Inverter Reactive Power Control for Grid Voltage Stability
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Solution Overview
Problem
Energy supply networks face instability due to fluctuations in reactive power, particularly when transformers fail, leading to voltage imbalances that can result in overvoltage or undervoltage, affecting the operation of regenerative energy systems like photovoltaic and wind turbines, which struggle to maintain the required cos phi value within specified limits.
Innovation Solution
A device and method that monitor reactive power transitions between voltage levels, using a measuring device, voltmeter, and computing device to calculate reactive power requests, and a regulation unit to control energy producers for reactive power management, ensuring voltage stability across the network by adjusting reactive power supply or demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reactive power is adjusted to maintain voltage stability, then voltage quality is improved, but compliance with cos phi limits becomes difficult to maintain
Solution Approach 1:
The system dynamically adjusts the reactive power reference value based on real-time voltage measurements. When voltage deviates from the nominal range, the reactive power reference is modified to counteract the deviation, enabling adaptive response to changing grid conditions while maintaining cos phi compliance within permissible limits
Solution Approach 2:
The invention changes the reactive power reference parameter dynamically rather than maintaining a fixed cos phi value. This allows the system to prioritize voltage stability by adjusting the reactive power setpoint according to actual voltage conditions, resolving the conflict between voltage quality and cos phi compliance
2Reliability
If reactive power is increased to compensate for voltage drops, then voltage level is improved, but reactive power consumption increases
Solution Approach 1:
The system continuously monitors voltage at the point of common coupling and uses this feedback to adjust reactive power output. The control unit modifies the reactive power reference based on voltage deviations, ensuring reactive power is only increased when actually needed to maintain voltage within acceptable ranges, thereby avoiding unnecessary reactive power consumption
3Adaptability or versatility
If cos phi is maintained at fixed value, then compliance with energy supplier limits is ensured, but voltage stability during transformer failure cannot be maintained
Solution Approach 1:
The system transitions from static cos phi control to dynamic reactive power reference adjustment. Upon detecting voltage deviations that may indicate transformer issues, the control unit dynamically modifies the reactive power reference to provide stabilization, temporarily prioritizing voltage stability over strict cos phi compliance while remaining within permissible limits
Solution Approach 2:
The system proactively adjusts reactive power output in response to voltage deviations before they lead to instability. By detecting voltage changes at the point of common coupling and immediately counteracting them through reactive power adjustment, the system prevents voltage collapse while maintaining compliance with energy supplier limits
Data Source
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AI summary
When at least one power generator (G-generator) operates in a power supply network, a reactive power transition between the two upper voltage levels (1, 2) is detected at a first transformer (T1) connecting them, and the voltage at a first grid connection point (5) of the lowest voltage level (3) is determined. The magnitude of a reactive power demand supplied by the G-generator is calculated based on the determined voltage value in order to keep the voltage determined at the lowest voltage level (3) within a predefined voltage range. Based on the calculated reactive power demand, a power inverter (WR) of the G-generator is controlled for reactive power consumption or supply.