PV Load Power Conversion Using Existing DC Strings for Night Operation
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Solution Overview
Problem
Large photovoltaic plants face challenges in efficiently and cost-effectively powering electrical loads with alternating current, as traditional solutions like new power lines and batteries are financially and structurally cumbersome, with batteries having limited lifespan and high costs.
Innovation Solution
A system comprising a main DC power line, a main AC power line, and converter apparatus that connects to both, allowing for the conversion of alternating current into direct current to energize photovoltaic generators and electrical loads, utilizing a DC/AC inverter and secondary converter to ensure continuous AC voltage supply, reducing the need for extensive cabling and battery infrastructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If new power lines are installed to connect electrical devices directly to the power distribution network, then the electrical devices can be reliably powered with alternating current, but the system complexity and installation cost increase due to complex excavation and positioning of long electric cables
Solution Approach 1:
The patent introduces an intermediary device (converter apparatus with DC/AC inverter) that converts DC power from existing photovoltaic panels to AC power locally at the electrical device. This intermediary solution eliminates the need for extensive AC power line installation while ensuring reliable power conversion, thereby resolving the contradiction between power supply reliability and cabling complexity
Solution Approach 2:
The system enables each electrical device to serve itself by converting DC power from nearby photovoltaic panels directly at the device location. The converter apparatus allows the device to autonomously convert power without requiring connection to the central AC distribution network, thus eliminating complex cabling while maintaining reliable power supply
2Adaptability or versatility
If batteries are used to power electrical devices, then the devices can operate independently of the power distribution network, but the system cost increases due to limited battery lifespan (1-4 years) and high replacement costs
Solution Approach 1:
The patent replaces expensive, long-lifespan batteries with a more economical solution using existing photovoltaic panels and a converter apparatus. The system utilizes the already-installed DC power generation infrastructure, eliminating the need for costly battery purchases and replacements while maintaining power supply independence
Solution Approach 2:
The system changes the power supply parameter from battery-based storage to direct DC-to-AC conversion from photovoltaic panels. This parameter change eliminates battery lifespan limitations and maintenance requirements while preserving the ability to operate independently of the external power distribution network
3Duration of action of stationary object
If batteries are protected from weather and temperature variations, then their useful lifespan is extended, but the system complexity increases due to the need for additional cabins or containers
Solution Approach 1:
The patent extracts the power conversion function from the central inverter location and places it directly at the electrical device through the converter apparatus. This eliminates the need for battery protection structures entirely, as the system no longer relies on batteries, thereby resolving the contradiction between extending lifespan and reducing structural complexity
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 provides a reliable, cost-effective, and structurally simple method to energize electrical loads in photovoltaic plants, ensuring continuous operation during both day and night, and minimizing structural complexity by leveraging existing electrical paths, thus reducing the need for extensive cabling and battery maintenance.
Implementation Method 1
converter apparatus connected to the main AC power line and to the main DC power line, and configured to convert an alternating current circulating in the main AC power line into a second direct current feeding the latter into the photovoltaic circuit through the main DC power line
Implementation Method 2
DC/AC secondary converter connected at the input of a secondary DC power line connected to the connectors of a circuit formed by one or by a plurality of said photovoltaic modules connected to one another in series, and at the output to the electrical load, the DC/AC secondary converter being configured to convert a direct current circulating in the secondary DC power line into an alternating supply current, feeding the latter into the electrical load
Implementation Method 3
photovoltaic generator (302) comprising a photovoltaic circuit (303) that is made up of one or more photovoltaic strings (304) connected in parallel to a main DC power line (301) and capable of generating a first direct current and a direct voltage
Data Source
Figure 1
Figure 2
AI summary
System to energise electrical loads (200) with alternating current in a photovoltaic plant (300), with the photovoltaic plant (300) comprising a main DC power line (301), a photovoltaic generator (302) comprising a photovoltaic circuit (303) that is made up of one or more photovoltaic strings (304) connected in parallel to the main DC power line (301) and is able to generate a first direct current (IDC1) and a direct DC voltage, and, a main AC power line (305) connected to an electric distribution network (306). The system (100) comprises a converter apparatus (109) adapted to be connected to the main AC power line (305) and to the main DC power line (301) and configured to convert an alternating current circulating in the main AC power line (305) into a second direct current (IDC2), feeding the latter into the photovoltaic circuit (303) through the main DC power line (301) if the DC voltage generated by the photovoltaic generator (302) is lesser than a pre-set limit, so as to energise the photovoltaic generator (302). The system (100) moreover comprises a DC/AC secondary converter (106) adapted to be connected at the input to a secondary DC power line (104) which is connected to the connectors of a photovoltaic module (308) of the photovoltaic generator (302), or of a circuit formed by a plurality of said photovoltaic modules (308) connected to one another in series, and at the output to the electrical load (200), the DC/AC secondary converter (106) being configured to convert a direct current circulating in the secondary DC power line (104) into an alternating supply current (IAC), feeding the latter into the electrical load (200) so as to energise it.