Inverter Segmentation for Reactive Power in Wind Turbines
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Solution Overview
Problem
Wind power installations face inefficiencies and reduced reactive power infeed when operating at reduced output, as not all inverters are utilized, leading to compromised efficiency and reactive power capabilities during network backup needs.
Innovation Solution
Implementing an inverter-controlled infeed unit with active, passive, and blocked inverters, where active inverters generate power, passive inverters remain connected but non-operational, and blocked inverters can rapidly switch to active mode to provide reactive power when needed, using a central control system to manage inverter operations based on output power levels and network conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If only some inverters are operated at reduced power output, then inverter efficiency is improved, but the maximum reactive power infeed capability is reduced
Solution Approach 1:
The inverter system is segmented into multiple independently controllable inverter units. Each inverter can be individually switched on or off, allowing the system to operate with an optimal number of inverters for active power generation while maintaining all inverters available for reactive power support. This segmentation enables the system to achieve both high efficiency (by operating fewer inverters at optimal load) and high reactive power capability (by having all inverters available for reactive power injection when needed).
Solution Approach 2:
The system dynamically adjusts the operating state of individual inverters based on real-time power output requirements and network conditions. The control unit determines which inverters should be active for power generation and which can be standby, optimizing efficiency while maintaining the capability to provide maximum reactive power support when network faults occur. This dynamic switching allows the system to adapt between efficiency optimization and reactive power support modes.
2Power
If all inverters are operated to maintain maximum reactive power infeed capability, then reactive power support is improved, but inverter efficiency deteriorates
Solution Approach 1:
The inverter system is divided into multiple independently controllable units, allowing selective operation of only the necessary number of inverters for active power generation. This segmentation enables the system to maintain maximum reactive power capability (since all inverters remain available) while improving efficiency by operating fewer inverters at optimal load points during normal operation.
Solution Approach 2:
Each inverter unit is designed with multi-functionality, capable of both active power generation and reactive power support. This universality allows the system to achieve maximum reactive power infeed capability using all inverters when needed, while during normal operation only a subset of inverters needs to be active, thereby maintaining efficiency. The same hardware serves dual purposes under different operating conditions.
3Power
If a compromise approach is used with more than necessary inverters operating, then reactive power infeed is improved, but overall infeed efficiency is reduced
Solution Approach 1:
By segmenting the inverter system into individually controllable units, the patent enables precise optimization of the number of active inverters. This eliminates the need for compromise approaches, as the system can operate with the exact minimum number of inverters required for active power generation while maintaining the capability to provide maximum reactive power support. This precise control achieves both high efficiency and adequate reactive power capability without the efficiency penalties of compromise solutions.
Solution Approach 2:
The system dynamically changes operational parameters (which specific inverters are active, their power output levels) to optimize efficiency while maintaining reactive power capability. By adjusting these parameters based on real-time conditions, the system avoids the fixed compromise approach and achieves optimal performance for each operating scenario.
Data Source
AI summary
A method for feeding electrical power into an electrical supply network using an inverter-controlled infeed unit is provided. The infeed unit has an inverter arrangement with a plurality of inverters to generate an output power and feed same into the network. Each inverter has an associated isolating switch to galvanically isolate the respective inverter from the network. Each inverter has a circuit composed of switches to generate an output current using pulsed actuation. Each inverter generates a variable partial power, and the output power is a sum of all partial powers. Depending on the output power, one or more of the inverters are operated as active inverters that respectively generates a partial power. The other inverters are operated as passive inverters that do not generate a partial power. One or more of the passive inverters are operated as blocked inverters and remain galvanically connected to the network.