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 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 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 A Fault Line Selection Method for DC Distribution Network Using Multiple Observers

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1245 ◽  
Author(s):  
Xipeng Zhang ◽  
Nengling Tai ◽  
Pan Wu ◽  
Xiaodong Zheng ◽  
Wentao Huang
Keyword(s):  
Distribution Network ◽  
Initial Result ◽  
Fault Current ◽  
Fault Line ◽  
Fault Line Selection ◽  
Dc Distribution ◽  
Line Selection ◽  
Selection For ◽  
Line Network ◽  
Peak Value

This paper proposes a method of fault line selection for a DC distribution network. Firstly, the 1-mode current is calculated using the measured currents of the positive and the negative line. Then, it is time reversed and further decomposed by wavelet technology. Secondly, the lossless mirror line network is established according to the parameters and the topology of the DC distribution network. Thirdly, it is presumed that several virtual current sources are employed at the locations where the corresponding observers are, and the values of these current sources are equal to the processed 1-mode currents. Fourthly, a fault is placed at every point of the lossless mirror line network the RMS value of every assumed fault current is calculated. During this process, the phase coefficient of every lossless mirror line is set to vary along with the length of the line obeying Gaussian distribution. Finally, the line with the peak value of the RMS values of the currents is selected as the fault line. The result of fault line selection is updated using the fewest observers that are set in advance according to the initial result. A DC distribution network is simulated in PSCAD/EMDTC to verify the correctness of the proposed method.

scholarly journals A Novel Optimization Method for a Multi-Year Planning Scheme of an Active Distribution Network in a Large Planning Zone

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3450
Author(s):  
Xuejun Zheng ◽  
Shaorong Wang ◽  
Zia Ullah ◽  
Mengmeng Xiao ◽  
Chang Ye ◽  
...  
Keyword(s):  
Power Distribution ◽  
Large Scale ◽  
Distribution Network ◽  
Electrical Energy ◽  
Distribution Networks ◽  
Optimization Method ◽  
Scheme Optimization ◽  
Optimization Task ◽  
Novel Approach ◽  
Planning Scheme

Electric power distribution networks plays a significant role in providing continuous electrical energy to different categories of customers. In the context of the present advancements, future load expansion in the active distribution networks (ADNs) poses the key challenge of planning to be derived as a multi-stage optimization task, including the optimal expansion planning scheme optimization (EPSO). The planning scheme optimization is a multi-attribute decision-making issue with high complexity and solving difficulty, especially when it involves a large-scale planning zone. This paper proposes a novel approach of a multi-year planning scheme for the effective solution of the EPSO problem in large planning zones. The proposed approach comprises three key parts, where the first part covers two essential aspects, i.e., (i) suggesting a project condition set that considers the elements directly related to a group of specific conditions and requirements (collectively referred to as conditions) to ADN planning projects; and (ii) Developing a condition scoring system to evaluate planning projects. The second part of our proposed scheme is a quantization method of correlativity among projects based on two new concepts: contribution index (CI) and dependence index (DI). Finally, considering the multi-year rolling optimization, a detailed mathematical model of condition evaluation and spatiotemporal optimization sequencing of ADN planning projects is developed, where the evaluation and optimization are updated annually. The proposed model has been successfully validated on a practical distribution network located in Xiantao, China. The investigated case study and comparisons verify the various advantages, suitability, and effectiveness of the proposed planning scheme, consequently saving more than 10% of the investment compared with the existing implemented scheme.

scholarly journals Examination of the Chance Constrained Optimal WT Penetration Level in Distorted Distribution Network with Wind Speed and Load Uncertainties

2021 ◽  
Vol 11 (4) ◽  
pp. 7311-7320
Author(s):  
I. C. Barutcu
Keyword(s):  
Wind Speed ◽  
Distribution System ◽  
Distribution Network ◽  
Flow Analysis ◽  
Harmonic Distortion ◽  
Distribution Networks ◽  
Optimization Method ◽  
Load Flow ◽  
Chance Constraint ◽  
Harmonic Load

Harmonic penetration can be problematic by the growing interconnection of Wind Turbines (WTs) in distribution networks. Since the active power outputs of WTs and loads in the distribution system have uncertainties, the optimal WT penetration level problem can be considered to have a stochastic nature. In this study, this problem is taken into account in the stochastic optimization method with the consideration of uncertainties in wind speed and distribution network load profile. Chance constraint programming is taken into account in the determination of optimal WT penetration levels by applying the Genetic Algorithm (GA) along with Monte Carlo Simulation (MCS). The harmonic power flow analysis based on the decoupled harmonic load flow approach is employed in the distorted distribution network. Chance constraints are considered for the harmonic issues such as the Total Harmonic Distortion of Voltage (VTHD), Individual Harmonic Distortion of Voltage (VIHDh), and Root Mean Square of Voltage (VRMS).

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.

scholarly journals An Efficient Approach for Reactive Power Compensation of Distribution Networks Using Particle Swarm Optimization

2020 ◽  
Vol 6 (7) ◽  
pp. 14-19
Author(s):  
Nikhil Dubey ◽  
Prof. Ranvijay
Keyword(s):  
Optimization Algorithm ◽  
Power Distribution ◽  
Reactive Power ◽  
Power Level ◽  
Distribution Network ◽  
Distribution Networks ◽  
Optimization Method ◽  
Power Distribution Network ◽  
Power Quality Conditioner ◽  
The One

The power compensation is the one of the problem in distribution network. The power compensation is done by maintain the reactive power in distribution network. The power is maintain the state of the UPQC (Uni?ed power quality conditioner). The UPAC controlled by the STATCOM or DSTATCOM. Different approaches use to maintain the power at needed level in the power distribution network the process done by MOPSO optimization method the MOPSO is the best for this process because we consider the lot of objective function to optimize the place of the UPQC. In our proposed work we find the power level in distribution network using optimization algorithm. The optimization algorithm is used to optimization the power and find which place is suitable for place the STATCOM or DSTATCOM. This is used to maintain the reactive power in distribution network.

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