Tag Archives: voltage quality

2639–2652 T. Vinnal, H. Puusepp, N. Shabbir, L. Kütt and M. N. Iqbal
Case study of non-linear PV inverter devices attached to the LV distribution network
Abstract |
Full text PDF (6 MB)

Case study of non-linear PV inverter devices attached to the LV distribution network

T. Vinnal, H. Puusepp, N. Shabbir, L. Kütt and M. N. Iqbal

Tallinn University of Technology, School of Engineering, Department of Electrical Power Engineering and Mechatronics, Ehitajate tee 5, EE19086 Tallinn, Estonia.

Abstract:

Every year, more and more solar power plants are connected to the grid, producing electricity in an environmentally sustainable manner. The increasing number of photovoltaic (PV) installations and their integration into the low voltage (LV) distribution network (DN) is having an impact in terms of power quality (PQ). For example, the voltage in the DN can sustain high distortion values. The impact of a PV installation on the LV network is analysed in this research. The field measurements were carried out over a 3-week period at a solar power plant with a total output power of 160 kW in an Estonian rural municipality. The measurement results provide the opportunity to look more closely at the effect of the solar power plant on the supply voltage of the LV DN. Parameters such as voltage variation within a one-minute period, the asymmetry of the voltages and the total harmonic distortion of the voltages are discussed here.

Key words:

, , , , , ,



1155–1164 V. Osadčuks, A. Pecka and A. Galiņš
Usage of grid support inverter on long distribution grid lines
Abstract |
Full text PDF (2 MB)

Usage of grid support inverter on long distribution grid lines

V. Osadčuks*, A. Pecka and A. Galiņš

Latvia University of Life Sciences and Technologies, Faculty of Engineering, Institute of Energetics, Čakstes blvd. 5, LV-3001 Jelgava, Latvia
*Correspondence: vtl@tvnet.lv

Abstract:

The paper focuses on the evaluation of new possibilities to improve voltage quality in remote branches of 230 V grid. Decrease of power electronic costs may potentially make battery-backed inverters a viable alternative to the costly reconstruction of 230 V distribution grid connections, which are of poor quality or cannot match changing load requirements, extending power transmission lines or adding boost transformers. The object of the current study is a household-type consumer with 20 A single-phase connection to distribution line with a distance of 2 km to a 20 kV transformer station. The calculated resistance of the power line is 2.8 ohms. The load profile was captured during 5 days in summer and 10 days in winter and was used to calculate the capacity of the grid support equipment. Measurements indicated, that in the worst case 2% of time the voltage was below 10% of nominal and 8% of time – below 5% of it. This is outside of the regulatory limits of EU and national regulations. The experimental setup for a voltage quality improvement system was based on an OutBack Power Radian series grid inverter with 7 kW output power. Battery consisting of 12 V 120 Ah VRLA accumulators wired in 48 V system was used. The inverter was configured to work in grid support mode using battery power when the consumer’s active load increased above 1.2 kW. Results showed improvement in voltage quality over the full consumer load range. The total efficiency of the grid support system was 89%. The use of DC bus and batteries allows easy incorporation of renewable energy sources, thus giving the opportunity to scale power and battery capacity of the system. An Additional benefit of using a battery-backed inverter in grid support mode is that consumer can temporarily use more power that is allowed by grid due to its capacity constraints.

Key words:

, , ,