Local Network Transformer Voltage Stability Control
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Solution Overview
Problem
Existing power grid systems face challenges in maintaining stability due to bidirectional energy flow, which leads to voltage compliance issues, particularly with the increasing role of reactive power from decentralized energy sources like PV converters, and are not designed to handle these dynamics effectively.
Innovation Solution
A device and method for controlling the stability of local networks using a controllable transformer with integrated current and voltage measurement units, which determine critical feeders, calculate equivalent impedance, and adjust tap positions on the transformer to maintain voltage within specified bands, accounting for both active and reactive power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If power grid systems are designed for unidirectional energy flow from power plant to consumer, then the system structure is simple and cost-effective, but the system cannot handle bidirectional energy flow from decentralized energy sources, leading to voltage compliance issues and network instability
Solution Approach 1:
The patent implements dynamic voltage control by continuously monitoring voltage at multiple measurement points and adjusting transformer tap positions in real-time based on the direction and magnitude of power flow. The control system adapts to changing network conditions by switching between different control modes (voltage rise prevention, voltage drop prevention, power flow direction detection) to maintain voltage within specified bands under bidirectional energy flow conditions
Solution Approach 2:
The system employs feedback control by measuring voltage at multiple points in the network, comparing these measurements against specified voltage bands, and automatically adjusting transformer tap positions to correct any deviations. The control algorithm uses real-time voltage measurements and power flow direction information to continuously optimize voltage regulation, ensuring compliance with voltage standards under varying operational conditions
2Reliability
If reactive power from PV converters is increased to maintain voltage, then voltage stability improves, but voltage bands according to EN 50160 are violated due to uncontrolled reactive power injection
Solution Approach 1:
The control system continuously monitors voltage at multiple measurement points and uses this feedback to adjust reactive power compensation and transformer tap positions. By comparing measured voltage against specified bands and automatically adjusting control parameters, the system maintains voltage stability while ensuring compliance with EN 50160 voltage requirements
Solution Approach 2:
The system dynamically changes operating parameters including transformer tap positions and reactive power compensation levels based on real-time voltage measurements and power flow conditions. By adjusting these parameters in response to changing network conditions, the system maintains voltage within specified bands while ensuring reliable operation
3Reliability
If voltage measurement is provided only at the transformer output, then the measurement system is simple, but voltage deviations in distant feeders cannot be detected, leading to poor voltage quality at consumer connections
Solution Approach 1:
The measurement system is segmented into multiple measurement points distributed throughout the network, including the transformer output and additional points in distant feeders. This segmentation allows independent monitoring of voltage conditions in different network sections, enabling targeted control actions to maintain voltage quality at all consumer connections
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 enables more reliable, cost-effective, and efficient maintenance of local network stability within specified voltage limits, avoiding overloading and voltage deviations by dynamically adjusting the transformer settings based on real-time measurements.
Implementation Method 1
A busbar, which connects the multiplicity of outgoing circuits of the local network to one another, is connected to a controllable local network transformer, which is also connected to the busbar via an electrical line
Implementation Method 2
An output voltage of the local network transformer can be set using an on-load tap changer
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
The invention relates to a device (1) and a method for controlling the stability of a local network (3). The local network (3) comprises a plurality of outgoing circuits (41, 42,..., 4M,), each having at least one load (5) and/or at least one decentralised energy generation system (6). Said device is provided with an on-load tap-changer (14) for adjusting an output voltage of the local network transformer (10). The device is characterised in that a unit (16) for measuring current, connected to at least one of the plurality of outgoing circuits (41, 42,..., 4M,), and a unit (18) for measuring voltage, connected to a busbar (8) of the local network (3), are arranged in a transformer housing (20).