Storage Battery Frequency Control to Prevent Grid Oscillation
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Solution Overview
Problem
Existing frequency control techniques for power systems using storage batteries can cause frequency vibrations or divergence, which are not effectively suppressed, leading to potential blackouts due to the decreasing number of rotary machines in renewable energy systems.
Innovation Solution
A storage battery system with a first converter unit that outputs constant active power when the system frequency falls below a threshold, and a second unit that outputs variable power based on frequency deviations, to stabilize the power system without causing frequency vibrations or divergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If storage battery systems control frequency by outputting active power based on frequency ranges, then frequency fluctuation suppression is improved, but frequency vibration and divergence occur
Solution Approach 1:
The patent implements a feedback control mechanism where the storage battery system continuously monitors system frequency and adjusts its active power output accordingly. When frequency drops below the reference value, the system outputs active power to raise frequency; when frequency exceeds the reference value, the system absorbs active power to lower frequency. This closed-loop feedback approach prevents frequency vibration and divergence while maintaining stability.
Solution Approach 2:
The patent applies partial action by setting threshold values (first threshold and second threshold) that define when frequency control should activate. The storage battery system only outputs or absorbs active power when frequency deviates beyond these thresholds, rather than continuously adjusting. This partial action approach suppresses frequency fluctuations without causing excessive control activity that would lead to vibration.
2Adaptability or versatility
If the number of rotary machines decreases to increase renewable energy utilization, then adaptability is improved, but frequency fluctuation increases
Solution Approach 1:
The patent introduces a storage battery system as an intermediary between renewable energy sources and the power system. The storage battery absorbs excess power when renewable generation is high and frequency rises, then releases stored power when renewable generation is low and frequency drops. This intermediary role allows high renewable energy utilization while maintaining frequency stability, solving the contradiction between adaptability and reliability.
Data Source
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AI summary
A storage battery system (130) includes a first storage battery unit (120A). First storage battery unit (120A) includes a first converter (121A) that converts alternating current and direct current, a first storage battery (122A), and a first controller that controls first converter (121A), and first storage battery unit (120A) is interconnected to a system for supplying power. The first controller detects a frequency of the system, and controls first converter (121A) such that first storage battery (122A) outputs constant active power to the system on the basis of the frequency of the system falling below a first threshold value.