Tower cranes are tasked with high-altitude lifting of steel bars, formworks, precast components and other heavy materials for main-structure building construction, with operating conditions greatly different from ordinary industrial equipment. Exposed on construction sites, tower cranes are subject to heavy dust, rain and moisture as well as temperature swings of dozens of degrees Celsius between […]
Power systems of high-speed EMUs impose extremely strict requirements for safety, stability and precision, different from ordinary industrial equipment. Complete vehicles are equipped with dozens of power-consuming devices including traction systems, braking systems, air-conditioning & ventilation systems, signal-control systems, on-board lighting and audio-visual systems, featuring large divergences in voltage levels, operating conditions and load characteristics
Underground coal-mine roadways are narrow, with methane-gas and suspended explosive coal-dust in ambient air, high-humidity conditions and heavy coal-dust accumulation. As heavy-duty tracked mobile equipment, mining excavators sustain heavy rock-impact and whole-machine vibration during bucket digging, boom lifting-lowering, body slewing and track travelling. Equipped with variable-frequency drive systems, excavators produce massive harmonics and inrush currents
Inverters realize stepless motor-speed regulation via high-frequency on-off of IGBT power devices and rank among the most-commonly-used equipment for industrial energy-saving renovation and automation-control. However, inverters are typical non-linear loads and bring a series of power-quality challenges: large switch-on inrush currents emerge upon power-up; high-frequency switching of power devices generates massive 5th, 7th, 11th and
Hydropower generation converts mechanical energy from water-driven hydro-turbine rotation into electric energy by synchronous generators. Excitation systems function as the “control heart” of synchronous generators. They regulate DC currents inside excitation windings to control generator-terminal voltages and output reactive-power magnitudes. Operating-condition fluctuations are obvious in hydropower houses: variations of upstream water levels, load increase-decrease transitions
PV systems are composed of PV modules, combiner boxes, inverters, box-type transformers and grid-connection switch-cabinets. PV panels produce DC power that undergoes DC-AC conversion via inverters and is stepped-up by step-up transformers before being fed into public power grids. The most-typical operating-condition characteristic of PV power-stations lies in unstable power outputs: cloud-cover-shielding, day-night-alternation and morning-evening-illumination-variations
Modern large-scale central air-conditioning systems widely adopt variable-frequency energy-saving control technologies. The rotating speeds of compressors, water pumps and fans are adjusted via frequency converters to achieve precise temperature control and energy-saving optimization. Nevertheless, the complete system is a typical multi-equipment non-linear load: frequent start-stop day and night, large-amplitude load variations caused by seasonal temperature
Vacuum sintering is a high-precision thermal-processing technology. Precise and stable power supply determines furnace-temperature performance. Temperature fluctuation, current ripple or voltage instability will directly cause uneven sintering density, cracking, deformation and substandard material properties, resulting in large-scale scrapping of finished goods. Vacuum sintering furnaces adopt rectifier-voltage-regulating and variable-frequency heating technologies and belong to typical non-linear
With popularization of new-energy vehicles, charging stations, battery-swap stations, community public-access charging piles and highway-side charging piles have been deployed on a large scale. Charging piles belong to typical high-frequency non-linear loads: frequent plug-in start-up, full-charge shutdown and dynamic-power adjustment produce large transient-current shocks; high-frequency rectification-and-inversion of charging modules generate rich harmonics; concurrent charging of
Public power-grid systems deliver power for industrial, commercial and residential consumers across whole regions. They feature wide coverage, complex-circuit layouts and highly-variable load-conditions. With massive integration of variable-frequency industrial equipment, new-energy generation, charging piles and energy-storage facilities into grids, non-linear-load proportions keep rising. Consequences include harmonic exceedance at distribution-station areas, reactive-power imbalance, excessive-voltage-deviation and increased
