Distributed Tertiary Frequency Modulation for Grid Balance Recovery

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Solution Overview

Problem

The existing frequency regulation mechanism in power systems relies heavily on secondary frequency modulation, which is vulnerable to central node failures, leading to instability and potential grid frequency imbalances, especially when thermal generating units exhaust their regulation resources.

Innovation Solution

A tertiary frequency modulation method that performs decentralized, distributed active power regulation in power plants, using reserved capacity, primary frequency modulation amounts, or random parameters to correct active power set values, thereby restoring grid frequency balance without relying on a central control node.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If secondary frequency modulation is used to regulate grid frequency, then frequency regulation precision is improved, but system reliability deteriorates due to central node failure vulnerability

Engineering Contradiction:

Improvefrequency regulation precisionVSAvoidsystem reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent segments the centralized frequency regulation function into distributed tertiary frequency modulation units across multiple power plants. Each plant independently calculates and executes frequency regulation based on local measurements, eliminating the single point of failure in centralized control while maintaining regulation precision through coordinated distributed action.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Power plants perform self-service frequency regulation by autonomously measuring grid frequency, calculating required power adjustments, and executing regulation without relying on central dispatch commands. This decentralized self-regulation maintains precision while improving reliability through elimination of central node dependency.

Inventive Principle:

Principle #25Self-service

2Speed

If primary frequency modulation is used for rapid response, then response speed is improved, but frequency regulation precision deteriorates due to deviating regulation

Engineering Contradiction:

Improveresponse speedVSAvoidfrequency regulation precision

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The tertiary frequency modulation performs preliminary calculation of precise power adjustment requirements based on frequency deviation, then guides primary frequency modulation to execute the pre-calculated regulation. This preliminary planning ensures both rapid response from primary modulation and precise final frequency restoration.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by continuously monitoring grid frequency, comparing it with rated frequency, and using the deviation signal to guide both primary and tertiary modulation actions. This closed-loop feedback ensures rapid response while achieving precise frequency regulation through iterative correction.

Inventive Principle:

Principle #23Feedback

3Stability of the object's composition

If thermal generating units are used for primary frequency modulation, then regulation stability is improved, but duration of action deteriorates when regulation resources are exhausted

Engineering Contradiction:

Improveregulation stabilityVSAvoidduration of regulation action

Core Design Contradiction:

Stability of the object's compositionVSDuration of action of moving object

Solution Approach 1:

The tertiary frequency modulation enables continuous frequency regulation by coordinating multiple power plants with different regulation resource characteristics. When thermal units exhaust their regulation resources, the system continuously transitions to and from other plants, ensuring uninterrupted regulation action while maintaining stability through coordinated control.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system achieves multi-functionality by enabling different types of power plants (thermal, hydro, etc.) to participate in frequency regulation based on their available resources. This universal approach allows the system to maintain stable regulation for extended durations by flexibly utilizing diverse regulation resources across multiple plants.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20240313539A1Tertiary frequency modulation method for power system

Publication Date: 2024.09.19 HUANENG LANCANG RIVER HYDROPOWER CO LTD

AI summary

A tertiary frequency modulation method for a power system, AGC based on power plant input performs active power regulation for tertiary frequency modulation in different modes in power plants in case of secondary frequency modulation failure of the power system and unidirectional deviation of grid frequency from rated frequency for a period: perform tertiary frequency modulation based on the reserved capacity of the secondary frequency modulation or the regulation amount of primary frequency modulation or random parameters. The invention relates to tertiary frequency modulation whose action sequence is later than that of the primary frequency modulation and the secondary frequency modulation to realize astatic frequency regulation. Compared with the secondary frequency modulation function, the tertiary frequency modulation function completely gets rid of the dependence on a central node; compared with the primary frequency modulation function, the tertiary frequency modulation method undoubtedly has higher stability and sustainability in the regulation effect.