Primary Frequency Reserve Procurement Under Multiple Damping States
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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 with the increasing penetration of renewable sources.
Innovation Solution
A method 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 determine frequency extremum points and stabilize the system by adding hyperplane-based frequency stability constraints, optimizing primary frequency regulation reserve procurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional frequency regulation methods are used in renewable energy power systems, then the system can operate with existing control mechanisms, but the frequency stability deteriorates due to the increasing proportion of renewable energy and UHV transmission
Solution Approach 1:
The patent applies dynamics by making the governor limiter value adjustable and adaptive rather than fixed. The method dynamically determines the governor limiter value based on system frequency dynamics, damping states, and disturbance conditions, allowing the system to adapt to varying renewable energy penetration levels and maintain frequency stability under different operating conditions.
Solution Approach 2:
The patent changes the governor limiter parameter from a conventional fixed value to a dynamically determined value. By transforming the frequency dynamics equation and solving for the optimal governor limiter value that achieves critical damping, the system adjusts this key parameter to maintain reliability while accommodating increased renewable energy capacity.
2Reliability
If the governor limiter value is increased to improve frequency stability, then frequency regulation performance improves, but the device complexity increases due to the need for complex modeling and calculation
Solution Approach 1:
The patent extracts the complex multi-machine frequency dynamics into a simplified equivalent system. By aggregating multiple generators and renewable energy sources into an equivalent unit with equivalent inertia and damping coefficients, the method extracts the essential frequency dynamics while removing unnecessary complexity, enabling straightforward calculation of the optimal governor limiter value.
Solution Approach 2:
The patent introduces an intermediary mathematical model (the frequency dynamics equation in s-domain and its transformation to time-domain) that mediates between the physical system and the control parameter. This intermediary model enables the determination of the governor limiter value without requiring direct complex control system modifications.
3Productivity
If conventional reserve procurement methods are used, then the procurement process is simple, but the operating costs increase due to excessive conservatism in reserve allocation
Solution Approach 1:
The patent applies preliminary action by pre-calculating the optimal governor limiter value and corresponding frequency regulation reserve requirements based on system characteristics and disturbance scenarios. This preliminary determination allows for more efficient reserve procurement that is neither excessively conservative nor insufficient, reducing unnecessary operating costs while maintaining reliability.
4Productivity
If the system operates with high renewable energy penetration, then clean energy utilization improves, but the frequency characteristics change leading to reduced frequency stability
Solution Approach 1:
The patent addresses the changing frequency characteristics by dynamically adjusting the governor limiter parameter. As renewable energy penetration increases and system inertia changes, the method recalculates the optimal governor limiter value to maintain appropriate damping and frequency stability, enabling high renewable utilization without sacrificing reliability.
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.