DC Bus Demand Response for Renewable Energy Integration
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Solution Overview
Problem
Integrating and managing multiple alternative energy sources, such as solar and wind power, into a common system is challenging due to their uncontrolled nature, complex power output characteristics, and the need for costly inverters to convert DC to AC, while also optimizing operating points and accommodating varying voltage outputs.
Innovation Solution
A modular and self-balancing system that uses a DC bus with floating voltage levels, allowing power-generators and consumers to operate within specific control voltage ranges, enabling automatic demand response and self-regulation without centralized control, by activating or deactivating devices based on bus voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If each renewable energy source has a separate inverter to convert DC to AC, then the voltage conversion is achieved, but the system cost increases significantly
Solution Approach 1:
The patent merges multiple separate inverter functions into a single shared inverter that serves multiple renewable energy sources. The system uses a common DC bus to aggregate power from multiple DC sources (solar panels, wind generators, batteries) and then uses one inverter to convert the combined DC power to AC for grid connection or local loads, eliminating the need for multiple individual inverters and reducing system cost.
Solution Approach 2:
The single inverter is designed to handle power from multiple different DC sources simultaneously, making it a universal device that performs the voltage conversion function for all renewable energy sources in the system. This multi-functional approach allows the same hardware to serve multiple purposes and multiple sources without requiring source-specific inverters.
2Reliability
If multiple renewable energy sources are combined, then the power reliability improves, but the system complexity increases
Solution Approach 1:
The system segments each renewable energy source into independent modular units that connect to a common DC bus. Each source (solar array, wind generator, battery bank) operates independently with its own characteristics and control, but they all interface with the same simplified common bus and shared inverter. This segmentation allows easy addition or removal of sources without affecting others, maintaining reliability while managing complexity.
Solution Approach 2:
The common DC bus acts as an intermediary that simplifies the integration of multiple diverse DC sources. Instead of directly connecting different sources to the inverter or grid, the DC bus provides a standardized intermediate interface that all DC sources can connect to uniformly, reducing the complexity of interfacing multiple different source types to a single inverter system.
3Adaptability or versatility
If the bus operating voltage is allowed to float within a range, then the system flexibility improves, but the voltage control complexity increases
Solution Approach 1:
The system implements dynamic voltage operation where the DC bus voltage is allowed to float within a specified range rather than being held at a fixed value. The inverter and connected sources dynamically adjust their operating points based on the instantaneous bus voltage level, enabling the system to adapt to varying power generation and load conditions without complex active control mechanisms.
Solution Approach 2:
The system changes the voltage parameter from a fixed constant to a variable that operates within a range. By allowing the bus voltage to vary dynamically within acceptable limits, the system gains flexibility to accommodate different operating conditions and source characteristics without requiring complex control systems to maintain a precise fixed voltage.
Data Source
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AI summary
A system, method, and apparatus for local demand response between alternative-energy power-generators, traditional controlled-energy power-generators, and power-consuming loads coupled to a DC bus are disclosed. As a DC bus operating voltage fluctuates between a minimum bus operating voltage to a maximum bus operating voltage, it triggers different power-generators and different power-consumers each having staggered control voltage ranges that enable them to come on-line or go off-line, depending on the bus operating voltage, thereby providing distributed, autonomous and self-regulating demand response performance. Loads vary from opportunistic loads at high alternative-energy generation scenarios, to necessary loads powered by backup or traditional power-generators for low alternative-energy generation scenarios. Safety limits are provided with voltage limits and foldback limits.