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How to Solve The Resonance of Diesel Generator Set and UPS

Nov. 26, 2021

Do you know how to solve the problem of resonance between diesel generator sets and UPS? The problem of capacitor self-excitation may be aggravated or covered by other electrical conditions, such as series resonance. When the ohmic value of the inductive reactance of the diesel generator set and the ohmic value of the capacitive reactance of the input filter are close to each other, and the resistance value of the system is small, oscillation will occur, and the voltage may exceed the rated value of the power system. The newly designed UPS system is essentially It is 100% capacitive input impedance. A 500kVA UPS may have a capacitance of 150kvar and a power factor close to zero.


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Shunt inductors, series chokes, and input isolation transformers are conventional components of UPS, and these components are all inductive. In fact, they and the capacitance of the filter together make the UPS behave as capacitive as a whole, and there may already be some oscillations inside the UPS. Coupled with the capacitive characteristics of the power lines connected to the UPS, the complexity of the entire system is greatly increased, beyond the scope of the analysis of ordinary engineers. Two additional factors have recently made these problems more common in critical applications. First of all, according to users' high-reliability data processing requirements, computer equipment manufacturers provide more redundant power inputs in their equipment.


Nowadays, typical computer cabinets are equipped with two or more power cords. Secondly, the equipment manager requires the system to support online maintenance. They hope that the critical load will also be protected when the UPS is shut down for maintenance. These two factors have increased the number of UPS installations in a typical data center, and the load capacity of each UPS has decreased, but the increase in diesel generator sets has not been consistent with UPS. In the eyes of equipment managers, generators are usually standby and easy to arrange for maintenance.


In addition, in some large projects, financial pressure limits the number of expensive high-power diesel generator sets. As a result, each generator has more UPS. The best defense against self-excitation and oscillation is the basic knowledge of physics. Engineers should Carefully determine the power factor characteristics of the UPS system under all load conditions. After the UPS equipment is installed, the owner should insist on a comprehensive test and carefully measure the working parameters of the entire system during commissioning and acceptance. When a problem is found, the best solution is to set up a project team composed of manufacturers, engineers, contractors, and owners to fully test the system and find a solution.


Starlight Power has advanced testing equipment, modern production technology, professional manufacturing technology, perfect quality management system, and strong technical research and development capabilities. It can provide 3KW~2500KW various specifications of ordinary, automatic, four protection, automatic switching, low noise and mobile generator sets, high quality and low energy consumption to meet the diverse power needs of customers, and can also meet users with different voltages and different frequencies. It is required to create a parallel power supply system for multiple units. If you are interested in our product or any question on generator, welcome to send email to sales@dieselgeneratortech.com.

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