A Renewable Energy Community of DC Nanogrids for Providing Balancing Services (original) (raw)

Autonomous and decentralized load sharing and energy management approach for DC microgrids

Electric Power Systems Research, 2019

Appropriate power sharing and energy management in DC microgrids for the optimal, reliable and efficient operation of renewable energies and storages are of high importance. Droop-based control methods have been presented for power sharing among DC sources, while the energy management approaches employ communication systems to monitor the demand, renewable generations and energy level of storage units in order to properly operate the energy sources. Employing communication systems may affect the system reliability and introduce infrastructure costs. Moreover, extending energy sources require modifying the energy management system. This paper proposes an autonomous and decentralized power sharing and energy management approach for DC microgrids without utilizing a communication system. Hence, it can be a reliable and economical solution for operation of DC microgrids. Furthermore, in the proposed approach, the energy sources can operate independently by using the local information, and hence, it introduces plug-and-play capability for extending the energy sources. The viability and effectiveness of the proposed approach are evaluated by simulations and validated by experiments.

Optimized energy management of a residential microgrid: interconnected nanogrid system

-The use of renewable energy is essential to reduce the consumption of final energy used in the residential and tertiary sectors. For their effective integration in buildings, the main obstacles to be overcome are the design of multi-source systems (where renewable sources coexist with conventional sources), their design and their control-command. The objective is to obtain an optimal system from an economic and energy point of view. Because of the spread of the use of renewable energy to achieve energy self-sufficiency in remote areas, microgrids can lead to sustainable development of clean power systems but they pose challenges to a reliable energy supply because of its intermittent nature. This article presents a microgrid model including a PV. The purpose of the energy management system (EMS) is to provide a reliable and optimal generation from multiple sources in the microgrid. The idea is based on exchanging intermittent energy between the houses of a local community. Each house is equipped with an AC nanogrid including photovoltaic panels. These nanogrids are equipped with a network controller that the power can be exchanged between the houses on an external AC power bus. In this way, the fluctuations in response to demand are absorbed between nanogrid to improve reliability, energy management and complementarity nanogrids.

Autonomous Power Control and Management Between Standalone DC Microgrids

IEEE Transactions on Industrial Informatics, 2018

Renewable integrated DC Microgrids (DCMGs) are gaining popularity by feeding remote locations in qualitative and quantitative manner. Reliability of autonomous DC microgrids (ADCMG) depend on battery capacity and size due to stochastic behavior of renewables. Over charging and discharging scenarios compel the microgrid into insecure zone. Increasing the storage capacity is not an economical solution because of additional maintenance and capital cost. Thus interconnecting neighbor microgrids increases virtual storing and discharging capacity when excess power and deficit scenario arises respectively in any of the DCMG. Control strategy plays vital role in regulating the power within and between microgrids. Power control and management technique is developed based on bus signaling method to govern sources, storages and loads to achieve effective coordination and energy management between microgrids. Proposed scheme is simple and reliable since bus voltages are utilized in shifting the modes without having dedicated communication lines. Proposed scheme is validated through real time simulation of two autonomous DC grids in real time digital simulator (RTDS) and its results are validated by hardware experimentation.

Controlling DC microgrids in communities, buildings and data centers

IET Smart Grid, 2020

Microgrid technology is poised to transform the electricity industry. In the context of commercial/domestic buildings and data centers, where most loads are native direct current, DC microgrids are in fact a natural choice. Voltage stability and current/power-sharing between sources within a DC microgrid have been studied extensively in recent years. DC voltage droop control is known to have its drawbacks in that current or power-sharing is relatively poor. To eliminate this drawback, some have proposed to add a communication-based consensus control in addition to the primary voltage droop control loop. The current sharing performance is improved, however, the voltage deviation inherent in droop control requires a further, slower control to achieve voltage quality control. To overcome this complication, and reduction in response time, a low latency communicationbased control technique that achieves proportional current sharing without significant voltage deviations is proposed in this work. The stability of the proposed control technique is compared to state-of-the-art using eigenvalue and transient analyses. The negative impact of communication delays on proposed control is discussed in detail.

Distributed Cooperative Control of DC Microgrids

IEEE Transactions on Power Electronics, 2015

A cooperative control paradigm is used to establish a distributed secondary/primary control framework for dc Microgrids. The conventional secondary control, that adjusts the voltage set point for the local droop mechanism, is replaced by a voltage regulator and a current regulator. A noise-resilient voltage observer is introduced that uses neighbors' data to estimate the average voltage across the Microgrid. The voltage regulator processes this estimation and generates a voltage correction term to adjust the local voltage set point. This adjustment maintains the Microgrid voltage level as desired by the tertiary control. The current regulator compares the local per-unit current of each converter with the neighbors' and, accordingly, provides a second voltage correction term to synchronize per-unit currents and, thus, provide proportional load sharing. The proposed controller precisely handles the transmission line impedances. The controller on each converter communicates with only its neighbor converters on a communication graph. The graph is a sparse network of communication links spanned across the Microgrid to facilitate data exchange. The global dynamic model of the Microgrid is derived, and design guidelines are provided to tune the system's dynamic response. A low-voltage dc Microgrid prototype is set up, where the controller performance, noise resiliency, linkfailure resiliency, and the plug-and-play capability features are successfully verified.

A Review on DC Microgrid and Decentralized Approach

IJRASET, 2021

DC Microgrid is going to be a very important part of the Distribution system soon. The given circumstances have forced us to find how to utilize renewable energy sources in the integration to increase its reliability in our day-today life. This paper gives a good idea of the DC Microgrid and various methods being used for the controlling part of it. As day by day cost incurred in renewable energy generation is decreasing, we need to find out significant parts where this kind of DC Microgrid can be utilized to provide electricity in all parts of the country.

Operation and control of a hybrid AC-DC nanogrid for future community houses

2014 Australasian Universities Power Engineering Conference (AUPEC), 2014

A hybrid AC-DC nanogrid (NG) can be considered as the power supply system for future community houses. In this paper, the operation and control of a NG are presented. The NG consists of an AC bus and a DC bus, interconnected through a tie-converter. Each bus may have several loads and micro sources. The NG should have an adequate generation capacity to supply its loads in off-grid mode as well as the capability of exchanging power with the utility grid. The tie-converter exchanges the power between two buses and regulates bus voltage in both buses in the case of off-grid operation. Several case studies are presented using PSCAD/EMTDC to verify the NG dynamics.

Analysis of Performance and Control of DC Microgrids as Electricity Providers for Renewable Energy

E3S Web of Conferences

The increase in demand for electrical energy is increasing rapidly, in line with economic growth. In developing the electricity system, electrical energy service providers must provide electrical energy according to demand with good quality. The generation of conventional electric energy systems that use fossil fuels faces depleting fossil fuel sources, poor efficiency, and environmental pollution. This technology is known as Distributed Generation (DG). Distributed Generation (DG) or Micro Grid (MG) is a small-scale power plant located close to the load. The use of distributed generators can improve the entire system's efficiency, reduce transmission losses, reduce pollution, and ensure the continuity of the distribution of electrical energy. However, the drastic increase in the use of DG causes problems in the form of voltage and frequency stability which will be disturbed due to rapid changes in the generation and loading rates. If this is left unchecked, it can harm system s...

Distributed consensus-based control of multiple DC-microgrids clusters

IECON 2014 - 40th Annual Conference of the IEEE Industrial Electronics Society, 2014

This paper presents consensus-based distributed control strategies for voltage regulation and power flow control of dc microgrid (MG) clusters. In the proposed strategy, primary level of control is used to regulate the common bus voltage inside each MG locally. An SOC-based adaptive droop method is introduced for this level which determines droop coefficient automatically, thus equalizing SOC of batteries inside each MG. In the secondary level, a distributed consensus based voltage control strategy is proposed to eliminate the average voltage deviation while guaranteeing proper regulation of power flow among the MGs. Using the consensus protocol, the global information can be accurately shared in a distributed way. This allows the power flow control to be achieved at the same time as it can be accomplished only at the cost of having the voltage differences inside the system. Similarly, a consensus-based cooperative algorithm is employed at this stage to define appropriate reference for power flow between MGs according to their local SOCs. The effectiveness of proposed control scheme is verified through detailed hardware-in-the-loop (HIL) simulations.

IMPLEMENTATION OF NANOGRIDS FOR FUTURE POWER SYSTEM

Microgrid is a new technology in power generation and this system is used to provide power and heat to its local area, such as cogeneration systems and renewable energy (wind turbines, photovoltaic cells, etc.). They are preferred for medium or high power applications. Nanogrid most likely to be used in small local loads for rural area as they will be more economic then the normal grid power system. Nano grids can operate independently or be connected to the mains and most likely the internal voltage can be utilized as ac or dc. In this research paper a small scale microgrid system is proposed for smart homes called "Nanogrid". Each houses have small electrical power system from them can be shared among houses. If it uses a DC system instead of a general AC system, it can reduce energy loss of inverter because each generator doesn't need an inverter. Furthermore, it can continue to provide a power supply when blackout occurs in the bulk power system. A model of a nanogrid is developed to simulate the operation of the centralized power control. Finally a Simulink model is presented for small houses power range 90-285 KW.