scholarly journals An Efficient Backward/Forward Sweep Algorithm for Power Flow Analysis through a Novel Tree-Like Structure for Unbalanced Distribution Networks

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 897
Author(s):  
Stefanos Petridis ◽  
Orestis Blanas ◽  
Dimitrios Rakopoulos ◽  
Fotis Stergiopoulos ◽  
Nikos Nikolopoulos ◽  
...  

The increase of distributed energy resources (DERs) in low voltage (LV) distribution networks requires the ability to perform an accurate power flow analysis (PFA) in unbalanced systems. The characteristics of a well performing power flow algorithm are the production of accurate results, robustness and quick convergence. The current study proposes an improvement to an already used backward-forward sweep (BFS) power flow algorithm for unbalanced three-phase distribution networks. The proposed power flow algorithm can be implemented in large systems producing accurate results in a small amount of time using as little computational resources as possible. In this version of the algorithm, the network is represented in a tree-like structure, instead of an incidence matrix, avoiding the use of redundant computations and the storing of unnecessary data. An implementation of the method was developed in Python programming language and tested for 3 IEEE feeder test cases (the 4 bus feeder, the 13 bus feeder and the European Low Voltage test feeder), ranging from a low (4) to a very high (907) buses number, while including a wide variety of components witnessed in LV distribution networks.

2020 ◽  
Author(s):  
Evangelos Pompodakis

<p><b>Conventional power flow (CPF) algorithms assume that the network resistances and reactances remain constant regardless of the weather and loading conditions. Although the impact of the weather in power flow analysis has been recently investigated via the weather-dependent power flow (WDPF) approaches, the magnetic effects in the core of ACSR conductors have not been explicitly considered. ACSR conductors are widely used in distribution networks. Therefore, this manuscript proposes a three-phase weather-dependent power flow algorithm for 4-wire multi-grounded unbalanced microgrids (MGs), which takes into consideration the impact of weather as well as the magnetic effects in the core of ACSR conductors. It is shown that the magnetic effects in the core can significantly influence the power flow results, especially for networks composed of single-layer ACSR conductors. Furthermore, the proposed algorithm explicitly considers the multi-grounded neutral conductor, thus it can precisely simulate unbalanced low voltage (LV) and medium voltage (MV) networks. In addition, the proposed approach is generic and can be applied in both grid-connected and islanded networks. Simulations conducted in a 25-Bus unbalanced LV microgrid highlight the accuracy and benefit of the proposed approach. </b></p>


2020 ◽  
Author(s):  
Evangelos Pompodakis

<p><b>Conventional power flow (CPF) algorithms assume that the network resistances and reactances remain constant regardless of the weather and loading conditions. Although the impact of the weather in power flow analysis has been recently investigated via the weather-dependent power flow (WDPF) approaches, the magnetic effects in the core of ACSR conductors have not been explicitly considered. ACSR conductors are widely used in distribution networks. Therefore, this manuscript proposes a three-phase weather-dependent power flow algorithm for 4-wire multi-grounded unbalanced microgrids (MGs), which takes into consideration the impact of weather as well as the magnetic effects in the core of ACSR conductors. It is shown that the magnetic effects in the core can significantly influence the power flow results, especially for networks composed of single-layer ACSR conductors. Furthermore, the proposed algorithm explicitly considers the multi-grounded neutral conductor, thus it can precisely simulate unbalanced low voltage (LV) and medium voltage (MV) networks. In addition, the proposed approach is generic and can be applied in both grid-connected and islanded networks. Simulations conducted in a 25-Bus unbalanced LV microgrid highlight the accuracy and benefit of the proposed approach. </b></p>


Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1623
Author(s):  
Lukas Held ◽  
Felicitas Mueller ◽  
Sina Steinle ◽  
Mohammed Barakat ◽  
Michael R. Suriyah ◽  
...  

An optimal power flow algorithm for unbalanced three-phase distribution grids is presented in this paper as a new tool for grid planning on low voltage level. As additional equipment like electric vehicles, heat pumps or solar power systems can sometimes cause unbalanced power flows, existing algorithms have to be adapted. In comparison to algorithms considering balanced power flows, the presented algorithm uses a complete model of a three-phase four-wire low voltage grid. Additionally, a constraint for the voltage unbalance in the grid is introduced. The algorithm can be used to optimize the operation of energy storage systems in unbalanced systems. The used grid model, constraints, objective function and solver are explained in detail. A validation of the algorithm using a commercial tool is done. Additionally, three exemplary optimizations are performed to show possible applications for this tool.


2020 ◽  
Author(s):  
Evangelos Pompodakis

<p><b>Conventional power flow (CPF) algorithms assume that the network resistances and reactances remain constant regardless of the weather and loading conditions. Although the impact of the weather in power flow analysis has been recently investigated via the weather-dependent power flow (WDPF) approaches, the magnetic effects in the core of ACSR conductors have not been explicitly considered. ACSR conductors are widely used in distribution networks. Therefore, this manuscript proposes a three-phase weather-dependent power flow algorithm for 4-wire multi-grounded unbalanced microgrids (MGs), which takes into consideration the impact of weather as well as the magnetic effects in the core of ACSR conductors. It is shown that the magnetic effects in the core can significantly influence the power flow results, especially for networks composed of single-layer ACSR conductors. Furthermore, the proposed algorithm explicitly considers the multi-grounded neutral conductor, thus it can precisely simulate unbalanced low voltage (LV) and medium voltage (MV) networks. In addition, the proposed approach is generic and can be applied in both grid-connected and islanded networks. Simulations conducted in a 25-Bus unbalanced LV microgrid highlight the accuracy and benefit of the proposed approach. </b></p>


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