Resynchronization of islanded unbalanced ADNs: Control, synchrocheck and experimental validation

Smart automatic synchronization system based on coherence algorithm for power grids

“…Traditionally, generator control systems include a synchronizing panel that includes indications of voltage magnitude, phase angle and slip, which show the necessary adjustments to the generator governor and exciter, and when they are acceptable for the operator, it performs the CB closing [8]. The automatic synchronization of the generator fetches many advantages over manual synchronization, where the computer plays the role of the operator in the automatic mode, which precisely judges the CB closing with predetermined synchronization logic and limit parameters [9]. Modern microprocessor-based SCRs properly monitor both angle and slip, and they are an improvement over earlier technology SCRs for power network applications [10].…”

“…In [9], two algorithms were proposed: in the first algorithm, an approximated optimal load flow was introduced to control active distribution networks' (ADNs') resources so as to quickly steer their Point of Common Coupling (PCC) downstream nodal voltages get close to their non-controllable upstream counterparts. The second algorithm, an Interpolated Discrete Fourier Transform (IpDFT)-based synchro-check that achieves the alignment of all three phases of both downstream and upstream nodal voltages at the PCC, was presented.…”

“…In addition, in [14], a distributed PI-controller-based criteria was suggested, where distributed generations (DGs) contact in a cooperative way with each other to adapt their local drooping so as to steer the downstream PCC nodal voltages towards their upstream counterparts. In the above works [9][10][11][12][13][14], the synchro-check operation was carried out through phasor locked loop (PLL)based algorithms that obtain both nodal voltage frequencies and phase angles coupled with standard magnitude measures. In the specified literature on synchro-check relays (SCRs), most techniques perform the same, however, some existing substitutional works.…”

“…Most algorithms depend on the root mean square (RMS) of the voltage and current waves. It is necessary to implement various measures during a weakness of power quality, such as change in total harmonic distortion (THD) and system frequency, which have an effect on the RMS of the measured waves [5,6,7,9,12,13,15,18,19,22]. 8.…”

“…The main drawbacks of the existing synchronization relays and systems are given below: The conventional SCRs select distinct predetermined settings for the three voltage variables (such as magnitude, frequency, and phase angle shift) [3, 4, 6, 7, 9, 11, 12, 16, 20, 22]. Some methods value the synchronization level more slowly [5, 6, 7, 9, 12, 13, 20, 21]. Some conventional methods react during the system abnormal situations [5, 6, 7, 10, 11, 15, 18].…”