The increasing interest in integrating intermittent renewable energy sources into microgrids presents major challenges from the viewpoints of reliable operation and control. In this paper, the major issues and challenges in microgrid control are discussed, and a review of state-of-the-art control strategies and trends is presented; a general overview of the main control principles (e.g., droop control, model predictive control, multi-agent systems) is also included. The paper classifies microgrid control strategies into three levels: primary, secondary, and tertiary, where primary and secondary levels are associated with the operation of the microgrid itself, and tertiary level pertains to the coordinated operation of the microgrid and the host grid. Each control level is discussed in detail in view of the relevant existing technical literature.

Trends in Microgrid Control

Many areas in power systems require solving one or more nonlinear optimization problems. While analytical methods might suffer from slow convergence and the curse of dimensionality, heuristics-based swarm intelligence can be an efficient alternative. Particle swarm optimization (PSO), part of the swarm intelligence family, is known to effectively solve large-scale nonlinear optimization problems. This paper presents a detailed overview of the basic concepts of PSO and its variants. Also, it provides a comprehensive survey on the power system applications that have benefited from the powerful nature of PSO as an optimization technique. For each application, technical details that are required for applying PSO, such as its type, particle formulation (solution representation), and the most efficient fitness functions are also discussed.

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Particle Swarm Optimization: Basic Concepts, Variants and Applications in Power Systems

Carbon capture and storage (CCS) is broadly recognised as having the potential to play a key role in meeting climate change targets, delivering low carbon heat and power, decarbonising industry and, more recently, its ability to facilitate the net removal of CO2 from the atmosphere. However, despite this broad consensus and its technical maturity, CCS has not yet been deployed on a scale commensurate with the ambitions articulated a decade ago. Thus, in this paper we review the current state-of-the-art of CO2 capture, transport, utilisation and storage from a multi-scale perspective, moving from the global to molecular scales. In light of the COP21 commitments to limit warming to less than 2 °C, we extend the remit of this study to include the key negative emissions technologies (NETs) of bioenergy with CCS (BECCS), and direct air capture (DAC). Cognisant of the non-technical barriers to deploying CCS, we reflect on recent experience from the UK's CCS commercialisation programme and consider the commercial and political barriers to the large-scale deployment of CCS. In all areas, we focus on identifying and clearly articulating the key research challenges that could usefully be addressed in the coming decade.

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Carbon capture and storage (CCS): the way forward

This paper provides an overview of grid code technical requirements regarding the connection of large wind farms to the electric power systems. The grid codes examined are generally compiled by transmission system operators (TSOs) of countries or regions with high wind penetration and therefore incorporate the accumulated experience after several years of system operation at significant wind penetration levels. The paper focuses on the most important technical requirements for wind farms, included in most grid codes, such as active and reactive power regulation, voltage and frequency operating limits and wind farm behaviour during grid disturbances. The paper also includes a review of modern wind turbine technologies, regarding their capability of satisfying the requirements set by the codes, demonstrating that recent developments in wind turbine technology provide wind farms with stability and regulation capabilities directly comparable to those of conventional generating plants.

A review of grid code technical requirements for wind farms

Plug-in electric vehicles (PEVs) present environmental and energy security advantages versus conventional gasoline vehicles. In the near future, the number of plug-in electric vehicles will likely grow significantly in the world. Despite the aforementioned advantages, the connection of PEV to the power grid poses a series of new challenges for electric utilities. This paper proposes a comprehensive approach for evaluating the impact of different levels of PEV penetration on distribution network investment and incremental energy losses. The proposed approach is based on the use of a large-scale distribution planning model which is used to analyze two real distribution areas. Obtained results show that depending on the charging strategies, investment costs can increase up to 15% of total actual distribution network investment costs, and energy losses can increase up to 40% in off-peak hours for a scenario with 60% of total vehicles being PEV.

Assessment of the Impact of Plug-in Electric Vehicles on Distribution Networks

The Single Electricity Market (SEM) target model envisages zonal market price coupling across Europe by 2014 as well as harmonization of transmission tariffs of the coupled countries. To date the majority of EU countries have uniform transmission charges with the exceptions of a few countries, which have geographically varying tariffs. This paper presents a robust modeling methodology for evaluating transmission charging arrangements and analyses two options for transmission pricing, namely uniform and locational transmission charges, by evaluating the economic efficiency of each tariff and how it affects integration of low-carbon energy sources. Our modeling framework combines investment and operational wholesale power market models with models of transmission investment and charging. We have used our methodology to compare the development of the Great Britain electricity system to 2030 under the two different charging regimes. Our analysis demonstrates that moving from the current locational to a uniform transmission charge would incentivize generation to locate in more remote parts of Great Britain. This in turn would drive significantly higher transmission investment costs and losses leading to reduced social welfare. At the same time, we find no significant difference in performance between the two charging regimes in terms of CO2 emissions and the achievement of the UK target for 30% of renewables in electricity consumption by 2020.

European transmission tariff harmonization: A modeling analysis

Integration of distributed reactive power sources through Virtual Power Plant to provide voltage control to transmission network

A direct load management scheme with two-way communication while considering end users comfort is proposed. First, the control algorithm is developed and the data required to be transmitted between system operator and controllable loads is identified. Then, the actions of controllable air conditioners and the power adjustment of dispersed generators to eliminate overloads in a substation transformer are simulated. The results indicate that the proposed load management technique performs effectively to reduce overloads on the transformer while maintaining energy consumption in each loads, and the performance is improved by coordination with the output of dispersed generators.

Investigation of Direct Load Management Scheme While Considering End Users Comfort

Introduction to EMP-E 2019 special issue “Modelling the implementation of ‘A Clean Planet for All’ strategy”

This paper demonstrates that the growth in application of corrective actions to enhance network utilization will require a probabilistic treatment of network security for determining efficient levels of investment in network reinforcement. A Benders decomposition based two-stage probabilistic optimization model for the operational and investment problems is proposed. For selecting relevant contingencies (beyond N-1 criteria), a novel filtering technique for efficient elimination of redundant outages is presented and successfully tested. In 2 numerical examples we compare efficiency of network reinforcement propositions under both deterministic and probabilistic frameworks, while optimizing available preventive and corrective control actions, and in particular focusing on the application of generation reserve in combination with Special Protection Schemes (SPS) for network congestion management purposes. We highlight the inadequacies of the deterministic approach with respect to its inherent inability to optimize accurately the portfolio of pre-fault post-fault actions since the impacts of corrective actions (in the form of SPS, demand response) and occurrence of “non-credible” events require explicit consideration of the likelihood of various outages. We concluded that deterministic approach drives less efficient and potentially more risky system operation that ultimately leads to inefficient network investment.

http://ieeexplore.ieee.org/iel7/6916492/6938773/06939279.pdf

Danny Pudjianto

Papers

European transmission tariff harmonization: A modeling analysis

Integration of distributed reactive power sources through Virtual Power Plant to provide voltage control to transmission network

Investigation of Direct Load Management Scheme While Considering End Users Comfort

Introduction to EMP-E 2019 special issue “Modelling the implementation of ‘A Clean Planet for All’ strategy”

Transmission network investment with probabilistic security and corrective control