The black start capability is vital for microgrids, which can potentially improve the reliability of the power grid. This paper proposes a black start strategy for microgrids based on a parallel restoration strategy. Considering the characteristics of distributed generations (DGs), an evaluation model, which is used to assess the black start capability of DGs, is established by adopting the variation coefficient method. Thus, the DGs with good black start capability, which are selected by a diversity sequence method, are restored first in parallel under the constraints of DGs and network. During the selection process of recovery paths, line weight and node importance degree are proposed under the consideration of the node topological importance and the load importance as well as the backbone network restoration time. Therefore, the whole optimization of the reconstructed network is realized. Finally, the simulation results verify the feasibility and effectiveness of the strategy.

A Parallel Restoration for Black Start of Microgrids Considering Characteristics of Distributed Generations

In the last two decades, emerging use of renewable and distributed energy sources in electricity grid has created new challenges for the utility regarding the power quality, voltage stabilization and efficient energy utilization. Power electronic converters are extensively utilized to interface the emerging energy systems (without and with energy storage) and smart buildings with the transmission and distribution systems. Flexible ac transmission systems (FACTSs) and voltage-source converters, with smart dynamic controllers, are emerging as a stabilization and power filtering equipment to improve the power quality. Also, distributed FACTSs play an important role in improving the power factor, energy utilization, enhancing the power quality, and ensuring efficient energy utilization and energy management in smart grids with renewable energy sources. This paper presents a literature survey of FACTS technology tools and applications for power quality and efficient renewable energy system utilization.

Review of FACTS technologies and applications for power quality in smart grids with renewable energy systems

Gravitational Search Algorithm (GSA) is an optimization method inspired by the theory of Newtonian gravity in physics. Till now, many variants of GSA have been introduced, most of them are motivated by gravity-related theories such as relativity and astronomy. On the one hand, to solve different kinds of optimization problems, modified versions of GSA have been presented such as continuous (real), binary, discrete, multimodal, constraint, single-objective, and multi-objective GSA. On the other hand, to tackle the difficulties in real-world problems, the efficiency of GSA has been improved using specialized operators, hybridization, local search, and designing the self-adaptive algorithms. Researchers have utilized GSA to solve various engineering optimization problems in diverse fields of applications ranging from electrical engineering to bioinformatics. Here, we discussed a comprehensive investigation of GSA and a brief review of GSA developments in solving different engineering problems to build up a global picture and to open the mind to explore possible applications. We also made a number of suggestions that can be undertaken to help move the area forward.

A comprehensive survey on gravitational search algorithm

A novel control approach for virtual synchronous generators to suppress frequency and voltage fluctuations in microgrids

The smart grid (SG) as a research area is advancing dealing with a wider range of topics such as power systems, energy generation and telecommunication. The conventional utility grid is used to operate in a passive mode absorbing energy from the substations and delivering it to the customers. This approach is well developed but the needs of the state-of-the-art technology require a bidirectional flow of power and data. Nevertheless, smart grid systems provide more flexible, reliable, sustainable, secure and two-way communication service. Especially, integration of renewable energy sources, electrical vehicles and distributed generations (DG) into network can be achieved in an efficient way in smart grid systems. Moreover, control and monitoring capabilities, automatic configuration of the grid, and active involvement of consumers in energy production extend the importance of smart grids. All these positive aspects of smart grids have been attained by integration of power electronics and telecommunication technologies with the grid. This study deals with contributions of power electronics to SG in the context of generation, conversion, distribution, and control of power. The recent power electronic devices and systems adapted to SG are also introduced in detail with several power control methods. Moreover, the renewable energy sources (RESs), which are an extensively studied topic of power engineering and their integration to smart grid, are also surveyed in terms of DG units, control and management features. Thus, a particular section is dedicated to RES utilization in SG covering almost all aspects of a monotype and hybrid energy plants. Finally, the survey is carried on by reviewing the most recent and comprehensive articles to highlight the importance of power electronics in a logical way in the smart grids for readers.

A survey on the contributions of power electronics to smart grid systems

Over the most recent couple of decades, tremendous consideration is drawn towards photovoltaic–thermal systems because of their advantages over the solar thermal and PV applications. This paper intends to show different electrical and thermal aspects of photovoltaic–thermal systems and the researches in absorber design modification, development, and applications. From the previous review articles, it has been concluded that the heat energy exhausted from the PV module can be further utilized in different ways and helps in achieving better efficiency. Furthermore, the types of photovoltaic–thermal systems such as air collector, water collector, and combi system, coupling with heat pump and their application to buildings are also stated. This paper also discussed certain design aspects like modifications in the flow channel by adding fins, thin metallic sheets, roll-bond absorber, and porous media and the effect of these modifications on the hybrid system’s efficiency. Furthermore, the use of the latest technologies such as nanofluids, thermoelectric generators, and phase-change materials improves the overall system performance. The role of soft-computing techniques is forecasting the impact of various parameters on the photovoltaic–thermal system is also discussed.

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Photovoltaic–thermal (PV/T) technology: a comprehensive review on applications and its advancement

Due to rapid depletion of fossil fuels availability and huge environmental pollution, focus is now changing from traditional method of power generation to the non-conventional DERs located at distribution voltage level. Technological advancement and more researches in the use of DERs result in the formation of microgrids and active distribution network. Small DER units when placed in a network near to load, makes the network stable as it can work in islanding mode in case of any fault outside the network. This paper proposes a scheme for reduction in losses and improvement of bus voltages in the active distribution network. A DG in the form of small renewable energy resources such as solar PV, wind, biomass, is placed optimally for reduction of losses in the network. However, placement of DG does not result in fulfilment of reactive power needs of the network, resulting in under voltage at several buses. This under voltage problem is solved by the optimal placement of DSTATCOM. DLF technique is used in this paper for load flow calculations and LSF along with voltage deviation is used in objective function for optimal location of DG on MATLAB platform. The methodology is tested on 33-bus radial distribution system.

Optimal placement of DG and DSTATCOM for loss reduction and voltage profile improvement

Congestion Management is an important technical challenge in power system deregulation. Congestion occurs in restructured electricity market, when transmission capacity is not sufficient to simultaneously accommodate all constraints for transmission of power through a line. Flexible alternative current transmission system (FACTS) devices can efficiently augment the power transmission capability, compensate reactive power, improve stability and power quality of the power system network. This paper presents the optimal location of series FACTS device TCSC to remove congestion with minimum cost of installation in a Deregulated Power System. For enhancement of the power capability of the line, reactance model of the thyristor controlled series capacitor (TCSC) is considered. A sensitivity factor based approach is used for optimal placement of the TCSC to remove the congestion. The sensitivity of the flow in congested line with respect to the flow in other lines has been used to find the optimal placement of the TCSC. The effectiveness of this method has been tested on 33-bus network of Delhi, India using MATLAB programming.

Congestion management in deregulated power system using FACTS device

The foremost issues of 21st century are challenging demand of electrical energy and to control the emission of Green House Gases (GHG) emissions. Renewable energy resources based sustainable microgrid emerges as one of the best feasible solution for future energy demand while considering zero carbon emission, fossil fuel independency, and enhanced reliability. In this paper, optimization and implementation of institutional based sustainable microgrid are discussed based on cost analysis, carbon emission, and availability of energy resources. Various microgrid topologies are considered for addressing the most ideal solution. The metrological data such as irradiance is acquired from solar satellite data of NASA (National Aero Space Agency) while the data for wind speed is taken from synergy enviro engineer’s site. HOMER® simulation tool is used for modelling and optimization purpose.

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Optimal configuration analysis for a campus microgrid—a case study

In deregulated power system, congestion management is a major problem due to operational constraints. Flexible AC transmission systems (FACTS) devices can be a choice to control the power flow in congested lines. This paper explores the use of two popular FACTS devices, TCSC and STATCOM for power flow control in electrical network and their capability to decongest the network. It suggests the optimal location of TCSC and STATCOM individually to relieve congestion with minimum power losses, voltage regulation and cost of the device. The proposed method has been verified on IEEE-14 bus system for its effectiveness. Simulation work is carried out in MATLAB software.

Anwar Shahzad Siddiqui

Papers

Photovoltaic–thermal (PV/T) technology: a comprehensive review on applications and its advancement

Optimal placement of DG and DSTATCOM for loss reduction and voltage profile improvement

Congestion management in deregulated power system using FACTS device

Optimal configuration analysis for a campus microgrid—a case study

Determination of optimal location of TCSC and STATCOM for congestion management in deregulated power system