Remote Transformer Control Using Safe Active and Reactive Power Limits

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Solution Overview

Problem

Existing remote power converter control systems for transformers face challenges due to grid state variability and signal delays, leading to inefficiencies and potential damage from overcurrents.

Innovation Solution

A method for controlling a transformer using a power converter located remotely, employing separate control loops for active and reactive power, with independent control modes to ensure operation within safe operating areas, allowing for hybrid control of the transformer and power converter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If remote power converter control is used to connect power grids and transfer energy, then power transmission capability is improved, but signal delay and grid state variability cause control inefficiency and potential overcurrent damage

Engineering Contradiction:
Improvepower transmission capabilityVSAvoidcontrol efficiency and transformer protection
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent introduces a local control device at the transformer location as an intermediary between the remote power converter and the transformer. This local control device receives control commands from the remote converter and executes them locally, eliminating signal delay issues. It also locally monitors transformer parameters and provides feedback, enabling real-time protection against overcurrent while maintaining the benefits of remote control architecture.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The control system is divided into local and remote components with different functions. The local control device handles time-critical functions like real-time monitoring and protection, while the remote converter handles high-level power management. This localization of control functions ensures that safety-critical operations are not affected by communication delays.

Inventive Principle:
Principle #3Local quality

2Adaptability or versatility

If the power converter is arranged remote from the transformer, then system flexibility and remote control capability are improved, but signal delay and communication issues reduce control precision and response time

Engineering Contradiction:
Improveremote control capabilityVSAvoidcontrol precision and response time
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The local control device acts as an intermediary that receives control commands from the remote converter and executes them locally with precise timing. It also serves as a local measurement point, directly monitoring transformer parameters without communication delay, thereby maintaining high measurement precision and control response time despite the remote converter location.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The local control device is pre-configured with control algorithms and protection settings, enabling it to execute control commands and provide protection immediately without waiting for remote processing. This preliminary preparation ensures fast response time while maintaining remote control capability.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If typical remote power control is used, then remote monitoring is achieved, but state of the grid and signal delay lead to control inefficiency

Engineering Contradiction:
Improveremote monitoring capabilityVSAvoidcontrol efficiency
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The local control device continuously monitors transformer parameters such as current, voltage, and temperature, and provides real-time feedback to both the local control system and the remote converter. This local feedback loop enables immediate detection of abnormal conditions and fast response, dramatically improving control efficiency while maintaining easy remote monitoring capability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The local control device autonomously executes control commands and provides protection without requiring constant remote intervention. It can independently adjust control parameters, detect faults, and trigger protection mechanisms, thereby improving control efficiency while maintaining remote monitoring capability.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4645624A1Method for controlling a transformer by a control device indirectly, control device, system, computer program product and computer-readable storage medium
Publication Date: 2025.11.05 HITACHI ENERGY LTD
  • EP4645624A1 patent drawingFigure 1~2
  • EP4645624A1 patent drawingFigure 3
  • EP4645624A1 patent drawing

AI summary

A method for controlling a transformer by a control device of a power converter is specified, wherein the power converter is arranged remote from the transformer, comprising: - providing remote power information at a location of the transformer (S1), - determining limited remote power information of the transformer dependent on the remote power information and a remote safe operating area (SOArem) of the transformer (S2), - providing local power information at a location of the power converter (S3), and - determining limited local power information of the power converter dependent on the local power information and a local safe operating area (SOAloc) of the power converter (S4), - controlling the transformer dependent on the limited local power information of the power converter (S5), wherein - the limited local power information is characteristic for an active power and a reactive power based on which the power converter is operated, and - a control mode of the active power and the reactive power of the limited local power information are selected independently from one another. Furthermore, a control device, a system, a computer program product and a computer-readable storage medium are specified.