(1) Select the transformer capacity based on the economic load rate. In addition to active power losses, transformers also have certain reactive power losses during operation. To generate and transmit this reactive power, active power losses occur in generators, lines, synchronous condensers, capacitors, and other equipment. Therefore, when considering the economic operation of transformers and determining the economic load rate, the additional active power loss caused by the no-load reactive power loss of the transformer should also be considered. Additionally, when determining the economic load rate, the fact that the transformer load is often changing should also be taken into account.
(2) Specify different standard loss values for transformers with different load rates. The efficiency of a transformer varies under different load conditions. To achieve economic operation, in addition to minimizing the product of the transformer's no-load loss and load loss, the ratio of no-load loss to load loss should also be appropriately selected to try to meet the economic load rate that maximizes transformer efficiency. For generator transformers, since the load rate is relatively high, to achieve economic operation, manufacturers should be required to reduce the load loss rate as much as possible. For substation transformers and distribution transformers, the load may not be very large, and in some cases even very small. The no-load loss value should be appropriately reduced to increase their load rate.
To this end, users should actually select the installed transformer capacity based on the load rate determined by economic analysis. Sometimes even "a big horse pulling a small cart" (i.e., capacity utilization rate below 50%) is economical. It is essential to conduct a careful investigation and prediction of load variations, and avoid possible overload operation of transformers, because overload operation can easily cause transformer aging or even damage.
(3) Change from cold standby to hot standby. To avoid losses to the power grid caused by transformer failures, many users install standby transformers that are not used normally, which is called cold standby. To improve efficiency, cold standby should be changed to hot standby, meaning the transformer is also put into operation during normal times, but with a low load rate. When one transformer fails and is taken out of operation, the others can still operate normally without overloading. By changing from cold standby to hot standby, the load rate of the transformer during normal times approaches the economic load rate, thereby improving operational efficiency.
In addition, using two different transformers to separate industrial power supply from lighting power supply is also a good method for energy conservation.
(4) Adopt parallel operation mode. According to actual conditions, for locations with significant annual load variations, such as irrigation and drainage stations, salt farms, and other areas, the seasonal load difference is very large. To reduce no-load loss, in addition to using variable-capacity transformers, multiple (groups of) smaller-capacity transformers can be operated in parallel. During peak hours, all transformers are put into operation, and during off-peak hours, only one (group) is put into operation. Alternatively, a "mother-child" transformer can be used, where a larger transformer is used during peak hours, and during off-peak hours, the large transformer is automatically disconnected and a small transformer is put into operation.
