scholarly journals Coordinated Control of Voltage Balancers for the Regulation of Unbalanced Voltage in a Multi-Node Bipolar DC Distribution Network

Electronics ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 166
Author(s):  
Chunsheng Guo ◽  
Yuhong Wang ◽  
Jianquan Liao
Keyword(s):  
Neutral Line ◽  
Distribution Network ◽  
Distribution Networks ◽  
Load Resistance ◽  
Consensus Algorithm ◽  
Primary Control ◽  
Consensus Control ◽  
Dc Distribution ◽  
Unbalanced Voltage ◽  
Unbalanced Load

In a bipolar DC distribution network, the unbalanced load resistance, line resistance and renewable energy source will cause an unbalanced current for each node of the neutral line and lead to its unbalanced voltage. This is a unique power quality problem of bipolar DC distribution networks, which will increase the power loss in the network and lead to overcurrent protection of the neutral line in serious cases. A voltage balancer can be adopted to suppress the unbalanced voltage and current. However, the existing literature does not consider the consistent application of multiple voltage balancers in a multi-node bipolar DC distribution network. This paper creatively proposes a consensus control topology combining primary control and secondary control in a radial multi-node bipolar DC distribution network with voltage balancers. In this paper, the formulas for the positive and negative current and duty cycle of a bipolar DC distribution network with voltage balancers are derived, and improved voltage balancer modeling based on a consensus algorithm is built. The radial multi-node bipolar DC distribution network is established in MATLAB/Simulink. The simulation results compare the consensus control with the traditional droop control and verify the effectiveness of the new control structure with voltage balancers.

scholarly journals Convex Approximation Algorithm for AC/DC Distribution Network With Energy Router

2021 ◽  
Vol 9 ◽  
Author(s):  
Tao Zhang ◽  
Yunfei Mu ◽  
Xiaoyu Wang ◽  
Youjun Deng ◽  
Yi Song ◽  
...  
Keyword(s):  
Approximation Algorithm ◽  
Distribution Network ◽  
Distribution Networks ◽  
Optimal Operation ◽  
Convex Programming Problem ◽  
Convex Approximation ◽  
Approximation Approach ◽  
Flow Equations ◽  
Dc Distribution ◽  
Highly Nonlinear

The optimal operation model of AC/DC distribution network with energy router (ER) is essentially a nonconvex nonlinear programming (NLP) problem. In order to improve the feasibility of solving the model, a convex approximation algorithm is proposed in this work. The steady-state model of ER is developed with considering the loss characteristics and multiport coordinated control strategy. It is embedded in the optimization formulations of AC/DC network as basic operating equations. Then, using second-order cone relaxation technology, the power flow equations of AC and DC distribution networks are convexly relaxed. On this basis, the highly nonlinear operating model of ER is linearized by introducing a successive approximation approach. Therefore, the original NLP problem is transformed into the convex programming problem and the solution efficiency is improved. Meanwhile, an iterative solution algorithm is developed to ensure the accuracy of the convex approximation approach. Simulation results verify the feasibility and efficiency of the proposed algorithm.

scholarly journals Design of Low-Ripple and Fast-Response DC Filters in DC Distribution Networks

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3128 ◽  
Author(s):  
Jianquan Liao ◽  
Niancheng Zhou ◽  
Qianggang Wang
Keyword(s):  
Transfer Function ◽  
Distribution Network ◽  
Low Frequency ◽  
Distribution Networks ◽  
Optimization Method ◽  
Fast Response ◽  
Resonance Peak ◽  
Dc Distribution ◽  
Filtering Effect ◽  
Peak Value

The design and parameter selection of low-ripple and fast-response direct current (DC) filters are discussed in this study with the aim of alleviating the influence of a DC-side low-frequency voltage pulsation on a sensitive load in a DC distribution network. A method for determining the DC filter parameters by using a mofatching most flat response algorithm is presented. The voltage transfer function of the DC-side filter in the DC distribution network is deduced to analyze its voltage transfer characteristics. The resonance peak value of the filter network is an important factor affecting the transfer speed of a filter. A pole-circle-based parameter optimization method is proposed to move the poles of the filter transfer function down and to the left of pole plane for finding the appropriate capacitance, inductance, and damping parameters. This approach effectively restricts the resonance peak value, accelerates the transfer speed, and maintains steady filtering results. Simulation and test results verify that the filter has low resonance value, rapid convergence ability, and an excellent filtering effect.

scholarly journals The LCOE-Indicator-Based Comprehensive Economic Comparison between AC and DC Power Distribution Networks with High Penetration of Renewable Energy

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4621 ◽  
Author(s):  
Yi Liu ◽  
Zhanqing Yu ◽  
Haibo Li ◽  
Rong Zeng
Keyword(s):  
Renewable Energy ◽  
Economic Evaluation ◽  
Power Loss ◽  
Distribution Network ◽  
Distribution Networks ◽  
Planning Stage ◽  
Stage Of Development ◽  
Dc Distribution ◽  
High Penetration ◽  
Economic Comparison

DC distribution networks are operationally economical from the perspective of renewable energy penetration due to the reduction of power loss from the simplified power conversion structure. However, the initial investment cost of a DC network is high because DC technology is in the early stage of development. So, selecting AC or DC technology becomes an important issue in the planning stage of a distribution network, where a comprehensive quantitative economic comparison between AC and DC distribution networks is necessary. To compare the economy between AC and DC distribution networks with high penetration of a renewable energy scenario, this paper introduces a comprehensive economic evaluation method. In this study, first, typical system models for AC and DC distribution networks were proposed as the foundation of the research. Then, a levelized cost of energy (LCOE)-indicator-based comprehensive economic evaluation model was established, where the operation cost was classified into power loss cost, reliability loss cost, and operational cost. A time sequential simulation model was applied to calculate the power loss. The simulation results showed that a DC distribution network has higher initial investment, operation, and maintenance costs than an AC distribution network, but the loss cost is far lower than an AC distribution network. A sensitivity analysis showed that the equipment cost and proportion of renewable energy are two of the most important factors that affect the economics of DC distribution networks at present.

Unbalanced Voltage Suppression in a Bipolar DC Distribution Network Based on DC Electric Springs

2020 ◽  
Vol 11 (2) ◽  
pp. 1667-1678 ◽  
Author(s):  
Jianquan Liao ◽  
Niancheng Zhou ◽  
Yuansheng Huang ◽  
Qianggang Wang
Keyword(s):  
Distribution Network ◽  
Dc Distribution ◽  
Unbalanced Voltage

scholarly journals Research on Cooperative Planning of Distributed Generation Access to AC/DC Distribution (Micro) Grids Based on Analytical Target Cascading

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1847 ◽  
Author(s):  
Hao Pan ◽  
Ming Ding ◽  
Rui Bi ◽  
Lei Sun
Keyword(s):  
Distributed Generation ◽  
Power Supply ◽  
Rapid Development ◽  
Distribution Network ◽  
Distribution Networks ◽  
Analytical Target Cascading ◽  
Distributed Power ◽  
Dc Distribution ◽  
Target Cascading ◽  
Micro Grids

With the wide application of distributed generation (DG) and the rapid development of alternating current/direct current (AC/DC) hybrid microgrids, the optimal planning of distributed generation connecting to AC/DC distribution networks/microgrids has become an urgent problem to resolve. This paper presents a collaborative planning method for distributed generation access to AC/DC distribution (micro) grids. Based on the grid structure of the AC/DC distribution network, the typical interconnection structure of the AC/DC hybrid microgrid and AC/DC distribution network is designed. The optimal allocation models of distributed power supply for the AC/DC distribution network and microgrid are established based on analytical target cascading. The power interaction between the distribution network and microgrid is used to establish a coupling relationship, and the augmented Lagrangian penalty function is used to solve the collaborative programming problem. The results of distributed power supply allocation are obtained, solving the problem so that distribution generation with different capacity levels is connected to the power grid system in a single form.

Decentralized and Per-Unit Primary Control Framework for DC Distribution Networks With Multiple Voltage Levels

2020 ◽  
Vol 11 (5) ◽  
pp. 3993-4004
Author(s):  
Xiaoming Wang ◽  
Yonggang Peng ◽  
Chudi Weng ◽  
Yanghong Xia ◽  
Wei Wei ◽  
...  
Keyword(s):  
Distribution Networks ◽  
Primary Control ◽  
Dc Distribution ◽  
Control Framework

A study on appropriate investment of pipeline rehabilitation for water distribution network

2005 ◽  
Vol 5 (2) ◽  
pp. 31-38
Author(s):  
A. Asakura ◽  
A. Koizumi ◽  
O. Odanagi ◽  
H. Watanabe ◽  
T. Inakazu
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Water Supply ◽  
Water Distribution ◽  
Ad Hoc ◽  
Distribution Network ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Optimal Basis ◽  
Model Case

In Japan most of the water distribution networks were constructed during the 1960s to 1970s. Since these pipelines were used for a long period, pipeline rehabilitation is necessary to maintain water supply. Although investment for pipeline rehabilitation has to be planned in terms of cost-effectiveness, no standard method has been established because pipelines were replaced on emergency and ad hoc basis in the past. In this paper, a method to determine the maintenance of the water supply on an optimal basis with a fixed budget for a water distribution network is proposed. Firstly, a method to quantify the benefits of pipeline rehabilitation is examined. Secondly, two models using Integer Programming and Monte Carlo simulation to maximize the benefits of pipeline rehabilitation with limited budget were considered, and they are applied to a model case and a case study. Based on these studies, it is concluded that the Monte Carlo simulation model to calculate the appropriate investment for the pipeline rehabilitation planning is both convenient and practical.

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