Inverter Plant Controller Grid Frequency Stabilization

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Solution Overview

Problem

Conventional power supply plants without rotating masses, such as those using power-electronic converters, struggle to provide an instantaneous reserve to stabilize AC voltage grids during frequency deviations and phase jumps, as they lack mechanical inertia and overcurrent capabilities.

Innovation Solution

A method involving a power supply plant with multiple inverters and a plant controller that dynamically adjusts the total interchange power by decoupling inverter control and influencing regulator circuits to provide an instantaneous reserve, simulating the behavior of a flywheel mass through droop regulation and reactive power management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If power supply plants use power-electronic converters instead of rotating masses, then device complexity is reduced and adaptability is improved, but the ability to provide instantaneous reserve and stabilize grid frequency is lost

Engineering Contradiction:

ImproveadaptabilityVSAvoidinstantaneous reserve capability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces mechanical flywheel masses with power-electronic converters (inverters) that use control algorithms to simulate inertial behavior. The converters adjust their power output dynamically in response to grid frequency deviations, replicating the stabilizing effect of mechanical inertia without physical rotating masses.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameters of the power-electronic converters by implementing droop regulation and dynamic power adjustment capabilities. The converters modify their power output based on grid frequency deviations, transforming from static devices to dynamic grid-supporting assets that can provide instantaneous reserve.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If power supply plants without rotating masses are used, then ease of manufacture and installation are improved, but overcurrent capability and mechanical storage capability are reduced

Engineering Contradiction:

Improveease of manufactureVSAvoidovercurrent capability

Core Design Contradiction:

Ease of manufactureVSPower

Solution Approach 1:

The patent implements dynamic control of the power-electronic converters with fast response times (sub-millisecond to millisecond range). The converters can rapidly adjust their power output and current injection to provide overcurrent capability during grid disturbances, achieving dynamic performance that compensates for the lack of mechanical inertia.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent introduces control algorithms and regulation mechanisms as intermediaries between the power-electronic converters and the grid. These control systems (including droop regulation and frequency-dependent power adjustment) enable the converters to deliver overcurrent capability and grid support functions traditionally provided by mechanical systems.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If droop regulation is implemented in power-electronic converters, then instantaneous reserve is provided and grid stability is improved, but control complexity and device complexity increase

Engineering Contradiction:

Improvegrid stabilityVSAvoidcontrol complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements feedback control mechanisms where the power-electronic converters continuously monitor grid frequency and adjust their power output accordingly. The droop regulation uses frequency deviations as feedback signals to automatically modulate converter power, creating a self-regulating system that provides grid stability through relatively simple proportional control.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20230187942A1Method for operating a power supply plant, and power supply plant

Publication Date: 2023.06.15 SMA SOLAR TECH AG

AI summary

In a method for operating a power supply plant having a plurality of inverters and a plant controller connected to the inverters for communication, the power supply plant has a grid connection, which is connected to an AC voltage grid. Via the grid connection, the inverters exchange electrical interchange powers with the AC voltage grid such that the power supply plant exchanges a total interchange power, composed of the respective electrical interchange powers, with the AC voltage grid. By means of a respective regulator, the inverters adjust their respective interchange powers depending on a respective deviation of a voltage profile of a grid voltage from a respective reference profile with respect to a respective reference frequency and/or depending on a respective voltage amplitude differential between a respective grid voltage and a respective reference voltage. The plant controller influences the regulators of the inverters depending on a power differential between the total interchange power and a specified interchange power. A power supply plant according to the application is designed to carry out this method.