scholarly journals Adaptive Volt-Var Control Algorithm to Grid Strength and PV Inverter Characteristics

2021 ◽  
Vol 13 (8) ◽  
pp. 4459
Author(s):  
Toni Cantero Gubert ◽  
Alba Colet ◽  
Lluc Canals Casals ◽  
Cristina Corchero ◽  
José Luís Domínguez-García ◽  
...  
Keyword(s):  
Distribution System ◽  
Control Algorithm ◽  
Low Voltage ◽  
Control Function ◽  
Accurate Information ◽  
Voltage Sensitivity ◽  
Sensitivity Matrix ◽  
Electrical Grid ◽  
Pv Inverter ◽  
Voltage Deviation

The high-penetration of Distributed Energy Resources (DER) in low voltage distribution grids, mainly photovoltaics (PV), might lead to overvoltage in the point of common coupling, thus, limiting the entrance of renewable sources to fulfill the requirements from the network operator. Volt-var is a common control function for DER power converters that is used to enhance the stability and reliability of the voltage in the distribution system. In this study, a centralized algorithm provides local volt-var control parameters to each PV inverter, which are based on the electrical grid characteristics. Because accurate information of grid characteristics is typically not available, the parametrization of the electrical grid is done using a local power meter data and a voltage sensitivity matrix. The algorithm has different optimization modes that take into account the minimization of voltage deviation and line current. To validate the effectiveness of the algorithm and its deployment in a real infrastructure, the solution has been tested in an experimental setup with PV emulators under laboratory conditions. The volt-var control algorithm successfully adapted its parameters based on grid topology and PV inverter characteristics, achieving a voltage reduction of up to 25% of the allowed voltage deviation.

scholarly journals Adaptive Volt-VAr Control Algorithm to Grid Strength and PV Inverter Characteristics

2021 ◽  
Author(s):  
Toni Cantero Gubert ◽  
Alba Colet ◽  
Lluc Canals Casals ◽  
Cristina Corchero ◽  
Jose Luís Domínguez-García ◽  
...  
Keyword(s):  
Distribution System ◽  
Control Algorithm ◽  
Low Voltage ◽  
Accurate Information ◽  
Voltage Sensitivity ◽  
Sensitivity Matrix ◽  
Electrical Grid ◽  
Pv Inverter ◽  
Control Functions ◽  
Voltage Deviation

High-penetration of Distributed Energy Resources (DER) in low voltage distribution grids, mainly photovoltaics (PV), might lead to overvoltage in the point of common coupling. Volt-VAr is one of the common control functions for DER power converters used to enhance the stability and the reliability of the voltage in the distribution system and, thus, fulfilling the network operator requirements. In this study, a centralized algorithm will provide local Volt-VAr control parameters to each PV inverter, based on the electrical grid characteristics where each equipment is installed. Since accurate information of grid characteristics is typically not available, the parametrization of the electrical grid is done using power meter data in DER location and a voltage sensitivity matrix. The algorithm has different optimization modes to both minimize voltage deviation and line current. In order to validate the effectiveness of the algorithm and its deployment in real infrastructure, it has been tested in an experimental setup with PV emulators in a set of 5-day tests. Volt-VAr control algorithm successfully adapted its parameters based on grid topology and PV inverter characteristics, achieving a voltage reduction up to 25% of the allowed voltage deviation.

scholarly journals High-Efficiency Bi-Directional Single-Phase AC/DC Converter Design and Field Application for LVDC Distribution

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2191 ◽  
Author(s):  
Juyong Kim ◽  
Hongjoo Kim ◽  
Jintae Cho ◽  
Youngpyo Cho
Keyword(s):  
Distribution System ◽  
Single Phase ◽  
High Efficiency ◽  
Low Voltage ◽  
Control Function ◽  
High Reliability ◽  
Power Converter ◽  
Field Application ◽  
Distribution Grid ◽  
Demonstration Site

This paper describes the design and field application of a high-efficiency single-phase AC/DC converter that is suitable for distribution lines. First, an appropriate AC/DC converter was designed in consideration of the environment of the application system. In order to ensure high efficiency and high reliability, we designed an optimum switching element and capacitor suitable for the converter, and the protection element of the AC/DC converter was designed based on these elements. The control function for the power converter suitable for an LVDC distribution system is proposed for highly reliable operation. The AC/DC converter was manufactured based on the design and its performance was verified during application in an actual low-voltage DC (LVDC) distribution grid through tests at the demonstration site. The application to a DC distribution system in an actual grid is very rare and it is expected that it will contribute to the expansion of LVDC distribution.

scholarly journals Investigation of Var Compensation Schemes in Unbalanced Distribution Systems

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Yinuo Huang ◽  
Licheng Wang ◽  
Kai Wang
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Low Voltage ◽  
Current System ◽  
Voltage Regulation ◽  
Voltage Sensitivity ◽  
Compensation Methods ◽  
Distribution System Planning ◽  
Var Compensation ◽  
Phase Conductors

Distributed rooftop photovoltaic (PV) generators prospered distributed generation (DG) in recent years. Certain randomness of rooftop PV connection may lead to significant PV power imbalance across three phases, especially in low-voltage distribution systems. Due to interphase line coupling, traditional Var compensation methods which typically have competent voltage regulation performance may become less effective in such PV imbalance scenarios. In this paper, the limitation of traditional Var compensation methods in voltage regulation with unbalanced PV power integration is demonstrated and comprehensively analyzed. After describing the voltage regulation challenge, based on the voltage sensitivity analysis, it is revealed that PV power unbalanced level together with equivalent mutual impedance among phase conductors has a significant impact on the effectiveness of traditional Var compensation methods on voltage regulation. On this basis, to improve the performance of voltage regulation methods, some suggestions are proposed for both current system operation and future distribution system planning. Numerical studies demonstrate the effectiveness of the proposed suggestions. Future rooftop PV integration in LV systems can benefit from this research.

scholarly journals Comparison of Measurement Methods of LV Grid Access Impedance in the Frequency Range Assigned to Nb‑Plc Technologies

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1155 ◽  
Author(s):  
Igor Fernández ◽  
David de la Vega ◽  
Dominique Roggo ◽  
Robert Stiegler ◽  
Lino Capponi ◽  
...  
Keyword(s):  
Distribution System ◽  
Low Voltage ◽  
Collaborative Work ◽  
Frequency Range ◽  
Electrical Grid ◽  
Power Line Communications ◽  
Theoretical Approaches ◽  
High Degree ◽  
Impedance Characterization

The paper presents and evaluates three advanced methods for the characterization of the low-voltage (LV) grid access impedance for the frequency range assigned to Narrow Band-Power Line Communications (NB-PLC): 9 kHz to 500 kHz. This study responds to the recent demand from both regulatory bodies and Distribution System Operators about the need for accurate and validated methods for this frequency band, due to the limited knowledge of the impedance values in the electrical grid and their influence on NB-PLC transmission channels. In this paper, the results of a collaborative work to develop different proposals to overcome the challenges for the proper characterization of the frequency and time-varying grid impedance, from different theoretical approaches, are presented. The methods are compared in a controlled and isolated scenario: the impedance characterization of passive filters. Then, the results are validated two-fold: first, against theoretical simulations, based on the schematics provided by the manufacturer, and second, against the measurement results of a precision impedance meter, used as a reference of accuracy. The results demonstrate a high degree of precision of the three proposals to characterize the access impedance of the LV grid.

scholarly journals A comparative study on AC/DC analysis of an operational low voltage distribution system

2021 ◽  
Vol 10 (3) ◽  
pp. 193
Author(s):  
Cihan Katar ◽  
Cengiz Polat Uzunoglu
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Low Voltage ◽  
Solar Panels ◽  
Power Losses ◽  
Voltage Distribution ◽  
Electrical Grid ◽  
Safety Regulations ◽  
Voltage Drops ◽  
Novel Approach

In the near future, the digitalizing world will continue to improve and the need for DC based devices will be increased beyond doubt. Today’s electrical grid is strictly dependent on AC-DC rectifiers. Each conversion process means additional power losses and signal quality deteriorations for the network. In addition, networks which are fed by batteries and renewable sources such as solar panels, and wind turbines are suffering from conversion-based power losses. In this respect, the idea of switching to DC on the low voltage side of the networks has become an intriguing subject. In this study, the applicability and efficiency of the low voltage direct current (LVDC) concept for low voltage distribution systems is discussed and a sample LVDC distribution system is analyzed. In this operational residential application electrical transient analyzer program (ETAP) is employed for comparison of different voltage levels such as 110 V<sub>DC</sub>, 250 V<sub>DC</sub>, 320 V<sub>DC</sub> and conventional 220/380 V<sub>AC</sub>. As a novel approach different DC voltage levels are compared with typical AC system in detail. Comparative analysis is conducted for safety regulations, voltage drops, current carrying capacities, power consumption and harmonic calculation of the proposed system. In this respect applicability, possible drawbacks and future aspects of LVDC systems are interpreted.

scholarly journals Photovoltaic Inverter Profiles in Relation to the European Network Code NC RfG and the Requirements of Polish Distribution System Operators

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1486
Author(s):  
Krzysztof Chmielowiec ◽  
Łukasz Topolski ◽  
Aleks Piszczek ◽  
Zbigniew Hanzelka
Keyword(s):  
Distribution System ◽  
Reactive Power ◽  
Low Voltage ◽  
Network Code ◽  
Electrical Networks ◽  
Pv Inverter ◽  
Technical Requirements ◽  
Eu Energy Policy ◽  
Support Programmes ◽  
The Eu

The presently observed rapid increase in photovoltaic (PV) micro-installation connections to low-voltage networks, resulting from numerous financial support programmes, European Union (EU) energy policy and growing social awareness of environmental and economic issues, raise the question if PV inverters widely available in EU market fulfil the numerous technical requirements specified in European and Polish regulations. The paper presents the results of an experimental study carried out on three PV Inverters widely available in the EU in accordance with the EU network code NC RfG, standard EN 50549-1:2019 and internal Polish distribution system operators’ (DSOs’) regulations, governing PV inverter cooperation with the low-voltage distribution network. The laboratory test stand scheme and its description are presented. In each test, at least one of the inverters encountered issues, either with the operation in required frequency ranges (one PV inverter), activating reactive power control modes (all three PV inverters), maintaining required power generation gradient after tripping (one PV inverter) or under-voltage ride through immunity (one PV inverter). The obtained results have shown that all tested PV inverters did not meet requirements that are the key to maintaining reliable and safe operation of transmission and distribution electrical networks.

scholarly journals Distributed Event-Triggered Voltage Control with Limited Re-Active Power in Low Voltage Distribution Networks

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 128
Author(s):  
Yanyu Luo ◽  
Minyou Chen ◽  
Wenfa Kang ◽  
Xiaoluo Sun
Keyword(s):  
Control Strategy ◽  
Low Voltage ◽  
Voltage Control ◽  
Distribution Networks ◽  
Voltage Sensitivity ◽  
Voltage Distribution ◽  
Level Control ◽  
Sensitivity Matrix ◽  
Voltage Control Strategy ◽  
Event Triggered

A high proportion of photovoltaic (PV) connections to a low-voltage distribution network (LVDN) causes serious voltage problems. In order to ensure voltage stability for renewable energy networks, we propose a distributed reactive voltage control strategy that is event-triggered. The voltage information of the PV nodes is transmitted to the upper layer of the communication network, where the agent calculates the output set value of the PV inverter. The underlying control strategy is based on the voltage sensitivity matrix, and the upper-level control strategy is based on an event-triggered consensus protocol. This strategy can accommodate the requirements for multi-time modeling and control. We verified the convergence of the event-triggered control algorithm using numerical analysis and proved the reduction of the communication times. We conducted case studies and simulation experiments to verify the effectiveness of our proposed voltage control strategies.

PV-Statcom based Smart Inverter in Distribution System

2021 ◽  
Vol 8 (1) ◽  
pp. 31-38
Author(s):  
S. Dinesh ◽  
Dr.S. Sentamilselvan
Keyword(s):  
Distribution System ◽  
Low Voltage ◽  
Voltage Control ◽  
Research Center ◽  
The Sun ◽  
Low Voltage Ride Through ◽  
Pv Inverter ◽  
Basic Framework

Shrewd PV Inverter can be used to give voltage control during basic framework needs on an every minute of every day premise. In the evening, the whole inverter limit is used for Smart PV Inverter activity. During a basic framework unsettling influence in the daytime, the shrewd inverter suspends its genuine force age work incidentally, and discharges its whole inverter limit with regards to Smart PV Inverter activity. When the aggravation is cleared and the requirement for network voltage control is satisfied, the sun oriented homestead gets back to its pre-unsettling influence genuine force creation. The Low Voltage Ride Through (LVRT) execution of the Smart PV Inverter is shown through both MATLAB reenactments and research center execution utilizing d-SPACE control. This proposed Smart PV Inverter with a reaction season of 1-2 cycles, can offer a comparable support as a genuine Smart PV Inverter in a given application and conceivably look for incomes for offering this assistance.

scholarly journals Low-voltage ride-through for a three-phase four-leg photovoltaic system using SRFPI control strategy

2019 ◽  
Vol 9 (3) ◽  
pp. 1524
Author(s):  
Haval Sardar Kamil ◽  
Dalila Mat Said ◽  
Mohd Wazir Mustafa ◽  
Mohammad Reza Miveh ◽  
Nasarudin Ahmad
Keyword(s):  
Control Strategy ◽  
Power Plants ◽  
Low Voltage ◽  
Photovoltaic System ◽  
Electrical Grid ◽  
Low Voltage Ride Through ◽  
Power Stations ◽  
Pv Inverter ◽  
Synchronous Reference Frame ◽  
Three Phase

With the innovative progresses in power electronics in recent years, photovoltaic (PV) systems emerged as one of the promising sources for electricity generation at the distribution network. Nonetheless, connection of PV power plants to the utility grid under abnormal conditions has become a significant issue and novel grid codes should be recommend. The low-voltage ride-through (LVRT) capability is one of the challenges faced by the integration of PV power stations into electrical grid under abnormal conditions. This work firstly provides a discussion on recent control schemes for PV power plants to enhance the LVRT capabilities. Next, a control scheme for a three-phase four-leg grid-connected PV inverter under unbalanced grid fault conditions using synchronous reference frame proportional integral (SRFPI) controller is proposed. Simulation studies are performed to investigate the influence of the control strategy on the PV inverter.

Development and Evaluation of a Fast Voltage Calculation Method for Low-Voltage Distribution System

2013 ◽  
Vol 133 (4) ◽  
pp. 343-349
Author(s):  
Shunsuke Kawano ◽  
Yasuhiro Hayashi ◽  
Nobuhiko Itaya ◽  
Tomihiro Takano ◽  
Tetsufumi Ono
Keyword(s):  
Calculation Method ◽  
Distribution System ◽  
Low Voltage ◽  
Voltage Distribution
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