Regenerative energy management-reuse algorithm in UPS- supplied systems. Fatmir Basholli 1, and Bexhet Kamo-

 

Regenerative energy management-reuse algorithm in UPS- supplied systems. Fatmir Basholli 1, and Bexhet Kamo 

Abstract 

Loads/equipment especially in industrial applications and other different applications that use electric motors, draw current from the network while rotating, but in case of a sudden force (braking effect) they start to produce electricity themselves. This energy is sent back to the source they are fed and in such a case the regenerative energy should be managed. If this type of load is fed by a UPS (uninterruptible power supply), in the braking mode, the UPS applies the extra energy to its DC BUS through the reverse diodes of the output power transistors (IGBT), which causes the DC BUS voltage to rise. This extra energy, regenerative energy, may be used by other equipment in the network when is possible and if not (technically), to prevent the DC BUS rise, a resistor group driven/ controlled by the respective controller is placed on the DC BUS to “re-route” the energy usage and prevent the UPS damage. In this paper we provide an algorithm that may be used to control this process of using regenerative energy by network or by re-routing it in the group of resistors.

VIEW FULL PAPER:

 https://www.researchgate.net/publication/378300082_Regenerative_energy_management-reuse_algorithm_in_UPS-_supplied_systems

Using UPSs to provide secondary power for emergency evacuation lifts - Standard UPS explode with regenerative energy from motors during motor braking.

Using UPSs to provide secondary power for emergency evacuation lifts

 Have you ever considered how you would evacuate people from a multistory building in case of power failure?

Do you have responsibility for people coming and going from public buildings? If you do, you need to consider how you’re going to handle evacuation in the event of an extended power failure and are not equipped with a standby generator.

It doesn’t need to be a dramatic situation just an extended power outage. Lifts by default should have the means to travel to the closest floor and open their doors so occupants can leave in the case of power failure.

That is fine for able-bodied persons who are capable of continuing evacuation using the staircase.

How Would You Evacuate People With Mobility Issues?

A simple cost-effective solution is to power lift through UPS, however, it may not be as simple as it seems.

Suppliers and installers of UPS systems intended to support lifts should be aware that some lifts have regenerative braking, which generates a potentially damaging back–EMF onto the DC Bus within the UPS.

Harnessing Energy with Regenerative Loads

The capacity of the lift motor, compactness, and high inrush are some of the features that can be easily managed for UPS’s on the market nowadays, but being able to handle regenerative loads is a completely different situation. Regenerative UPS units use the regenerative load from braking action; this load is used for creating regulated power which is connected to machines generating regenerative load.

Regenerative Uninterruptible Power Supply (UPS)

Forwarding Mode

• When the Elevator is moving upwards with the load, the motor drive is in forwarding mode (normal mode) drawing energy from Utility or UPS.
• The motor will converts the supplied electrical energy into kinetic energy.

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  Breaking Mode

• Every elevator motors operate like a generator while braking when moving downwards with load.
• During regenerative braking, the motor restores part of the kinetic energy into electrical energy.
• This electrical energy will be directed to the UPS, and use to charge the UPS BATTERY or recycle back to the utility.
• No energy is wasted.
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  REGENERATIVE LOAD OPERATION
•  The EF LIFT UPS incorporates an intelligent braking system, using IGBT controllers to electronically absorb any regenerative back feed energy from the lift. Regenerative load causes reverse current to flow to the output of the UPS system. This reverse energy causes the internal DC bus within the UPS to rise above safe levels of the UPS design and can cause damage to the DC Capacitors, Rectifier and Inverter. The PowerPro EF Lift system has a separate IGBT Controlled Regeneration Box that connects directly to the UPS DC Bus. The DC bus voltage of the UPS typically floats at ±405Vdc and can boost up to 435Vdc. The Regen Box monitoring system continuously analyses the internal rise of the DC bus voltage, when the voltage increases over 435Vdc fast switching IGBTs connect DC resistors and dissipate the energy into heat, protecting the UPS components and Inverter operation. When the DC bus voltage decreases back down to an acceptable level, the Regen Box self deactivates.
• SOURCE 1:https://www.kohler-ups.co.uk/using-upss-to-provide-secondary-power-for-emergency-evacuation-lifts/
• SOUCE2: https://www.everexceed.com/blog/ups-for-lift-application_b267

Institute of Energy and Environment of the University of São Paulo-BRAZIL

 

Institute of Energy and Environment of the University of São Paulo-BRAZIL- The Institute of Energy and Environment of the University of São Paulo, formerly known as the Institute of Electrotechnics and Energy (IEE),[1] [2] is a specialized unit of the University of São Paulo, created by State Decree 11.684 of December 11, 1940 and inaugurated on April 25, 1941, whose activities are focused on research, teaching and university extension in the areas of energy and environmental science. The Electrical Machines Laboratory of the IEE-USP performs tests to evaluate the performance of motors, generators, transformers and electrical energy conditioning systems, in their most varied forms of construction, use or type. Energy and Environment Institute of the University of São Paulo (USP)-University of São Paulo-BRAZIL The Energy and Environment Institute of the University of São Paulo, formerly known as the Institute of Electrical Engineering and Energy (IEE),[1] [2] is a specialized unit of the University of São Paulo, created by State Decree 11.684 of December 11, 1940 and inaugurated on April 25, 1941, whose activities are focused on research, teaching and university extension in the areas of energy and environmental science. The Electrical Machines Laboratory of the IEE-USP performs tests to evaluate the performance of motors, generators, transformers and electrical energy conditioning systems, in their most varied forms of construction, use or type. The largest Institute of Energy, Electrical Engineering, Electronic Engineering, Photovoltaic Energy, Renewable Energies, and Biomass in South America.

An Effective Solution for Regeneration Protection in Uninterruptible Power Supply-Jinghang Lu, Member, IEEE, Josep M Guerrero, Fellow, IEEE, Mehdi Savaghebi, Senior Member, IEEE, Amer M.Y.M.Ghias, Member IEEE, Yajuan Guan, Member, IEEE, Xiaochao Hou, Student Member, IEEE, Juan C. Vasquez, Senior Member, IEEE

 An Effective Solution for Regeneration Protection in Uninterruptible Power Supply 

Abstract – In this paper, a regeneration protection solution is proposed to address the DC-link overvoltage issue and the unequal power sharing in the parallel Uninterruptible Power Supply (UPS) systems. First, a DC-link Voltage Protection (DCVP) control strategy is proposed to protect the inverter against the excessive DC-link voltage that may trigger the protection mechanism of the UPS system. In addition, an active power sharing control strategy by regulating the virtual resistance is proposed to solve the circulating current caused by UPS regeneration issue. Finally, the feasibility of the proposed regeneration protection solution is verified by experimental results from the parallel UPS system prototype.

VIEW FULL PAPER:

 https://portal.findresearcher.sdu.dk/files/170700480/An_Effective_Solution_for_Regeneration_Protection_in_Uninterruptible_Power_Supply_002_.pdf

Instituto de Energia e Ambiente da USP-Universidade de São Paulo-BRASIL

 

  

 

O Instituto de Energia e Ambiente da Universidade de São Paulo, anteriormente denominado Instituto de Eletrotécnica e Energia (IEE),[1] [2]é uma unidade especializada da Universidade de São Paulo, criado pelo Decreto Estadual 11.684 de 11 de dezembro de 1940 e inaugurado em 25 de abril de 1941, cujas atividades são voltadas à pesquisa, ao ensino e à extensão universitária nos âmbitos da energia e ciência ambiental.