Market power and strategic interaction in electricity networks

The modern power system is progressing from a synchronous machine-based system towards an inverter-dominated system, with large-scale penetration of renewable energy sources (RESs) like wind and photovoltaics. RES units today represent a major share of the generation, and the traditional approach of integrating them as grid following units can lead to frequency instability. Many researchers have pointed towards using inverters with virtual inertia control algorithms so that they appear as synchronous generators to the grid, maintaining and enhancing system stability. This paper presents a literature review of the current state-of-the-art of virtual inertia implementation techniques, and explores potential research directions and challenges. The major virtual inertia topologies are compared and classified. Through literature review and simulations of some selected topologies it has been shown that similar inertial response can be achieved by relating the parameters of these topologies through time constants and inertia constants, although the exact frequency dynamics may vary slightly. The suitability of a topology depends on system control architecture and desired level of detail in replication of the dynamics of synchronous generators. A discussion on the challenges and research directions points out several research needs, especially for systems level integration of virtual inertia systems.

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Virtual Inertia: Current Trends and Future Directions

Due to different viewpoints, procedures, limitations, and objectives, the scheduling problem of distributed energy resources (DERs) is a very important issue in power systems. This problem can be solved by considering different frameworks. Microgrids and Virtual Power Plants (VPPs) are two famous and suitable concepts by which this problem is solved within their frameworks. Each of these two solutions has its own special significance and may be employed for different purposes. Therefore, it is necessary to assess and review papers and literature in this field. In this paper, the scheduling problem of DERs is studied from various aspects such as modeling techniques, solving methods, reliability, emission, uncertainty, stability, demand response (DR), and multi-objective standpoint in the microgrid and VPP frameworks. This review enables researchers with different points of view to look for possible applications in the area of microgrid and VPP scheduling.

A comprehensive review on microgrid and virtual power plant concepts employed for distributed energy resources scheduling in power systems

The deployment of energy storage systems (ESSs) is a significant avenue for maximising the energy efficiency of a distribution network, and overall network performance can be enhanced by their optimal placement, sizing, and operation. An optimally sized and placed ESS can facilitate peak energy demand fulfilment, enhance the benefits from the integration of renewables and distributed energy sources, aid power quality management, and reduce distribution network expansion costs. This paper provides an overview of optimal ESS placement, sizing, and operation. It considers a range of grid scenarios, targeted performance objectives, applied strategies, ESS types, and advantages and limitations of the proposed systems and approaches. While batteries are widely used as ESSs in various applications, the detailed comparative analysis of ESS technical characteristics suggests that flywheel energy storage (FES) also warrants consideration in some distribution network scenarios. This research provides recommendations for related requirements or procedures, appropriate ESS selection, smart ESS charging and discharging, ESS sizing, placement and operation, and power quality issues. Furthermore, this study identifies future research opportunities in relation to challenges for optimal ESS placement planning, development and implementation issues, optimisation techniques, social impacts, and energy security.

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Overview of energy storage systems in distribution networks: Placement, sizing, operation, and power quality

http://users.ntua.gr/pgeorgil/Files/J78.pdf

A review of power distribution planning in the modern power systems era: Models, methods and future research

Decision making of a virtual power plant under uncertainties for bidding in a day-ahead market using point estimate method

This paper proposes a decision-making framework, based on stochastic programming, for a retailer: 1) to determine the sale price of electricity to the customers based on time-of-use (TOU) rates, and 2) to manage a portfolio of different contracts in order to procure its demand and to hedge against risks, within a medium-term period. Supply sources include the pool, self-production facilities and several instruments such as forward contracts, call options, and interruptible contracts. The objective is to maximize the profit and simultaneously to minimize the risks in terms of a multi-period risk measure. Moreover, the risks are measured using conditional value at risk (CVaR) methodology. The reaction of the customers to the retailers' selling prices as well as the competition between the retailers is modeled through a market share function. The problem is formulated as a mixed-integer stochastic programming. It is solved by a decomposition technique, and the decomposed parts are solved by a branch-and-bound algorithm.

A Stochastic-Based Decision-Making Framework for an Electricity Retailer: Time-of-Use Pricing and Electricity Portfolio Optimization

Deregulation in the power system industry and invention of new technologies for producing electrical energy have led to innovations in distribution system planning (DSP). Distributed generation (DG) is one of the most attractive technologies that brings different kinds of advantages to a wide range of entities, engaged in power systems. In this paper, a new model for considering DGs in the DSP problem is presented. In this model, an optimal power flow (OPF) is proposed to minimize capital costs for network upgrading, operation and maintenance costs, and the cost of losses for handling the load growth for the planning horizon. The term “dynamic” is used to refer to the planning over a specific period so that dynamic distribution system planning is, in fact, proposed. Besides, a modified genetic algorithm is used to find the optimal topology solution. The effectiveness of this method is demonstrated through examination on a radial distribution network.

A Dynamic Approach for Distribution System Planning Considering Distributed Generation

Power System Planning, Basic Principles.- Optimization Techniques.- Some Economic Principles.- Load Forecasting.- Single Bus Generation Expansion Planning.- Multi-bus Generation Expansion Planning.- Substation Expansion Planning.- Network Expansion Planning, a Basic Approach.- Network Expansion Planning, an Advanced Approach.- Reactive Power Planning.- Research Trends in Power System Planning.- Comprehensive Example.- Appendices.- Index

Hossein Seifi

Papers

Decision making of a virtual power plant under uncertainties for bidding in a day-ahead market using point estimate method

A Stochastic-Based Decision-Making Framework for an Electricity Retailer: Time-of-Use Pricing and Electricity Portfolio Optimization

A Dynamic Approach for Distribution System Planning Considering Distributed Generation

Electric Power System Planning: Issues, Algorithms and Solutions

Optimal selling price and energy procurement strategies for a retailer in an electricity market