Analysis of Measures of Transformer Energy-Saving Operation

I . Optimization of Energy-Saving and Economic Distribution Transformer
Energy-saving and economic products with low control loss rate should be selected based on feasible technology when choosing and designing type and volume of distribution transformer. Take energy-saving and economic distribution transformer S11 & S13 for examples, which are well applied in projects. Comparing with S9 series transformer, control loss and control current of S11 & S13 can reduce about 30% and 40% respectively while they have strong overload capability and obvious synthesis energy-saving effect. The S13 series distribution transformer with little line loss is more suitable for operating distribution system with large load fluctuation range and is applicable for modern distribution system projects with large load fluctuation.

II. Adopt Energy-Saving scheduling Mode of Combined Operation of Multiple Distribution Transformers
With continuous expansion of distribution network system in scale and capacity, system load capacity is changing frequently and loss under different operation modes varies largely. Optimal operating condition spots and scheduling mode should also change in order to save energy and reduce loss.

When distribution transformer is in operation, no-load loss and load loss generated by itself jointly form active loss and nonlinear variation will occur with the change of load loss. No-load loss is a specific coefficient, which will not change with change of load rate of transformer, while load loss is a variant that changes with load and is in direct proportion to square of transformer load current. During combined operation of multi-transformers, there is always a lowest point of load coefficient, also the lowest point of comprehensive power economic load coefficient during combined operation of distribution transformer. Best load operating point and economic load area should be calculated reasonably according to actual condition of distribution system and multiple distribution transformers should be combined and operated economically; based on load characteristics of enlargement during operation, number of transformers in combined operation in different load area should be calculated; best economic operation area of multiple distribution transformers should be confirmed according to comprehensive power load relationship in order to avoid non-economic operating condition and effectively provide safe, reliable and energy-saving power generated by distribution transformer.

III. Adjust Inter-phase Unbalanced Load Rate of Distribution Transformer to Realize Energy-Saving and Economic Operation 
Because single-phase electric load takes a large proportion of total electric load in the distribution transformer and its supply and distribution system, and with wide application of various energy-saving electric devices and energy-saving luminaries, degree of  three-phase load unbalance of distribution transformers, especially public distribution transformer being very large, causing big loss correspondingly. Therefore, large load loss caused by three-phase imbalance becomes a key point of research in energy-saving and economic operation of transformer. Reasonable optimization and adjustment of inter-phase load and reducing unbalanced degree among three phases make load relationship of three-phase distribution transformer close to balance, gaining good inter-phase balance relationship and reducing active loss and reactive loss during operation of distribution transformer and improving conversion efficiency of power distribution scheduling.

IV. Conduct Proper Reactive Power Compensation
According to operation condition of distribution transformer and load curve between condition and load, reactive load of distribution transformer is mainly focused on light-load or no-load operating condition, during which reactive power excitation is generated. Its consumption of reactive capacity is about 10%-15% of rated capacity of distribution transformer. Therefore, measures of collective reactive power compensation can be taken. Reasonably select reactive power devices such as SVC, SVG and TSC, and connect reactive power compensation capacitor to busbar side of the distribution transformer through load switch. When the system operates in light load or no-load condition, the tap of capacitor is reasonably changed to conduct real-time reactive power compensation, and improve 10kV of distribution system power factor, thus effectively reducing operation loss of distribution transformer and improving low voltage at terminal and energy-saving and economic effect of voltage quality.