What are the compensation devices commonly used for voltage sag control

Foreword: The power supplied to us by the power grid system is often dynamically balanced. Usually, as long as the voltage is limited within a specified range, we can obtain a better environment for using electricity. But the power supply system does not provide a perfect power supply. In addition, there is no way for equipment manufacturers to provide equipment that is immune to voltage dips for all electrical equipment. The voltage sag problem will cause a lot of inconvenience and trouble to daily life and production. So what good compensation devices are there to reduce the impact of voltage sags? Usually, we use three types of compensation devices: UPS (Uninterruptible Power Supply), Solid State Transfer Switch (SSTS), and Dynamic Voltage Restorer (DVR—Dynamic Voltage Restorer). By placing these compensation devices between the power supply system and the user’s electricity network. These three compensation devices have their own advantages and disadvantages.



Uninterruptible Power Supply (UPS—Uninterruptible Power Supply): UPS for short, is the most commonly used device for reducing voltage sag compensation. The working principle of UPS is usually to use chemical energy such as batteries to store electrical energy. When encountering the problem of sudden power failure of the power supply system, the UPS can use the power stored in advance to maintain the power supply for several minutes to several hours. In this way, the voltage sag problem caused by the power supply system can be solved within a certain period of time. But UPS also has its more prominent weaknesses. Electricity is stored through chemical energy, and this design itself consumes a lot of energy. Energy storage batteries not only take up a lot of space, but are also quite difficult to maintain. At the same time, for those loads that have a greater impact on the grid, it is necessary to increase its own power. Otherwise, it is easy to cause the energy storage battery to fail.

Solid State Transfer Switch (SSTS—Solid State Transfer Switch), referred to as SSTS. In the process of industrial manufacturing factories or actual electricity consumption by users. There are usually two different busbars or power supply lines from different substations for power supply. At this time, once one of the power supply lines has an interruption or a voltage sag, it can be quickly (5-12ms) switched to another power supply by using SSTS, thus ensuring the continuity of the entire power supply line. The emergence of SSTS is aimed at the UPS solution. Not only is the overall cost of equipment investment low, but it is also an ideal solution to the voltage drop of high-power loads. Compared with UPS, SSTS also has many advantages such as low price, small footprint, and maintenance-free. The only disadvantage is that a second busbar or industrial lines from different substations are required for power supply, that is, a backup power supply is required.

Dynamic Voltage Restorer (DVR—Dynamic Voltage Restorer), referred to as DVR. Generally, it will be installed between the power supply and the load equipment. The DVR can compensate the load side for an appropriate drop voltage within milliseconds, restore the load side to normal voltage, and eliminate the impact of voltage sag. The most important function of DVR is to provide fast enough response time, and it can also increase the depth of voltage sag protection. The protection depth can be interpreted as the range of voltage sag that DVR can accommodate. Especially for factory users, generally speaking, once there is a voltage sag fluctuation during the normal operation of the machine and equipment, it will easily lead to a problem in the production success rate, that is, there will be defective products. By using DVR, the normal operation requirements of the factory can be guaranteed, and the disturbance caused by low voltage fluctuations can hardly be felt. But the DVR has no way to compensate the voltage disturbance exceeding the voltage sag protection depth. Therefore, when the voltage drop is within the range of the voltage sag protection depth, the DVR can only play its due role when it is guaranteed to be uninterrupted.

The DVR produced by Hongyan Electric has quite reliable practicability: high reliability, specially designed for industrial loads, high system efficiency, fast response, superior rectifier performance, no harmonic injection, full digital control technology based on DSP, reliable High performance, advanced parallel expansion function, modular design, multi-function panel with graphic TFT true color display, completely maintenance-free, low operating cost, no need for cooling equipment, compact structure design, small footprint and many other advantages.

Post time: Apr-13-2023