Abstract : In response to the problem of poor power quality of the power grid, relevant improvement methods are proposed to ensure that equipment such as low-voltage control circuits, frequency converters, and PLCs can work normally during power grid flicker. Keywords : power grid flicker, frequency converter, PLC 0 Introduction In continuous production, many equipment cannot be shut down in the process. Once the power grid fails, it will cause huge losses. Therefore, continuous production has high requirements for power grid quality. We have found that the impact of power grid voltage problems is significant in actual production, especially short-term voltage problems (generally referred to as power grid flicker in factories), including the following types: (1) Voltage surge and drop, lasting from 0.5 cycles to 1 minute, with the effective voltage value rising or falling to 110% to 180% or 10% to 90% of the nominal voltage. (2) Voltage flicker, with the voltage waveform envelope showing regular changes or a series of random changes in voltage amplitude. It is generally manifested as the visual perception of abnormal lighting caused by voltage fluctuations. (3) Short-term power outage, with the power supply interruption lasting from 0.5 cycles to 3 seconds. 1. Problem Statement Our factory is a continuous production enterprise mainly producing polyester fiber products. Power is supplied from 10kV high voltage via overhead lines to a high-voltage substation, then via buried cables to various low-voltage distribution stations where it is stepped down to 400V by transformers to supply electrical equipment. When grid flicker occurs, it can have a significant impact on normal production, causing product downgrading, scrapping, and even equipment failure. We used a Fluke VR101 voltage event recorder (detecting single-phase voltage) to monitor our factory's low-voltage grid. Figure 1 shows the voltage events that occurred over a month. Events marked with 'e' (H-N, phase-to-neutral voltage) caused equipment shutdowns. Comparing the observed equipment shutdowns, the magnitude and duration of voltage rises and falls determine the degree of impact on electrical equipment. Our factory's grid voltage flicker mainly manifests as voltage drops and short-term power outages. Voltage drops occur frequently, accounting for 90% of voltage events. However, voltage drops below 20% have little impact on equipment operation. Voltage drops exceeding 20%, depending on their duration, can cause some equipment to shut down. Short-term power outages generally cause widespread equipment malfunctions. Our factory's own load is stable and without impact; all frequency converters are equipped with filters and reactors, and the UPS has PFC circuitry; measured harmonics are not significant. Since nearby factories can feel the effects of grid flicker, we believe it is mainly caused by the external power grid, which our factory cannot fundamentally eliminate; we can only take appropriate technical measures to reduce its impact. Generally speaking, the impact of voltage flicker on equipment operation includes the following aspects: [b][align=center]For details, please click: Methods to reduce the impact of grid flicker on continuous production[/align][/b]