Voltage Source Inverter Control via Frequency-Linked Parallel Regulator
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Solution Overview
Problem
Existing methods for controlling self-commutated converters connected to AC voltage networks lack effective stabilization of the AC voltage grid, which is crucial for maintaining grid stability during power transmission.
Innovation Solution
The method involves using a parallel controller to determine the converter control voltage as a function of both active and frequency control differences, with the orthogonal component regulating active power and the parallel component regulating reactive power, thereby stabilizing the AC voltage network by linking power and frequency control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If self-commutated converters independently set up the AC voltage grid without centralized control, then each converter can operate autonomously, but the AC voltage network lacks effective stabilization and grid stability deteriorates
Solution Approach 1:
Each converter independently determines its own control voltage using local measurements of network voltage and converter current, combined with locally stored setpoint values for active power and frequency. The converters self-regulate by calculating control differences and adjusting their output without external control signals, enabling autonomous operation while maintaining grid stability through distributed control logic.
2Length of stationary object
If converters are connected over large distances in the AC voltage network, then the coverage area and transmission capability increase, but the complexity of maintaining stable operation increases
Solution Approach 1:
The control method continuously measures actual network voltage and converter current at each converter location, compares these measurements with stored setpoint values for active power and frequency, and adjusts the converter control voltage based on the calculated control differences. This closed-loop feedback mechanism compensates for disturbances and maintains stable operation even over large transmission distances.
3Device complexity
If the converter control voltage is determined using only active power control, then the control system is simple, but reactive power exchange and frequency stabilization are insufficient
Solution Approach 1:
The converter control voltage is segmented into two orthogonal components: a first component (parallel to network voltage) that controls reactive power exchange and frequency stabilization, and a second component (orthogonal to network voltage) that controls active power exchange. This segmentation allows independent optimization of each control function while maintaining overall system simplicity through modular control structure.
Data Source
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AI summary
The invention relates to a method for regulating a self-commutated converter that can be connected on the AC side to an AC network via an inductive component, wherein: an actual power value and an actual frequency value are determined from a network voltage measured on the AC side of the converter and from a converter current measured at the converter; an active power regulation difference is formed as the difference between an active power portion of the actual power value and a desired active power value, and a frequency regulation difference is formed as the difference between the actual frequency value and a predefined desired frequency value; an orthogonal portion of a converter control voltage is determined by means of an orthogonal regulator in accordance with the active power regulation difference, wherein an active power exchanged between the converter and the AC network is determined by means of the orthogonal portion, a parallel portion of the converter control voltage is determined by means of a parallel regulator in accordance with the active power regulation difference, wherein a reactive power exchanged between the converter and the AC network is determined by means of the parallel portion. The method is characterised in that the frequency regulation difference is supplied to the parallel regulator, such that the determining of the parallel portion of the converter control voltage is carried out in accordance with the frequency regulation difference. The invention also relates to a self-commutated converter for transmission with a regulation unit for regulating the transmitted power, which is designed to carry out the method according to the invention.