customs transaction analysis

List of contents of this article:

• 1,customs transaction analysis What is the frequency characteristic of the system? What are the commonly used geometric representation methods?
• 2, What is the frequency of the power system?
• 3, frequency characteristics of the system Sex
• 4, What is the standard frequency of the power system stipulated by the state and its allowable deviation?
• 5, How does the power system adjust the frequency?

What is the frequency characteristic of the system? What are the commonly used geometric representation methods?

1. The basic concept of frequency characteristics: Under the action of a sinusoidal signal, when the frequency of the system input changes from 0 to , the law of the amplitude and phase difference between the steady-state output and the input. The frequency of steady-state output is the same as that of input, only the amplitude and phase are different.

2. Generally, it is plural, and the amplitude and phase can be expressed as (6-4). Therefore, the output is (6-5). This formula shows that the amplitude change factor introduced by the system is , and the phase change is .

3. The logarithmic frequency characteristic is to express the frequency characteristic in the logarithmic coordinates.The logarithmic frequency characteristic curve, also known as the Bode diagram, includes two curves: logarithm amplitude and logarithm phase frequency. Take the logarithm on both sides of the pair, and this is the expression of the logarithmic frequency characteristic. Usually, the coefficient of 0.434 is not considered, but only the phase shift itself.

4. The frequency characteristics of the system. Frequency characteristics are also a form of expression of the mathematical model of the system. The definition of frequency characteristics can be applied to both stable and unstable systems. The frequency characteristics of the stable system can be determined by experimental methods.

5. In the principle of automatic control, like the transfer function and the differential equation, the frequency characteristic is a form of expression of the mathematical model of the system. It characterizes the law of motion of the system and becomes the theoretical basis for the frequency domain analysis of the system.

What is the frequency of the power system?

Hello: 1. [Frequency] is the number of changes per second of AC power. The frequency of AC power in China is 50Hz. 2. [Waveform] is the shape of the alternating current change curve, and the waveform of the mains current changes according to the law of sine wave.

The relationship between active power and voltage: When the active power emitted by the power grid is equal to the user's active load, the frequency remains unchanged;When it is less than the active load, the frequency decreases; when it is greater than the active load, the frequency rises. Therefore, changing the active power output of the generator can adjust the frequency of the power grid.

The frequency of China's power system is 50HZ (Hz), that is, the frequency changes 50 times per second, and the frequency changes once every 0.02 seconds. The power is divided into active power, the unit is W watt, kW kilowatt, MW megawatt; reactive power, the unit is var, kvar thousand, and Mvar megawatt.

The electricity used in China is a sinusoidal alternating current with a frequency of 50Hz, that is, 50 periodic changes have been made in one second. The frequency of alternating current is called power frequency in industrial terms. In 2013, there were two types of power frequencies in power systems around the world, one was 50Hz and the other was 60Hz.

frequency characteristics of the system

The known differential equation of the system can substitute the sinusoidal function to find the steady-state solution of the system output. The complex ratio of the steady-state solution of the output variable and the input sinusoidal function is the frequency characteristic of the system.

What characteristics of the system reflect the frequency characteristics of a system: the ratio of the steady-state response of the system or link to the sinusoidal input signal to the input function is called the frequency characteristic.

is the response characteristic of the control system to the sinusoidal input signals of different frequencies. The frequency characteristic of the control system is an important concept in the design of the control system, which can be used to analyze the stability and performance of the system.

is the frequency characteristic of the system. Frequency characteristics are also a form of expression of the mathematical model of the system. The definition of frequency characteristics can be applied to both stable and unstable systems.The frequency characteristics of the stable system can be determined by experimental methods.

What is the standard frequency of the power system stipulated by the state and its allowable deviation?

1. China stipulates that the standard frequency of the power system is 50Hz. The allowable deviation of power supply networks of different grades is also different, which is ± (0.2~1) Hz.

2. The allowable value of the normal frequency deviation of China's power system is ±0.2HZ. When the system capacity is relatively small, the frequency deviation value can be relaxed to ±0.5HZ.

3. The allowable deviation of the power supply frequency is: the installed capacity of the power grid is ±0.2 Hz if the installed capacity is 3 million kilowatts or more; the installed capacity of the power grid is less than 3 million kilowatts, it is ±0.5 Hz. Under the abnormal conditions of the power system, the allowable deviation of the power supply frequency should not exceed ±1.0 Hz.

How does the power system adjust the frequency?

1. Under normal circumstances, the total active power emitted by the generator in the power system and the total active power consumed by the load are balanced, and the system frequency can be maintained at the rated value. The change of system frequency directly reflects the balance of active power. The sending is greater than the use, and the frequency of the system increases. The use is greater than the one sent, and the system frequency is reduced.

2. This adjustment is completed by the effect of the power frequency regulation effect of the power system. In the power system, all generators, loads and transmission lines are interconnected, and the frequency adjustment is to maintain this balance.When the load in the power system suddenly becomes larger, the frequency will be reduced accordingly, and there will be an adjustment depending on the situation.

3. The control and adjustment of the frequency of the power grid mainly depends on scheduling the active output and line load of each power plant to achieve the purpose. If the output of the power plant is greater than the power grid load, the frequency will increase. On the contrary, if the active output of the power plant cannot meet the load of the power grid, the frequency will decrease.

4. In summary, the method of realizing secondary FM in the power system mainly includes two aspects: frequency response and frequency control. The frequency response method is mainly used to adjust the output of the generator and maintain the stability of the system frequency; the frequency control method is mainly used to adjust the frequency of the entire power system and control the frequency by adjusting the output of the generator.

5. There are mainly one-time adjustment, second-time adjustment and three-time adjustment of frequency.The primary adjustment of the frequency of the power system refers to the adjustment method of using the inherent load frequency characteristics of the system and the role of the speed regulator of the generator set to prevent the system frequency from deviating from the standard.