real-time visual operation analysis through software can fully and completely display the grid operation. Every detail in the state provides management with decision support and evidence.
2. Grid load trend forecast
Not only that, through the analysis of historical data and real-time data of grid load through big data, the real-time load status of the whole network is displayed, and the trend of grid load change can be predicted. Through comprehensive management, the equipment utilization rate is increased and the power loss is reduced, making the grid operation more economical and efficient.
3. Equipment failure trend forecast
Through big data analysis of the fault type, historical state and operational parameters of the faulty equipment in the power grid, predict the law of grid fault occurrence, evaluate the grid operation risk, and realize real-time warning, so that technicians can do equipment maintenance and inspection in advance. jobs.
4, the grid to achieve self-healing
In the smart grid, the faulty equipment in the grid is isolated from the grid system at the fastest speed, and the system is self-recovering to normal operation in an almost automated state (with little or no human intervention). To almost no interruption to the power supply to the user. We can analogize the human immune system, which is similar to the self-healing of the smart grid. Combined with the two predictions, the grid system can make continuous self-predictions and take immediate action to control or correct when it finds a fault that already exists or is likely to occur.
5, secondary equipment independent communication
In existing grid systems, communication of secondary devices is often accomplished through buses and dedicated communication devices. This kind of equipment is called "master control unit" (commonly known as RTU in foreign countries). In the smart grid, secondary devices such as monitoring and protection will be equipped with adaptive and self-interactive information modules that can communicate with each other adaptively. This flexibility and adaptability will greatly improve reliability, just like letting the device "autonomy". As a result, even if some systems fail, other devices can still work stably.
New energy seamless access, plug and playTraditional power generation is generally thermal power generation and hydropower generation, and nuclear power is now gradually developing. In the past, new energy sources such as photovoltaic power generation, wind power, and geothermal power generation have been difficult to connect with traditional power grids. And the smart grid will change this situation. Smart grids simplify the process of generating new energy into the grid, and improved interconnection standards will make it easy to access a wide range of power generation and energy storage systems. Do "seamless access, plug and play". From small to large, power generation and energy storage devices of different capacities can be interconnected at all voltage levels (including photovoltaics, wind power, battery systems, plug-in hybrid vehicles and fuel cells). In the future, users can even install their own power generation equipment to achieve self-production and sales.
At the 2015 Power Industry Informatization Technology Innovation Conference, Academician Xue Yusheng, an academician of the Chinese Academy of Engineering and vice president of the State Grid Electric Power Research Institute, pointed out: As more and more renewable energy resources such as solar energy and wind energy are applied, the grid must consider how to ensure "Intermittent energy sources" such as solar energy and wind energy enter the power grid safely. Xue Yusheng said that the proportion of new energy access to the power grid is only 7%-10%. There will be many problems in large-scale access in the future. This requires a significant increase in the level of informatization and the use of big data technology for intelligent analysis.
Energy storage technology, electric vehicleIn the past, the production of electric energy was one-off, and it must be used immediately after production, making it difficult to achieve large-capacity storage. The energy storage technology in the smart grid will be the highlight. Whether it is a centralized large-capacity energy storage power station, or a distributed small-capacity energy storage power station, even as small as the energy storage of electric vehicle batteries, and even energy storage batteries for solar street lamps. They are all forms of energy storage in the smart grid. Among them, electric vehicles are the easiest to implement for the average user, and it is foreseeable that the development of electric vehicles will be unstoppable.
The energy storage technology is mainly divided into physical energy storage (such as pumped storage, compressed air energy storage, flywheel energy storage, etc.), chemical energy storage (such as various types of batteries, renewable fuel cells, flow batteries, supercapacitors, etc.) And electrical energy storage (such as superconducting magnetic energy storage, etc.). In the development of energy storage technology, Germany has developed very fast, and their energy storage battery research and development is the world leader.
In the future, users will have their own power generation and energy storage facilities. When they are self-sufficient, they may also be sent to the grid to achieve mutual adjustment. For example, when the electricity supply in my home is low, the energy supplied by the grid can not be used up, so I can store it first, so that I can support myself or my neighbors during peak hours. When my household electricity peaks, I use my own storage. When the power supply is insufficient, the energy stored by the neighbors can immediately make up for their own electricity demand.
Defense against terrorist attacksIn the current world anti-terrorism environment, the smart grid as a country's lifeline industry, of course, is indispensable to enhance self-defense capabilities. This requires grid security to reach a high level. When a terrorist attack occurs, use the self-healing solution mentioned in the fourth point above to make the attacked location recover quickly. Not only that, from the design and operation of the smart grid, anti-terrorism considerations will be added to prevent attacks as much as possible and minimize the damage caused by damage. Smart grid security strategies will include deterrence, prevention, detection, response, etc. to minimize and mitigate the impact of terrorist attacks on the grid and economic development.
It is worth mentioning that both physical attacks and cyber attacks are required defenses. The internal communication system of the smart grid will be completely isolated from the external network and operate independently, and each node will be autonomous.
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