Hierarchical Reactive Voltage Control for Wind and PV Grid Connection
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Solution Overview
Problem
Large-scale wind and photovoltaic power grid connections cause frequent voltage fluctuations, making it difficult to maintain optimal reactive voltage control, which is not adequately addressed by existing technologies.
Innovation Solution
An optimal control method for reactive voltage that involves setting actuating stations, substations, and a master station to collect data, calculate voltage references using the 3σ method, and adjust compensation equipment to maintain busbar voltage within a set interval, considering the sensitivity and minimum adjustable capacity of each substation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If large-scale wind/photovoltaic power plants are built to improve energy structure, then energy structure is improved, but network voltage stability deteriorates due to randomness and volatility
Solution Approach 1:
The patent divides the control system into hierarchical levels: master station for overall optimization, substations for regional control, and actuating stations for local adjustments. This segmentation allows each level to handle voltage control independently, preventing widespread voltage fluctuations while accommodating large-scale renewable energy integration.
Solution Approach 2:
The patent implements dynamic voltage reference adjustment by calculating time-varying voltage references based on real-time power output from wind and photovoltaic plants. The system continuously adapts the voltage reference to match changing conditions, maintaining stability despite the randomness and volatility of renewable energy sources.
2Device complexity
If traditional optimal control for reactive voltage is used, then control simplicity is maintained, but it cannot adapt to frequent voltage fluctuations caused by large-scale wind/photovoltaic power
Solution Approach 1:
The system transitions from static voltage references to dynamic voltage references that are continuously updated based on real-time measurements of wind and photovoltaic power output. This allows the control system to adapt to frequent voltage fluctuations while maintaining a relatively simple control architecture through automated calculations.
Solution Approach 2:
The patent implements a feedback mechanism where the master station collects real-time data from substations and actuating stations, calculates optimal voltage references, and sends control commands back to the equipment. This closed-loop feedback enables the system to adapt to changing conditions automatically without requiring complex manual intervention.
3Reliability
If voltage reference is adjusted frequently to maintain optimal control, then voltage stability is improved, but equipment adjustment frequency increases leading to higher wear and operational complexity
Solution Approach 1:
The patent applies different control strategies to different parts of the system based on their specific characteristics. Substations with sufficient capacity handle voltage control locally, while actuating stations provide supplementary control. This local differentiation reduces the need for frequent adjustments across the entire system while maintaining voltage stability where needed.
Solution Approach 2:
The system uses voltage reference intervals rather than precise single-point references, allowing voltage to fluctuate within acceptable bounds. This partial control approach reduces the frequency of equipment adjustments while maintaining adequate voltage stability, avoiding unnecessary wear from excessive adjustments.
Data Source
AI summary
The present invention has disclosed an optimal control method for reactive voltage of wind power and photovoltaic power centralized grid connection in the field of wind power and photovoltaic power grid connection control technology, comprising: setting actuating stations used to control single wind power plant/photovoltaic power plant, setting substations used to control actuating stations and set master station used to control all the substations; master station calculates setting voltage reference Uref of each substation; adopting 3σ method to process set voltage reference Uref to obtain set voltage reference interval; regulating high-side voltage of substation to make it fall in set voltage reference interval; if high-side voltage of substation does not fall in set voltage reference interval, then regulating the equipment in wind power plant/photovoltaic power plant via actuating station. The present invention guides the actual operations of electric power system.