A Survey on Optimal Control and Operation of Integrated Energy Systems <s> Complexity <s> The operating modes directly influence the system performance of combined cooling, heating and power (CCHP) systems. To improve the comprehensive operational performance, in this paper, based on two typical operating modes, i.e., following the electric load (FEL) and following the thermal load (FTL), a novel optimal operational strategy depending on an integrated performance criterion (IPC) is proposed. Using this strategy, the whole operating space of the CCHP system can be divided into several regions by one to three border surfaces determined by energy requirements and the IPC. Then the operating point of the CCHP system is located in a corresponding operating mode region to achieve improved IPC. The IPC simultaneously considers the primary energy consumption, the operational cost and the carbon dioxide emissions. The carbon tax is also included in the operational cost. A hypothetical hotel building is modeled as the reference system to evaluate the proposed strategy. Simulation results show that, for the same CCHP system of the hypothetical hotel, the IPC with the proposed strategy is better than that with the traditional strategy. The proposed strategy can reflect and balance the influences of energy requirements, energy prices and emissions effectively. <s> BIB001 </s> A Survey on Optimal Control and Operation of Integrated Energy Systems <s> Complexity <s> This paper presents a two-stage stochastic programming model for provision of flexible demand response (DR) based on thermal energy storage in the form of hot water storage and/or storage in building material. Aggregated residential electro-thermal technologies (ETTs), such as electric heat pumps and (micro-) combined heat and power, are modeled in a unified nontechnology specific way. Day-ahead optimization is carried out considering uncertainty in outdoor temperature, electricity and hot water consumption, dwelling occupancy, and imbalance prices. Building flexibility is exploited through specification of a deadband around the set temperature or a price of thermal discomfort applied to deviations from the set temperature. A new expected thermal discomfort (ETD) metric is defined to quantify user discomfort. The efficacy of exploiting the flexibility of various residential ETT following the two approaches is analyzed. The utilization of the ETD metric to facilitate quantification of the expected total (energy and thermal discomfort) cost is also demonstrated. Such quantification may be useful in the determination of DR contracts set up by energy service companies. Case studies for a U.K. residential users' aggregation exemplify the model proposed and quantify possible cost reductions that are achievable under different flexibility scenarios. <s> BIB002 </s> A Survey on Optimal Control and Operation of Integrated Energy Systems <s> Complexity <s> At present, renewable energy sources (RESs) integration using microgrid (MG) technology is of great importance for demand side management. Optimization of MG provides enhanced generation from RES at minimum operation cost. The microgrid optimization problem involves a large number of variables and constraints; therefore, it is complex in nature and various existing algorithms are unable to handle them efficiently. This paper proposed an artificial shark optimization (ASO) method to remove the limitation of existing algorithms for solving the economical operation problem of MG. The ASO algorithm is motivated by the sound sensing capability of sharks, which they use for hunting. Further, the intermittent nature of renewable energy sources is managed by utilizing battery energy storage (BES). BES has several benefits. However, all these benefits are limited to a certain fixed area due to the stationary nature of the BES system. The latest technologies, such as electric vehicle technologies (EVTs), provide all benefits of BES along with mobility to support the variable system demands. Therefore, in this work, EVTs incorporated grid connected smart microgrid (SMG) system is introduced. Additionally, a comparative study is provided, which shows that the ASO performs relatively better than the existing techniques. <s> BIB003 </s> A Survey on Optimal Control and Operation of Integrated Energy Systems <s> Complexity <s> Combined heat and power (CHP), with its limited flexibility, is one of the leading causes for the curtailment problem of variable renewable energy source (VRES) in Northern China. To increase the flexibility for CHP, thermal energy storage (TES) is considered to be an effective solution, and a phase-change TES demonstration pilot project is now being constructed in Northern China. Almost all the previous studies have modeled the TES device without considering the heat transfer process, which is a main constraint in thermal system analysis. Thus, in this contribution, we consider the heat transfer process for the phase-change TES device installed in a CHP plant based on the steam's three-stage heat transfer model and the entransy dissipation-based thermal resistance theory. An integrated electrical–thermal dispatch model concerning conventional thermal units, VRESs, and CHP units with phase-change TES device is given, and an iteration method for solving this nonlinear programming problem is proposed. Case studies show that it is vital to consider the heat transfer process in the modeling of CHP plant with phase-change TES device, and it has significant influence on the flexibility that the TES device can provide when the working conditions vary. <s> BIB004 </s> A Survey on Optimal Control and Operation of Integrated Energy Systems <s> Complexity <s> This paper is focused on utilizing customersi¯ flexible energy demand, including both heat demand and electricity demand, to provide balancing resources and relieve the difficulties of integrating variable wind power with the combined heat and power (CHP). The integration of heat and electricity energy systems providing customers with multiple options for fulfilling their energy demand is described. Customer aggregators are introduced to supply downstream demand in the most economical way. Controlling customersi¯ energy consumption behaviors enables aggregators to adjust their energy demand in response to supply conditions. Incorporating aggregatorsi¯ flexible energy demand into the centralized energy dispatch model, a two-level optimization problem (TLOP) is firstly formed where the system operator maximizes social welfare subject to aggregatorsi¯ strategies which minimize the energy purchase cost. Furthermore, the sub-problems are linearized based on several reasonable assumptions. Optimal conditions of the sub-problems are then transformed as energy demands to be described as explicit piecewise-linear functions of electricity prices corresponding to the demand bid curves. In this way, the TLOP is transformed to a standard optimization problem, which requires aggregators to only submit a demand bid to run the centralized energy dispatch program. All the parameters pertaining to the aggregatorsi¯ energy consumption models are internalized in the bid curves. The proposed technique is illustrated in a modified testing system. <s> BIB005 </s> A Survey on Optimal Control and Operation of Integrated Energy Systems <s> Complexity <s> As a promising distributed energy resource, solar-powered heat pumps (SPHPs) can achieve significant system benefits. On the one hand, the accommodation of solar generation can be highly improved on the demand side. On the other hand, SPHPs can efficiently provide heat energy for consumers, which reduces the operational costs of central heat supply from combined heat and power (CHP) units. In this paper, a planning framework is developed to evaluate the economic benefits of integrating SPHPs into a CHP system. The framework is formulated as a bilevel market equilibrium model. On the upper level, given the locational marginal prices (LMPs) and district heating prices (DHPs), the consumers at different buses will strategically invest in SPHPs. Thus, the net electric and heating loads vary with the investment in the SPHPs. On the lower level, LMPs are updated by direct current optimal power flow, and DHPs are updated by a cost-plus pricing method. Because of the nonlinearity of this market equilibrium problem, an algorithm is proposed to iteratively solve the bilevel model, and a criterion is designed to achieve a desired solution. Case studies based on the IEEE 14-bus and 118-bus systems demonstrate that by investing in SPHPs on the demand side, the operational costs of CHP systems can be effectively reduced in both the electric and heating sectors. <s> BIB006 </s> A Survey on Optimal Control and Operation of Integrated Energy Systems <s> Complexity <s> A robust security-constrained unit commitment (robust SCUC) model is proposed in this paper to enhance the operational reliability of integrated electricity-natural gas system (IEGS) against possible transmission line outages. In this work, adjustable capability of natural gas contract is considered to avoid dramatic changes in real-time gas demand. Distributed natural gas storage is also included to smooth out power system demand curve and further improve operational efficiency at normal state and during contingencies. Nonlinear and nonconvex natural gas flow functions are relaxed into second-order cone (SOC) constraints, then the SOC-based column and constraint generation method is adopted to solve the proposed two-stage robust convex optimization problem. In this iterative method, the security-check subproblem feeds back worst case constraints to the first-stage master problem, until no violated scenarios can be detected. Simulations tested on 6-bus-6-node and 118-bus-10-node IEGS with natural gas storage show that the proposed storage model is effective in the robust SCUC solution for IEGS considering possible N − k contingencies with limited natural gas adjustments. <s> BIB007 </s> A Survey on Optimal Control and Operation of Integrated Energy Systems <s> Complexity <s> As the rapid development of natural-gas fired units (NGUs), power systems begin to rely more on a natural gas system to supply the primary fuel. On the other hand, natural gas system contingency might cause the nonavailability of NGUs and inevitably jeopardize power system security. To address this issue, this paper studies security-constrained joint expansion planning problems for this combined energy system. We develop a computationally efficient mixed-integer linear programming (MILP) approach that simultaneously considers N-1 contingency in both natural gas system and electricity power system. To reduce the combinatorial search space of MILP models, an extension of a reduced disjunctive model is proposed to decrease the numbers of binary and continuous variables as well as constraints. The involving nonlinear terms in N-1 constraints are exactly linearized without sacrificing any optimality. Numerical results on two typical integrated energy systems demonstrate the necessity of extending N-1 criterion to the whole network of a combined energy system. Experimental results also show that compared with the conventional approach, our proposed MILP approach achieves a great computational performance improvement in solving security-constrained co-optimization expansion planning problems. <s> BIB008 </s> A Survey on Optimal Control and Operation of Integrated Energy Systems <s> Complexity <s> In this paper, the impact of electric thermal storage (ETS) systems on the operation of Northern Communities’ microgrids is analyzed. A mathematical model of the ETS system is developed and integrated into an energy management system (EMS) for isolated microgrids, in which the problem is divided into unit commitment and optimal power flow subproblems, to dispatch fossil-fuel-based generators, energy storage systems, and ETS charging. To account for the deviations in the forecast of renewables, a model predictive control technique is used. The proposed ETS-EMS framework is tested and studied on a modified CIGRE medium voltage benchmark system, which comprises various kinds of distributed energy resources, and on the real Kasabonika Lake First Nation isolated microgrid system. It is shown that the ETS significantly reduces operating costs, and allows for better integration of intermittent wind and solar sources. <s> BIB009 </s> A Survey on Optimal Control and Operation of Integrated Energy Systems <s> Complexity <s> Coupling between electricity systems and heating systems are becoming stronger, leading to more flexible and more complex interactions between these systems. The operation of integrated energy systems is greatly affected, especially when security is concerned. Steady-state analysis methods have been widely studied in recent research, which is far from enough when the slow thermal dynamics of heating networks are introduced. Therefore, an integrated quasi-dynamic model of integrated electricity and heating systems is developed. The model combines a heating network dynamic thermal model and the sequential steady-state models of electricity networks, coupling components, and heating network hydraulics. Based on this model, a simulation method is proposed and quasi-dynamic interactions between electricity systems and heating systems are quantified with the highlights of transport delay. Then the quasi-dynamic interactions were applied using security control to relieve congestion in electricity systems. Results show that both the transport delay and control strategies have significant influences on the quasi-dynamic interactions. <s> BIB010 </s> A Survey on Optimal Control and Operation of Integrated Energy Systems <s> Complexity <s> Electricity and heat energy carriers are mostly produced by the fossil fuel sources that are conventionally operated independently, but these carriers have low efficiency due to heat losses. Moreover, a high share of variable renewable energy sources disrupts the power system reliability and flexibility. Therefore, the coupling of multiple energy carriers is underlined to address the above-mentioned issues that are supported by the latest technologies, such as combined heat and power, heat pumps, demand response, and energy storages. These coupling nodes in energy hubs stimulate the conversion of the electric power system into the integrated energy system that proves to be cost-effective, flexible, and carbon-free. The proposed work uses EnergyPLAN to model electricity, district, and individual heating integrated energy system of China for the year 2020. Furthermore, the addition of heat pumps, thermal storage, and demand response is analyzed in different scenarios to minimize the annual costs, fuel consumption, and CO2 emissions. Technical simulation strategy is conducted for optimal operation of production components that result in the reduction of the above-mentioned prominent factors while calculating the critical and exportable excess electricity production. The simulation results demonstrate that demand response and thermal storage significantly enhance the share of variable renewable energy sources. In addition, it substantially reduces the annual costs and fuel consumption, while heat pump increases the system efficiency. <s> BIB011
scholars have re ned the loss model in the process of heat energy transmission, and the thermal energy storage (TES) device is proposed in BIB004 , which proves that TES device can provide exibility for the electro-thermal coupling system. Sauter et al. BIB009 analyzes the impact of electro-thermal storage (ETS) system on the operation of community microgrid in northern China, and proved that ETS can signi cantly reduce the operating cost of the system and better absorb wind and solar energy. Pan et al. BIB010 develops an integrated quasidynamic model of integrated electricity and heating systems, a simulation method is proposed and quasi-dynamic interactions between electricity systems and heating systems are quanti ed with the highlights of transport delay, results show that both the transport delay and control strategies have signi cant in uences on the quasi-dynamic interactions. Some researches focus on demand response technology. e energy consumption behavior of users is in uenced by demand response technology in BIB005 , which shows that demand response can improve the regional wind power consumption. In BIB011 , the Energy PLAN is used to model IES, and analyses the application of heat pump, heat storage equipment, and demand response technology in di erent scenarios. Results show that the total operating cost and carbon dioxide emissions of the system can be minimized, and the introduction of heat pump improves the operating e ciency of the system. Park-level IES mainly considers the optimal dispatch of cogeneration units. Good et al. BIB002 chooses the optimal operation strategy for CHP system considering energy demand and integrated performance criterion under two operating modes of "electricity by heat" and "heat by electricity". e emergence of heat pumps and heat storage devices provides a powerful support for the exibility of electro-thermal coupling systems. Fang et al. BIB001 presents a physics-based model which is applicable to both electricity generating ETTs (aggregated residential electro-thermal technology), the presented model determines the expected energy and discomfort costs for a variety of cases. Research on CHP and CCHP has been mature. Power cycle that e ciently converts low-grade thermal energy into power combining organic Rankine cycle (ORC) has become a hot research topic. In BIB003 , the ORC turbogenerator is used in cement industry to improve economy and energy e ciency by recycling heat. e researches considering the characteristics of heat network and temperature variation of heat medium, and the connections of heat pump and heat storage into systems have also attracted extensive attention. Wang et al. BIB006 proposes an IES with solar energy heat pump, which shows that increasing solar energy heat pump can e ectively reduce the cost of central heating supply of cogeneration unit. In addition, some Complexity 8 or incorrect operation of protective device caused by power generation of high-penetration renewable energy. is study reveals the application of bidirectional converter in integrated electric-gas system, and proposes a new real-time algorithm, which is veri ed e ectively by simulation with real data. He and Shahidehpour BIB007 proposes a robust security-constrained unit commitment model to enhance the operating reliability of integrated electro-gas system against possible transmission lines outages. Zhang et al. BIB008 considers the N-1 accident of natural gas system and power system, a mixed integer linear programming (MILP) method is developed, and the experimental results show that the proposed method has good computational performance.