Analysis of ITECH IT7600 Programmable AC Power Harmonic Simulation Function

IT7600 Harmonic Simulation

introduction:

With the development of power Electronic technology, various power electronic devices and switching power supply products have been widely used. With the rapid development of technology, it also causes serious pollution to the electricity environment. A large number of harmonics are generated in the mains network. These harmonics have more and more serious effects on the power system, industry, transportation and household electrical products. harm. Countries around the world have paid full attention to the harmonic problem, and many countries and international organizations have formulated standards and regulations to limit harmonics in power systems and electrical equipment.

First, the definition of harmonics:

Harmonic wave, in a strict sense, harmonic wave refers to the electric quantity whose frequency is an integer multiple of the fundamental wave contained in the current, generally refers to the Fourier series decomposition of periodic non-sinusoidal electric quantity. , and the rest of the electricity generated by the current greater than the fundamental frequency. As shown in the figure below, a periodic distortion waveform can be formed by the superposition of the fundamental wave and multiple harmonics.

According to the different harmonic frequencies, it can be divided into:

Odd: Harmonics whose rated frequency is an odd multiple of the fundamental frequency are called “odd harmonics”, such as the 3rd, 5th, and 7th harmonics

Even order: The harmonics whose rated frequency is an even multiple of the fundamental frequency are called “even order harmonics”, such as the 2nd, 4th, 6th, and 8th harmonics.

Second, the causes and hazards of harmonics:

The main reasons for the generation of harmonics are: because the sinusoidal voltage is applied to the nonlinear load, the fundamental current is distorted to generate harmonics. The main nonlinear loads are UPS, switching power supply, rectifier, frequency converter, inverter, etc.

Harm of harmonics: reduce the capacity of the line, for example, the maximum capacity of the line is 20kW, but due to the interference of harmonics, the line may be saturated when using 17kW; accelerate the aging of the equipment, shorten the service life of the equipment, or even damage the equipment; waste electric energy, and harmonics also consume energy, but they are all useless work; harmonics reduce the efficiency of electric energy production, transmission and utilization, make electrical equipment overheat, generate vibration and noise, and cause insulation aging, shortened service life, and even failure or burnout; for power electronics In terms of equipment, power electronic equipment is sensitive to harmonic distortion of the supply voltage, and such equipment often has to rely on the zero-crossing of the voltage waveform or other voltage waveforms to achieve synchronous operation. Voltage harmonic distortion can cause voltage zero-crossing drift to change the voltage position. The wrong judgment of the control system on these two points can lead to the loss of control of the control system. The inductive or capacitive coupling between power and communication lines may also cause interference to communication equipment.

3. Harmonic simulation:

For power electronic equipment, in the design stage, R&D personnel are required to take into account the impact of various harmonics in the power grid on electrical equipment. In the field of EMI/EMC AC power filter testing, at least the 50th power grid harmonics need to be simulated.

EMI/EMC Filters

IT7600 series high-performance programmable AC power supply has powerful voltage harmonic simulation capability, up to the 50th harmonic. Within the frequency range of 10-500Hz, the 50th harmonic can be simulated; above the frequency of 500Hz, the 20th harmonic can be simulated.

AC 220V 50Hz Superimposed 3rd harmonic and 5th harmonic simulation.

1. Select THDWave on the main interface of IT7600, it will appear at the bottom of the pageTHD Config tab, press[THD Config] Enter”THD Wave Configure” interface, as shown in the figure below.

2. Set the 3rd harmonic, harmonic distortion rate 0.01 and harmonic phase 60°; 5th harmonic, harmonic distortion rate 0.1 and harmonic phase 180°, press[Enter] After the key is confirmed, press the composite key on the front Panel[Shift] + [Recall](Save) key to save the set waveform. As shown below.

Set the AC 220V 50HZ power supply on and the output waveform is as shown below.

IT7600 series power supplies not only have powerful harmonic simulation capabilities, but also built-in a full range of power meter and large-screen oscilloscope functions, power up to 54KVA, support master-slave parallel connection, built-in arbitrary waveform generator, can simulate harmonics and various Arbitrary waveform output and powerful AC measurement and analysis functions can be widely used in the development and application of new energy, home appliances, power electronics, avionics, military and IEC standard testing.