1. The source of harmonic governance
The term pulse current began with the mathematical analysis of pulse current related to acoustic materials. It has established a good foundation in the 18th and 19th centuries. Fourier et al. clearly proposed the harmonic analysis method, which is still widely used in power supply systems. The problem of pulse current is as early as the 20th century. The era and the 1930s drew everyone’s attention. At that time, France’s use of stationary mercury arc converters caused the wave changes in voltage and current. In 1945, J.C.Read published related converter pulse currents. In the 1950s and 1960s, due to the development of high-voltage direct current transmission technology, related converters were released, which caused a lot of pulse current problems in the power supply system. Since the 1970s, due to the rapid development of power electronics technology, various power electronic devices The power supply system, industrial production, transportation and home use are becoming more and more common. The adverse effects of pulse currents are becoming more and more serious. All over the world have paid enough attention to the pulse current problem. Several academic conferences on pulse current problems have been held internationally. All major academic research institutes have formulated regulations and requirements for limiting the pulse current of the power supply system and power consumption equipment. Electrical equipment is overheated, causing vibration and noise, and making the insulating layer brittle. The service life is shortened, and even faults or damage occur. The pulse current causes part of the power supply system to resonate in series or in parallel. It will cause the relay protection device and protection device to malfunction, make the electromagnetic energy measurement and verification go wrong, and the external pulse current of the power supply system will cause serious interference to communication equipment and electronic products.
How to regulate the pulse current? Especially in the aspect of switching power supply and motor maintenance, with the improvement of industrial control automation, environmental protection and energy saving, energy saving and emission reduction policies, motors are rarely directly connected to the power grid and directly used. Generally, they are driven by soft starters. The inverter can flexibly control the output power and speed ratio of the motor, meet the requirements of the function, and has remarkable effects in environmental protection and energy saving. As everyone knows, the soft starter has caused the problem of harmonic current to the power grid. All power companies do not allow customers to introduce excessive harmonic current to the power grid. Customers are obliged to eliminate the harmonic current caused by the soft starter. With the soft starter The wide application and protection of motors, MTE includes series reactors, output reactors, dv/dt filters and other products, the unique design of dV Sentry provides better load side protection, allowing AC motors, cables and Soft starters are protected from operating voltage spikes and interference from common mode operating voltages.
The well-designed filter integrates about 50% reduction in common mode, valley voltage protection and rise time reduction.
2. Harmonic control maintains power-saving purpose and relevance
Don’t think that the existence of pulse current will only affect the power quality of the power grid. In fact, it is also related to the energy consumption and the level of water and electricity. In other words, if the harmonic current in the power grid system can be eliminated, it will help to maintain the goal of saving electricity.
With the improvement of national energy-saving and emission-reduction regulations, various power-saving measures will be adopted by big cities, and harmonic control will also become a very good breakthrough point.
Although the implementation of harmonic control is mostly just to improve the power quality, but to ensure the normal use of equipment, but with the gradual improvement of technology, it is not too bad to use it as one of the measures to maintain the power saving effect possible.
There are generally two ways to achieve the purpose of saving electricity, one is to reduce redundant power work, and the other is to improve the efficiency of power work.
Harmonic currents can cause a cascade of damage, one of which is the resulting wasted energy, or heat loss in the circuit. These heat losses are reflected in the active power of the single-phase electric meter. If the loss of harmonic current in the line can be reduced, the purpose of saving electricity can be achieved.
But what about the actual effect of the specific work? As far as the current harmonic control method is concerned, the main selection is the active filter and the notch power circuit type passive filter. This kind of filter is installed in series on the line, and the actual effect obtained is not very good.
In contrast, the effect of harmonic control at the pulse current source load will be more ideal. If a pulse current filter is installed at each pulse current source load, not only can a good power saving effect be obtained, but also It can ensure the quality of the company’s internal power network, which is a plan for this promotion.
Post time: Apr-13-2023