Renewable Plant Converter Control for Single-Phase Fault Ride-Through
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Solution Overview
Problem
Existing renewable power generation plants, such as wind turbines, experience downtime and revenue loss due to single-pole phase-to-ground faults in power transmission networks, leading to instability and transient overvoltages, which existing control techniques cannot effectively manage, resulting in prolonged shutdowns and reduced Annual Energy Production (AEP).
Innovation Solution
A method for controlling renewable power generation plants that involves detecting single-pole phase-to-ground faults and issuing control signals to keep circuit breakers closed and power converters operational, allowing the plants to ride through faults by injecting negative sequence current to counteract transient overvoltages, thus maintaining connection to the grid and eliminating the need for synchronization checks upon reclosure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing control techniques are used to respond to single-pole phase-to-ground faults, then circuit breakers are opened to protect equipment from overvoltages, but this causes complete disconnection of all three phases and prolonged shutdowns reducing Annual Energy Production
Solution Approach 1:
The invention segments the fault response by phase, allowing the affected single phase to be isolated while maintaining connection of the other two healthy phases. The controller selectively opens only the circuit breaker for the faulty phase rather than all three phases, enabling partial operation during fault conditions and reducing energy production loss.
Solution Approach 2:
Instead of completely disconnecting all phases as done in existing techniques, the invention applies partial action by keeping two out of three phases connected and operational. This partial maintenance of connection allows the plant to continue generating and transmitting power through the healthy phases, improving productivity during fault events.
2Reliability
If circuit breakers are opened in response to phase-to-ground faults, then equipment is protected from damaging overvoltages, but synchronization checks are required upon reclosure causing additional downtime
Solution Approach 1:
The invention performs preliminary action by maintaining synchronization of the healthy phases throughout the fault event. Since these phases remain connected and synchronized with the grid, no additional synchronization checks are needed when the affected phase is reclosed, eliminating downtime delays and enabling immediate resumption of full three-phase operation.
Solution Approach 2:
The healthy phases continue to operate continuously throughout the fault event, maintaining their synchronized connection to the grid. This continuous operation means that when the affected phase is restored, the system is already synchronized and can immediately resume full power transmission without interruption or additional synchronization procedures.
3Reliability
If all pole breakers are opened during single-pole faults, then the plant is protected from instability and transient overvoltages, but the plant cannot sell power during the fault event and requires several hours to restart
Solution Approach 1:
The invention segments the protection strategy by phase, isolating only the affected phase while maintaining operation of the healthy phases. This allows the plant to continue selling power through the two healthy phases during the fault event, converting a complete shutdown scenario into a partial operation scenario that maintains revenue flow.
Solution Approach 2:
The invention converts the harmful effect of the single-pole fault into a beneficial situation by using the two healthy phases to continue power transmission. What would normally be a complete shutdown becomes an opportunity for partial operation, where the fault condition actually demonstrates the resilience of the system by allowing continued operation through unaffected phases.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach prevents downtime and revenue loss during single-pole auto-reclose events, enables continuous operation, and allows for immediate resumption of full power output without additional hardware, as the unaffected phases remain synchronized, thereby enhancing the operational efficiency and AEP of renewable power generation plants.
Implementation Method 1
issuing control signals to the power converter to ride through the phase-to-ground fault event by injecting negative sequence current to counteract transient overvoltages
Data Source
AI summary
Provided is a renewable power generation plant, a computer program product and method of controlling a renewable power generation plant including a power converter for connecting the renewable power generation plant to a power transmission network; a circuit breaker arrangement between the power converter and the power transmission network including a circuit breaker for each phase of the renewable power generation plant; and a converter controller configured to generate control signals for the power converter and control signals for the circuit breaker arrangement; which method includes the steps of detecting the occurrence of a phase-to-ground fault event in one of the phases of the power transmission network; issuing control signals to the circuit breaker arrangement to keep the circuit breakers closed during the phase-to-ground event; and issuing control signals to the power converter to ride through the phase-to-ground fault event.