## 1 Introduction  
Considering the background of energy internet and low-carbon electricity, the integrated energy system (IES) has played an important role in energy conservation and emission reduction processes [1; 2; 3; 4]. In recent years, the concept of IES and its application have gradually become widely accepted with the rapid development and engineering application of renewable generation and a variety of energy storage technologies [1; 3; 4; 5]. The IES is of great importance to improve energy efficiency and achieve the sustainable development of energy, therefore, in the past few years, there have been many results considering IES [1; 4; 5]. The district heating system, electricity system, natural gas system, plug-in hybrid electric vehicles (PHEVs) of future energy systems, and other various energy system forms are becoming tightly linked to each other in IES [5; 6], in which the heat pump, diversified storage devices, combined cooling, heating and power (CCHP)/combined heating and power (_CHP_), power to gas (_P2G_), power to heating (_P2H_), absorption chiller, gas turbine, micro-gas turbine, gas furnace/boiler, etc., are all integrated. The energy coupling relationship is close and complex [2; 6]. Energy hub (EH) is defined as an input-output port model that describes the energy, load, network switching, and coupling relationships in a multi-energy system [3; 4; 5]. As a new coupling method [2; 4; 5; 6; 7], EH can solve coupling problems between electric power systems, district heating systems, natural gas systems, etc. EH can play a role in mutual transformation, distribution, and storage of various types of energy, which is highly flexible. Besides, EH can adjust the output and operation states of different equipment according to different optimization objectives of the model, so as to meet the demand of corresponding loads [6; 7]. Recently, there have been some results considering hybrid cold, heat, and power, or power and heat, or power, heat, and gas problems. In the literatures [8; 9], a comprehensive simulation model was presented and the relationship between a power system and natural gas system was analyzed, which showed that there was a strong interdependence between the two systems. In a past paper [10], a probabilistic steady-state analysis of integrated heating, gas, and electricity systems was proposed. The probabilistic energy flow problem of IES considering correlated uncertainties and operation modes in wind, solar power, and heat, gas and electricity loads were formulated and solved by Monte Carlo method. A hierarchical energy management framework for a microgrid including multi-timescale battery energy storage and demand response was discussed previously [11], the aim was to optimize the system's operation considering the uncertainty of renewable energy sources as well as the load. In another past paper [12], a robust optimization model was used to manage the combined heat and power systems through linear decision rules. In a different past paper [13], the heat load related to its temperature was modeled and controlled. Both of the latter references coordinated power load reduction, heat load control, and energy storage to enhance the efficiency and operational profitability of CCHP plants. In past studies [14; 15], a robust optimization model was utilized to manage a building's energy system with a _CHP_ system, where the randomness of power load, heat load, and solar power generation were considered. In a past paper [16], hybrid energy solutions based on split air conditioning units were presented, and four different hybrid energy options, which could reduce overall energy consumption, were analyzed. In another past paper [17], several schemes for the coordination of power systems and gas systems were presented to improve security and economic aspects.