Technical measures to reduce line loss in the hott

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Technical measures for power supply enterprises to reduce line loss Abstract: line loss is one of the important assessment indicators of power supply enterprises. It directly affects the economic benefits, management level and other power quality of enterprises. It has always been a hot issue for power supply enterprises. This paper puts forward some specific improvement methods and measures based on the analysis of line loss in view of the current situation of small and medium-sized power supply enterprises in China

key words: power factor voltage line loss power supply system after the transmission and transformation equipment is determined, the main factors affecting line loss are power factor and operation status. 1. Problems that should be paid attention to when paying attention to the power factor (1) check whether the power factor number of the current month is above 0.9 on the monthly reporting day. If it is insufficient, consider using high-voltage compensation. Large users should also be equipped with reactive energy meters with time-sharing billing for peak power factor assessment. Class 1.0 and class 2.0 reactive meters shall be selected as the charging active energy meters. If possible, class 0.5 full-function electronic energy meters with time-sharing charging (one active/reactive/time-sharing meter) shall be preferred. The current 1.5A pressure testing machine is also known as the electronic pressure testing machine, with a range of 4 ~ 6 times. (2) The reactive energy meter used to assess the power factor shall be of two-way billing wide range (4 ~ 6 times) level 2.0, so as to avoid the false high power factor phenomenon of reverse in case of power factor automatic controller failure and manual over compensation. (3) Users who use special transformers and special lines for billing shall verify the starting sensitivity of the metering device. If the starting power requirements cannot be met, S-type high dynamic thermal stability wide range 0.2-level S-type current transformer (such as lazbj type) shall be considered. The monthly power consumption of the electric energy meter shall be 0.5, 1.0 and 1.5A (4 ~ 6 times of wide range electric energy meter) according to the regulations to avoid the loss caused by the reduction of power consumption at night and the loss of power when the transformer is unloaded. The starting power sensitivity of the instrument is as follows: (when conditions permit, the ordinary 0.5 ~ 1.0 three-phase active electronic energy meter shall be preferred). Where i- starting current of electric energy meter (0.5% of calibration current) cos φ- The power factor is equal to the u-voltage of 1 k2-ta transformation ratio value. The loss of kV (4) distribution transformer is very important to the line loss, including the load loss of transformer and the no-load loss of transformer. For the distribution transformer of power system, its load loss is more important. Therefore, high-efficiency and energy-saving transformer with excellent performance should be actively used to replace the high loss transformer, Taking the replacement of a sj1000kva high loss transformer with a S9 1000KVA high-efficiency energy-saving transformer as an example, the high-efficiency energy-saving transformer can save 50% energy than the high loss transformer. (5) The controller used for power factor compensation shall be the power factor automatic compensation controller with automatic tracking compensation. The compensation controller with this function can well track the changes of electricity and load and the power factor, and work automatically. Once the specified target power factor is determined, it can work well and reliably for a long time. Some models even work continuously for several years without readjustment, such as blr-mc, The phenomena of under compensation and over compensation are effectively eliminated. The premise for the normal operation of the automatic power factor controller is that the signal current and polarity must be provided according to the phase sequence required by the product, and its working sensitivity should conform to the following formula (refer to the product operation manual, and the general index of the controller sensitivity is 50mA):io=ic × Io%, working sensitivity: i2=io × In 5/ta (MA), io- no-load current at the primary side of transformer io%- no-load current percentage of transformer i2- as a plastic material for food packaging, its properties include: protection performance, health and safety, non toxicity, biological invasion resistance, processing technology, printing adaptability, etc. no-load current at the secondary side of high voltage ic- rated current at the primary side of transformer to ensure reliable operation under no-load and low-voltage no-load current of transformer, The voltage circuit of the original power research institute can be connected to the low-voltage side in the wiring mode, and the signal circuit providing current can be connected to the corresponding TA secondary circuit at the high-voltage side of the transformer φ 1> φ 2. Therefore, the purpose of compensating transformer reactive power consumption can be achieved. (6) For large shopping malls and residential areas, domestic electricity should be paid attention to. With the large-scale use of elevators, fluorescent lamps, air conditioners, secondary water pumps, refrigerators and color TV sets in recent years, the power factor of such domestic power consumption has decreased compared with that in the past when it was used only for lighting. Therefore, capacitor compensation devices should be installed in time once found during the inspection. Table 1 increase of line voltage loss reduction effect voltage increase% 1234567810112 variable loss reduction% 1.97 3.88 5.74 7.54 9.31112.66 14.27 15.83 17.36 18.84 20.28 (7) for secondary voltage drop, users with excessive load shall conduct TV voltage drop test, and according to the test results, if it is greater than 0.25V, corresponding voltage compensator shall be installed, or the secondary conductor section shall be replaced to reduce TV secondary load, Check whether the contact part in the circuit is good and reliable to meet the pressure drop requirements. For TA, the following classification methods for fatigue test shall be given. The group with higher accuracy shall be selected for measurement and shall not share the same circuit with measurement and protection devices. The secondary wiring of TV shall control the load within the TV rated load according to the actual situation. When the conditions cannot be met, the device location and conductor shall be changed. If there are connecting terminals in the TA circuit, ensure that the wiring is firm and reliable, the contact resistance is small, and there is no oxidation, rust, looseness and other phenomena. Special attention shall be paid to the increase of secondary circuit impedance, which will affect the accuracy of measurement. 2. In terms of electrical operation conditions, the following points shall be paid attention to (1) keep operating under the rated voltage and frequency, strive to improve the voltage qualification rate, and effectively reduce the variable line loss. When the transmission power remains unchanged, for example, when the actual operating voltage of a 10kV line is only 9KV and the rated voltage is increased to 10kV

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