scholarly journals Optimal Control Strategy for Distributed Energy Resources in a DC Microgrid for Energy Cost Reduction and Voltage Regulation

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 992
Author(s):  
Phi-Hai Trinh ◽  
Il-Yop Chung
Keyword(s):  
Control Strategy ◽  
Distribution System ◽  
Distribution Systems ◽  
Control Method ◽  
Voltage Regulation ◽  
Energy Resources ◽  
Distributed Energy Resources ◽  
Sensitivity Factor ◽  
Voltage Sensitivity ◽  
Distributed Energy

Distributed energy resources (DERs), including renewable energy resources (RESs) and electric vehicles (EVs), have a significant impact on distribution systems because they can cause bi-directional power flow in the distribution lines. Thus, the voltage regulation and thermal limits of the distribution system to mitigate from the excessive power generation or consumption should be considered. The focus of this study is on a control strategy for DERs in low-voltage DC microgrids to minimize the operating costs and maintain the distribution voltage within the normal range based on intelligent scheduling of the charging and discharging of EVs, and to take advantage of RESs such as photovoltaic (PV) plants. By considering the time-of-use electricity rates, we also propose a 24-h sliding window to mitigate uncertainties in loads and PV plants in which the output is time-varied and the EV arrival cannot be predicted. After obtaining a request from the EV owner, the proposed optimal DER control method satisfies the state-of-charge level for their next journey. We applied the voltage sensitivity factor obtained from a load-flow analysis to effectively maintain voltage profiles for the overall DC distribution system. The performance of the proposed optimal DER control method was evaluated with case studies and by comparison with conventional methods.

scholarly journals Hierarchical, Grid-Aware, and Economically Optimal Coordination of Distributed Energy Resources in Realistic Distribution Systems

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6399
Author(s):  
Mads Almassalkhi ◽  
Sarnaduti Brahma ◽  
Nawaf Nazir ◽  
Hamid Ossareh ◽  
Pavan Racherla ◽  
...  
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Large Scale ◽  
Optimization Methods ◽  
Energy Resources ◽  
Distributed Energy Resources ◽  
Solar Pv ◽  
Ancillary Service ◽  
Distributed Energy ◽  
Optimal Coordination

Renewable portfolio standards are targeting high levels of variable solar photovoltaics (PV) in electric distribution systems, which makes reliability more challenging to maintain for distribution system operators (DSOs). Distributed energy resources (DERs), including smart, connected appliances and PV inverters, represent responsive grid resources that can provide flexibility to support the DSO in actively managing their networks to facilitate reliability under extreme levels of solar PV. This flexibility can also be used to optimize system operations with respect to economic signals from wholesale energy and ancillary service markets. Here, we present a novel hierarchical scheme that actively controls behind-the-meter DERs to reliably manage each unbalanced distribution feeder and exploits the available flexibility to ensure reliable operation and economically optimizes the entire distribution network. Each layer of the scheme employs advanced optimization methods at different timescales to ensure that the system operates within both grid and device limits. The hierarchy is validated in a large-scale realistic simulation based on data from the industry. Simulation results show that coordination of flexibility improves both system reliability and economics, and enables greater penetration of solar PV. Discussion is also provided on the practical viability of the required communications and controls to implement the presented scheme within a large DSO.

scholarly journals Integration of distributed energy resources in isolated microgrids: the Colombian paradigm

TecnoLógicas ◽  
2018 ◽  
Vol 21 (42) ◽  
pp. 13-30 ◽  
Author(s):  
Dahiana López-García ◽  
Adriana Arango-Manrique ◽  
Sandra X. Carvajal-Quintero
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Energy Resources ◽  
Distributed Energy Resources ◽  
Environmental Concerns ◽  
Distributed Energy ◽  
Current State ◽  
Potential Benefits ◽  
Technical Issues ◽  
And Storage

The electrification of rural or isolated areas coupled with increasing environmental concerns have promoted the emergence of Distributed Energy Resources (DER) and the operation by isolated microgrids. However, the integration of such resources involves technical issues related to the reliability and continuity of the electricity supply. Indeed, the uncertainty of renewable generation sources and the reduced inertia of isolated microgrids are challenges for the operation of these distribution systems. One way to address them is by providing ancillary services through all the resources involved in the system’s operation (generation assets, demand share, and storage systems). Accordingly, this paper first presents a literature review of the challenges and potential benefits of integrating DERs into the operation of a distribution system. It also includes some common strategies to mitigate the vulnerability of the introduction of these technologies in microgrids. Afterwards, the current state of each type of resource in Colombia is assessed. Finally, some basic strategies that enhance the benefits of DER integration are outlined along with the overcoming of challenges of microgrid operation in said country. To that end, we consider isolated Colombian regions to be natural laboratories where the effects of DER integration and the requirements for the operation by local production units can be analyzed.

scholarly journals Fault analysis considering fault current contributions from distributed energy sources

2021 ◽  
Author(s):  
Adnan Arapovic
Keyword(s):  
Renewable Energy ◽  
Distribution System ◽  
Distribution Systems ◽  
Energy Resource ◽  
Fault Analysis ◽  
Energy Resources ◽  
Distributed Energy Resources ◽  
Fault Current ◽  
Renewable Energy Resources ◽  
Distributed Energy

With emerging concerns over climate change and the need for reduced greenhouse gas emissions, together with the growing awareness of the importance of the natural environment and the depletion of the earth's non-renewable energy resources, the generation of electricity from distributed renewable energy resource such as solar photovoltaic (PV) and wind energy has begun to expand at a rapid pace. Proliferation of convert-based distributed energy resources in distribution systems has introduced new challenges in determining the maximum possible fault currents that a power system must be able to withstand without being compromised. Therefore is is imperative to develop the mathematical and software simulation models that approximate the response of converter-based distributed energy resources during a fault on the transmission or distribution system in order to determine the fault current contributions to the electrical grid that a transmission or distribution utility needs to reflect in their connection impact assessments.

scholarly journals Fault analysis considering fault current contributions from distributed energy sources

2021 ◽  
Author(s):  
Adnan Arapovic
Keyword(s):  
Renewable Energy ◽  
Distribution System ◽  
Distribution Systems ◽  
Energy Resource ◽  
Fault Analysis ◽  
Energy Resources ◽  
Distributed Energy Resources ◽  
Fault Current ◽  
Renewable Energy Resources ◽  
Distributed Energy

With emerging concerns over climate change and the need for reduced greenhouse gas emissions, together with the growing awareness of the importance of the natural environment and the depletion of the earth's non-renewable energy resources, the generation of electricity from distributed renewable energy resource such as solar photovoltaic (PV) and wind energy has begun to expand at a rapid pace. Proliferation of convert-based distributed energy resources in distribution systems has introduced new challenges in determining the maximum possible fault currents that a power system must be able to withstand without being compromised. Therefore is is imperative to develop the mathematical and software simulation models that approximate the response of converter-based distributed energy resources during a fault on the transmission or distribution system in order to determine the fault current contributions to the electrical grid that a transmission or distribution utility needs to reflect in their connection impact assessments.

scholarly journals DSO–TSO Coordination of Day-Ahead Operation Planning with the Use of Distributed Energy Resources

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3559
Author(s):  
Rafal Dzikowski
Keyword(s):  
Distribution System ◽  
Power Plants ◽  
Distribution Systems ◽  
Transmission System ◽  
Energy Resources ◽  
System Level ◽  
Distributed Energy Resources ◽  
Operation Planning ◽  
Distributed Energy ◽  
Unit Commitment Problem

Growing penetration of uncoordinated Distributed Energy Resources (DERs) in distribution systems is contributing to the increase of the load variability to be covered at the transmission system level. Forced, fast and substantial changes of power plants’ output powers increase the risk of their failures, which threatens the reliable and safe delivery of electricity to end users in the power system. The paper handles this issue with the use of DERs and proposes a bilevel coordination concept of day-ahead operation planning with new kind of bids to be submitted by Distribution System Operators (DSOs) to the Transmission System Operator (TSO). This concept includes the extension of the Unit Commitment problem solved by TSO and a new optimization model to be solved by DSO for planning a smoothed power profile at the Transmission–Distribution (T–D) interface. Both optimization models are described in the paper. As simulations show, the modified 24-h power profiles at T–D interfaces result in a reduction of the demand for operation flexibility at the transmission system level and, importantly, result in a decrease of the number of conventional power plants that are required to operate during a day. Additionally, it has been proved that the modified profiles reduce the congestions in the transmission network. Hence, the concept presented in the paper can be identified as an important step towards the transformation of power systems to low-emission and reliable systems with high share of DERs.

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