scholarly journals An Evolutionary Computational Approach for the Problem of Unit Commitment and Economic Dispatch in Microgrids under Several Operation Modes

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2143 ◽  
Author(s):  
L. Alvarado-Barrios ◽  
A. Rodríguez del Nozal ◽  
A. Tapia ◽  
J. L. Martínez-Ramos ◽  
D. G. Reina
Keyword(s):  
Power Systems ◽  
Unit Commitment ◽  
Operation Mode ◽  
Economic Dispatch ◽  
Demand Forecasting ◽  
Energy Resources ◽  
Distributed Energy ◽  
Physical Constraints ◽  
Confidence Levels ◽  
Operation Modes

In the last decades, new types of generation technologies have emerged and have been gradually integrated into the existing power systems, moving their classical architectures to distributed systems. Despite the positive features associated to this paradigm, new problems arise such as coordination and uncertainty. In this framework, microgrids constitute an effective solution to deal with the coordination and operation of these distributed energy resources. This paper proposes a Genetic Algorithm (GA) to address the combined problem of Unit Commitment (UC) and Economic Dispatch (ED). With this end, a model of a microgrid is introduced together with all the control variables and physical constraints. To optimally operate the microgrid, three operation modes are introduced. The first two attend to optimize economical and environmental factors, while the last operation mode considers the errors induced by the uncertainties in the demand forecasting. Therefore, it achieves a robust design that guarantees the power supply for different confidence levels. Finally, the algorithm was applied to an example scenario to illustrate its performance. The achieved simulation results demonstrate the validity of the proposed approach.

scholarly journals Evolutionary Priority-Based Dynamic Programming for the Adaptive Integration of Intermittent Distributed Energy Resources in Low-Inertia Power Systems

Eng ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 643-660
Author(s):  
Pavlos Nikolaidis ◽  
Andreas Poullikkas
Keyword(s):  
Dynamic Programming ◽  
Power Systems ◽  
Optimal Power Flow ◽  
Unit Commitment ◽  
Renewable Energy Sources ◽  
Minimum Cost ◽  
Energy Resources ◽  
Distributed Energy Resources ◽  
Distributed Energy ◽  
Priority List

The variability and uncertainty caused by the increased penetrations of renewable energy sources must be properly considered in day-ahead unit commitment, optimal power flow, and even real-time economic dispatch problems. Besides achieving minimum cost, modern generation schedules must satisfy a larger set of different complex constraints. These account for the generation constraints in the presence of renewable generation, network constraints affected by the distributed energy resources, bilateral contracts enclosing independent capacity provision, ancillary power auctions, net-metering and feed-in-tariff prosumers, and corrective security actions in sudden load variations or outage circumstances. In this work, a new method is presented to appropriately enhance the integration of distributed energy resources in low-inertia power grids. Based on optimal unit commitment schedules derived from priority-based dynamic programming, the potential of increasing the renewable capacity was examined, performing simulations for different scenarios. To ameliorate the expensive requirement of computational complexity, this approach aimed at eliminating the increased exploration-exploitation efforts. On the contrary, its promising solution relies on the evolutionary commitment of the next optimum configuration based on priority-list schemes to accommodate the intermittent generation progressively. This is achieved via the collection of mappings that transform many-valued clausal forms into satisfiability equivalent Boolean expressions.

THE ANALYSIS OF OPERATION MODES OF ENERGY STORES IN AUTONOMOUS HYBRID POWER PLANTS WITH RENEWABLE ENERGY RESOURCES

2018 ◽  
pp. 55-67
Author(s):  
S. G. Obukhov ◽  
I. A. Plotnikov ◽  
V. G. Masolov
Keyword(s):  
Renewable Energy ◽  
Power Systems ◽  
Low Frequency ◽  
Rechargeable Batteries ◽  
Energy Resources ◽  
Renewable Energy Resources ◽  
Hybrid Power ◽  
Operation Modes ◽  
Energy Stores ◽  
Energy Store

The paper presents the results of the comparative analysis of operation modes of an autonomous hybrid power complex with/without the energy store. We offere the technique which defines the power characteristics of the main components of a hybrid power complex: the consumers of the electric power, wind power and photo-electric installations (the last ones have been constructed). The paper establishes that, in order to compensate the seasonal fluctuations of power in autonomous power systems with renewable energy resources, the accumulative devices are required, with a capacity of tens of MWh including devices that are capable to provide energy storage with duration about half a year. This allows abandoning the storage devices for smoothing the seasonal fluctuations in the energy balance.The analysis of operation modes of energy stores has shown that for a stock and delivery of energy on time intervals, lasting several hours, the accumulative devices with rather high values of charging and digit power aren't required. It allows using the lead-acid rechargeable batteries of the deep category for smoothing the daily peaks of surplus and a capacity shortage. Moreover, the analysis of operation modes of energy stores as a part of the hybrid complexes has demonstrated that in charging/digit currents of the energy store the low-frequency and high-frequency pulsations of big amplitude caused by changes of size of output power of the renewable power installations and loading are inevitable. If low-frequency pulsations (the period of tens of minutes) can partially be damped due to the restriction of size of the maximum charging current of rechargeable batteries, then it is essentially impossible to eliminate high-frequency pulsations (the period of tens of seconds) in the power systems with the only store of energy. The paper finds out that the combined energy store having characteristics of the accumulator in the modes of receiving and delivery of power on daily time intervals, and at the same time having properties of the supercondenser in the modes of reception and return of impulses of power on second intervals of time is best suited to requirements of the autonomous power complexes with renewable energy resources.

scholarly journals Cybersecurity Considerations for Grid-Connected Batteries with Hardware Demonstrations

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3067
Author(s):  
Megan Culler ◽  
Hannah Burroughs
Keyword(s):  
Power Systems ◽  
Network Connectivity ◽  
Energy Resources ◽  
System Stability ◽  
Distributed Energy Resources ◽  
Distributed Energy ◽  
Defense Strategies ◽  
Storage Devices ◽  
Attack Surface ◽  
Area Of Concern

The share of renewable and distributed energy resources (DERs), like wind turbines, solar photovoltaics and grid-connected batteries, interconnected to the electric grid is rapidly increasing due to reduced costs, rising efficiency, and regulatory requirements aimed at incentivizing a lower-carbon electricity system. These distributed energy resources differ from traditional generation in many ways including the use of many smaller devices connected primarily (but not exclusively) to the distribution network, rather than few larger devices connected to the transmission network. DERs being installed today often include modern communication hardware like cellular modems and WiFi connectivity and, in addition, the inverters used to connect these resources to the grid are gaining increasingly complex capabilities, like providing voltage and frequency support or supporting microgrids. To perform these new functions safely, communications to the device and more complex controls are required. The distributed nature of DER devices combined with their network connectivity and complex controls interfaces present a larger potential attack surface for adversaries looking to create instability in power systems. To address this area of concern, the steps of a cyberattack on DERs have been studied, including the security of industrial protocols, the misuse of the DER interface, and the physical impacts. These different steps have not previously been tied together in practice and not specifically studied for grid-connected storage devices. In this work, we focus on grid-connected batteries. We explore the potential impacts of a cyberattack on a battery to power system stability, to the battery hardware, and on economics for various stakeholders. We then use real hardware to demonstrate end-to-end attack paths exist when security features are disabled or misconfigured. Our experimental focus is on control interface security and protocol security, with the initial assumption that an adversary has gained access to the network to which the device is connected. We provide real examples of the effectiveness of certain defenses. This work can be used to help utilities and other grid-connected battery owners and operators evaluate the severity of different threats and the effectiveness of defense strategies so they can effectively deploy and protect grid-connected storage devices.

scholarly journals Methods for Aggregation and Remuneration of Distributed Energy Resources

2018 ◽  
Vol 8 (8) ◽  
pp. 1283 ◽  
Author(s):  
Pedro Faria ◽  
João Spínola ◽  
Zita Vale
Keyword(s):  
Power Systems ◽  
Energy Resource ◽  
Energy Resources ◽  
Distributed Energy Resources ◽  
Virtual Power ◽  
Distributed Energy ◽  
Distributed Energy Resource ◽  
Technical Operation ◽  
Made In

Distributed energy resource integration in power systems has advantages and challenges in both the economic and the technical operation of the system. An aggregator, as in the case of a Virtual Power Player, is essential in order to support the operation of these small size resources. Innovative approaches capable of supporting the decisions made in terms of resource scheduling, aggregation and remuneration are needed. The present paper addresses a methodology capable of managing resources through the activities of an aggregator, providing different choices of aggregation and remuneration strategies. The methodology is validated in a case study regarding a 21-bus network, composed of 20 consumers and 26 producers.

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