Multitimescale Coordinated Adaptive Robust Operation for Industrial Multienergy Microgrids With Load Allocation

This paper focuses on the optimal operations of an industrial power plant equipped with a Combined Cooling, Heat and Power (CCHP). The goal of the control strategy is to minimize the generation and maintenance costs of the power plant, scheduling the CCHP's operations, the usage of the auxiliary generators (used to meet the demand when the CCHP is turned OFF), the purchasing/selling phase from/to the main grid and integrating the renewable energy sources. The overall problem is stated as a constrained mixed integer linear optimization problem with both continuous and logical variables. A Model Predictive Control (MPC) approach is used to compensate forecasts uncertainties in the control strategy. Being the industrial work load related to the production lines consumption, an optimal load allocation algorithm is implemented to optimally schedule the production lines over the planning day. The simulation results are performed on an industrial plant layout located in the city of Benevento, in Italy.

Over the past decade, rising energy demand and cost have created a surge of interest in alternative methods of power generation. As a result, the implementation of combined cooling, heating, and power (CCHP) systems has become a potential candidate for substitution in conventional power generation. The evaluation of a CCHP system must be based on its potential for savings in cost and primary energy reduction. In general, a CCHP system includes several components to satisfy the electric and thermal demands of the facility. These components include the prime mover, heat recovery system, auxiliary boiler, absorption chiller, heating coil unit, and hot water system unit. In practice, the most common prime mover used in CCHP technology is the internal combustion engine, which is limited by low thermal efficiency and poor emissions. Hence, this paper proposes the use of a Stirling engine prime mover that makes use of waste wood chips for fuel. In addition to the standard CCHP components, the Stirling engine houses heat exchangers to aid heat addition and rejection processes. These heat exchangers must be considered along with the other components when analyzing energy requirements. The goal of this study is to determine how the operational characteristics of a constant output biomass-fired Stirling CCHP system are affected by the performance of the individual CCHP system components. The results of this sensitivity analysis are useful in determining the most important parameters to be considered when implementing and designing the system. Results suggest that fuel cost, engine efficiency, engine size, chiller efficiency, and the Stirling engine’s hot side heat exchanger play the most important roles in the CCHP system operational cost. For example, the results show that increasing the engine size leads to increases in primary energy. In addition, an optimum engine size is suggested for cost savings, with smaller and larger engines both leading to increases in operational cost.

Due to the soaring costs and demand of energy in recent years, combined cooling, heating, and power (CCHP) systems have arisen as an alternative to conventional power generation based on their potential to provide reductions in cost, primary energy consumption, and emissions. However, the application of these systems is commonly limited to internal combustion engine prime movers that use natural gas as the primary fuel source. Investigation of more efficient prime movers and renewable fuel applications is an integral part of improving CCHP technology. Therefore, the objective of this study is to analyse the performance of a CCHP system driven by a biomass fired Stirling engine. The study is carried out by considering an hour-by-hour CCHP simulation for a small office building located in Atlanta, Georgia. The hourly thermal and electrical demands for the building were obtained using the EnergyPlus software. Results for burning waste wood chip biomass are compared to results obtained burning natural gas to illustrate the effects of fuel choice and prime mover power output on the overall CCHP system performance. Based on the specified utility rates and including excess production buyback, the results suggest that fuel prices of less than $23/MWh must be maintained for savings in cost compared to the conventional case. In addition, the performance of the CCHP system using the Stirling engine is compared with the conventional system performance. This comparison is based on operational cost and primary energy consumption. When electricity can be sold back to the grid, results indicate that a wood chip fired system yields a potential cost savings of up to 50 per cent and a 20 per cent increase in primary energy consumption as compared with the conventional system. On the other hand, a natural gas fired system is shown to be ineffective for cost and primary energy consumption savings with increases of up to 85 per cent and 24 per cent compared to the conventional case, respectively. The variations in the operational cost and primary energy consumption are also shown to be sensitive to the electricity excess production and buyback rate.

Information gap decision theory for operation of combined cooling, heat and power microgrids with battery charging stations

A novel framework for operation optimization of a combined cooling, heating, and power (CCHP) system has been proposed. The goal of the study was to develop an automatic optimization tool based on the integration of IPSEpro simulation software and the MATLAB programming environment to strategically manage the operation of a hybrid energy system of micro gas turbine (MGT), auxiliary boiler, and absorption chiller. Data exchange between the tools was organized via a COM interface. An experimentally validated model of the commercial AE-T100 CCHP unit was utilized, the objective being to minimize a cost function of operational and capital investments costs, subject to a set of constraints. The micro CCHP plant was considered to be a part of a grid. Electricity trading was therefore taken into account. The performance of the developed framework was investigated through the optimization task, case study data for a 24-hour period in July and December, different electricity and gas price profiles and ambient conditions being used. The operation strategy could be heat-led or power-led. The optimum number and load of the CCHP units and the boilers and the amount of electricity which should be bought from and/or sold to the grid were therefore determined by the optimization strategies. Lastly, the results were analyzed and show that the integrated optimization tool developed provides a valuable contribution to the enhanced management of such a CCHP system, specifically when a large number of distributed units are considered. In other words, the proposed framework was flexible enough and has the potential to be extended and further developed to handle more complicated energy systems and operational conditions.

Combined heating and power (CHP) and combined cooling, heating, and power (CCHP) systems generate electricity and usable heat on-site from one fuel source while organic Rankine cycles (ORC) generate power from low-temperature heat sources. During the operation of CHP and CCHP systems, there are many instances when the recovered exhaust heat is greater than the required thermal load of the building. In these situations, an ORC can be used to capture the excess heat in order to produce additional electricity. Therefore, combining an ORC system with a CHP system (CHP-ORC) or a CCHP system (CCHP-ORC) can further increase the fuel utilization of the system, thereby reducing the operational costs, primary energy consumption (PEC), and carbon dioxide emissions (CDE). This article examines the economic, energetic, and environmental performance of CHP-ORC and CCHP-ORC systems under the operational strategies of follow the electric load (FEL) and follow the electric load with the option of turning off (FEL/OFF) for the city of Boulder, Colorado. Their performance is compared to a stand-alone CHP and CCHP system, respectively, between systems, and to a reference building. Results show that under the FEL operation, the addition of an ORC to either the CHP or CCHP system lowered the operational costs, PEC, and CDE by about 12 per cent, 13 per cent, and 17 per cent, respectively, from the standalone system. In addition, only when the systems operate FEL/OFF strategy minimizing cost or PEC, the cost and PEC could be reduced below the levels of the reference building.

Combined cooling, heat and power (CCHP) systems have the potential for energy efficiency through the utilization of waste heat. Using energy utilizing efficiency as optimization target, CCHP's operation is optimized based on the principles of CCHP's basic units: gas turbine, exhaust heat boiler and chiller. Operation parameter with best energy utilization efficiency is achieved. On the basis of the solution, the economic efficiency considering capital cost and operation cost relative to time is brought out, and economic operation optimization is carried out . EIS software is also used to predict CCHP's performance. Then CCHP system using Capstone C60 micro gas turbine is operated to verified the result. The result in this paper can be the guidance for the design and operation of CCHP system in industrial and commercial building.

With the proposal and implementation of the "double carbon" goal in China, it is necessary to further improve the dynamic energy efficiency of the operation process of combined cooling, heating and power (CCHP) units to maximize the economic efficiency of the system. In this paper, the optimization algorithm based on the combination of chaos search of Tent map and nonlinear adaptive particle swarm optimization combines the schedulable resources of energy production, energy storage and energy consumption into a CCHP "source storage" system, which can simultaneously meet the power, heat and cooling needs of the user side. Taking the operation cost and pollutant emission of CCHP system as the objective, a multi-objective optimization model is established. Under the constraint conditions of equipment output, power balance and so on, the equipment operation hourly output with the best economic and environmental benefits is obtained. The calculation results show that the CCHP "source storage and load" system reduces the operation and maintenance costs by 22.31%, and carries out the economic and environmental advantages.

Because of the performance of the power generation equipment is almost perfect, how to integrate the thermally-activated technologies and use the waste heat deeply are a critical issue for CCHP (Combined cooling heating and power) system. According to the characteristics of a typical end user’s demands, a CCHP system with the flue gas and geothermal energy is proposed. The system is composed of an internal combustion engine, a soil source absorption heat pump driven by the flue gas, and other assistant facilities, such as pumps, fans, and end user devices. In the winter, the flue gas is used to drive absorption heat pump to recover the waste heat of the soil source and the condensation heat of the flue gas simultaneously, and in the summer, the waste heat of the flue gas is used to drive absorption heat pump to cooling, and the heat sink is the soil. In the paper, the energy analysis of the system is done. Compared with the conventional CCHP system, the operation cost is lowered greatly and the increased investment could be returned within one year. It is show that the system is the efficient integration of clean energy, renewable energy, the discharge of the flue gas could be reduced to below 30°C, and the water steam could be catch to avoid the white smoke of the stack.

Evaluation of CCHP systems performance based on operational cost, primary energy consumption, and carbon dioxide emission by utilizing an optimal operation scheme

Novel design of a CCHP system to boost nearly zero-carbon building concept

Combined cooling, heating, and power (CCHP) systems generate electricity at or near the place of consumption and utilize the accompanying waste heat to satisfy the building’s thermal demand. CCHP systems have often been cited as advantageous alternatives to traditional methods of power generation and one of the critical components affecting their performance is the power generation unit (PGU). This investigation examines the effect of the PGU on the energy, economical, and environmental performance of CCHP systems. Different size PGUs are simulated under the following operational strategies: follow the building’s electric load, follow the building’s thermal load, and operate at constant load. An internal combustion engine is used as the PGU in the CCHP system to meet hourly electric, cooling, heating, and hot water loads of a typical office building for a year. Annual operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDE) are found for two cities and compared to a conventional building. Finally, a simple optimization is performed to determine the best engine load for each hour during the simulation. Among the results, the smallest engine generally yielded the lowest costs and lowest PEC; but, no such trend was found with regards to CDE.

Smart grid systems, which have gained much attention due to its ability to reduce operation and management costs of power systems, consist of diverse components including energy storage, renewable energy, and combined cooling, heating and power (CCHP) systems. The CCHP has been investigated to reduce energy costs by using the thermal energy generated during the power generation process. For efficient utilization of CCHP and numerous power generation systems, accurate short-term load forecasting (STLF) is necessary. So far, even though many single algorithm-based STLF models have been proposed, they showed limited success in terms of applicability and coverage. This problem can be alleviated by combining such single algorithm-based models in ways that take advantage of their strengths. In this paper, we propose a novel two-stage STLF scheme; extreme gradient boosting and random forest models are executed in the first stage, and deep neural networks are executed in the second stage to combine them. To show the effectiveness of our proposed scheme, we compare our model with other popular single algorithm-based forecasting models and then show how much electric charges can be saved by operating CCHP based on the schedules made by the economic analysis on the predicted electric loads.

Combined cooling, heat and power (CCHP) systems can supply electric and thermal energy to customers. With thermal storage units, energy usage efficiency of the CCHP systems with auxiliary boilers can be improved with low operational costs. However, uncertainty exists in renewable power generation as well as electric and thermal loads which significantly affects the CCHP system operation. Operational limit violation would occur due to errors in predictions of the uncertainty. In this paper, a two-stage robust operation approach is proposed to coordinate the operation of the thermal storage units and the CCHP units with the boilers while satisfying the operational limits. The thermal storage units are dispatched a day ahead in the first stage and the CCHP outputs are dispatched hourly in the second stage. The two-stage operation is coordinated through a robust optimization method with full consideration of the uncertainty. Thus, the second stage CCHP outputs can compensate the first stage thermal storage dispatch without any operational violation. Simulation results indicate high solution robustness against the uncertainty.

This paper first distinguishes the Multi-Energy Coupling System (MECS) from the Energy Internet and the Integrated Energy System, and defines technique features of the Multi-energy Coupling System. Then, on the basis of the CCHP technical proposal and the photovoltaic configuration, a MECS design scheme which is suitable for campus is presented. Next, by studying the cold, hot, and electric load characteristic of a typical campus which is located in Hebei province, we allocate the Multi-Energy Coupling System. In addition, this paper analyses the economic benefit, the environmental benefit, and the energy-conserving benefit of the MECS. Introduction Nowadays, the problems such as energy shortage, environment pollution is more and more become one of the key factors which restrict the development of the world. To improve and solve these problems, experts put forward several new energy system concept, such as the Energy Internet, the Integrated Energy System and so on. In reference [1], a famous American scholar J Rifikin put forward the vision of the Energy Internet for the first time, and most studies about this concept are focus on solving the problem of energy development on the angle of Internet. The Integrated Energy System is in the process of planning, design, construction and operation, through the generation, transmission and distribution of all kinds of energy (energy supply network), conversion, storage and consumption, social comprehensive energy supply, which is formed by the Integrated System. The Multi-Energy Coupling System (MECS), in contrast, much more from the system perspective to consider issues such as energy distribution. It mainly has the following technical characteristics: (1) The Combined Cooling, Heating, and Power (CCHP) system. This running mode refers to the natural gas as the main energy, the high grade heat energy to generate electricity, low grade heat energy to generate heating and cooling. (2) Clean and renewable energy. Traditional CCHP system combined with renewable energy, the internal load fluctuation can be effectively regulated. (3) Electric cars. Electric vehicles in the MECS, either as an energy storage unit, and can be as a distributed power supply. It can not only greatly reduce the amount of electricity generation and energy storage device system, but also can effectively alleviate the pressure of the power grid. The MECS Design Scheme CCHP. The turbine-direct combustion LiBr absorption unit reduces the waste heat boiler, standby boiler and related auxiliary system, and greatly reduces the system cost, operation cost and maintenance difficulty. This makes the system configuration is more reasonable, and has a broader market. Thus, in view of the campus, this paper will adopt the gas turbine-direct combustion LiBr absorption unit. Photovoltaic Diagram. The MECS contains an array of photovoltaic array, which receive solar energy to generate power. Photovoltaic power generation of electricity by distributor communication sent to the local load, excess electricity through the circuit to the electric car battery or feedback to power grid. 3rd International Conference on Materials Engineering, Manufacturing Technology and Control (ICMEMTC 2016) © 2016. The authors Published by Atlantis Press 648 Design Scheme. The MECS is connected to the power grid through distribution transformer. The distributed power supply system consists of photovoltaic, gas turbine and the corresponding configuration has generator, turbine-direct combustion LiBr absorption unit, the electric car. System with cooling load (including electric refrigeration load and the cooling load of LiBr refrigeration unit), heat load (including the heat load for heating and hot water supply), electricity load (including important pure electricity load, general pure electric load and electric refrigeration load). System of gas turbine and the turbine-direct combustion LiBr absorption unit constitute the CCHP system. Electric load can be supply by three directions: when the light is enough, it can be supplied by photovoltaic system, excess electricity can be transported to electric vehicles or power grid; when light is insufficient, it can be supplied by both the MECS and the power grid, which ensures the reliability of power supply. Electric cars can be either as an energy storage unit, and can be as a distributed power supply. For the above MECS, this paper describes its energy flow relations which are shown in figure 1.