Power Blending Controller for Solar Grid Stability

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Solution Overview

Problem

Rising residential and commercial electricity prices, particularly for air conditioning and pump loads, and the instability caused by the increasing number of solar photovoltaic (PV) systems connected to the AC grid, which can lead to grid instability due to bidirectional power flow issues.

Innovation Solution

The Power Blending Controller (PBC) combines solar PV power with AC sources like the electrical grid, diesel, wind, or micro-hydro turbines, and includes an energy storage component to ensure uninterrupted power supply by blending energy from multiple sources, minimizing grid usage during peak hours and stabilizing the grid.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If solar PV systems are connected to the AC grid with net metering, then the number of installed solar systems increases, but grid stability deteriorates due to bidirectional power flow issues

Engineering Contradiction:

Improvenumber of solar PV installationsVSAvoidgrid stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system segments the power flow control by separating the solar PV input from the grid output through a dedicated controller that manages power conversion independently. The solar PV array is processed through a DC-DC converter and DC-AC inverter with anti-islanding protection, isolating the bidirectional flow issues from the main grid while allowing solar installations to increase without compromising grid stability.

Inventive Principle:

Principle #1Segmentation

2Productivity

If power is drawn from the grid during peak hours, then the load operates continuously, but electricity costs increase

Engineering Contradiction:

Improveload operation continuityVSAvoidelectricity cost

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The system performs preliminary action by storing energy in batteries during off-peak hours when electricity rates are lower. The controller charges the battery bank during nighttime or low-demand periods, then discharges during peak hours to replace expensive grid power, thereby reducing electricity costs while maintaining continuous load operation.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If solar PV power is used directly without energy storage, then the system complexity is reduced, but power supply reliability deteriorates during non-sunny periods

Engineering Contradiction:

Improvesystem structureVSAvoidpower supply continuity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system introduces an intermediary energy storage system (battery bank) between the solar PV array and the load. The controller manages power flow between the solar PV, battery, and load, allowing the system to maintain reliability during non-sunny periods by switching to battery power, while keeping the overall structure manageable through centralized control.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Productivity

If the solar array voltage is increased to match grid voltage, then power transfer efficiency improves, but the risk of islanding and grid instability increases

Engineering Contradiction:

Improvepower transfer efficiencyVSAvoidislanding risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system employs feedback control through the DC-AC inverter controller that continuously monitors grid presence and voltage conditions. Anti-islanding protection mechanisms detect grid failures and automatically disconnect the solar PV output, preventing islanding while maintaining efficient power transfer during normal grid operation through regulated voltage matching.

Inventive Principle:

Principle #23Feedback

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 PBC provides a stable and cost-effective power solution by ensuring 100% of the load power is met from blended sources, reducing grid usage during peak hours and maintaining uninterrupted operation, thereby minimizing electricity bills and grid instability risks.

Implementation Method 1

solar photovoltaic (PV) installs

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Implementation Method 2

the solar array coupled through a DC-DC converter to the energy blending node

Methodology Applied

Scientific EffectElectrical energy conversion:

Implementation Method 3

a rectifier receiving the first input, the rectifier coupled through a first DC-DC converter configured for power factor correction

Methodology Applied

Scientific EffectRectification:

Data Source

PatentUS11171486B2Solar PV and AC source power blending controller

Publication Date: 2021.11.09 THUNDERBIRD SOLAR SUPPLY LLC

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.