Modern society is more dependent on power supply than ever before. The power supply in modern society is more dependent than ever before. I can't imagine what the world would be like if the power supply in the world were interrupted. It can't imagine what the world would look like if the whole world were blacked out. The power system (or electric energy system) that provides electricity for modern society has become an indispensable part of the industrial world. The power system (or power energy system) that provides electricity for modern society has become an indispensable part of industry.
The first complete power system (including generators, cables, fuses, meters and loads) was built by Thomas Edison-the historic Pearl Street Station in New York City, which started operation in September 1882. The first complete power system (including generator, cable, fuse, metering and loading) was built by Thomas Edison, and the history of Pearl Street in new york began to run in September 1882. This is a DC system, which consists of a DC generator driven by a steam engine and supplies power to 59 users in an area with a radius of about 1.5 km. T Heload is consistent with the emergency light, and the power supply is 1 10V through the underground cable system. This is a DC generator driven by a steam engine, with a DC system with a radius of 1.5 km and 59 customers. The load, including the complete incandescent lamp, is supplied to V through the underground cable system 1 10. Within a few years, similar systems were running in most big cities around the world. As Frank Sprague developed the motor in 6543 8+0884, the motor load was added to this system. This is the beginning of developing into one of the largest industries in the world. Although DC systems were widely used at first, they were almost completely replaced by AC systems. By 1886, the limitations of DC system are becoming more and more obvious. They can only transmit electricity very close to the generator.
In a similar system, it has been running in most big cities in the world for several years. With Frank sprague developing the motor in 1884, the motor load is increased in these systems. This is one of the largest industries in the world. Although DC systems were widely used at first, they were almost completely replaced by air conditioning systems. By 1886, the limitations of DC system have become increasingly obvious. They can only provide electricity very close to the generator.
In order to keep the transmission power loss (I 2 R) and voltage drop at an acceptable level, the voltage level of long-distance power transmission must be very high. Such a high voltage is unacceptable for power generation and power generation; In this case, a convenient voltage conversion method becomes essential. In order to keep the transmission power loss (I 2 R) and voltage drop at an acceptable level, the voltage level of long-distance transmission must be very high. It is acceptable for such a high voltage to consume electricity without generating electricity. Therefore, voltage conversion is necessary to be a convenient means.
The development of transformers and AC transmission by L. Gaulard and JD Gibbs in Paris, France, led to the emergence of AC power system. Developing transformers, France and AC transmission lead to AC power system.
1889, the first AC transmission line in North America was put into operation between Willamette Falls, Oregon and Portland. 1889, the first AC transmission line in North America will be implemented in Willamette Falls between Portland, Oregon.
This is a single-phase line that transmits 4000 volts at a distance of 2 1 km. With the development of multiphase system in nikola tesla, AC system becomes more attractive. By 1888, Tesla has many patents on AC motors, generators, transformers and transmission systems. Westinghouse Electric Company purchased patents of early inventions, which form the basis of today's communication system. This is a single-phase line with a transmission power of 4000 kilometers, which exceeds the distance of 2 1 V system. With the development of communication, the multiphase system from nikola tesla is more and more attractive. Through 1888, Tesla holds a number of patents for AC motors, generators, transformers and transmission systems. Westinghouse bought these early invention patents and formed the basis of the system, which is now communication.
In the 1890 s, there was considerable controversy about whether the power industry should be standardized on DC or AC. At the turn of the century, the AC system defeated the DC system for the following reasons: In the 1990s, there was a great controversy about whether the AC power industry should be unified with DC. At the turn of the century, the AC system won because of the following DC systems:
(1) In an AC system, the voltage level can be easily converted, so different power generation voltages, transmission voltages and power consumption voltages can be flexibly used. (1) can easily change the air conditioning system, thus providing transmission flexibility and generating different voltages and consumed power.
(2) Alternator is much simpler than DC generator. Alternator is much simpler than DC generator.
(3) AC motors are much simpler and cleaner than DC motors. (3) AC motors and motors are much cheaper and simpler than DC motors.
The first three-phase line in North America was put into operation in 1893-a 2300V and 12 km line in Southern California. The first three stages of the Northern Line of the United States were put into operation 1893- 1 2300 V, Southern California Route Research 12 km. In the early days of AC transmission, the frequency was not standardized. At the beginning of power transmission, the frequency was not standardized. Many different frequencies are used: 25, 50, 60, 125 and 133 Hz. There are many different frequencies: 25, 50, 60, 125 and 133 Hz. This brings problems to each other. Finally, 60 Hz was adopted as the standard in North America, although 50 Hz is also used in many other countries. This is the problem of interconnection. Finally, the 60 Hz standard was adopted and became the United States of North America, although many other countries also used 50 Hz.
The increasing demand for long-distance transmission of large amounts of electricity has prompted people to gradually use higher voltage levels. In order to avoid an infinite number of voltage increases, voltage levels have been standardized in industry. In the United States, the standards for high voltage (HV) grades are 1 15, 138, 16 1 and 230 kV, and the standards for extra high voltage (EHV) grades are 345, 500 and 765 kV. In China, the voltage levels for high voltage level are 10, 35, 1 10, and the voltage levels for ultra-high voltage level are 220, 330 (only in northwest China) and 500 kV. Longer distances require more and more power transmission to encourage them to gradually use high voltage levels. To avoid unlimited voltage multiplication, the industry standard voltage level. In the United States, the standards are 1 15, 138, 16 1, 230 kV high voltage (high voltage) and 345,500,765 kV extra high voltage (ultra high voltage). In China, the voltages used at all levels are10,35,1/kloc-0,220, China 330 (only in the northwest) and 500 kV EHV.
The first 750 kV transmission line will be built in the northwest of China in the near future. The first 750 kV transmission line will be built in northwest China in the near future.
With the development of AC /DC conversion equipment, high voltage DC (HVDC) transmission system has become more attractive and economical under special circumstances. With the development of communication /DC conversion equipment, HVDC transmission system is becoming more and more attractive and economical. HVDC transmission can be used to transmit large blocks of power over long distances and provide asynchronous links between systems that cannot achieve AC interconnection due to system stability considerations or due to different nominal frequencies of systems. HVDC transmission can be used for long-distance calls above transmission lines, but in AC networking system, it is impractical to provide asynchronous connections between different systems due to stability considerations or nominal frequency systems.
The basic requirement of power system is to provide uninterrupted energy supply to users at acceptable voltage and frequency. The basic requirement of power supply system is to provide uninterrupted energy supply at a voltage and frequency acceptable to customers. Because electricity cannot be stored in large quantities in a simple and economical way, the production and consumption of electricity must be carried out at the same time. The failure or misoperation of any link in the power system may lead to the interruption of power supply to users. Since electricity cannot be stored in large quantities in a simple and economical way, the production and consumption of electricity must be carried out at the same time. System failure or misoperation of power may cause interruption of power supply to customers at any stage. There, the normal and continuous operation of the power system to provide reliable power supply to users is extremely important. Therefore, it is very important for a normal power system to run continuously and provide reliable power supply to users.
The stability of power system can be broadly defined as the characteristics that the power system maintains an operating equilibrium state under normal operating conditions and an acceptable equilibrium state after being disturbed. The power system is stable, which can be broadly defined as a power system that interferes with property. Under the state of continuous operation, the balance condition between normal operation and backwardness can be restored to an acceptable balance state.
Instability in power system may be manifested in many different ways, depending on system configuration and operation mode. The instability of power system may be manifested in operation mode and many different modes, depending on the configuration of the system.
Traditionally, the problem of stability is to keep synchronous operation. Because the power system relies on synchronous motors to generate electricity, it is a necessary condition for the system to run well that all synchronous motors keep synchronous, or in layman's terms, "keep in step". The stability in this aspect is dynamically influenced by the relationship between the rotor angle and the power angle of the generator, and then it is called "rotor angle stability". Traditionally, the problem of stability has always been to keep synchronous operation. Due to the power generated by the power system, the necessary condition for a satisfactory system operation is that synchronous motors keep synchronous or popular "pace". On the one hand, it is to stabilize the power angle of generator rotor and the relationship between power angles, and then it is mentioned that "power angle stability".