Fast Frequency Reserve in D-IEGS for Grid Frequency Stability
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Solution Overview
Problem
The increasing reliance on converter-interfaced power sources like wind and photovoltaic generation poses challenges for maintaining power system frequency stability, as traditional frequency regulation resources from thermal and hydro power generators become insufficient, necessitating the development of flexible and reliable frequency regulation methods.
Innovation Solution
The implementation of energy management strategies for distribution-level integrated electric-gas systems (D-IEGS) that utilize gas-fired turbines (GTs) and power-to-gas (P2G) units to provide fast frequency reserve (FFR) services, incorporating dynamic modeling of frequency and gas flow dynamics to enhance primary frequency regulation (PFR) capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If converter-interfaced power sources (wind and photovoltaic generation) are increased to decrease fossil energy consumption and carbon emission, then environmental benefits are improved, but frequency regulation capability deteriorates
Solution Approach 1:
The patent introduces a frequency support system that acts as an intermediary between converter-interfaced power sources and the main grid. This system includes frequency control units that monitor grid frequency and adjust the active power output of wind and photovoltaic generators accordingly, enabling these renewable sources to provide frequency regulation services without requiring fossil fuel-based generators.
Solution Approach 2:
The patent changes the operational parameters of converter-interfaced power sources by dynamically adjusting their active power output based on grid frequency conditions. The system modifies the power generation parameters of wind and photovoltaic generators in response to frequency deviations, allowing them to participate in frequency regulation while maintaining their renewable energy generation function.
2Reliability
If thermal and hydro power generators are used for frequency regulation, then frequency stability is improved, but their decreasing share among overall generation assets reduces available regulation resources
Solution Approach 1:
The patent makes converter-interfaced power sources multi-functional by enabling them to simultaneously perform their primary function of renewable energy generation and a secondary function of frequency regulation. The frequency support system allows wind and photovoltaic generators to provide primary frequency regulation services, thereby expanding the pool of available regulation resources beyond traditional thermal and hydro generators.
Solution Approach 2:
The frequency support system serves as an intermediary that enables converter-interfaced power sources to participate in frequency regulation. This system includes control units that communicate with the main grid and adjust the output of renewable generators, effectively transferring frequency regulation capability from traditional generators to renewable sources.
3Reliability
If fast frequency reserve (FFR) service is provided by gas-fired turbines and power-to-gas units, then primary frequency regulation capability is improved, but computation burden increases
Solution Approach 1:
The patent segments the frequency regulation problem into distinct components: a main optimization problem that determines FFR procurement strategies, and a feasibility check sub-problem that verifies gas network operation constraints. This segmentation allows the complex two-stage robust optimization problem to be solved more efficiently using the column-and-constraint generation algorithm, reducing the overall computation burden while maintaining accuracy.
Solution Approach 2:
The patent incorporates dynamic modeling of frequency regulation behaviors of gas-fired turbines and power-to-gas units, including dead zones, limiting ranges, and time constants of governors. By dynamically formulating these constraints and integrating them into the optimization framework, the system accurately captures the real-time operational characteristics without requiring excessive computational resources.
Data Source
AI summary
In this disclosure, the energy management problem of the D-LEGS with FFR is analyzed, so as to enhance the frequency stability of the main grid. The post-disturbance frequency response behaviors of both the main grid and the D-IEGS are precisely depicted, where the dead zones, limiting ranges and time constant of the governors are considered. The frequency regulation units of the D-IEGS include GTs and P2G units, whose impacts of providing frequency regulation service on the gas networks are quantified. Considering the time-scale similarity of the frequency dynamics and the dynamics of the GDN, the gas flow dynamics model is adopted. The frequency response dynamics of the GTs and P2G units, and the gas flow dynamics of the GDN, a variable-step difference scheme and a binary variable reduction method are devised.