Hydraulic PV AC Supply Without Inverters for Low Harmonic Output
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Solution Overview
Problem
Conventional electronic power inverters used in photovoltaic systems produce AC electricity with total harmonic distortion and lack inertia, leading to power quality issues and susceptibility to thermal damage, making them costly and complex to integrate with power grids.
Innovation Solution
A hydraulically-coupled motor generation system that converts DC electricity from photovoltaic systems to AC electricity without electronic power inverters, utilizing a motorized pump, water turbine, and electric generator to produce a cleaner waveform with inherent ride-through capability and inertia, allowing for efficient energy storage and reduced grid integration costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electronic power inverters are used to convert DC to AC electricity, then the conversion function is achieved, but the AC electricity suffers from total harmonic distortion and power quality degradation
Solution Approach 1:
The patent replaces electronic power inverter components with a mechanical hydraulic system consisting of a DC motor, water pump, elevated water tank, and water turbine. This mechanical-hydraulic substitution eliminates the electronic switching components that generate harmonic distortion, producing a cleaner sine wave AC output through the natural mechanical rotation of the turbine-driven generator.
Solution Approach 2:
The patent employs a hydraulic energy storage system where a DC motor drives a water pump to store water in an elevated tank. During power generation, water flows from the elevated tank through a turbine connected to an AC generator. The hydraulic system provides inherent inertia and smooth energy conversion, eliminating the need for electronic power electronics and their associated harmonic distortion problems.
2Reliability
If electronic power inverters with switching components are used, then DC to AC conversion is achieved, but the components are susceptible to thermal damage from electromagnetic transients
Solution Approach 1:
The patent replaces fragile electronic switching components (weighing a gram or less) with robust mechanical-hydraulic components including a DC motor, water pump, elevated water tank, and water turbine. These mechanical components have inherent thermal mass and inertia, making them resistant to thermal damage from electromagnetic transients such as lightning strikes or grid faults.
Solution Approach 2:
The elevated water tank serves as a physical cushion of stored gravitational potential energy that provides ride-through capability during grid disturbances. The hydraulic system's inherent inertia and the mass of water in the elevated tank absorb and dampen transient shocks, protecting the system from thermal and electromagnetic damage before it can propagate to sensitive components.
3Ease of manufacture
If electronic power inverters without inertia are used, then the conversion is achieved, but additional expensive mitigation is needed for power quality issues when connecting to the power grid
Solution Approach 1:
The patent replaces electronic power inverters with a mechanical-hydraulic system where a DC motor converts DC electricity to mechanical rotation, driving a water pump that stores water in an elevated tank. During generation, water flows through a turbine connected to an AC generator. This mechanical system provides inherent rotational inertia that stabilizes grid connection, eliminating the need for expensive power quality mitigation equipment required by inertless electronic inverters.
4Quantity of substance
If hydraulic energy storage with water tanks is used, then energy storage and discharge is achieved, but the system requires elevation space for water storage
Solution Approach 1:
The patent utilizes the vertical dimension by storing water in an elevated tank positioned at height. The gravitational potential energy stored in the elevated water mass provides the energy storage capacity, converting vertical space into usable energy storage. This approach trades elevation space for energy storage capacity, allowing the system to store energy mechanically through water position rather than requiring horizontal expansion or chemical storage materials.
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 provides high power quality AC electricity with reduced harmonic distortion, fewer grid integration challenges, and lower interconnection costs, enabling easier marketability and integration of energy storage through hydraulic means, such as water tanks, which can be used multiple times without capacity loss.
Implementation Method 1
photovoltaics (PV) in which light is converted to electricity
Implementation Method 2
a motorized pump configured to receive direct current (DC) electricity from a source of electric power, and convert the DC electricity to first motive power
Implementation Method 3
a turbine configured to convert kinetic energy of the water supplied from the at least one supply location to second motive power
Implementation Method 4
an electric generator connected to the turbine, the electric generator configured to convert the second motive power to the AC electricity
Implementation Method 5
hydraulic storage at altitude, such as a water tank on a hill or another elevation
Data Source
AI summary
A method is provided for supplying alternating current (AC) electricity. The method includes receiving direct current (DC) electricity from a source of electric power at a motorized pump, and converting the DC electricity from the source of electric power to AC electricity. This includes converting the DC electricity to first motive power at the motorized pump to move water from a source location to at least one supply location. The water is supplied from the at least one supply location to a turbine, and kinetic energy of the water is converted to second motive power at the turbine. The second motive power is converted to the AC electricity at an electric generator that is connected to the turbine, and the AC electricity is supplied from the electric generator.