Electricity: electrical systems and devices – Safety and protection of systems and devices – Feeder protection in distribution networks
Reexamination Certificate
2001-12-10
2004-02-24
Jackson, Stephen W. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
Feeder protection in distribution networks
C361S062000, C361S066000, C361S078000
Reexamination Certificate
active
06697240
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to improvements in control of an electric power distribution system, and more specifically to the use of intelligent autonomous nodes for isolating faulted sections of distribution lines, reconfiguring, and restoring service to end customers (circuit reconfiguration), and improving circuit protection.
2. Description of Related Art
The power distribution systems of this invention are generally of low to medium-voltage distribution feeders (ranging from approximately 4 KV to 69 KV) originating in power distribution substations and leading to the source of supply for end customers of an electrical supply utility or agency. Although the electrical principles governing operation of these feeders are identical to those governing the operation of the higher voltage generation and transmission systems, the methodologies for building, operating and maintaining the lower voltage systems are different. These methodologies are dictated by much larger quantities and geographical dispersion of distribution equipment, and by much lower quantities of electrical power supplied per mile of circuit. This creates requirements for lower cost, modular, standardized equipment, which can be installed, operated and maintained with minimal labor and human supervision.
Failures of the distribution feeder (faults) occur due to downed power lines, excavation of underground cable or other causes and are typically detectable by sensing excess (short circuit/overcurrent) current, and occasionally by detecting loss of voltage. In distribution systems, it is sometimes the case that a loss of voltage complaint by the customer is the means by which the utility senses the outage, responding by dispatching a crew to isolate the fault and reconfigure the distribution system. The typical devices for isolating these faults are circuit breakers located primarily in distribution substations and fuses located on tap lines or at customer transformers. The substation breakers are generally provided with reclosing relays that cause the breaker to close several times after the breaker has detected an overcurrent condition and tripped open. If during any of these “reclosures”, the fault becomes undetectable, service is restored and no extended outage occurs. Particularly on overhead distribution lines, temporary arcing due to wind, lightening, etc causes many faults. Thus, the majority of faults are cleared when the breaker opens and service is restored on the automatic reclose. Alternatively, after some number of reclosure attempts, if the overcurrent condition continues to be present, the recloser goes into a “lockout” state which prevents further attempts to clear the fault.
Other than manually operated switches, most distribution feeders have no other means to isolate a fault between the substation and the fuses, thus any failure of the feeder results in lengthy, costly, inconvenient and potentially dangerous outages. The primary exceptions to this involve the use of devices known as “line reclosers”, “interrupters” and “automatic line sectionalizing switches” or “sectionalizers”. These are automatically operated devices, well known to those skilled in the art, and are referred to categorically in this document as “fault isolating devices”. The reader should be aware that the term “sectionalizer” refers to a specific family of automatic, fault isolating devices described below, while the terms “sectionalizing” and sectionalize” are used to describe the process of isolating a faulted section of line, which can be performed by all of the classes of switches described above.
The “line recloser” is typically a pre-packaged, version of the substation breaker with reclosing relay. Line reclosers typically consist of a fault-break switching device with integrated current sensing, plus a control enclosure containing fault detection hardware, control logic, user interface module, and battery-backed power supply. When placed on the distribution line between the substation and customer loads, a line recloser is typically set up with fault detection settings coordinated to operate before the substation breaker trips and to correspondingly prevent the substation breaker from tripping. This has the effect of reducing the number of customers affected by an end of line fault. On very long feeders, the more sensitive settings can be used to protect the feeder from faults of a magnitude too low to be detected reliably by the substation circuit breaker. Multiple line reclosers can be placed on a distribution line in series, although it becomes increasingly difficult or impossible to coordinate their settings such that only the nearest recloser on the source side of the fault operates.
The “interrupter” is typically a pre-packaged breaker and fault relay without automatic reclosing capability. Interrupters are used primarily in underground power distribution systems.
The “automatic line sectionalizer” or “sectionalizer” is typically a prepackaged combination of a load-break switch used in conjunction with a device known as a “line sectionalizer control”. The sectionalizer senses current (and optionally voltage) such that the operation of the circuit and the source-side protective device can be monitored. The sectionalizer is configured to open its switch under certain circumstances when the circuit is de-energized after some number of pre-configured voltage losses have occurred within a brief time interval. The circumstances vary from product to product, but are always based upon sensing of conditions caused by faults followed shortly by voltage losses. Sectionalizers are designed to coordinate with the operation of the circuit's protective devices. Typical sectionalizers are devices such as the Cooper Power Systems Sectionalizer type GV or GW manufactured by Cooper Industries, Inc, or the EnergyLine Systems Model 2801-SC Switch Control manufactured by EnergyLine Systems. These are all well-known devices within the industry, and thus need not be described in detail herein.
Although utility acceptance of more sophisticated automation solutions to fault isolation and reconfiguration has been limited, many methods have been developed and marketed. The most primitive methods have typically involved placing control equipment and switchgear at strategic points in the power distribution grid and coordinating their operation entirely with the use of circuit parameters sensed and operated on locally and independently at each point. An example system of this type is the Kearney FILS system. More sophisticated methods have been developed for isolating/reconfiguring these circuits by communicating information sensed locally at the strategic points to a designated, higher level control entity(s). Example methods of this type are disclosed in U.S. Pat. Nos. 5,513,061 and 5,701,226 (Gelbein) and 5,341,268 (Ishiguro). Utilizing intelligent, distributed control methodologies, several methods have been developed to isolate/reconfigure distribution circuits without the need for the higher-level control entity(s). In systems implementing these methods, information is sensed and processed locally, acted on as much as possible locally, and then shared with other cooperating devices to either direct or enhance their ability to take action. Examples of these methods can be found in U.S. Pat. Nos. 3,970,898 (Baumann) and 5,784,237 (Velez), and in a prior version of EnergyLine Systems IntelliTEAM (Reg. T.M.) product and related U.S. patent application Ser. No. 08/978,966 (Nelson et al).
Most of these methods and systems contain significant restrictions on the power distribution equipment types and topologies supported. For example, Baumann, Velez, and Gelbein disclose methodologies tailored to non-fault break sectionalizing switches with breakers or reclosers only at the sources of supply. Thus, methodologies for integrating substation breakers, line reclosers, sectionalizers, and other equipment into generalized, automatic circuit reconfiguration systems have been li
Berkowitz Donald S.
Bik Witold
Maloney Michael A.
Nelson William Christian Tracy
EnergyLine Systems, Inc.
Graybeal Jackson Haley LLP
Jackson Stephen W.
Lapacek James V.
LandOfFree
Method and apparatus for automated reconfiguration of an... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for automated reconfiguration of an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for automated reconfiguration of an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3287875