In power systems or in user main transformers higher than 110 kV , most of them will be equipped with on-load voltage regulating devices (transformer on-load voltage regulating switches ), because this can ensure that when the power is supplied normally, it will help to By adjusting the tap position, the voltage of the busbar can be guaranteed to ensure that it can meet the voltage quality requirements.
Normally, there are two adjustment methods for the on-load voltage regulating device, that is, you can set it to automatic adjustment or manual adjustment. Today I will share with you some knowledge about on-load voltage regulation of transformers, such as what are the basic principles of online voltage regulation of transformers, why no arc light is generated when adjusting taps, etc.
Basic principles and methods of voltage regulation
The basic principle of voltage regulation is to change the voltage ratio of the transformer by adding or subtracting turns on the primary or secondary winding of the transformer. Voltage regulation method: When both the primary and secondary sides of the non-excitation voltage regulating transformer are disconnected from the power supply , the voltage is regulated by changing the high-voltage side tap to change the number of winding turns. On-load voltage regulation uses an on-load tap -changer to change the high-voltage winding tap to change the number of high-voltage turns without cutting off the load current .
The basic functions of on-load tap-changers and the two basic functions of large-type on-load tap-changers are: first, to “select” a tap in the event of an open circuit; second, to “switch” the power without interrupting the passing current. ” or “swap” to the selected tap. The switching of the large type load current divided by the on-load tap-changer from the connecting tap to the pre-selected tap can be completed by resistive transition or reactor transition (USA), which is divided into resistive on-load tap-changer and reactance-type On-load tap changer. On-load tap-changers can also be divided into vacuum on-load tap-changers and oil-immersed on-load tap-changers.
Basic structural diagram of oil-immersed on-load tap-changer. Arc will be generated when switching power. The decomposition of insulating oil caused by arc will pollute the oil of the transformer, so the following structures are formed: 1. Buried type 2. Separated type
The basic structure of a fast resistive on-load tap-changer is a selector switch structure in which the tap selector and diverter switch functions are combined in one device, that is, a V-shaped on-load tap-changer, a combined on-load tap selector and diverter switch that are separated. Tap changer for M type and other types of on-load tap changers
Basic wiring method of on-load voltage regulation A Linear voltage regulation B Positive and negative voltage regulation C Coarse-fine voltage regulation
Types of oil-immersed on-load tap-changers · V-type on-load tap-changer · MS-type on-load tap-changer · M-type on-load tap-changer · RM-type on-load tap-changer · R-type on-load tap-changer ·G type on-load tap-changer
Application conditions of V-type oil-immersed on-load tap-changer V-type is the most compact on-load tap-changer suitable for small and medium-sized transformers
At present, the maximum rated through current of MR Company is 700A for single-phase and 500A for three-phase (at this time, its working positions become up to 12 and up to 23).
Application conditions of MS type oil-immersed on-load tap-changer MS type is suitable for on-load tap-changers of medium-capacity transformers, with a maximum through current of 300 A
Application conditions of M-type oil-immersed on-load tap-changer M-type on-load tap-changer has the widest application range and can be used in medium-capacity transformers, large power transformers, industrial transformers and special transformers.
The basic principle of the transformer on-load tap-changer is that the on-load tap-changer will switch the tap voltage regulating device when the load current is not cut off. This requires that both taps be connected at the same time at the moment of switching. When a voltage level between the two taps is short-circuited, a very large circulating current will ensue.