Power Unit Commitment Scheduling for N-1 Fault Frequency Security
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Solution Overview
Problem
The integration of high levels of renewable energy and power electronics in power systems has reduced system frequency modulation capability and increased the complexity of power system faults, leading to frequent and severe instantaneous power imbalances and frequency dynamic deterioration, which poses a challenge to frequency security.
Innovation Solution
A unit commitment method for power systems that determines the commitment values of thermal and renewable energy units using a pre-scheduling optimization model considering N−1 faults and frequency security, and verifies these values through a re-scheduling optimization model, updating the model until verification is successful.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high penetration of renewable energy is integrated into the power system, then clean energy supply is improved, but frequency modulation capability is reduced
Solution Approach 1:
The patent performs day-ahead unit commitment scheduling that proactively determines the operational status of thermal power units before actual operation begins. By pre-calculating which units should be committed or held in standby mode, the system prepares frequency modulation resources in advance to counteract the inherent frequency instability caused by high renewable energy penetration, thus resolving the contradiction between renewable energy integration and frequency security.
Solution Approach 2:
The patent applies preliminary anti-action by pre-positioning thermal power units in commitment or standby states that will counteract anticipated frequency disturbances from renewable energy variability. The day-ahead optimization model anticipates frequency security challenges and pre-deploys thermal units with frequency modulation capability to neutralize the harmful effects of renewable energy's lack of spontaneous frequency modulation, before actual frequency problems occur.
2Object-generated harmful factors
If thermal power units are withdrawn from operation to reduce emissions, then environmental impact is reduced, but frequency modulation capability is reduced
Solution Approach 1:
The patent uses day-ahead unit commitment scheduling to determine optimal thermal unit status before operation begins, allowing thermal units to be withdrawn for environmental benefits while pre-positioning alternative frequency modulation resources. The model calculates which thermal units can be safely committed or held in standby to maintain frequency security, enabling emissions reduction without sacrificing reliability.
Solution Approach 2:
The patent introduces day-ahead unit commitment scheduling as an intermediary mechanism that mediates between the conflicting goals of emissions reduction and frequency security. This scheduling model acts as a bridge, translating environmental requirements into operational decisions that maintain adequate thermal unit availability for frequency modulation, thus resolving the contradiction between reducing harmful emissions and maintaining frequency security.
3Device complexity
If day-ahead unit commitment scheduling is performed without considering N-1 fault and frequency security, then computational complexity is reduced, but system reliability is reduced
Solution Approach 1:
The patent segments the unit commitment problem into distinct components: base operational requirements, N-1 fault contingency considerations, and frequency security constraints. By dividing the complex scheduling model into these manageable segments, the patent makes the problem computationally tractable while still incorporating all necessary reliability considerations, thus resolving the contradiction between model complexity and system reliability.
Solution Approach 2:
The patent transforms complex frequency security constraints into simplified mathematical parameters and constraints that can be efficiently processed by optimization algorithms. By changing the representation of frequency security requirements from complex dynamic simulations to streamlined optimization parameters, the patent maintains high reliability standards while reducing computational complexity, enabling practical day-ahead scheduling.
Data Source
AI summary
The present application provides a unit commitment method for a power system and associated components, the method includes: determining a unit commitment value of the thermal power unit and a unit commitment value of the renewable energy unit obtained based on a pre-scheduling stage optimization model by considering an N−1 fault and frequency security of the power system; verifying the unit commitment value of the thermal power unit and the unit commitment value of the renewable energy unit based on a re-scheduling stage optimization model; when the verification successes, taking the unit commitment value of the thermal power unit and the unit commitment value of the renewable energy unit as a final unit commitment value; when the verification fails, updating the pre-scheduling stage optimization model and repeating the determining step and the verifying steps, making decisions to the unit commitment of the power system to obtain a unit commitment plan ensuring frequency security and power supply-demand balance after N−1 fault occurred in the power system.