Island Network Frequency Control for Renewable Stability
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Solution Overview
Problem
Conventional island networks require additional investment and complexity due to the need for energy storage devices or diesel generators to manage fluctuating renewable energy output, increasing operational costs and maintenance requirements.
Innovation Solution
A method for operating an island network using at least one voltage-adjusting converter that adjusts power consumption based on a frequency-power characteristic curve, allowing the renewable energy source to operate at maximum available power without the need for energy storage devices or diesel generators, by varying the voltage amplitude of the alternating voltage to adapt power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If energy storage devices or diesel generators are added to manage fluctuating renewable energy output, then power balance stability is improved, but device complexity and investment costs increase
Solution Approach 1:
The patent extracts the grid-forming function from traditional energy storage devices or diesel generators and transfers it to the renewable energy generator itself through frequency-power characteristic control. This eliminates the need for separate grid-forming units while maintaining power balance stability, directly resolving the contradiction between reliability and device complexity
Solution Approach 2:
The renewable energy generator is given dual functionality: it both generates power and performs grid-forming operations through its frequency-power characteristic curve. This multi-functionality removes the need for dedicated energy storage devices or diesel generators, reducing system complexity while maintaining stability
2Reliability
If energy storage devices or diesel generators are added to manage fluctuating renewable energy output, then power balance stability is improved, but operating costs increase
Solution Approach 1:
By extracting the grid-forming function from separate energy storage devices or diesel generators and assigning it to the renewable energy generator, the patent eliminates ongoing operating costs associated with fuel consumption and maintenance of these auxiliary systems, while maintaining power balance through frequency-power characteristic control
3Productivity
If renewable energy generator operates at maximum available power output, then energy storage efficiency is improved, but power balance stability deteriorates due to fluctuating output
Solution Approach 1:
The patent implements feedback control through the frequency-power characteristic curve, where the renewable energy generator continuously adjusts its power output based on the grid frequency. This allows the system to operate at maximum available power while automatically responding to frequency deviations, thereby maintaining power balance stability without sacrificing energy storage efficiency
Solution Approach 2:
The frequency-power characteristic curve provides dynamic adjustment capability, allowing the renewable energy generator to adapt its power output in real-time according to grid conditions. This dynamic response enables maximum energy utilization while maintaining stability, resolving the contradiction between productivity and reliability
Data Source
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Figure 3a
AI summary
The invention relates to a method for operating an island network (1) comprising a group of voltage-adjusting converters (9a, 9b) for converting power of regenerative energy sources (3a, 3b) into AC power in a manner corresponding to a frequency/power characteristic curve (20a, 20b). The island network (1) further comprises a load (6), which depends on a voltage amplitude Û0 of an alternating voltage of the island network (1), and a control unit (11) which transmits a specification value of the voltage amplitude Û0 to the group. The power Pload to be consumed by the load (6) is adapted by changing the frequency/power characteristic curve (20a, 20b) of one of the converters (9a, 9b) depending on the available power of the regenerative energy source (3a, 3b) to a higher frequency for a given power in order to check whether the available power of the regenerative energy source (3a, 3b) lies above the current power or to a lower frequency for a given power if the regenerative energy source (3a, 3b) cannot generate the power assigned to the current frequency according to the frequency/power characteristic curve (20a, 20b); determining a frequency f2 of the alternating voltage in the island network (1) as a result of the change of the frequency/power characteristic curve (20a, 20b) by the control unit (11); and increasing a specification value of the voltage amplitude Û0 to the group by means of the control unit (11) if the determined frequency f2 lies above a nominal frequency fnom of the island network (1) or lowering the specification value if the determined frequency f2 lies below the nominal frequency fnom. The invention also relates to an island network (1) for carrying out the method.