[Visitor (112.0.*.*)]answers [Chinese ] | Time :2023-05-10 | It can be divided into two methods: improving the natural power factor and using artificial taste: Ways to improve the natural factor: 1). Properly select the motor capacity, reduce the reactive power consumption of the motor, and prevent the "big horse-drawn trolley". 2). For light-load motors with an average load less than about 40% of their rated capacity, the coil can be changed to a delta connection (or automatic conversion). 3). Avoid running the motor or equipment without load. 4). Reasonably configure the transformer and properly select its capacity. 5). Adjust the production shift, balance the electricity load, and improve the electricity load ratio. 6). Improve the layout of distribution lines to avoid twists and turns, etc. Labor compensation method: In practice, circuit capacitors or condensers can be used, and power capacitors are generally used to compensate for reactive power, that is, capacitors are connected in parallel on inductive loads. The following is the theoretical explanation: The method of parallel connecting capacitors on inductive loads can use the reactive power of the capacitors to compensate for the reactive power of inductive loads, thereby reducing or even eliminating the original energy exchange between inductive loads and power supplies. In the AC circuit, the pure resistance circuit, the current in the load is in phase with the voltage, the current in the pure inductor load lags behind the voltage 90, and the current in the pure capacitor is ahead of the voltage 90, and the current in the capacitor and the current in the inductor are 180 different and can cancel each other. Most of the load in the power system is inductive, so the total current will lag the voltage by one angle, as shown in Figure 1, if the parallel capacitor is connected to the load, the current of the capacitor will cancel out a part of the inductor current, so that the total current is reduced and the power factor will increase. The compensation methods of shunt capacitors can be divided into: 1. Individual Compensation. That is, a capacitor bank is installed near the electrical equipment according to the demand for its own reactive power, and it is put into operation and disconnected at the same time as the electrical equipment, that is, the capacitor is directly connected to the electrical equipment in practice. It is suitable for low-voltage networks, and the advantage is that the compensation effect is good, and the disadvantage is that the capacitor utilization rate is low. 2. Group compensation. That is, the capacitor bank is installed in groups on each branch outlet line of the workshop distribution room or substation, which can be put in or cut off at the same time as the change of the partial load of the factory, that is, the capacitor is actually installed on the busbar of the distribution board of each workshop. The advantage is that the capacitor utilization rate is higher and the compensation effect is also ideal (more compromise). 3. Centralized compensation. That is, the capacitor bank is centrally installed on the bus bar on the primary or secondary side of the substation. In practice, the capacitor is connected to the high-voltage or low-voltage bus of the substation, and the capacity of the capacitor bank is selected according to the total reactive load of the power distribution station. Advantages: It is a high utilization rate of capacitors, which can reduce the reactive load of the power grid and user transformers and power supply lines. Disadvantages: It cannot reduce the reactive load of the user's internal power distribution network. The significance of improving the power factor 1. For the power supply part of the power system, the generator that provides electric energy is designed according to the required rated voltage and rated current, and the voltage and current cannot exceed the rated value in the long-term operation of the generator, otherwise it will shorten its service life and even damage the generator. Since the generator is fixed by the product of rated current and rated voltage, this means that when its load is resisted, the generator is theoretically fully utilized, because P=U*I*cos in COS = 1; but when the load is dry or capacitive, COS <1, the generator is not fully utilized. In order to maximize the capacity of the generator, its power factor must be increased. 2. For the transmission part of the power system, the loss on the transmission line: Pl=RI*I, the average power absorbed by the load: P.=V*I*cos, because I=P./V/cos, so Pl=R*P./V/cos (V is the rms value of the voltage at the load end). As can be seen from the above equation, increasing the power factor cos will reduce the power loss on the transmission line when both V and P are unchanged! In practice, increasing the power factor means: 1) Improve the quality of electricity and improve the operating conditions of the equipment to ensure that the equipment works under normal conditions, which is conducive to safe production. 2) It can save electric energy, reduce production costs, and reduce the electricity expenses of enterprises. For example, the loss at COS = 0.5 is 4 times higher than when COS = 1. 3) It can improve the utilization rate of the enterprise's electrical equipment and give full play to the potential of the enterprise's equipment. 4) It can reduce the power loss of the line and improve the transmission efficiency of the power grid. 5) Due to the limitation of the generator's power generation capacity, increasing the COS also makes the generator have more active power. In the actual power consumption process, improving the power factor of the load is the most effective way to improve the utilization rate of power resources. At a time when available resources are close to scarcity, better use of existing resources is the only way to solve our urgent needs, in addition to developing new energy sources as soon as possible. For the current use of electric energy, which is widely used and incomparably dependent on human beings, power factor will be the top priority. |
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