What are the adjustment methods of the generator excitation regulator?

The generator parameters include the excitation method. So, in the actual use process, what are the adjustment methods of the generator excitation regulator?

〖1〗Constant terminal voltage (automatic) operation mode

This is a closed - loop automatic adjustment mode of the generator excitation system. In this operation mode, the main task of the digital excitation regulator is to keep the generator terminal voltage constant. Generally, the terminal voltage is used as the feedback variable to realize PID adjustment. Meanwhile, in order to improve the stability conditions of the power system operation, the digital excitation regulator can also implement more complex control laws, such as power system stabilizer (PSS) - what you must know about the PSS of the excitation system? Additional control, linear optimal excitation control (LOEC), non - linear excitation control (NEC), etc.

〖2〗 Constant excitation current (manual) operation mode

Generally speaking, the excitation regulator has two operation modes: "automatic" and "manual", and the digital excitation regulator is no exception. In the constant excitation current (manual) operation mode, the digital excitation regulator samples the input signal, compares it with the given value, and then sends the control signal to the phase - shifting trigger unit after the operation of the proportional (integral) control law. Since the voltage setting range of the automatic operation mode is limited, during the generator voltage - boosting test after the unit installation, maintenance or accident tripping, the manual mode is usually used to adjust the generator excitation so as to regulate the terminal voltage or the reactive power of the generator. In this way, the adjustment is relatively stable and the adjustment range can be very wide.

1） Three-unit system operation mode

Compared with the operation mode where two regulators are used as backups for each other, the main purpose of adopting the three - unit system is to further improve the reliability and safety of the digital excitation regulator device operation by increasing the hardware investment. The three - unit operation mode can be divided into the three - unit standby operation mode and the two - out - of - three voting operation mode.

2）Three-unit standby operation mode

The working principle of this mode is that in addition to the automatic switching between Unit A and Unit B as backups for each other, a backup Unit C is also designed. When both Unit A and Unit B fail, Unit C can automatically switch to online operation. Unit C can be designed to have the same functions as Unit A and Unit B. However, in general, the probability of simultaneous failure of Unit A and Unit B is relatively small. To simplify the scheme, Unit C can be designed to have relatively simple excitation control functions, for example, only ensuring that the generator continues to operate in the constant excitation current (manual) operation mode.

3）Two-out-of-three voting operation mode

In this operation mode, all three units work online. The three sets of regulators receive the same external input signals, and their software and hardware structures are completely the same. When the output results of two of the three sets of regulators are consistent, this output result is sent as the output of the digital excitation regulator to the controlled object part of the excitation system. When two of the three units fail, the digital excitation regulator cannot work. Therefore, the two - out - of - three voting operation mode does not improve the reliability compared with the operation mode where two units are used as backups for each other. The advantage of the two - out - of - three voting mode lies in the improvement of the device operation safety, that is, it can better avoid the output of wrong excitation control signals, thus avoiding phenomena such as mis - excitation and out - of - control of the generator.

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