# US 12,763,576 B2 · Power distribution system reconfigurations for multiple contingencies

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,763,576 B2
- Document ID: US12763576B2
- Status: Granted
- Kind: B2
- Application number: 18/245,017
- Filed: 2021-08-30
- Published: 2023-11-09
- Granted: 2026-10-13
- Earliest claimed: 2020-09-14
- Assignees: Siemens Aktiengesellschaft
- Applicants: Siemens Corporation
- Inventors: Yubo Wang; Siddharth Bhela; Ulrich Muenz
- Web page: https://patentgrep.com/patent/US12763576B2

## CPC

- H02J 3/0073: by providing alternative feeding paths when the main path fails
- H02J 3/388: Arrangements for the handling of islanding, e.g. for disconnection or for avoiding the disconnection of power
- H02J 2103/35: Grid-level management of power transmission or distribution systems, e.g. load flow analysis or active network management
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY

## Abstract

System and method simulate power distribution system reconfigurations for multiple contingencies. Decision tree model is instantiated as a graph with nodes and edges corresponding to simulated outage states of one or more buses in the power distribution system and simulated states of reconfigurable switches in the power distribution system, Edges related to each outage are disconnected. A reconfiguration path is determined with a plurality of switches reconfigured to a closed state by an iteration of tree search algorithms. A simulation estimates feeder cable and transformer loading and bus voltages on the reconfigured path for comparing against constraints including system capacity ratings and minimum voltage. Further iterations identify additional candidate reconfiguration paths which can be ranked by total load restoration.

## Claims

### Claim 1

A computer system for simulating power distribution system reconfigurations for multiple contingencies, the computer system comprising:
a processor; and
a memory storing program instructions executable by the processor to:
instantiate a decision tree model configured as a graph with nodes and edges corresponding to simulated outage states of one or more buses in the power distribution system and simulated states of reconfigurable switches in the power distribution system, the model spanning from parent nodes to child nodes in a radial pattern of branches;
disconnect edges in the model related to each outage; and
determine a reconfiguration path with a plurality of switches reconfigured to a closed state by a Monte Carlo tree search (MCTS) algorithm that executes an iterative method where every iteration has four steps: selection, expansion, simulation, and backpropagation, wherein the MCTS algorithm calls a spanning tree search (STS) algorithm during the expansion to determine possible decisions to be made by setting open a subset of configurable switches in the model, identifying islands of connected components through aggregation of connected loads, and reconstructing a condensed graph from spanning trees across aggregated components;
generate a simulation to estimate feeder cable and transformer loading and bus voltages on the reconfigured path in response to a simulation trigger from the MCTS algorithm with a selection of at least one switch closure;
compare the estimates against constraints including feeder cable capacity ratings, transformer capacity ratings, and minimum bus voltage, the constraints extracted from a power distribution system database; and
classify the reconfiguration as successful under safety and system stability requirements when the constraints are satisfied within the defined tolerance; and
wherein further iterations of the Monte Carlo tree search (MCTS) algorithm and the spanning tree search (STS) algorithm repeated to identify additional candidate reconfiguration paths and to rank reconfiguration paths classified as successful.

### Claim 2 (depends on 1)

The computer system of claim 1, wherein the decision tree tree model includes chance nodes for tracking probabilities for a reconfiguration branch decision of a parent node to either of two child nodes, wherein the probabilities relate to a successful reconfiguration classification.

### Claim 3 (depends on 2)

The computer system of claim 2, wherein the processor comprises a set of parallel processors, and the probabilities are computed in a parallelized manner across the parallel processors.

### Claim 4 (depends on 1)

The computer system of claim 1, wherein the program instructions further cause the processor to determine an aggregated load under each feeder line by traversing the decision tree using a breadth-first-search traversal algorithm.

### Claim 5 (depends on 4)

The computer system of claim 4, wherein the program instructions further cause the processor to determine all combinations of load loss scenarios and parent-child relationships among outage edges, and to calculate a total load loss for all aggregated loads for each distribution circuit lost in the outage.

### Claim 6 (depends on 5)

The computer system of claim 5, wherein the parent-child relationships are determined based on recorded intime values for when outage nodes are pushed into a stack and recorded outtime values for when the outage nodes are popped out of the stack during a depth-first-search traversal of the decision tree model.

### Claim 7 (depends on 1)

The computer system of claim 1, wherein the program instructions further cause the processor to apply empirical thresholds to reduce the number of candidate loss loads based on outages having low probability or outages having aggregated load below a low threshold.

### Claim 8 (depends on 1)

The computer system of claim 1, wherein k outages are known to have occurred, and the program instructions further cause the processor to determine which switch to close by:
reducing the model into multiple connected components including grid-connected components and islanded components;
ranking islanded components in order of importance criteria;
evaluating open switches that connect islanded components to the grid and down-selecting branches with largest operating margin based on feeder cable and transformer capacity ratings;
filtering highest ranking components based on loading of a grid connected feeder on energized side of the switch, and nodal voltage being above minimum specifications; and
selecting a switch with highest rank.

### Claim 9 (depends on 1)

The computer system of claim 1, wherein the program instructions stored in the memory are configured to cause the processor to perform operations including:
determining probabilities for contingencies based on historical outage data stored in the power distribution system database; sending resiliency level distributions to a display as a graph of contingency probability versus load loss for the contingency; and ranking candidate reconfigurations according to resiliency level based on aggregated load restoration metrics.

### Claim 10

A computer-implemented method simulating power distribution system reconfigurations for multiple contingencies, the method comprising:
instantiating a decision tree model configured as a graph with nodes and edges corresponding to simulated outage states of one or more buses in the power distribution system and simulated states of reconfigurable switches in the power distribution system, the model spanning from parent nodes to child nodes in a radial pattern of branches;
disconnecting edges in the model related to each outage; and
determining a reconfiguration path with a plurality of switches reconfigured to a closed state by a Monte Carlo tree search (MCTS) algorithm that executes an iterative method where every iteration has four steps: selection, expansion, simulation, and backpropagation, wherein the MCTS algorithm calls a spanning tree search (STS) algorithm during the expansion to determine possible decisions to be made by setting open a subset of configurable switches in the model, identifying islands of connected components through aggregation of connected loads, and reconstructing a condensed graph from spanning trees across aggregated components;
generating a simulation to estimate feeder cable and transformer loading and bus voltages on the reconfigured path in response to a simulation trigger from the MCTS algorithm with a selection of at least one switch closure;
comparing the estimates against constraints including feeder cable capacity ratings, transformer capacity ratings, and minimum bus voltage, the constraints extracted from a power distribution system database; and
classifying the reconfiguration as successful under safety and system stability requirements when the constraints are satisfied within the defined tolerance;
wherein further iterations of the Monte Carlo tree search (MCTS) algorithm and the spanning tree search (STS) algorithm are repeated to identify additional candidate reconfiguration paths and to rank reconfiguration paths classified as successful.

### Claim 11 (depends on 10)

The method of claim 10, further comprising: generating chance nodes in the decision tree model for tracking probabilities for a reconfiguration branch decision of a parent node to either of two child nodes, wherein the probabilities relate to a successful reconfiguration classification, and wherein the probabilities are derived from historical outage data.

### Claim 12 (depends on 10)

The method of claim 10, further comprising:
determining an aggregated load under each feeder line by traversing the decision tree using a breadth-first-search traversal algorithm;
determining all combinations of load loss scenarios and parent-child relationships among outage edges; and
calculating a total load loss for all aggregated loads for each distribution circuit lost in the outage;
wherein the parent-child relationships are determined based on recorded intime values for when outage nodes are pushed into a stack and recorded outtime values for when the outage nodes are popped out of a the stack during a depth-first-search traversal of the decision tree model.

### Claim 13 (depends on 10)

The method of claim 10, wherein k outages are known to have occurred, the method further comprising: determining which switch to close by:
ranking islanded components in order of importance criteria, and
filtering highest ranking components based on loading of a grid connected feeder on energized side of the switch, and nodal voltage being above minimum specifications.