Frequency converter harmonics management method - Database & Sql Blog Articles

Filter 18.432M

(1) Isolation, shielding, and grounding of the inverter: To minimize electromagnetic interference, the inverter’s power supply should be isolated from other equipment. This can be achieved by using an isolating transformer on the input side or placing the inverter inside a grounded metal enclosure. The inverter's output cables should be kept away from control cables—ideally at least 50mm apart. If they must cross, do so at a right angle. When laid parallel, limit the length to no more than 1m and ensure the cables are run through grounded steel conduits for additional protection.
(2) Installing AC and DC reactors: When the distribution transformer has a capacity greater than 500KVA and is more than ten times the inverter’s capacity, an AC reactor should be added to the input side. If the transformer’s output voltage is unbalanced with a ratio exceeding 3%, it may cause excessive current peaks, leading to overheating. In such cases, an AC reactor is necessary, and in severe situations, a DC reactor may also be required.
(3) Using passive filters: Passive filters are installed on the AC side of the inverter and consist of inductors, capacitors, and resistors to form harmonic resonance circuits. These filters help prevent higher harmonics from entering the grid when their frequency matches that of the LC circuit. They are cost-effective, easy to maintain, and reliable. However, they are sensitive to system parameters and may amplify certain subharmonics, making them less flexible.
(4) Implementing active filters: Active filters, introduced in the early 1970s, detect and compensate for high-order harmonics in real-time by injecting opposite-phase currents. They offer better control, faster response, and multi-functionality compared to passive filters. They also avoid resonance issues and automatically track harmonic changes. However, they are larger in size and more expensive.
(5) Installing static reactive power compensation devices: For systems with large fluctuating loads, static reactive power compensation devices can provide quick reactive power support, improving the power factor and reducing harmonic injection into the grid. Among these, the self-saturated reactance type (SR type) offers the best performance, with high reliability, fast response, and ease of maintenance.
(6) Separating power lines: Harmonic currents generated by nonlinear loads can distort voltage waveforms. To prevent this, separate the power lines used by harmonic-generating loads from those serving sensitive equipment. This ensures that distorted voltages from nonlinear loads do not affect linear loads connected at the same point.
(7) Diversifying and multiplexing circuits: Parallel operation of multiple inverter units can cancel out harmonic components through waveform superposition. Multi-pulse rectification (such as 12, 18, or 24 pulses) also reduces harmonics. Advanced methods like vector voltage modulation further enhance performance.
(8) Improving inverter control: With advancements in power electronics and microcontroller technology, modern inverters use digital control systems. These systems employ microcontrollers like MCS51 or 80C196MC, along with LCD displays, to achieve more precise control. Combining various control strategies helps reduce harmonics and improve efficiency.
(9) Green inverters: A green inverter is designed to produce clean sinusoidal input and output currents, with a controllable power factor. It allows for flexible power output and minimizes harmonic pollution, offering a sustainable and efficient solution for modern electrical systems.

FRP Cable Pipe

FRP Cable Protection Pipe and FRP Filament Wound Pipe, created to manage cable management, are constructed of FRP to ensure both durability and lightness. While FRP Cable Protection Pipe protects electrical and communication cables against damage and corrosion, while CPFRP Filament Wound Pipe produced through filament winding process offers greater strength and flexibility for protecting cables in high-stress or dynamic settings.

FRP Cable Pipe,fiberglass cable pipe,frp composite pipe,Fiber reinforced pipe

Hebei Dingshengda Composite Material Co., Ltd. , https://www.frpdsd.com