Voltage Source Converter Harmonic Compensation for Thyristor Reactors
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Solution Overview
Problem
Existing reactive power compensation technologies, such as Thyristor Controlled Reactors (TCRs), Thyristor Switched Reactors (TSRs), and Thyristor Switched Capacitors (TSCs), generate harmonics and cause voltage disturbances, requiring expensive harmonic filters and large footprints, while Voltage Source Converter (VSC) based solutions are costly due to advanced power electronics and control technology.
Innovation Solution
A power compensation arrangement using a voltage source converter connected to thyristor controlled reactors, thyristor switched reactors, or thyristor switched capacitors, which detects requests for reactive power and compensates disturbances, allowing for reduced costs by leveraging less expensive components and minimizing harmonic issues through the VSC's ability to handle harmonics and transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If TCR is used for reactive power compensation, then reactive power control is achieved, but harmonics are generated requiring expensive filter branches
Solution Approach 1:
The patent introduces an intermediary device (active power filter or voltage source converter) between the TCR and the power system. This intermediary actively compensates for the harmonics generated by the TCR, allowing the TCR to provide reactive power compensation while the intermediary cleans up the harmonic emissions, thus resolving the contradiction between achieving reactive power control and avoiding harmonic pollution
2Power
If TCR is used for reactive power compensation, then reactive power control is achieved, but large footprint is required for filter branches
Solution Approach 1:
The patent uses an active power filter or voltage source converter as an intermediary that can provide harmonic compensation in a more compact form factor compared to traditional passive filter branches. This intermediary device actively cancels harmonics through controlled power electronics, reducing the need for large physical filter components and thereby reducing the overall substation footprint while maintaining reactive power compensation functionality
3Object-generated harmful factors
If TSR is used for reactive power compensation, then low order harmonics are avoided, but large current transients cause voltage disturbances
Solution Approach 1:
The patent introduces an intermediary device (active power filter or voltage source converter) that monitors and compensates for the current transients and voltage disturbances caused by TSR switching. This intermediary provides real-time compensation to counteract the voltage disturbances, allowing the TSR to operate with reduced harmonics while the intermediary maintains voltage stability
4Power
If TSC is used for reactive power compensation, then reactive power support is provided, but energizing transients require frequency and amplitude limitation
Solution Approach 1:
The patent uses an active power filter or voltage source converter as an intermediary that detects and compensates for the voltage oscillations and transients caused by TSC energizing. This intermediary provides real-time counteracting signals to dampen the voltage oscillations, allowing the TSC to provide reactive power support while the intermediary maintains voltage stability and prevents overvoltages
5Reliability
If VSC based chain-link technology is used for power compensation, then high performance is achieved, but implementation cost increases
Solution Approach 1:
The patent segments the power compensation function into two parts: a passive thyristor-based component (TCR, TSR, or TSC) that provides the bulk of the reactive power compensation at lower cost, and an active power filter or voltage source converter that provides high-performance harmonic and transient compensation. This segmentation allows the system to achieve high overall performance while reducing implementation costs by using less expensive passive components for the majority of the compensation function
6Adaptability or versatility
If multiple capacitor banks are switched back-to-back, then reactive power flexibility is improved, but overvoltages are generated
Solution Approach 1:
The patent introduces an active power filter or voltage source converter as an intermediary that monitors the voltage conditions during back-to-back capacitor bank switching and provides real-time compensation to counteract the generated overvoltages. This intermediary allows the system to maintain flexible reactive power control through multiple capacitor banks while preventing harmful overvoltages through active compensation
Data Source
AI summary
A method is performed in a control device for controlling a power compensation arrangement including a voltage source converter and one or more power compensation branches, each power compensation branch including a thyristor controlled reactor, a thyristor switched reactor or a thyristor controlled capacitor. The voltage source converter and the one or more power compensation branches are connected to a same busbar. The method includes: detecting a request in an electrical power system to which the power compensation arrangement is connected; determining, based on the request, a need for reactive power supply to the electrical power system; providing reactive power by means of the voltage source converter and/or by one or more of the power compensation branches; and compensating, by means of the voltage source converter, any disturbances caused by the power compensation branches when providing the reactive power to the electrical power system. Corresponding devices are also disclosed.