Abb Research Ltd.

Abb Schweiz Ag

Hitachi Energy Switzerland Ag

Hitachi Energy Ltd

Xiaoming Feng

Jiuping Pan

Ernst Scholtz

Fang Yang

William Peterson

Ning Kang

Khosrow Moslehi

James Stoupis

Gregory F Rossano

George Q Zhang

Zhenyuan Wang

Luiz V Cheim

David Lubkeman

Vaibhav Deepak Donde

Debrup Das

Le Tang

Mani Subramanian

John Dennis Finney

Craig Stiegemeier

Luiz Av Cheim

Lan Trinh

Anil Pahwa

Qingfeng He

Maddumage Gamini Wickramasekara

Adolfo Fonseca

Yuan Liao

Peng Peng

Will Briggs

Christian Krueppel

William L Peterson

Prior methods of state estimation, based on a constrained optimization problem with equality and/or inequality constraints, rely on penalty-based heuristics which can produce very large weight values, resulting in ill-conditioning of the gain matrix. Disclosed embodiments of state estimation convert the constrained optimization problem into an unconstrained convex optimization problem in which violated equality and/or inequality constraints are represented as parameterized potential functions, each comprising a center-of-attraction parameter. This unconstrained convex optimization problem can be iteratively formed, using successively updated values for the center-of-attraction parameters, and solved, until no equality and/or inequality constraints are violated, to produce a final estimated state. This final estimated state may then be used to control the system being monitored, such as a power system.

Parameterized potential functions for equality constraints

Embodiments of the disclosure includes operating a power grid, including: generating, by a power management system of the power grid, a power grid resource allocation profile indicative of an operation of the power grid constrained by operational information of the power grid; generating a difference between a value of upper bounds from a plurality of obtained convergence paths and a value of lower bounds from the obtained convergence paths, the obtained convergence paths being based on a plurality of different initial conditions for the generated power grid resource allocation profile; and generating a resource allocation schedule for power grid resources operating within the power grid if the generated difference is smaller than a pre-determined threshold, the resource allocation schedule corresponding to a convergence path associated with the value of the upper bounds, the resource allocation schedule being configured to be received at the power grid resources.

Power grid resource allocation

A method of operating a power grid includes: generating, by a power management system of the power grid, an intermediate resource allocation schedule that provides a tentative schedule of resource allocation for power grid resources operating within the power grid; determining, by the power management system, whether the intermediate resource allocation schedule is feasible by checking whether the intermediate resource allocation schedule satisfies coupling constraints of a power grid resource allocation profile of the power grid indicative of an operation of the power grid constrained by power grid operational information; and in response to determining that the intermediate resource allocation schedule is infeasible, repairing, by the power management system, the intermediate resource allocation schedule to generate a feasible resource allocation schedule, where the repairing comprises determining whether a first dispatch solution obtained by solving a dispatch problem with fixed integer decisions from the intermediate resource allocation schedule is feasible.

The present application is directed to an electrical system including a housing configured to hold electrical components within an internal volume. In one aspect the electrical system is a power transformer. A sensor is mounted to the housing and is configured to sense a parameter associated with one or more electrical components during operation of the electrical system. A control system including a communication unit and a data processing unit is operable for analyzing the sensed parameter and comparing the sensed parameter to a predetermined minimum or maximum threshold value.

Systems and methods for monitoring components in a power transformer or the like

Systems, methods, techniques and apparatuses of state estimation are disclosed. One exemplary embodiment is a method comprising determining, with a state estimator, a state estimate based on power grid data corresponding to characteristics of a power grid received from a plurality of local controllers; calculating, with the state estimator, a first gain matrix based on a Gauss-Newton method; updating, with the state estimator, the state estimate based on the first gain matrix; calculating, with the state estimator, a second gain matrix based on Newton's method; updating, with the state estimator, the state estimate based on the second gain matrix; and iteratively recalculating the second gain matrix and updating the state estimate based on the second gain matrix until the state estimate converges.

Adaptive state estimation for power systems

The present application relates generally to Volt-VAR optimization for power distribution systems having advanced metering infrastructure (AMI). Distributed energy resources (DER) such as photovoltaic arrays are becoming prevalent in distribution systems. These DER systems inject power into the distribution system which can cause unfavorable changes, such as a rise in voltage across the feeder lines of the distribution system. Existing control proposals suffer from a number of shortcomings, drawbacks and disadvantages. In some instances, traditional controllers for distribution systems with DER systems may require information related to the arrangement of the distribution system which is unknown and cannot be provided by the advanced metering infrastructure. There remains a significant need for the apparatuses, methods, systems and techniques disclosed herein.

AMI based volt-VAR optimization using online model learning

Apparatuses, method and systems featuring model predictive voltage and VAR controls with coordination with and optional optimization of autonomous reactive power control such as autonomous distributed energy resource and/or autonomous switched capacitor banks One embodiment includes an electronic control system structured to construct a linearized model of the power distribution system including a plurality of predetermined nodes, operate a model predictive controller to identify optimized control commands using an objective function defined over a plurality of future scenarios over a look ahead time horizon and a plurality of constraints, and transmit the identified control commands to control operation of at least the voltage regulators and the switched capacitor banks.

Hierarchical robust model predictive voltage and VAR control with coordination and optimization of autonomous DER voltage control

Fault analysis for an electric network having a plurality of multi-phase buses is performed by computing equivalent circuits for the multi-phase buses of interest. Each equivalent circuit includes an N&#xd7;N impedance matrix, N corresponding to the number of phases of the multi-phase bus for which that equivalent circuit is computed. Elements of the impedance matrices are determined based on voltages resulting from a plurality of experimental current injection vectors and a factorized pre-fault admittance matrix. The pre-fault admittance matrix represents nodal admittance of the multi-phase buses without faults. A fault current injection vector for each multi-phase bus and fault type of interest is determined based on the equivalent circuit determined for that multi-phase bus. A fault voltage vector for each multi-phase bus and fault type of interest is determined based on the factorized pre-fault admittance matrix and the fault current injection vector determined for that multi-phase bus and fault type.

Fault analysis in electric networks having a plurality of multi-phase buses

According to one aspect of the teachings herein, various feeder connection arrangements and architectures are disclosed, for collecting electricity from wind turbines in an offshore collection grid that operates at a fixed low frequency, e.g., at one third of the targeted utility grid frequency. Embodiments herein detail various feeder arrangements, such as the use of parallel feeder connections and cluster-based feeder arrangements where a centralized substation includes a common step-up transformer for outputting electricity at a stepped-up voltage, for low-frequency transmission to onshore equipment. Further aspects relate to advantageous generation arrangements, e.g., tower-based arrangements, for converting wind power into electrical power using, for example, medium-speed or high-speed gearboxes driving generators having a rated electrical frequency for full-power output in a range from about 50 Hz to about 150 Hz, with subsequent conversion to the fixed low frequency for off-shore collection.

Method and apparatus for obtaining electricity from offshore wind turbines

The teachings herein disclose an advantageous method and apparatus for performing Security Constrained Economic Dispatch (SCED) for a hybrid power system that includes one or more AC grids interconnected with one or more multi-terminal High Voltage DC (HVDC) grids. The teachings include optimizing a non-linear objective function, subject to a set of constraints that include AC and DC grid constraints, for determining the SCED solution using successive linear approximation. The linear programming model used in the linear approximations is advantageously augmented with a DC grid portion in a manner that accounts for the effects of the DC grid on the AC grid, but which does not require exposing proprietary DC grid modeling details, and which conforms the resultant SCED solution to all applicable AC and DC grid constraints, including AC grid line flow constraints, AC grid power balance constraints, DC grid line flow constraints, and DC grid power balance constraints.

Method and apparatus for security constrained economic dispatch in hybrid power systems

A power system grid is decomposed into several parts and decomposed state estimation steps are executed separately, on each part, using coordinated feedback regarding a boundary state. The achieved solution is the same that would be achieved with a simultaneous state estimation approach. With the disclosed approach, the state estimation problem can be distributed among decomposed estimation operations for each subsystem and a coordinating operation that yields the complete state estimate. The approach is particularly suited for estimating the state of power systems that are naturally decomposed into separate subsystems, such as separate AC and HVDC systems, and/or into separate transmission and distribution systems.

Power system state estimation using a two-level solution

A power distribution system has a plurality of reactive power resources including capacitor banks and distributed energy resources connected to branches of the power distribution system. Power loss is reduced in the distribution system by determining discrete switch states for the capacitor banks and continuous set points for the distributed energy resources, so that the reactive power provided by the reactive power resources reduces power loss while optionally correcting voltage violations in the power distribution system when the capacitor banks are set in accordance with the respective discrete switch states and the distributed energy resources are operated at the respective continuous set points. The range of values for the continuous set points is constrained based on maximum and minimum reactive power limits for each distributed energy resource under consideration.

Power distribution system loss reduction with distributed energy resource control

A voltage regulation optimization (VRO) system receives inputs from a DCS or other distribution network control/monitoring system. The VRO then calculates optimized control commands for various network devices including the controllable taps of voltage regulating transformers.

Voltage regulation optimization

A method is described for collecting inference execution events from forward-chaining business rule engines and constructing causality network graphs for visual presentation to an end user. Using the causality network graph, the user may navigate logic paths leading to particular conclusions or actions.

Method of constructing causality network graphs and visual inference presentations for business rule applications

A method and computer program product for optimization of large scale resource scheduling problems. Large scale resource scheduling problems are computationally very hard and extremely time consuming to solve. This invention provides a Lagrangian relaxation based solution method. The method has two distinct characteristics. First, the method is formal. It is completely structure-based and does not use any problem domain specific knowledge in the solution process, either in the dual optimization or the primal feasibility enforcement process. Second, updating the Lagrangian multipliers after solution of every sub-problem without using penalty factors results in fast and smooth convergence in the dual optimization. The combination of high quality dual solution and the structure-based primal feasibility enforcement produces a high quality primal solution with very small solution gap. An optimal solution is first found to the dual of the resource scheduling problem by sequentially finding a solution to a plurality of sub-problems and updating a set of values used in the dual problem formulation after each sub-problem solution is obtained. Coupling constraint violations are systematically reduced and the set of values are updated until a feasible solution to the primal resource scheduling problem is obtained. An initial set of multiplier values is further determined by solving a relaxed version of the primal problem where most of the local constraints except the variable bounds are relaxed.

Growing community of inventors

Cary, NC, United States of America

Xiaoming Feng