Distributed Secondary Control for Islanded Microgrids—A Novel Approach
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Citations
Extended secondary control with grid-forming inverters for communication-free island operation
Distributed Finite-Time Secondary Control of Islanded Microgrids by Coupled Sliding-Mode Technique
Consensus-Based Distributed Control in Microgrid Under Switching Topology
A Distributed Predictive Control Strategy Based on State Estimator for islanded microgrid
References
Hierarchical control of droop-controlled DC and AC microgrids — a general approach towards standardization
Defining control strategies for MicroGrids islanded operation
Advanced Control Architectures for Intelligent Microgrids—Part I: Decentralized and Hierarchical Control
Control of parallel connected inverters in stand-alone AC supply systems
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Frequently Asked Questions (15)
Q2. What is the effect of the proposed distributed secondary control method?
The proposed distributed secondary control is able to keep the reactive power shared between DG units when the load changes frequently as well.
Q3. What is the main advantage of a centralized secondary control system?
secondary controllers for large power systems are based on frequency restoration, since the frequency of the generator-dominated grids is highly dependent on the active power.
Q4. What is the effect of the droop control on the MG?
It can be seen that frequency and voltage values are slowly and successfully regulated inside the islanded MG, removing the static deviations produced by the droop control.
Q5. What is the procedure for restoring the voltage in a MG?
When the voltage in the MG is out from a certain range of nominal rms values, a slow PI control that compensates the voltage amplitude in the MG, pass the error through a dead band, and send the voltage information by using low bandwidth communications to each DG unit.
Q6. What are the main steps to be considered for the islanded MG?
The main steps to be considered include building the islanded MG, connecting distributed generations (DGs) which feed their own protected loads, controlling voltage and frequency, synchronizing DG units inside islanded MG, connecting controllable loads and MG synchronization with the LV network [31].
Q7. What is the power requirement for the proposed DSC using the average method?
It is worth noting that power change requirement for the proposed DSC using the average method depends on the power rates of the MG units.
Q8. What is the role of communication latency in the MG?
Impact of Communication LatencyCommunication has a predominant role in providing the infrastructure that enables data to be exchange among the different elements of the MG.
Q9. What is the advantage of the secondary control method in front of the conventional one?
The advantage of this method in front of the conventional one is that the remote sensing used by the secondary control is not necessary, so that just each DG terminal voltage, which can be substantially different one from the other, is required.
Q10. Why is the voltage not common in the whole MG?
The reason is that as opposed to the frequency, the voltage is not common in the whole MG as well as the impedance between the DG units and common point is not the same.
Q11. What is the performance of DSC applied to a MG?
The performance of DSC applied to a MG has been depicted in Fig. 13. Fig 13(a) and Fig 13(b) showing how the new secondary control strategy restores frequency and voltage deviation of the DGs.
Q12. What is the way to restore the voltage of a DG?
a possible solution is to implement a secondary control for power sharing locally, so that each DG unit sends the measured Q (or P in high X/R MicroGrids) to the other DG units in order to be averaged.
Q13. What is the main structure of a dc/ac MG?
As depicted in Fig.1, each DG system comprises a renewable energy source (RES), an energy storage system (ESS), and a power electronic interface, which normally consist of a dc-ac inverter.
Q14. What is the drawback of the MGCC?
The drawback is that the MGCC is not highly reliable since a failure of this controller is enough to stop the secondary control action.
Q15. How much of the data drop-out is seen in the graph?
It can be seen that both controllers has an acceptable performance in restoring frequency and voltage deviation for 50% of data drop-out.