PFR Reserve Procurement Using Equivalent Governor Frequency Dynamics
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Solution Overview
Problem
Renewable energy power systems face challenges in primary frequency regulation due to the complexity of governor limiters and damping states, leading to instability and inefficiency in frequency reserve procurement, especially when transitioning between under-damped and over-damped states.
Innovation Solution
A method is introduced that aggregates generators and renewable energy sources into an equivalent unit with a determined governor limiter, transforming system frequency dynamics from the s-domain to the time-domain to stabilize frequency and determine primary frequency reserve procurement, incorporating a hyperplane-based frequency stability constraint to ensure system stability post-disturbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If renewable energy sources participate in frequency regulation using VSM control, then frequency regulation capability is improved, but system complexity increases due to multiple damping states and governor limiters
Solution Approach 1:
The patent aggregates multiple generators and renewable energy sources into an equivalent unit with an equivalent governor, combining complex individual governor limiters into a single equivalent governor limiter. This merging approach maintains frequency regulation capability while reducing the complexity of analyzing and controlling each individual component's governor behavior.
Solution Approach 2:
The patent transforms the system frequency dynamics from s-domain to time-domain equations, and further develops a hyperplane-based frequency stability constraint. These parameter transformations and domain changes simplify the mathematical representation of complex damping states and governor limiter behaviors, making the system more tractable for control and analysis.
2Reliability
If governor limiter parameters are adjusted to improve frequency stability, then frequency stability is improved, but operating costs increase due to conservative reserve procurement
Solution Approach 1:
The patent develops dynamic time-domain equations that capture the transient behavior of frequency dynamics under different damping states. By using dynamic rather than static models, the system can optimize governor limiter parameters to achieve frequency stability without overly conservative reserve procurement, reducing operating costs while maintaining stability.
Solution Approach 2:
The patent replaces traditional conservative frequency stability assessment methods with a hyperplane-based frequency stability constraint in the time domain. This substitution allows for more precise determination of frequency extrema and enables optimization of reserve procurement, reducing the conservativeness and associated operating costs while ensuring frequency stability.
3Ease of operation
If traditional frequency regulation methods are used, then system operation is simpler, but frequency stability cannot be ensured under large disturbances due to ignoring governor limiters and damping states
Solution Approach 1:
The patent segments the complex frequency dynamics into distinct damping states (over-damped and under-damped) and develops separate time-domain equations for each state. This segmentation allows the system to account for governor limiters and damping states without requiring complex real-time analysis, maintaining ease of operation while ensuring frequency stability under various disturbance conditions.
Data Source
AI summary
A method for primary frequency regulation (PFR)reserve procurement of a renewable energy power system is provided. The renewable energy power system includes synchronous power sources and renewable energy sources, and the renewable energy sources participate in frequency regulation using virtual synchronous machine (VSM) control. The method includes: aggregating generators in the synchronous power sources and renewable energy sources into an equivalent unit having an equivalent governor; based on the equivalent unit, determining system frequency dynamics of the renewable energy power system in a s-domain; transforming the s-domain to a time-domain equation for the system frequency dynamics in both over-damped and under-damped states; according to a first-order optimality condition of the time-domain equation, determining a time domain expression of frequency extremum; stabilizing system frequency of the renewable energy power system by adding a hyperplane based frequency stability constraint; and determining the PFR reserve procurement of the renewable energy power system.