Solar PV AC Source Power Blending Controller
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Solution Overview
Problem
Commercial and industrial motor loads connected to the grid through variable frequency drives (VFDs) remain significant energy consumers, despite the use of incentives for energy efficiency, and existing grid-tied solar inverters require complex regulatory processes and export solar power to the grid, limiting flexibility and backup capabilities.
Innovation Solution
A Power Blending controller system that manages multiple parallel solar PV arrays to provide a DC output power connected to the DC port of VFDs, blending solar and AC power at the DC link level, allowing for real-time management of maximum power generation and voltage stability, enabling direct offset of AC consumption without grid export and providing backup power during grid shutdowns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If solar PV is connected to the grid via inverter, then solar power can be exported to the grid, but system efficiency is reduced due to AC conversion and regulatory complexities increase
Solution Approach 1:
The patent extracts the solar PV connection from the grid-tied inverter path and directly connects it to the VFD's DC port. This removes the unnecessary AC conversion step and grid export requirement, directly addressing the efficiency loss and regulatory complexity issues by taking out the problematic intermediate components (inverter and grid connection) while preserving the core function of power delivery to the load.
Solution Approach 2:
Instead of the conventional approach of converting solar DC to AC through an inverter for grid export, the patent inverts the approach by directly utilizing the solar DC power at the VFD's DC port. This inversion eliminates the DC-to-AC conversion loss and the associated regulatory requirements, achieving both efficiency improvement and complexity reduction.
2Loss of energy
If solar PV directly offsets AC consumption at load level, then energy efficiency increases, but backup power capability during grid shutdowns is limited
Solution Approach 1:
The patent incorporates an energy storage system (battery) that预先 stores energy during periods when solar power is abundant and grid power is available. This preliminary action ensures that when the grid shuts down, the stored energy can immediately support the load through the VFD, maintaining backup power capability while preserving the efficiency benefits of direct solar-to-DC connection.
Solution Approach 2:
The energy storage system acts as a cushion or buffer between the solar PV source and the load. It absorbs excess solar energy when available and releases it when the grid fails, providing beforehand protection against power interruptions. This cushioning mechanism ensures continuous operation during grid shutdowns while maintaining the efficient direct solar connection architecture.
3Productivity
If multiple parallel solar PV arrays are managed, then maximum power generation is achieved, but DC link voltage stability becomes more difficult to maintain
Solution Approach 1:
The patent implements a control system that continuously monitors the DC link voltage and the output of each solar PV array. Based on this feedback, the controller dynamically adjusts the operating point of each array and the switching of the DC-DC converter to maintain stable DC link voltage. This feedback mechanism enables the system to handle multiple parallel arrays while preserving voltage stability.
Solution Approach 2:
The patent employs a dynamic DC-DC converter that can adapt its switching duty cycle and conversion ratio in real-time based on the combined output of multiple solar arrays and the instantaneous load requirements. This dynamic adjustment capability allows the system to maximize power extraction from multiple arrays while actively maintaining DC link voltage stability through continuous adaptation.
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 system efficiently reduces grid energy consumption by directly using solar power to offset AC loads, eliminates the need for grid export, and ensures continuous operation of AC loads during grid failures by utilizing stored solar energy, enhancing energy efficiency and reducing regulatory complexities.
Implementation Method 1
a second input for connection to a solar array, the voltage of the solar array being regulated at a pre-set value to match a maximum power voltage of the solar PV panels
Implementation Method 2
the solar array coupled through a DC-DC converter to the energy blending node, the energy blending node providing power to a load interface device
Implementation Method 3
an energy storage system having a battery coupled either directly to the energy blending node or through a bidirectional energy storage interface to the energy blending node
Data Source
AI summary
An energy blending device has a first input for alternating current, a second input for connection to a solar array, and an output, the energy blending device receiving energy from the first input, both inputs coupled to power an energy blending node. The device is in a configuration either with the solar array matching a voltage of the energy blending node, the blending node providing power through a DC-DC converter to a load interface device, and the solar array coupled through a DC-DC converter to the energy blending node, the energy blending node providing power to a load interface device. A microcontroller controls the DC-DC converter and a load interface device. The energy blending device has an energy storage system having a battery coupled either directly to the energy blending node or through a bidirectional energy storage interface to the energy blending node.