Automatic Voltage Regulator

This article is closely related to the article on the excitation system because the working principle of the AVR is to regulate the flow of reinforcement on the exciter.

Units operating system AVR (Automatic Voltage Regulator) function to keep the generator voltage remains constant in other words, the generator will remain stable release tension that always is not affected at the expense of change was always changing, because the load affects the voltage output of the generator.

AVR is the working principle of strengthening the current set on the exciter. If the generator output voltage below the nominal voltage of the generator voltage, the AVR will improve the flow of reinforcement on the exciter. And vice versa if the generator output voltage exceeds the nominal voltage generator AVR will reduce the flow of reinforcement on the exciter. Thus, if the generator output voltage changes can be stabilized by the AVR will automatically due equipped with equipment such as tools used for the minimum or maximum limitation of the amplifier that works automatically.






AVR is operated with a power supply of the permanent magnet generator (PMG) is an example AVR voltage 110V, 20A, 400Hz. And got the sensor from potential transformer (PT) and current transformers (CT).





The sections on AVR unit

a. Sensing circuit
Three-phase generator voltage sensing circuit is given in the PT and 90R past the first, three-phase current and voltage output is derived from the 90R and then rectified by diode circuit, and flattened by a series of capacitors and resistors and voltage can be adjusted by VR (variable resistance). The advantage of the sensing circuit is to have a fast response to the generator output voltage.

Output voltage response is proportional to the generator output voltage is directly proportional as shown in the picture.





b. Comparative amplifier
Comparative amplifier circuit is used as a comparison between the sensing circuit with the set voltage. Sensing voltage with a large set of voltage does not have the same value, thus the difference / voltage range is large. Voltage difference is called the error voltage. This will be eliminated by setting a VR (variable resistance) on the set of voltage and voltage sensing.

c. Amplifier circuit
Current flow from the D11, D12, and R34 is the main amplifier circuit or the strengthening of the lowest levels. Comparative output from the amplifier and the output from over-excitation limiter (OEL) is a negative voltage and the negative voltage then the input OP201. When over-excitation limiter (OEL) or the minimum excitation limiter (MEL) is not operating, the output of the amplifier was confirmed by comparative OP201 and OP301 OP301 summed with the input of the output from dumping circuit. Amplifier OP401 is to balance the relationship between the voltage meter entrance and the output voltage of OP201 and OP401 are shown in the chart below.





d. Automatic and manual change over the mixer circuit
The circuit is arranged in Auto-manual shifting relationships and a circuit for controlling voltage generators penguatanmedan. Auto-manual change over and mixer circuit voltage settings on manual operation performed by the strengthening of the generator field 70E, and at the automatic and manual change over manually operate the mixer circuit AVR (automatic voltage Rregulator) can not operate. And if this series on the AVR auto condition should be working to arrange a large generator field current.

e. Limited circuit
Limited circuit is to determine more restrictions and less reinforcement (excitation) for setting the output voltage on the system excitacy, VR125 to bookmark more than the output terminal C6 and VR126 for a minimum of limiting the output terminal C6.

f. Syncronizing phase circuit
Thyristors are used to control the unit output voltage thyristors by using control signals provided at the gates of thyristors by altering the angle signal at the gate of thyristors. Phase synchronization circuit is used to change the angle of the gate thyristors in accordance with the voltage output from the boundary of synchronization and control signals are also provided on the thyristors below the image synchronization.

g. Thyristor firing circuit
This series of complementary thyristors to provide control signals to the gates of thyristors.

h. Dumping circuit
Dumping the sensor circuit will provide the reinforcement of the AC voltage applied to the exciter and amplifier to be used as feed back circuit with an input terminal OP301.

i. Thyristors Unit
An array of thyristors and diodes. And also use a fuse (fuse) is used as a safety melting and is also equipped with indicators to monitor the working of thyristors are mounted on the front of thyristors for each phase are given two parallel arranged fuse and when mistakes or broken one is still able to operate.

j. MEL (minimum excitacy limiter)
MEL (minimum excitation limiter) is to prevent excessive output on the generator and the addition of reinforcement (excitacy) to increase the generator terminal voltage at a constant level. This circuit is used to detect the operation of the generator that is by detecting the output voltage and current in the generator. Inijuga circuit used for comparing the output voltage of the generator with minimum excitation that has been setup. This circuit will give a signal in the circuit limit the AVR when the excitation exceeds the minimum, and then from the MEL output (Minimum Excitation Limiter) upheld by the amplifier.





k. Automatic follower
The working principle of this tool is to complement the strengthening of the settings manually by 70E. To adjust the operation of generators in the benchmarking of the terminal voltage fluctuations by the error signal. This enabled them to maintain the stability of the voltage on the generator. This operation is used for manual setting (70E) to accuracy levels which have been adjusted excitacy. Operating conditions and comparing the fluctuations of the generator terminal voltage by an error voltage signal. It is used as the handle to maintain stability of the voltage on the generator with the change of load.
Automatic Follower is used to detect the signal output from the voltage regulator error and automatic operation with manual adjuster makes a zero value. The circuit is to increase the signal and reduce signal controlled by 70E. By rotating 70E for controlling the signal on this circuit.