Three-Port DC/AC Converter for Grid Regulation
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Solution Overview
Problem
Existing DC/AC power converters cannot participate in grid voltage and frequency regulation without affecting the operation of the DC port, limiting their ability to provide continuous demand response and frequency response, especially in applications like wind and solar power systems.
Innovation Solution
A DC/AC converter with a storage port is introduced, allowing for grid regulation by varying the storage voltage within a specified range while maintaining a constant DC port voltage, using a three-port converter topology and universal droop control to manage power exchange with the grid without increasing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a DC/AC converter is used for grid regulation, then voltage and frequency regulation capability is improved, but the DC port operation is affected
Solution Approach 1:
The converter is divided into two independent control loops: one for AC port grid regulation and another for DC port voltage maintenance. This segmentation allows each port to be controlled independently, enabling the converter to participate in grid voltage and frequency regulation while maintaining stable DC port operation without interference between the two functions.
Solution Approach 2:
A storage element (capacitor or battery) is introduced as an intermediary between the AC and DC ports. This storage element acts as a buffer that decouples the two ports, allowing power exchange with the grid at the AC port while maintaining constant voltage at the DC port, thus enabling grid regulation without affecting DC port operation.
2Productivity
If conventional DC/AC converters operate, then power conversion is achieved, but continuous demand response and frequency response are limited
Solution Approach 1:
The converter employs dynamic control strategies including droop control and virtual synchronous machine emulation, allowing it to continuously adjust its operation in response to grid conditions. This dynamic capability enables continuous demand response and frequency response participation, transforming the converter from a static power conversion device to an active grid regulation participant.
Solution Approach 2:
The converter dynamically changes operating parameters such as impedance, power factor, and reactive power output in response to grid voltage and frequency deviations. These parameter changes enable continuous adaptation to grid conditions, allowing the converter to provide continuous demand response and frequency response without interruption.
3Reliability
If DSM methods are used for demand-side regulation, then grid stability improvement is achieved, but digital communication infrastructure and human action are required
Solution Approach 1:
The converter is equipped with autonomous control capabilities including droop control and virtual synchronous machine emulation, enabling it to automatically respond to grid voltage and frequency deviations without external communication or human intervention. The converter monitors grid conditions and self-adjusts its operation to provide demand response and frequency response, making the system self-regulating and eliminating the need for complex communication infrastructure.
Solution Approach 2:
The converter implements local feedback control by continuously monitoring grid voltage and frequency and automatically adjusting its power output accordingly. This closed-loop feedback mechanism enables the converter to respond directly to grid conditions in real-time, providing grid stability support without requiring external communication signals or human action.
Data Source
AI summary
This invention discloses a DC/AC power electronic converter system that takes part in the regulation of grid voltage and frequency without affecting the normal operation of the DC port, which is either connected to a load when operated as a rectifier or to a DC source when operated as an inverter. In addition to the normal DC and AC ports of a DC/AC converter, the disclosed converter has an extra port for the connection of storage units. Its controller consists of a storage voltage controller to make sure that the storage voltage VDC does not exceed the specified range, a power controller to interact with the grid, and an inner-loop controller that takes the grid voltage and/or the grid current as the feedback. This turns the disclosed converter into a continuous reserve. It enables rectifier-fed loads to provide continuous demand response and inverter-fed sources to provide continuous frequency response. Possible applications include any field that adopts a DC/AC converter, e.g. in wind power, solar power, storage systems, home appliances, IT equipment, motor drives, electric vehicles, and LED lights.