Mechanical Switching Reactive Power Compensation with Preliminary Detection
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Solution Overview
Problem
Existing reactive power compensation systems for AC voltage networks, such as those in offshore wind farms, require high control dynamics to address sudden voltage fluctuations but are expensive due to the use of fast-responding power semiconductor switches, while mechanical switching units are slow and previously deemed unsuitable.
Innovation Solution
A device with mechanical switching units that connect or disconnect inductive or capacitive loads in discrete steps, determining network characteristics to estimate the necessary number and type of switching branches for reactive power compensation, avoiding iterative switching and using mechanical switches to meet control dynamics requirements at a lower cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If power semiconductor switches are used for reactive power compensation, then control dynamics are improved, but device cost increases
Solution Approach 1:
The system performs preliminary detection of voltage changes and network characteristics before executing reactive power compensation. By detecting voltage deviations and calculating required reactive power in advance, the system prepares switching commands that account for mechanical switch response time, enabling cost-effective mechanical switches to achieve the required 90% reactive power provision within 1 second without needing expensive semiconductor switches
Solution Approach 2:
The system dynamically adapts its control strategy based on detected network characteristics. By continuously monitoring voltage changes and adjusting reactive power compensation in discrete steps according to actual network conditions, the system optimizes the performance of mechanical switches to meet dynamic response requirements without requiring fast-responding semiconductor switches
2Ease of manufacture
If mechanical switching units are used for reactive power compensation, then device cost decreases, but control dynamics worsen
Solution Approach 1:
The control unit calculates the required reactive power compensation and determines the appropriate switching commands in advance based on detected voltage changes. This preliminary calculation compensates for the mechanical switching delay by preparing the correct number of switching branches to be activated, ensuring that despite the slower mechanical response, the system meets the 90% reactive power provision requirement within 1 second
Solution Approach 2:
The system continuously detects voltage changes at the network connection and uses this feedback to adjust reactive power compensation. By monitoring voltage deviations and comparing them against control characteristics, the system dynamically adjusts switching commands to maintain voltage within acceptable ranges, compensating for the slower mechanical switch response through continuous closed-loop control
3Adaptability or versatility
If iterative switching of switching branches is performed, then adaptive control is improved, but switching operations and time consumption increase
Solution Approach 1:
The control unit calculates the required reactive power compensation and determines the exact number and type of switching branches to be activated in a single step based on detected voltage changes and network characteristics. This preliminary calculation eliminates the need for iterative switching by directly computing the optimal switching configuration, thereby reducing switching time and operational complexity while maintaining adaptive control
Solution Approach 2:
The reactive power compensation system is divided into multiple discrete switching branches with different impedance values. By segmenting the compensation capacity into distinct controllable units, the system can selectively activate specific branches based on calculated requirements, achieving precise adaptive control without needing iterative adjustments
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a device (1) for exchanging electrical power with an AC voltage supply system (9). The prior art discloses a device which has a supply system connection (8) for connection of the AC voltage supply system (9), a main system (2) which is connected to the supply system connection (8) and provides an electrical power which can be fed to the AC voltage supply system (9), a reactive power compensation system (3) having a plurality of switching branches (13, 14) which each have a unit (17, 18) with a capacitive or inductive impedance and can be connected to the supply system connection (8) in parallel with the AC voltage supply system (9) by means of a controllable switching unit (7), and a regulation unit (10, 16) for regulating the exchange of power, wherein the regulation unit (10, 16) has a regulation characteristic curve which is used to determine a reactive power ?Q which is to be exchanged and which sets a desired change ?V in voltage at the supply system connection unit (8). So that a device (1) of this kind meets the requirements for regulation dynamics and is cost-effective at the same time, the invention proposes that each switching unit is a mechanical switching unit (7) and the regulation unit (10, 16) has probing means which are designed to detect a supply system characteristic of the connected AC voltage supply system (9), and the switching branches (13, 14) to be switched are defined on the basis of the ascertained supply system characteristic.