Shared Integrator Control Channels for Stable Power System Transitions

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Solution Overview

Problem

Existing control systems for power systems, such as microgrids, experience transient fluctuations and transients during transitions between multiple PID controllers, leading to equipment damage, contractual breaches, and increased time consumption due to complex initialization processes.

Innovation Solution

A control system with multiple control channels sharing a single integrator, allowing seamless transitions without initialization, maintaining independent gain sets, and avoiding significant transients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple independent PID controllers are used to control different functions (frequency control and power control), then each controller can be independently tuned with separate gain sets, but transient fluctuations occur during transitions between controllers causing equipment damage and contractual breaches

Engineering Contradiction:
ImproveIndependent control capabilityVSAvoidTransition stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent merges multiple independent PID controllers into a single unified controller that can handle both frequency control and power control functions. This is achieved by integrating the control algorithms and sharing the integrator state, allowing seamless transitions without the transient fluctuations that occur when switching between separate controllers. The unified controller maintains independent gain sets for different functions while eliminating the harmful transients during mode transitions.

Inventive Principle:
Principle #5Merging (Combining)

2Adaptability or versatility

If separate integrators are used in each PID controller to maintain independent control, then each controller can operate autonomously, but complex initialization logic is required to avoid transients during controller transitions

Engineering Contradiction:
ImproveController independenceVSAvoidInitialization logic
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple separate integrators into a single shared integrator that serves all PID controllers. This shared integrator maintains a unified state that is accessible to all control functions, eliminating the need for complex initialization logic during transitions. The integrator state is preserved and shared across different control modes, allowing seamless switching without requiring pre-transition initialization procedures.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If initialization logic is implemented to prevent transients during controller transitions, then equipment damage is avoided, but engineering time and transition time are significantly increased

Engineering Contradiction:
ImproveEquipment protectionVSAvoidTransition time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent prepares the control system in advance by establishing a unified integrator state that is valid for all control modes before transitions occur. This preliminary setup ensures that when a transition between frequency control and power control is needed, the integrator state is already properly configured, eliminating the need for time-consuming initialization procedures during the actual transition moment.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If additional initialization logic is added to PID controllers to avoid transients, then transition stability improves, but controller complexity and communication requirements increase

Engineering Contradiction:
ImproveTransition stabilityVSAvoidController structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent simplifies the overall controller structure by merging multiple independent PID controllers with separate integrators into a single unified controller with a shared integrator. This consolidation reduces the complexity of initialization logic and communication requirements while maintaining transition stability, as the shared integrator naturally provides consistent state information across all control functions without requiring additional synchronization mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4625746A1A control system for a power system comprising at least two control channels and a common integrator
Publication Date: 2025.10.01 HITACHI ENERGY LTD
  • EP4625746A1 patent drawingFigure 1
  • EP4625746A1 patent drawingFigure 2a
  • EP4625746A1 patent drawingFigure 2b

AI summary

Embodiments of the present disclosure provide a control system (100) for controlling unit of a power system (1000). The control system (100) comprises at least two control channels (102) with different control targets. Each control channel (102) of the at least two control channels (102) is arranged to perform one or more control operations for controlling the unit of the power system (1000). Further, at least one control operation is performed as a response to a respective input signal received from the power system (1000). Each of the at least two control channels (102) is connected to a merged control output to the unit of the power system (1000) through a shared integrator (104).