Impact of transient load on power consumption of power equipment and its elimination
With the development of society, capacitor reactive power compensation frequency conversion technology, 9 intermediate frequency furnace, large AC-DC conversion equipment, various seasonal energy lamps, etc. uv usually short-term peak transients only when voltage and current rise suddenly, f transient load is sinusoidal communication A transient distortion of current and voltage in a circuit, the main manifestations of which are surge peak harmonics, intermittent waves, and so on. At present, most of the power equipment manufacturers in China use ferromagnetic materials as the core part of motors, transformer ballasts and relays. The hysteresis load generates iron loss and copper loss in the hysteresis of ferromagnetic materials. These losses are in the equipment. The total energy consumption usually accounts for 15%~25% of P-active power; Q-a reactive power. New technologies and new equipment are constantly appearing. These devices send more and more instantaneous currents and harmonics through capacitive coupling and inductance induction and pollute the power grid. Professor Chen Shousun of Tsinghua University puts forward the concept of “distortion powerâ€. And propose a derivation calculation formula S2=P2+Pan+D2; Q is a reactive power caused by the interaction of voltage and current in different phases of the same frequency; D is “distortion powerâ€, a kind of transient current and harmonic generation Power. 1 Analysis of the influence of transient load on equipment energy consumption Since the hysteresis of ferromagnetic material hinders the working magnetic field from penetrating the core portion of the material, the alternating change of the instantaneous flow direction causes the ferromagnetic eddy current and copper loss to be generated by the electric equipment. In a general environment where the instantaneous flow rate changes, the power consumption of the electrical equipment can be increased by 5%. In an environment where the transient current changes are very active, the power consumption can be increased by 2 (% or more). The change is active in the case of constant power demand, the power consumption per transient accounted for the percentage of normal power loss left 0.083% / owed, in the actual power use, because most of the instantaneous flow contains IF frequency, Set the power loss to r: Wei LC2 because the power equipment impedance is designed based on the minimum resistance loss, R is usually small, and can be neglected in actual calculations, so its power loss approximation formula is: most instantaneous current flow current equipment current Suddenly interrupted. In a single-phase power system, when the voltage or current crosses zero, the transient current does not generally appear. However, in the three-phase power system, the instantaneous current appears almost in two phases, the main reason is that the voltage and current are separated by 120. The two phases cannot be zero at the same time. The typical transient surge voltage in a three-phase system is shown in Table 1: The typical instantaneous surge voltage values ​​in the three-phase system of Table 1 are different from the sine wave phase / (voltage label) The conversion of electric energy and field energy during the value 2 current transient is due to the sudden interruption of the magnetic energy Wm of an inductive device, which must be interchanged (oscillated) with the alternating electrostatic energy Wc present in the device. The energy performance is: the line voltage (maximum value). Due to the resonance phenomenon, the inductor energy and the electrostatic energy must be exchanged in equal amounts, so that the oscillation of the Wm inductor energy and the electrostatic charge is exchanged until it completely disappears in the line resistance R. The electrical energy loss inside the core of the electric equipment is the energy loss of the electric equipment with the iron core. The hysteresis curve shows that Rc is the copper loss caused by the resistance and the skin effect, and Rh is the inside. Magnetic loss caused by the molar effect. Rm is the eddy current loss caused by the current flowing through the core. This loss is used in the total energy loss WT, and Il is the average current, then EIl=Wl is the wattage lost per hour of transient load. Using this formula and the various values ​​mentioned above, the ferromagnetic loss parameters of the transient power to the electrical equipment are obtained according to the relevant measurements. The expression of energy loss in equation (7) is as follows: ab1-one transient magnetic induction The amount of intensity; - the amount of change in the main magnetic flux of a system; - the time of change of a main magnetic field; - the time of change of a transient load magnetic field; - the period of change of the magnetic field, which is 0.02 s in a 50 Hz power supply system; 3 Eliminate the input of the instantaneous flow device, meter reading, meter reading, time period, number of days, anaerobic meter, digital daily average word, 4 transient power, power loss, based on the above loss analysis, it can be clearly seen that the transient power is in the power equipment. It is a typical useless work. In addition to the increase in temperature of the equipment, it will cause distortion of the voltage waveform, affecting the normal operation of the equipment, and shortening the life of the equipment. In preparation, the higher the frequency of the instantaneous flow, the greater the loss of the electrical equipment caused by the transient flow. Through comparative research, we determined to reduce the power of the transient power of the electrical equipment to save energy, in fact, using hardware equipment to eliminate the system. Transient power. The current method is to eliminate the hardware of the instantaneous flow device in parallel with the power supply end of the electrical equipment, and put the instantaneous flow in the power grid into the ground through the grounding device of the hardware device to reduce the transient power in the equipment core and coil. Consumption in the middle, saving energy. Western advanced countries invested a large amount of money in the mid-1980s to suppress the development of power system transient power hardware devices, and developed a variety of electronic devices to suppress the transient flow of power systems. And formed a variety of series, and achieved significant power-saving effect. 5 Statistical analysis of the effect of saving energy In order to verify the power-saving situation of the electrical equipment installed to eliminate the instantaneous flow device, we chose to install in a certain workshop of a steel group company. Eliminate the instantaneous flow device for experimentation, and take measures to ensure that the output does not show large fluctuations during the experiment, and maintain the contrast environment. 2 Eliminate the instantaneous flow device before the meter reading, the meter reading time period, the number of days, the energy meter, the number of the daily average word number, and the experimental records are listed in Table 2, the statistical analysis is available, without the installation of the instantaneous flow device In the case of constant output, the average daily average number of words is 4.66. After the installation of the instantaneous flow elimination device, the total number of meter reading days is 127 days, the total electric energy meter reading number is 475.4; the average daily word reading number is 3.74, and the installation eliminates the instantaneous flow device. After the power saving rate is 19.74%, the power saving effect is very obvious. 6 Conclusion In view of the above analysis of transient power, the transient power has a great influence on the power consumption of power equipment. The effect of saving power after eliminating transient load measures is very obvious. Therefore, in the case of a serious shortage of power resources in China, the elimination is adopted. The social benefits of power saving for transient power are very obvious and should be promoted to the whole society under the guidance of the government. 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