DC-Link Voltage Balancing Strategy Based on SVM and Reactive Power Exchange for a 5L-MPC Back-to-Back Converter for Medium-Voltage Drives

This paper introduces a novel local Volt/var control strategy in a low-voltage smart grid. Nowadays, various Volt/var local control strategies built on customer photovoltaic inverters, e.g., cosφ(P) and Q(U), are introduced to mitigate the upper voltage limit violations in feeders with high prosumer share. Nevertheless, although these strategies are further refined by including more local variables, their use is still very limited. In this study, the effects of a new concentrated Volt/var local control strategy in low-voltage grids are investigated. Concentrated var-sinks, e.g., coils-L(U), are set at the end of each violated feeder. The concentrated local control strategy L(U) is compared with the distributed cosφ(P) and Q(U) strategies. Initially, both control strategies are theoretically investigated, followed by simulations in a test feeder. Finally, the expected practical significance of the findings is verified through simulations in a real typical urban and rural grid. Additionally, the impact of the different local control strategies used in low-voltage grids on the behavior of the medium-voltage grid is analyzed. The results show that the concentrated Volt/var control strategy eliminates the violation of upper voltage limit even in longer feeders, where both distributed local strategies fail. In addition, the concentrated L(U) local control causes less reactive power exchange on the distribution transformer level than the distributed cosφ(P) and Q(U) strategies. Therefore, the reactive power exchange with the medium-voltage grid and thus the distribution transformer loading are smaller in the case of concentrated local control strategy.

Download Full-text

DC Side Voltage Balancing Control for The Medium Voltage Cascaded H Bridge APF

2018 37th Chinese Control Conference (CCC) ◽

10.23919/chicc.2018.8484037 ◽

2018 ◽

Author(s):

Jianghao Huang ◽

Min Lin ◽

Yabin Li ◽

Yonglong Peng ◽

Xuyang Zhao

Keyword(s):

Voltage Balancing ◽

Medium Voltage ◽

Balancing Control

Download Full-text

Application-Oriented Reactive Power Management in German Distribution Systems Using Decentralized Energy Resources

Energies ◽

10.3390/en14164949 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4949

Author(s):

Haonan Wang ◽

Markus Kraiczy ◽

Denis Mende ◽

Sebastian Stöcklein ◽

Martin Braun

Keyword(s):

Power Management ◽

Distribution System ◽

Distribution Systems ◽

Reactive Power ◽

Control Strategies ◽

Renewable Energy Sources ◽

Measurement Data ◽

Power Exchange ◽

High Investment ◽

Decentralized Energy

Due to higher penetration of renewable energy sources, grid reinforcements, and the utilization of local voltage control strategies, a significant change in the reactive power behavior as well as an increased demand for additional reactive power flexibility in the German power system can be predicted. In this paper, an application-oriented reactive power management concept is proposed, which allows distribution system operators (DSO) to enable a certain amount of reactive power flexibility at the grid interfaces while supporting voltage imitations in the grid. To evaluate its feasibility, the proposed concept is applied for real medium voltage grids in the south of Germany and is investigated comprehensively in different case studies. The results prove the feasibility and reliability of the proposed concept, which allows the DSO to control the reactive power exchange at grid interfaces without causing undesired local voltage problems. In addition, it can be simply adjusted and widely applied in real distribution grids without requiring high investment costs for complex information and communication infrastructures. As a significant contribution, this study provides an ideal bridging solution for DSOs who are facing reactive power issues but have no detailed and advanced monitoring system for their grid. Moreover, the comprehensive investigations in this study are performed in close cooperation with a German DSO, based on a detailed grid model and real measurement data.

Download Full-text

Research on Reactive Power and Voltage Optimization of Regional Distribution Network

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.58-60.474 ◽

2011 ◽

Vol 58-60 ◽

pp. 474-479

Author(s):

Yu Du

Keyword(s):

Reactive Power ◽

Regional Distribution ◽

Distribution Networks ◽

Radiation Characteristic ◽

Reactive Power Optimization ◽

Voltage Level ◽

Medium Voltage ◽

Regulation Effect ◽

Practical Operation ◽

Transformer Taps

The high-medium voltage level distribution networks have their own characters. Because of the radiation characteristic of the network, this paper looks on the network as the combination of some small optimization unit. The paper simplifies the resolution of the reactive power optimization by the way of alternatively solving the adjusting transformer taps and switching capacity banks. At the same time, considering the practical operation request, the paper evaluates the regulation effect and improves the practicability of the software.

Download Full-text

Research on the Control Method of STATCOM Based on MMC

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.448-453.2167 ◽

2013 ◽

Vol 448-453 ◽

pp. 2167-2170

Author(s):

Kai Li ◽

Yi Hui Zheng ◽

Xin Wang ◽

Li Xue Li ◽

Gang Yao ◽

...

Keyword(s):

Closed Loop ◽

Reactive Power ◽

Control Method ◽

Modular Multilevel Converter ◽

Energy Balancing ◽

Multilevel Converter ◽

Voltage Fluctuation ◽

Loop Control ◽

Voltage Balancing ◽

High Voltage Direct Current

To realize the STATCOM based on Modular Multilevel Converter (MMC), a simplified double-closed loop structure, simplifying from the control method of High Voltage Direct Current (HVDC) based on MMC, is presented. Considering MMCs DC side using capacitors, a part-controlling method based on energy balancing is proposed, to solve the voltage balancing problem. With the part-controlling fixing the changing capacitors voltage and the simplified double-closed loop control method, voltage fluctuation could be reduced, and the loads reactive power could be compensated. The correctness and the effectiveness of the MMC-STATCOM controlling scheme is verified by Matlab/Simulink.

Download Full-text

An Emergency Active and Reactive Power Exchange Solution for Interconnected Microgrids

IEEE Journal of Emerging and Selected Topics in Power Electronics ◽

10.1109/jestpe.2019.2954113 ◽

2019 ◽

pp. 1-1 ◽

Cited By ~ 2

Author(s):

Mobin Naderi ◽

Yousef Khayat ◽

Qobad Shafiee ◽

Tomislav Dragicevic ◽

Frede Blaabjerg ◽

...

Keyword(s):

Reactive Power ◽

Active And Reactive Power ◽

Power Exchange

Download Full-text

The influence of the network asymmetry on the settings and sensitivity of an earth fault protection using higher harmonics

E3S Web of Conferences ◽

10.1051/e3sconf/20198402008 ◽

2019 ◽

Vol 84 ◽

pp. 02008

Author(s):

Lubomir Marciniak ◽

Mateusz Piątek

Keyword(s):

Reactive Power ◽

Higher Harmonics ◽

Medium Voltage ◽

Earth Fault ◽

Power Setting ◽

Zero Sequence ◽

The Asymmetry ◽

Supply Voltages ◽

Zero Sequence Voltage

Detection of high resistance earth faults in medium voltage networks is an important problem due to ineffectiveness of traditional earth fault protections. Such short circuits can be detected by the criterion of a reactive power of higher harmonics for zero sequence current and voltage. The main problem is determination of the power setting value in the protection, which depends on the asymmetry of phase-to-earth capacitances and higher harmonics in supply voltages, which are generated by non-linear loads. The intensive tests of the asymmetry of the zero sequence currents and voltages for harmonics and their reactive power have been carried out in 15 kV compensated network as a function of all relevant parameters, i.e.: maximum capacitance deviation of the network and protected line, percentage content of harmonics in supply voltages, capacitive current of the network and the line. It has been shown that third harmonics of the zero sequence voltage and current are the best suited for practical use, since the asymmetry reactive power of these components is the smallest among the considered harmonics and the protection sensitivity will be the highest.

Download Full-text

Stochastic Optimization of PQ Powers at the Interface between Distribution and Transmission Grids

Energies ◽

10.3390/en12214057 ◽

2019 ◽

Vol 12 (21) ◽

pp. 4057

Author(s):

Jérôme Buire ◽

Frédéric Colas ◽

Jean-Yves Dieulot ◽

Xavier Guillaud

Keyword(s):

Reactive Power ◽

Daily Basis ◽

Control Effort ◽

Control Laws ◽

Medium Voltage ◽

Distributed Generators ◽

Real Size ◽

Grid Codes ◽

Distribution Grids ◽

Hourly Basis

This paper addresses the volt-var control of distribution grids embedding many distributed generators (DGs). Specifically, it focuses on the compliance of powers to specified PQ diagrams at the high voltage/medium voltage (HV/MV) interface while the voltages remain well controlled. This is achieved using a two-stage optimization corresponding to two different classes of actuators. The tap position of capacitor banks is selected on a daily basis, given a stochastic model of the input powers prediction, which allows infrequent actuation and increases the device lifespan. In a second stage, a confidence level optimization problem allows to tune on an hourly basis the parameters of the DGs reactive power affine control laws. Results on a real-size grid show that the combined tuning of these actuators allows the ability to comply with European grid codes while the control effort remains reasonable.

Download Full-text