Determination of reactive power compensation capac

Determination of reactive power compensation capacity of 10kV line

Abstract: our county is the second batch of "two reforms and one same price" counties in China. In the technical loss reduction, the line mainly adopts measures such as shortening the power supply radius, increasing the conductor section, eliminating circuitous power supply, and taking capacitor decentralized compensation on the road. Here is an example to illustrate the determination of reactive power compensation capacity of 10kV spring line in our county

key words: active power reactive power our county is the second batch of "two changes and one same price" counties in the country. In the technical loss reduction, the line mainly adopts measures such as shortening the power supply radius, increasing the conductor section, eliminating circuitous power supply, and taking capacitor decentralized compensation on the road. Here is an example to illustrate the determination of reactive power compensation capacity of 10kV spring line in our county. (1) Basic information:

Quanshui line is one of the main trunk lines of Chengguan substation in our county, with a total length of 25km, a conductor model of lgj-120, a total of 108 distribution transformers and a capacity of 7085kva. In the first half of 2000, the line transmitted 480000kw · h of active power and 430000kvar · h of reactive power in January. According to the operation records of the substation, the maximum active power of the line is 2700kw, the minimum active power is 500kW, the active power in regular operation is 1200kW, and the bus power factor is 0.4. The compliance test is evaluated according to the expected service conditions of the product 78

(2) situation analysis:

since the reactive power loss of the distribution transformer of the line is a fixed loss, the loss factor is mainly the excitation current that is expected to maintain a slight increase in the future market, so the minimum reactive power loss can reach 280kvar (the excitation current of the distribution transformer is 4% - 5%)

according to the active and reactive electricity of the line, its power factor is determined to be between 0.78-0.81, which is basically consistent with the bus power factor. From this, we can determine that the maximum reactive power is 2100kvar, the reactive power under regular load is 960kvar, and the reactive power under minimum load is 400kvar. cos φ= [] 1/2 (3) determination of compensation mode:

due to the long line and large load, the combination of fixed compensation and automatic compensation is implemented, and decentralized compensation is carried out at three places on the road

(4) determination and comparison of compensation capacity:

according to the fixed loss of reactive power of the line is 280kvar, select 2 × 100kvar is compensated by two fixed compensation circuits

selection of automatic compensation capacity: it is determined as 300kvar by subtracting half of the fixed compensation from the reactive power under the condition of frequent operation load

effect comparison:

① at the maximum load, all reactive power compensation of the line is put into operation, and the power factor is increased to Cos φ= [] 1/2 =0.86 ② the power factor of the line under regular operating load is cos in the field of material innovation φ= [] 1/2 =0.93 ③ under the minimum load, the power factor of the line is cos φ= [] 1/2 =0.96 (leading) automatic compensation automatically disconnects and exits the operation line according to the power factor angle, and installs the four shockproof sizing blocks. Only the fixed compensation operates. At this time, the line power factor is cos φ= [] 1/2 =0.92 if the automatic compensation capacity is temporarily selected as 200kvar, reactive power compensation oscillation will occur, resulting in frequent switching. In this way, the power factor of the power supply of the line should be controlled between 0.86-0.93 to meet the requirements of rural electricity. Therefore, 2 is selected for the capacitor compensation device × 100kvar fixed compensation and 300kvar automatic compensation. (5) Determination of compensation location: the first assembly is set at 2/7 of the line for fixed compensation; The second group is automatic compensation, which is installed at 4/7 of the line, and it is also a section with relatively concentrated load; The third group is fixed compensation, which is installed at 6/7 of the line