Granted Patent B2

US 9,026,256 · App. 13/227,936 · Granted May 5, 2015

Abstract

Claims (29)

1. A method for real-time feeder reconfiguration for load balancing of transformers and feeders by load transfer from an overloaded transformer or feeder to an adjacent transformer or feeder, the method comprising:

a. obtaining a System Load Index (SLI) of a distribution system and load indices of any transformers and feeders;

b. optimizing an objective function formulated as a function of the SLI and load indices; and

c. obtaining load balance by transferring load to align the load indices of a transformer and/or feeder with the SLI,

wherein the optimizing step includes:

defining the objective function as a sum of squares of a load deviation of transformers/feeders;

minimizing the objecting function to determine optimal operating states including any open or closed states of isolating devices for load break and load pick up; and

changing open positions of isolating devices subject to constraints of transformer and feeder capacities to avoid an overload condition for uniform and balanced distribution of load.

2. The method for real-time feeder reconfiguration for load balancing of transformers and feeders by load transfer from an overloaded transformer or feeder to an adjacent transformer or feeder as claimed in claim 1 , wherein said transferring load comprises:

(a) determining a source feeder and a sink feeder for load transfer;

(b) tracing a path between said source feeder and said sink feeder;

(c) cutting the path into two parts by an open switch;

(d) selecting a neighboring section of said open switch for load transfer; and

(e) carrying out said transfer successively in a next section to achieve a balanced system.

3. The method for real-time feeder reconfiguration for load balancing of transformers and feeders by load transfer from an overloaded transformer or feeder to an adjacent transformer or feeder as claimed in claim 2 , wherein determination of a source feeder is based on:

(a) choosing a feeder with a largest load deviation as the source feeder when equipment with greatest load deviation is a feeder; or

(b) when the equipment with greatest load deviation is a transformer with negative load deviation, choosing a feeder with a smallest load deviation amongst all feeders of said transformer as source feeder; or

(c) when the equipment with a greatest load deviation is a transformer with positive load deviation, choosing a feeder with a largest load deviation amongst all feeders of said transformer as source feeder.

4. The method for real-time feeder reconfiguration for load balancing of transformers and feeders by load transfer from an overloaded transformer or feeder to an adjacent transformer or feeder as claimed in claim 2 , wherein said determination of a sink feeder comprises:

(a) calculation of a maximum load transfer for all feeders connected to said source feeder; and

(b) choosing a feeder with a largest value of Maximum Load Transfer as the sink feeder;

wherein, maximum load transfer is a difference between actual overload and capacity.

5. The method for real-time feeder reconfiguration for load balancing of transformers and feeders by load transfer from an overloaded transformer or feeder to an adjacent transformer or feeder as claimed in claim 1 , wherein the load deviation is based on loads of transformers and feeders at balanced condition and actual loads of transformers and feeders.

6. The method for real-time feeder reconfiguration for load balancing of transformers and feeders by load transfer from an overloaded transformer or feeder to an adjacent transformer or feeder as claimed in claim 1 , wherein said load balancing operation of a transformer and a feeder is carried out by a single operation in which a plurality of switches is reconfigured.

7. The method for real-time feeder reconfiguration for load balancing of transformers and feeders by load transfer from an overloaded transformer or feeder to an adjacent transformer or feeder as claimed in claim 1 , wherein a same configuration of said distribution system remains during a calculation process except for open/close states of switches.

8. A distribution management system for performing load balancing of transformers and feeders based on a System Load Index (SLI) and load indices values of transformers and feeders in a distribution network, the system comprising:

a. a control system for determining a System Load Index (SLI) of a distribution system and load indices of transformers and feeders in a distribution network, and for optimizing an objective function formulated as a function of the SLI and load indices, the control system being configured to optimize the objective function by defining the objective function as a sum of squares of a load deviation of transformers/feeders, minimizing the objecting function to determine optimal operating states including any open or closed states of isolating devices for load break and load pick up, and changing open positions of isolating devices subject to constraints of transformer and feeder capacities to avoid an overload condition for uniform and balanced distribution of load; and

b. an output for identifying a transferring of load to align the load indices of transformer and feeder with the SLI to achieve load balance.

9. The distribution management system as claimed in claim 8 in combination with transformers and feeders in a distribution network, wherein the system is configured for performing the load balancing of the transformers and feeders by a single operation in which a plurality of switches is reconfigured.

Assignments (6)