How to deal with voltage dips

With the development of economy and the wide application of high-tech equipment, users are demanding more and more high quality of electric energy (voltage). Previous power quality problems that people are concerned about are frequency deviation, voltage qualification rate, harmonics, voltage imbalance, and flicker. In recent years, people have paid more and more attention to the problem of instantaneous voltage drop caused by a power grid fault, ie, voltage dips (./01234567 or ./01234823). According to relevant information, most of the causes of abnormal operation or outage of the user's electrical equipment are voltage sags.

The main quantitative indicator reflecting the frequency of voltage dips is SARFX (χ). For a supply point selected in a system, SARFX (χ) is the number of voltage dips below χ% for the RMS value of the voltage that occurred in a batch over a year. The U.S., Europe, and South Africa are undergoing a quantitative assessment of power system voltage sag.

1. Relevant regulations for voltage sags
First of all, it is necessary to understand the characteristics of the electrical equipment that are sensitive to changes in the RMS voltage, that is, what level of voltage dips causes the electrical equipment to operate abnormally. At present, China has no uniform regulations on the ability of electrical equipment to withstand or sudden voltage drop. This is due to the fact that different types of electrical equipment have no uniform regulations on the ability of the voltage to droop. This is because the sensitivity of different types of electrical equipment to voltage dips is not the same. It takes a lot of tests to understand and grasp the actual situation. Some international guilds have established corresponding technical standards and stipulated the ability of electricity equipment to use a sudden drop in voltage, including the CBEMA curve proposed by the Computer Manufacturers Association of the United States. It describes the voltage dips that computers can tolerate to a certain extent and duration. Capability, the International Semiconductor Manufacturers Organization also developed the SEMI F47 standard.

2. The measures to solve the problem of voltage dips mainly include:
(1) Optimize the design and operation structure of the output distribution system to reduce the impact of faults on the supply voltage of the grid user point.
(2) Adopt static (power electronics) fast load switch.
(3) Apply power adjustment devices to provide customized power for users.
(4) Optimize the design of electrical equipment and layout to improve the ability of equipment to have a sudden drop in transient voltage.
(5) Constant voltage transformers, static load switches, voltage dips dynamic regulators, energy storage generators, etc.

The voltage dips optimization solution also needs to consider the factors of my aspects, including the performance of the system, the characteristics of power quality changes (voltage sag amplitude, time, etc.), the sensitivity of the electrical equipment, the size of the electrical equipment, and the objective Environmental and maintenance requirements, etc.