Microgrid Voltage Control Using Reactive Power Feedback
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Solution Overview
Problem
Existing voltage control solutions for microgrids with decentralized energy sources are insufficient to maintain network stability during high active power transfers, leading to overvoltage issues and inefficiencies due to asymmetrical reactive power contributions from production groups.
Innovation Solution
A control device and method that adjusts the voltage and reactive power of centralized and decentralized units using a central automaton and secondary control algorithms to minimize voltage differences across nodes, ensuring stable operation by modulating the voltage reference based on total active and reactive power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing voltage control solutions are used in microgrids with decentralized energy sources, then the control system structure is simple, but the network stability deteriorates during high active power transfers leading to overvoltage issues
Solution Approach 1:
The patent implements a secondary control algorithm that continuously monitors voltage levels across microgrid nodes and provides feedback to adjust the voltage reference. The algorithm calculates the difference between actual voltage U and reference voltage Uref, then modulates the voltage reference accordingly to maintain stability during high active power transfers and prevent overvoltage conditions.
Solution Approach 2:
The patent dynamically changes the voltage reference parameter Uref based on total active power Pt and reactive power Qt measurements. The secondary control algorithm adjusts Uref using a modulation function that responds to power flow conditions, allowing the system to adapt voltage levels to maintain stability under varying operational conditions without requiring complex structural changes.
2Ease of operation
If voltage control is implemented without considering total active and reactive power dynamics, then the control algorithm is simple, but overvoltage issues occur during high active power transfers
Solution Approach 1:
The secondary control algorithm performs preliminary adjustment of the voltage reference Uref before overvoltage conditions develop. By continuously monitoring total active power Pt and reactive power Qt, the algorithm proactively modulates Uref to prevent voltage excursions, rather than reacting after overvoltage occurs. This preliminary action maintains simplicity while preventing harmful effects.
3Productivity
If asymmetrical reactive power contributions from production groups are not addressed, then the system operation is simple, but efficiency deteriorates due to suboptimal voltage distribution
Solution Approach 1:
The patent applies local quality control by adjusting the voltage reference at each node based on local measurements of total active power Pt and reactive power Qt. The secondary control algorithm allows each production group to contribute reactive power according to its local conditions and capabilities, optimizing voltage distribution across the microgrid without requiring complex centralized coordination of asymmetrical contributions.
Data Source
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AI summary
The present invention relates to a control device for a power plant with a unit for generating and/or storing electricity and a connection terminal intended to be connected to a microgrid, comprising a control automaton (100), configured to calculate a setpoint voltage Uref(i) for each unit, measuring or calculating elements (1, 2, 3, 4i, 5) for a voltage URmes of the common connection terminal (10), a reference voltage UcentraleRef according to a function f, an individual reactive power Qmes(i) for each unit, a voltage corrector (5), having a second prescribed transfer function corr, the automaton being configured to calculate Uoffset=corrUcentraleRef−URmes Urefi=Uoffseti−KUQi.Qmesi, the control automaton (100) comprising a receiving element (5) for values (Usources-decentralized-k) of voltage telemetry from decentralized sources of the microgrid and values (Upostes-consumers-l) of voltage telemetry from decentralized consumer posts of the microgrid.