Reactive Power Compensator Voltage Balancing Control
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Solution Overview
Problem
Reactive energy compensators face performance degradation and potential deactivation due to imbalances between the first and second voltages of inverters, which are exacerbated by transient states caused by electrical disturbances, and existing solutions are inadequate in terms of correction speed.
Innovation Solution
A reactive energy compensator with a control system that includes a voltage correction unit capable of generating a balancing current vector to reduce the difference between the first and second voltages, using a combination of capacitors and controllable electronic switches, and a control signal correction mechanism to rapidly adjust the output current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional control algorithms are used to correct voltage imbalances, then the compensator can operate, but the correction speed is too slow during transient states
Solution Approach 1:
The control system calculates a correction current in advance based on the detected voltage imbalance between the two DC buses. This preliminary calculation allows the system to prepare the corrective action before the transient state fully develops, enabling faster response when the imbalance occurs. The correction current is computed using the formula Icorr = k(V1 - V2), where k is a gain factor, V1 and V2 are the voltages of the two buses, allowing the system to proactively address imbalances rather than reactively correcting them after they fully manifest.
Solution Approach 2:
The system continuously monitors the voltages of the two DC buses and uses this feedback to dynamically adjust the correction current. The control unit compares the actual voltage values with the desired balanced state and automatically generates corrective switching signals for the electronic switches. This closed-loop feedback mechanism ensures that the correction speed adapts to the severity and duration of the imbalance, maintaining reliability while maximizing balancing speed during transient states.
2Productivity
If the inverter continues to operate with voltage imbalance, then operation is maintained, but performance degrades and deactivation may occur
Solution Approach 1:
The system detects voltage imbalances early and applies correction current before the imbalance reaches critical levels that would cause deactivation. By continuously monitoring the voltage difference between the two DC buses and applying corrective action through the electronic switches, the system cushions against the harmful effects of prolonged imbalance. This preventive approach allows the compensator to maintain operation during transient states without performance degradation, as the correction current counteracts the imbalance before it can cause damage or trigger protection mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly increases the balancing speed between the voltages of the inverters, effectively mitigating the impact of disturbances and maintaining compensator performance by rapidly correcting voltage imbalances.
Implementation Method 1
at least one voltage inverter connected to the DC voltage bus and capable of converting a DC input current into an AC output current
Implementation Method 2
the or each inverter comprising in addition to a first capacitor having a first voltage at its terminals and a second capacitor having a second voltage at its terminals, the two capacitors being connected in series between the two input terminals of the inverter
Data Source
Figure 1~3
Figure 2
Figure 4~5
AI summary
This reactive power compensator (10), suitable for electrical connection to an alternating current electrical network (12), comprises: - at least one DC input voltage bus (18), - at least one voltage inverter (20), the inverter or each inverter (20) comprising switches (34), the inverter or each inverter (20) further comprising a first capacitor (C1) presenting a first voltage (VDC1) across its terminals and a second capacitor (C2) presenting a second voltage (VDC2) across its terminals, - means (22) for controlling the switches (34), comprising calculation means for generating a target control current, means for combining the target control current and the current at the output of the inverter (20), means for emitting a control signal suitable for driving the switches (34), and means for correcting the control signals of the switches (34).The correction means are designed to reduce the difference between the value of the first voltage and that of the second voltage. The correction means are designed to add a balancing current to the target control current, the balancing current being designed to correct the target control current in order to reduce the difference between the values of the first (VDC1) and second (VDC2) voltages, the target control current being increased for an even harmonic of the network frequency.