Active Compensator Circuit for Power Grid Resonance Suppression
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Solution Overview
Problem
In distributed power generation systems, the interaction between grid impedance and switching power converter output impedance can lead to system instability due to resonance, causing coupling between power sources and controllers, which results in unfavorable phase differences and intersection frequencies.
Innovation Solution
An active compensator circuit is connected between power sources and the point of common coupling in the power grid, detecting electrical properties to provide a voltage output that emulates a resistor to suppress filter resonance and reduces equivalent impedance, using a bi-directional power converter with a controller to regulate voltage and generate gating signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If distributed power sources are coupled with switching power converters to provide power to the grid, then power generation capability is improved, but system instability occurs due to resonance between grid impedance and converter output impedance
Solution Approach 1:
An active compensator circuit is introduced as an intermediary component between the distributed power sources and the point of common coupling. This compensator detects electrical properties (voltage and current) and generates a compensating voltage output that acts as a mediator to counteract the harmful resonance effects, allowing the system to maintain both high power generation capability and stability simultaneously
2Productivity
If grid impedance and converter output impedance interact, then power transfer occurs, but resonance is excited around transfer function complex conjugate poles causing coupling between power sources and controllers
Solution Approach 1:
The compensator circuit converts the harmful resonance effect into a beneficial control action. By detecting the electrical properties and generating a compensating voltage that is 180 degrees out of phase with the resonance, the system transforms the harmful resonant interaction into a damping effect that suppresses oscillations while maintaining power transfer
3Stability of the object's composition
If additional power filters are added to suppress resonance, then system stability is improved, but device complexity and cost increase
Solution Approach 1:
The invention replaces traditional passive mechanical/electrical filter systems with an active control-based compensator circuit. Instead of using bulky inductors and capacitors to form passive filters, the system uses active voltage generation and control to achieve resonance suppression, significantly reducing device complexity while maintaining or improving stability performance
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
This solution effectively dampens filter resonance and cancels grid impedance without requiring knowledge of grid parameters, improving system stability and eliminating the need for additional power filters, while being applicable to both AC and DC power grids.
Implementation Method 1
suppressing filter resonance associated with the one or more power sources
Implementation Method 2
voltage source inverter coupled with each of the PV strings
Data Source
AI summary
An electric circuit for regulating power transfer in a power grid includes a compensator circuit arranged to be connected between outputs of one or more power sources and a point of common coupling in the power grid. The compensator circuit is arranged to detect one or more electrical properties associated with the outputs and one or more electrical properties associated with the point of common coupling; and provide, based on the detection, a voltage output to emulate a resistor for suppressing filter resonance associated with the one or more power sources and to reduce equivalent impedance of the power grid.