Optimal operation of energy hub in competitive electricity market considering uncertainties

International Journal of Energy and Environmental Engineering https://doi.org/10.1007/s40095-018-0274-8 ORIGINAL RESEARCH Optimal operation of energy hub in competitive electricity market considering uncertainties V. V. Thang1 · Yongjun Zhang2 · Thanhtung Ha2 · Siliang Liu2 Received: 8 August 2017 / Accepted: 10 April 2018 © The Author(s) 2018 Abstract This paper proposes a novel energy hub model for areas using both heat and cold demands that arise due to the major changes in environmental temperature in different periods of the year. The energy demand and the electrical price in a competitive electricity market are uncertain with stochastic values which are usually performed by a probability distribution function. Therefore, a stochastic mathematical model representing an optimal operation of energy hub is based on the objective function of minimization of energy costs (including electricity and gas). Several constraints such as energy balance, limited capacity of the transformer, air conditioners, gas boilers, absorption chillers, combined heat, and power and battery energy storage system are also incorporated into the model to guarantee the required specifications. The high-level algebraic modeling software, general algebraic modeling system has been employed to undertake calculations. Finally, numerical results have illustrated the efficiency and capability of the proposed models. Keywords Energy hub · Mathematical model · Optimization · Stochastic · Uncertainties · GAMS Introduction The energy internet covering all popular forms of energy (electric, thermal and gas energy) is an indispensable model in future. The model has been studied significantly and continued to be developed, because it offers many benefits such as high-energy efficiency and lower energy supply costs. The concept of the Energy Hub (EH) has been introduced in this model [1]. The power center is derived by the connection between the source and the load through the mixture of inputs and outputs of energy. The types of energy sources and storage devices are described in the form of matrices. This concept has promoted many effects on the planning and optimization process of the operation of the energy system [2]. Studies on EH in the energy internet in recent years are quite abundant with particular attention to the optimal operation of the EH in the energy network [3]. The primary * V. V. Thang 1 Department of Electric Power Systems, Thai Nguyen University of Technology (TNUT), Thai Nguyen, Vietnam 2 School of Electric Power, South China University of Technology (SCUT), Guangzhou, China applications of the EH model are residential load [4] and industrial load [5]. The EH model is developed primarily by a Combined, Heat and Power (CHP) architecture. CHP uses primary energy as less polluting energy, providing highefficiency electrical and thermal loads. The current CHP model has been developed strongly all around the world. It is predicted that by 2023, total capacity will reach 483.7 GW [6]. CHP with various technologies has been introduced such as diesel engine, natural gas engine, steam turbine, gas turbine, micro-turbine, and fuel cells with efficiency up to 90%. In particular, the gas turbine and micro-turbine have many advantages such as less space, low noise, flexibility in control, high efficiency, and reduced environmental pollution and it should be used widely [7, 8]. Consequently, more researches on CHP applications in energy systems have been conducted. CHP enables the energy systems to improve their efficiency such as reducing energy purchase costs, improving energy efficiency and reducing environmental pollution [9, 10]. At a higher level, the combined cooling, heat and power (CCHP) model was introduced in [11–13] with the aim of supplementing the additional cooling demand of the system air conditioner (AC) or absorption chiller (ACh). Over the past decades, the electricity sector has made tremendous changes in business and administration. One of them is the process of restructuring the electricity market 13 Vol.:(0123456789) International Journal of Energy and Environmental Engineering from the monopoly model to the competitive electricity market (CEM) model [14]. In CEM, customers can choose suppliers and prices which vary in terms of time and market rather than fixed price over time [15]. It has a great impact on the planning, design, and operation of power systems [16, 17]. Indeed, CEM has opened up the opportunity to introduce and adopt new approaches to increase the efficiency of energy systems. In particular, the energy price mechanism is one of the primary constraints in the optimal management of energy use [18]. In [19], a survey of 1000 households using a heat pump to optimize the demand for switching between electricity and heat, derived from fixed gas prices and electricity prices vary from time to time. The results show that in multi-energy systems, the household can be supplied without having to adjust the demand manually. Similarly, [19] establishes a mechanism for minimizing the cost of energy use based on the electricity price factor through the CCHP model, thereby optimizing the need for heating in winter and cooling in summer of the system. Power pricing uses the time of use (TOU) schedule and the typical load characteristics of the load in terms of time are used. The EH model with random wind, electricity, and power tariffs is also presented in [21, 22] with a minimal objective function of daytime running costs as well as technical constraints of the EH. The load is a factor that is of a random nature, changes over time and the need to use it. Hence, there have been many studies on the random characteristic of loads through the Probability Distribution Functions (PDF) [23–25]. These studies mainly focus on solving the problem of operation and planning of the power grid considering the randomness of the load while assessing their impact on the economic and technical criteria of the power network. However, when considering the electrical power grid, especially the optimal operation problem, many studies have not mentioned this problem yet. A number of recent studies, such as [26], present a new perspective on the ability to exploit multienergy systems through EH, and the paper also extends some concepts of the uncertainty of the load and electricity price thus helping to regulate available energy sources within the allowable limits. Reference [27] examines some uncertainties then proceeded to optimize the energy output of dispersed sources and storage systems with the smallest total cost of the objective function. Although these studies have mentioned in detail the randomness of the load, it only considers electricity and heat loads, there are no studies to solve the optimal operations of the EH model while considering the randomness of all three types of load (electricity, heat, and cold). At present, optimizations and optimization methods are widely (...truncated)