Power Quality Assessment in a Real Microgrid-Statistical Assessment of Different Long-Term Working Conditions

Abstract

Power quality (PQ) becomes a more and more pressing issue for the operation stability of power systems with renewable energy sources. An important aspect of PQ monitoring of distribution networks is to compare the PQ indicators in different operating conditions. This paper evaluates the impact of a microgrid implementation in a real distribution network on power quality indicators at the point of common coupling in an LV network. The study includes a classical assessment of the long-term PQ parameters according to the EN 50160 standard, such as nominal frequency deviations, voltage RMS variations, voltage fluctuations (represented by long-term flicker severity), voltage unbalance and total harmonic distortion. The PQ evaluation is extended in statistical assessment based on cluster analysis. The case study contains 5 weeks of power quality observation results obtained at the assessment point in two different working conditions of the distribution system: before and after implementing the microgrid. The study allows establishing general conclusions regarding a microgrid interconnection in order not to exceed power quality limits and considering the influence of photovoltaic generation on power quality parameters.

Comprehensive Power Quality Assessment Based on a Data-Driven Determinant-Valued Extension Hierarchical Analysis Approach

“…(1) Voltage deviation [17]: Voltage deviation refers to the difference between the actual voltage and the rated voltage, including those caused by the working mode of the power supply and distribution control system or load changes.…”

“…Based on Equation (17), we can get P 1 = 2.64, P 2 = 1.1. At this time, we have the two evaluation indicators to the target layer of the ranking of P = (0.855, 0.456) T .…”

Integration of PV Sources in Prosumer Installations Eliminating Their Negative Impact on the Supplying Grid and Optimizing the Microgrid Operation

“…The most typical problems include an excessive voltage rise in the network nodes, which may appear if an extensive power is injected into the network, and the voltage unbalance caused by the load unbalance and the fact that PV sources are often the single-phase ones [7]. It is obvious that these phenomena negatively affect power quality (PQ), result in additional power and energy losses, and can cause disruptions in the operation of prosumer installations and the supplying network [8][9][10][11][12]. A major problem for prosumers is switching-off the PV inverters due to the effect of unacceptable voltage rise [7,13].…”

A Novel Power Quality Comprehensive Estimation Model Based on Multi-Factor Variance Analysis for Distribution Network with DG

“…Generally, in the estimation process, the typical power quality indicators are selected firstly, and then the data of those power quality indicators are collected. A further step is that the power quality indicators will be quantified and weighted to obtain the power quality evaluation result [17][18][19][20][21][22][23][24][25][26][27][28][29]. The estimation model can provide a useful reference for power quality management.…”