Electrical transmission or interconnection systems – Plural supply circuits or sources – Substitute or emergency source
Reexamination Certificate
1998-11-25
2001-02-20
Paladini, Albert W. (Department: 2836)
Electrical transmission or interconnection systems
Plural supply circuits or sources
Substitute or emergency source
C307S068000, C307S065000, C307S072000
Reexamination Certificate
active
06191500
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system and method for providing an uninterruptible power supply to a critical load. More particularly, the present invention relates to a system and method for providing N+2 redundancy and on-line maintenance capability in an uninterruptible power supply system with no single points of failure.
2. Discussion of the Related Art
Electric power pervades our world to such an extent that lack of it can lead to disaster, especially the financial, medical, and communications industries. As a result, standby and/or emergency power supply systems have been developed to answer the need for an uninterrupted supply of power. Typically, these so-called uninterruptible power supplies or supply systems are designed to handle a critical load during brief periods when service from a main power supply (e.g. a utility) becomes “interrupted” or unavailable. The critical load varies depending on the application and may, for example, include computer systems, communication systems, emergency lighting, life support systems, or anything whose continuous operation is necessary and/or whose interruption may prove disastrous.
Various uninterruptible power supplies have been developed and may include a battery backup system or a generator(s) for providing an alternate source of power. More complex systems may include transfer switches for selecting between alternate power sources and redundant feeds for providing alternate pathways to conduct power between the source(s) and the critical load. However, these conventional uninterruptible power supplies typically have a single point source of failure making them unsatisfactory for many important applications.
Other problems exist with respect to uninterruptible power supply systems, some of which are discussed in further detail below. A need exists for an improved uninterruptible power supply system that solves the problems described herein.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a system and method for providing an uninterruptible supply of power to a critical load that alleviates the problems associated with conventional uninterruptible power supply systems. In particular, an uninterruptible power supply (UPS) system of the present invention provides N+2 redundancy to the critical load in a manner in which single points of failure are eliminated.
The present invention is a UPS system that includes a plurality of UPS modules electrically coupled to at least two utility sources. A UPS paralleling switchgear is used to control the UPS modules and combine their outputs so that the output of a particular UPS module matches that of each other UPS module regardless of which utility source the particular UPS module receives power. The combined outputs of the UPS modules are provided to a ring bus. The ring bus provides multiple feeds to the critical load. The UPS system of the present invention provides an uninterruptible supply of power to the critical load.
One of the features of the present invention is that during normal operation, the critical load is supplied with power combined from at least two utility sources. In particular, two utility sources each provide power to the plurality of UPS modules. The UPS modules are controlled so that their outputs match one another regardless of the utility source driving the particular UPS module. The outputs are provided on a single bus to the critical load so that each online UPS module equally shares the critical load.
Another feature of the present invention is that the N+2 redundancy is accomplished with a reduced number of UPS modules over conventional systems. In particular, because the outputs of the UPS modules are combined onto a single bus and because either utility source can be used to power any of the UPS modules, a fewer number of UPS modules can be used to deliver the same level of redundancy.
Yet another feature of the present invention is a ring bus which provides alternate paths between the UPS modules and the critical load so that uninterrupted power is supplied to the critical load. In particular, the ring bus isolates and sectionalizes the critical load from the UPS modules so that portions of the critical load can be brought offline or serviced while still providing power to the remaining portions of the critical load.
Still another feature of the present invention is that any component in the UPS system can fail or be brought offline for servicing or maintenance without interrupting the power supplied to the critical load. This is accomplished through the various redundancy and backup systems as will be discussed in detail below.
Additional features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the process particularly pointed out in the written description and claims hereof as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
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Kling Lindquist Partnership, Inc.
Morgan & Lewis & Bockius, LLP
Paladini Albert W.
Roberto Rios
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