Load Frequency Control Using Merit Order and Fast Output Response
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Solution Overview
Problem
Existing load frequency control methods fail to effectively reduce fuel costs while maintaining system frequency stability, especially with the integration of renewable energy sources, as they often reduce the number of power generators distributing area requirements, leading to frequency fluctuations.
Innovation Solution
A load frequency control device that calculates area requirements and determines output distribution ratios based on economic efficiency, using a merit order method to allocate regulated power to power generators, prioritizing distribution according to fuel cost for both increases and decreases in power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If area requirement is distributed to fewer power generators based on merit order, then fuel cost is reduced, but frequency fluctuation increases
Solution Approach 1:
The patent dynamically adjusts the area requirement distribution strategy based on real-time system frequency conditions. When frequency deviation exceeds thresholds, the system switches from pure merit order distribution to a mode that includes faster-response generators, thereby adapting the distribution criterion to current system needs and resolving the contradiction between cost reduction and frequency stability
Solution Approach 2:
The patent changes the distribution parameters (distribution criteria, time constants, weighting factors) based on system frequency conditions. By adjusting these parameters dynamically, the system optimizes the balance between economic efficiency and frequency control performance, allowing merit order to prevail under normal conditions while ensuring frequency stability during disturbances
2Reliability
If area requirement is distributed based on output change speed, then frequency fluctuation is suppressed, but fuel cost increases
Solution Approach 1:
The patent applies partial action by using output change speed as a distribution criterion only when necessary (when frequency deviation exceeds thresholds), rather than continuously. This partial application of the faster-response strategy minimizes fuel cost increase while providing frequency stabilization only when needed, resolving the contradiction with the more economical merit order approach
3Adaptability or versatility
If renewable energy is introduced to power system, then energy diversity is improved, but frequency control capability deteriorates
Solution Approach 1:
The patent introduces regulated power sources as intermediaries between renewable energy sources and the frequency control system. These regulated sources (thermal or hydro generators) compensate for the frequency control deficiencies of renewable energy, allowing high renewable penetration while maintaining frequency stability through the mediating action of controllable generators
Data Source
AI summary
In order to suppress frequency fluctuation caused by a load frequency, an AR calculating section calculates an AR using system frequency deviation and tie-line power flow deviation as inputs. An output distribution ratio determining section determines a ratio of output distribution according to merit order based on the AR calculated by the AR calculating section. An output distributing section determines output distribution according to an output change speed based on the output distribution ratio determined by the output distribution ratio determining section according to the output change speed. An output distributing section determines output distribution according to the merit order based on the output distribution ratio determined by the output distribution ratio determining section according to the merit order. An output distribution instruction value determining section determines an output distribution instruction value to each regulated power source using, as inputs, output distribution values determined by the output distributing sections.