scholarly journals Multi-Time-Scale Optimal Scheduling in Active Distribution Network with Voltage Stability Constraints

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7107
Author(s):  
Tianhao Song ◽  
Xiaoqing Han ◽  
Baifu Zhang
Keyword(s):  
Time Resolution ◽  
Time Scale ◽  
Voltage Stability ◽  
Renewable Energy Sources ◽  
Stability Index ◽  
Distribution Networks ◽  
Optimal Scheduling ◽  
Coarse Grained ◽  
Scheduling Model ◽  
Network Losses

The uncertainty associated with loads and renewable-energy sources affects active distribution networks in terms of the operation and voltage stability on different time scales. To address this problem, a multi-time-scale voltage stability constrained optimal scheduling framework is proposed, which includes a day-ahead model with a coarse-grained time resolution and an intra-day model with a fine-grained time resolution. The day-ahead economic-scheduling model maps out a scheme to operate different types of devices with the aim of minimizing the network losses. Following the scheme, the intra-day corrective-adjustment model based on model predictive control is proposed to regulate the flexible devices, such as the energy storage systems and the photovoltaic converters. In particular, the proposed optimal scheduling framework embeds a voltage stability constraint which is constructed by using a novel index, defined based on the Distflow model Jacobian. As the index at each bus is a linear function of the locally measurable power flow variables, the proposed constraint does not introduce additional computational burdens. Simulation results demonstrate the necessity and effectiveness of the proposed multi-time-scale voltage stability constrained optimal scheduling model. The results also show that the variation trend of the proposed index is consistent with that of the commonly used voltage stability index.

scholarly journals Comparison of Economical and Technical Photovoltaic Hosting Capacity Limits in Distribution Networks

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2405
Author(s):  
Samar Fatima ◽  
Verner Püvi ◽  
Ammar Arshad ◽  
Mahdi Pourakbari-Kasmaei ◽  
Matti Lehtonen
Keyword(s):  
Power Distribution ◽  
Renewable Energy Sources ◽  
Distribution Networks ◽  
Power Distribution Networks ◽  
Network Losses ◽  
Network Costs ◽  
Cost And Benefit Analysis ◽  
Cost Parameters ◽  
The Cost ◽  
Pv Penetration

Power distribution networks are transitioning from passive towards active networks considering the incorporation of distributed generation. Traditional energy networks require possible system upgrades due to the exponential growth of non-conventional energy resources. Thus, the cost concerns of the electric utilities regarding financial models of renewable energy sources (RES) call for the cost and benefit analysis of the networks prone to unprecedented RES integration. This paper provides an evaluation of photovoltaic (PV) hosting capacity (HC) subject to economical constraint by a probabilistic analysis based on Monte Carlo (MC) simulations to consider the stochastic nature of loads. The losses carry significance in terms of cost parameters, and this article focuses on HC investigation in terms of losses and their associated cost. The network losses followed a U-shaped trajectory with increasing PV penetration in the distribution network. In the investigated case networks, increased PV penetration reduced network costs up to around 40%, defined as a ratio to the feeding secondary transformer rating. Above 40%, the losses started to increase again and at 76–87% level, the network costs were the same as in the base cases of no PVs. This point was defined as the economical PV HC of the network. In the case of networks, this level of PV penetration did not yet lead to violations of network technical limits.

Swarm-Intelligence-Based Optimal Placement and Sizing of Distributed Generation in Distribution Network

2018 ◽  
pp. 29-48 ◽  
Author(s):  
Mahesh Kumar ◽  
Perumal Nallagownden ◽  
Irraivan Elamvazuthi ◽  
Pandian Vasant ◽  
Luqman Hakim Rahman
Keyword(s):  
Distributed Generation ◽  
Radial Distribution ◽  
Distribution System ◽  
Voltage Stability ◽  
Reactive Power ◽  
Distribution Network ◽  
Stability Index ◽  
Pso Algorithm ◽  
Distribution Networks ◽  
Optimal Placement

In the distribution system, distributed generation (DG) are getting more important because of the electricity demands, fossil fuel depletion and environment concerns. The placement and sizing of DGs have greatly impact on the voltage stability and losses in the distribution network. In this chapter, a particle swarm optimization (PSO) algorithm has been proposed for optimal placement and sizing of DG to improve voltage stability index in the radial distribution system. The two i.e. active power and combination of active and reactive power types of DGs are proposed to realize the effect of DG integration. A specific analysis has been applied on IEEE 33 bus system radial distribution networks using MATLAB 2015a software.

Voltage Stability Index of Radial Distribution Networks by Considering Distributed Generator for Different Types of Loads

2016 ◽  
Vol 5 (1) ◽  
pp. 1-22 ◽  
Author(s):  
Tapan Kumar Chattopadhyay ◽  
Sumit Banerjee ◽  
Chandan Kumar Chanda
Keyword(s):  
Stability Analysis ◽  
Radial Distribution ◽  
Distribution Systems ◽  
Voltage Stability ◽  
Stability Index ◽  
Distribution Networks ◽  
Voltage Collapse ◽  
Distributed Generator ◽  
Voltage Stability Index ◽  
Different Types

The paper presents an approach on voltage stability analysis of distribution networks for loads of different types. A voltage stability index is proposed for identifying the node, which is most sensitive to voltage collapse. It is shown that the node, at which the value of voltage stability index is maximum, is more sensitive to voltage collapse. For the purpose of voltage stability analysis, constant power, constant current, constant impedance and composite load modeling are considered. Distributed generation can be integrated into distribution systems to meet the increasing load demand. It is seen that with the insertion of distributed generator (DG), load capability limit of the feeder has increased for all types of loads. By using this voltage stability index, one can measure the level of voltage stability of radial distribution systems and thereby appropriate action may be taken if the index indicates a poor level of stability. The effectiveness of the proposed method is demonstrated through two examples.

Voltage Stability of Medium and Low Voltage Distribution Networks with Wind Generation Based on Hilbert-Huang Transform

2011 ◽  
Vol 347-353 ◽  
pp. 2200-2206
Author(s):  
Guang Long Xie ◽  
Bu Han Zhang ◽  
Cheng Xiong Mao ◽  
Yan Li
Keyword(s):  
Wind Power ◽  
Voltage Stability ◽  
Low Voltage ◽  
Stability Index ◽  
Distribution Networks ◽  
Wind Generation ◽  
Intrinsic Mode Functions ◽  
Distribution Grid ◽  
End Effects ◽  
Hilbert Huang Transform

Nowadays the voltage instability problems occur in the distribution grid due to the integration of more and more fluctuant distributed generators. This paper focuses on voltage stability of distribution networks with wind generation. A voltage stability index is presented, and calculated by an expanding Newton-Raphson power flow method in which the wind power generation nodes are modified according to the P-Q(V) character. In order to obtain the key components of fluctuant wind power, the Hilbert-Huang transform algorithm is utilized to reveal the inherent characteristics of wind power. The extrema extending method based on the mirror periodic is used in the empirical mode decomposition and can handle the end effects. According to the Hilbert spectrum and instantaneous energy of each intrinsic mode functions, the components with lower instantaneous frequency are selected to rebuild the wind power. The new rebuilt series consist of stationary and monotonic components which are smoother, and the rebuilt series can reflect the main fluctuant characteristic of the initial wind power data by comparing the index.

scholarly journals A Distributed and Robust Optimal Scheduling Model for an Active Distribution Network With Load Aggregators

2021 ◽  
Vol 9 ◽  
Author(s):  
Jidong Wang ◽  
Qiuming Xu ◽  
Huiling Su ◽  
Kaijie Fang
Keyword(s):  
Power Flow ◽  
Distribution Network ◽  
Optimization Methods ◽  
Distribution Networks ◽  
Optimal Scheduling ◽  
Economic Optimization ◽  
Voltage Security ◽  
Distributed Modeling ◽  
Scheduling Model ◽  
Flexible Loads

Increasing penetration of distributed generation (DG) has brought more uncertainty to the operation of active distribution networks (ADNs). With the reformation of the power system, increasingly more flexible loads access to distribution network through load aggregators (LAs), which becomes an effective way to solve these issues. Since LAs and ADNs are separate entities with different interests, the traditional centralized and deterministic optimization methods fail to meet the actual operational requirements of ADNs. Based on the linear power flow model, a robust optimal dispatching model of ADNs considering the influence of renewable DG’s uncertain output on voltage security constraints is established. Then, an independent optimal scheduling model for LAs is modeled based on the analysis of the composition and characteristics of flexible load in LAs. LAs and ADNs, as two different stakeholders, use a distributed modeling method to establish different economic optimization goals. The optimization problem is solved by decoupling the coupling exchanging power between LAs and ADNs into virtual controllable loads and virtual DGs. Finally, with the case study of a modified IEEE 33-bus system, the correctness and effectiveness of the proposed method are verified. The effects of the robust level and demand response incentive on the results are also analyzed.

Multi-time scale optimal scheduling model for active distribution grid with desalination loads considering uncertainty of demand response

Desalination ◽  
2021 ◽  
Vol 517 ◽  
pp. 115262
Author(s):  
Bowen Zhou ◽  
Jiyu Xia ◽  
Dongsheng Yang ◽  
Guangdi Li ◽  
Jun Xiao ◽  
...  
Keyword(s):  
Demand Response ◽  
Time Scale ◽  
Optimal Scheduling ◽  
Distribution Grid ◽  
Scheduling Model
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