Optimized operation method of electricity-heat-gas comprehensive energy system

Abstract

The invention discloses an optimized operation method for an electricity-heat-gas comprehensive energy system. The method comprises the following steps: constructing an optimization model; the optimization model comprises an output model of each type of equipment in the electric-thermal-gas comprehensive energy system and an energy network balance relation model; the objective function of the optimization model comprises a cost item and a load reduction item, and decision values and weight values related to the optimization model are calculated. And determining weight values in the target function in different operation states. And selecting a weight value in a corresponding objective function according to the current actual operation state, and then solving the model. According to the method, the two targets of the lowest cost and the lowest load reduction amount are comprehensively considered, the weight value needed for solving is determined based on the current state, the cost and load requirements are considered, efficient energy integration of the power network, the heat power network and the natural gas network is achieved, and the obtained output configuration is better matched with the system characteristics.

Description

Technical Field

[0001] The present invention relates to an energy system operation method, in particular to an operation method of an electricity-heat-gas integrated energy system. Background Art

[0002] Compared with the traditional independent multi-energy system, the interaction between energy carriers such as electricity, gas and thermal energy is becoming increasingly close. In recent years, technologies such as distributed power generation technology and natural gas-driven cogeneration devices have developed rapidly and been widely used, which has had a profound impact on energy transmission, generation and consumption, and has given rise to synergistic effects between multiple energy sources and promoted the evolution of energy systems towards a more integrated direction.

[0003] The goal of the integrated energy system is to build a safer energy utilization model to meet the dual challenges of environmental protection and energy crisis. The system integrates the supply, storage and conversion facilities of multiple energy sources, and realizes the integration of different energy sources in multiple links such as network, charging and source. In particular, the combined heat and power (CHP) system has received more and more attention because it can meet the demand for heating and electricity at the same time. In addition, with the access of a large number of renewable energy devices to the power grid, such as wind power and solar photovoltaics, the volatility and uncertainty of energy have brought new challenges to the operation of the system, and more in-depth research is urgently needed to seek solutions. Energy storage technology has therefore become a key component of the power grid to effectively compensate and balance the fluctuations of renewable energy and improve the overall performance of the power grid. It can be seen that the coupling between the distribution network and the natural gas network and the addition of multiple energy devices have brought new challenges to the short-term operation of the integrated energy system.

[0004] Those skilled in the art have conducted extensive research on the operation strategies and optimization methods of integrated energy systems. Existing solutions mainly focus on using power prediction technology to estimate the output of wind energy, solar photovoltaics, and the demand for thermal energy and electrical energy. Such solutions only focus on minimizing operating costs. However, when the system has voltage over-limit, air pressure over-limit and other faults, if only the lowest cost is considered, the reduction amount of various loads will inevitably increase significantly, making it impossible to meet the normal load demand of users, and even expanding the scope of the fault. On the other hand, when the system is in different states (including normal operating states and states when different types of faults occur), the operating characteristics of the system are also very different. If a fixed method is used to allocate the output of each device, satisfactory results are often not obtained, and costs often increase and normal load demands cannot be met. Summary of the invention

[0005] The present invention proposes an optimized operation method for an electric-heat-gas integrated energy system, the purpose of which is: 1. to solve the problem that the existing operation method cannot take into account both cost and load demand. 2. to solve the problem that the operation mode of the system under different conditions does not match the system characteristics.

[0006] The technical solution of the present invention is as follows:

[0007] A method for optimizing operation of an electric-heat-gas integrated energy system, comprising the following steps:

[0008] Step 1: Build an optimization model;

[0009] The optimization model includes output models of various types of equipment in the electric-heat-gas integrated energy system and an energy network balance relationship model of the electric-heat-gas integrated energy system; the energy network balance relationship model includes an electric power network balance relationship model, a thermal network balance relationship model and a natural gas network balance relationship model;

[0010] The objective function of the optimization model includes a cost term and a load reduction term, and the calculation of the objective function involves a decision value and a weight value of the optimization model;

[0011] Step 2: Determine the weight value in the objective function under different operating conditions;

[0012] Step 3: Select the weight value in the corresponding objective function according to the current actual operating status of the electricity-heat-gas integrated energy system, then solve the model, and control the operation of the electricity-heat-gas integrated energy system in the next operating cycle according to the optimal operating configuration obtained.

[0013] As a further improvement of the method for optimizing the operation of the electric-heat-gas integrated energy system: the equipment in the electric-heat-gas integrated energy system includes: a distributed power generation device, a fuel cell, a gas boiler, a cogeneration unit, an electric boiler, a power-to-gas device, an electric storage device, a heat storage device and a gas storage device;

[0014] The electric load is provided by distributed power generation devices, fuel cells, cogeneration units and power storage equipment connected to the power grid; the thermal load is provided by gas boilers, cogeneration units, electric boilers and heat storage equipment connected to the thermal network; and the gas load is provided by cogeneration units, power-to-gas equipment and gas storage equipment connected to the natural gas network.

[0015] The distributed power generation device includes a distributed wind turbine and a distributed photovoltaic power generation device;

[0016] The combined heat and power unit includes a gas turbine and a waste heat boiler.

[0017] As a further improvement of the method for optimizing the operation of the electricity-heat-gas integrated energy system:

[0018] The output model of distributed wind turbine generator is:

[0019]

[0020] Where: w is the speed of the distributed wind turbine generator set during period t, P WT (t) is the output power of the distributed wind turbine generator set during period t, w1, w cutout and w r are the cut-in speed, cut-off speed and rated speed of the distributed wind turbine generator set, P nom is the rated output power of the distributed wind turbine generator set, k1 and k2 are the linear coefficients of the distributed wind turbine installed power;

[0021] The output model of distributed photovoltaic power generation device is:

[0022]

[0023] Where: P PV (t) is the output power of the distributed photovoltaic power generation device during period t, Y PV is the rated capacity of distributed photovoltaic power generation, I S It is the rated solar radiation that the photovoltaic surface can withstand, which is related to the photovoltaic manufacturing materials. T is the total solar radiation on the photovoltaic surface during period t, f PV is the attenuation factor;

[0024] The output model of the combined heat and power unit is:

[0025]

[0026] Where: P GFT (t) and H GFT (t) are the output electric power and thermal power of the gas turbine during period t, G GFT (t) is the fuel consumption of the gas turbine during period t, H WHB (t) is the output thermal power of the waste heat boiler during period t, η GFT，e and η GFT，h are the electrical conversion efficiency and thermal conversion efficiency of the gas turbine, respectively, WHB is the conversion efficiency of the waste heat boiler, LHV is the lower heating value of natural gas;

[0027] The fuel cell output model is:

[0028] P FC (t) = η FC LHV·G FC (t);

[0029] Where: PFC (t) is the output power of the fuel cell during period t, η FC is the power generation efficiency of the fuel cell during period t, G FC (t) is the fuel consumption of the fuel cell during period t;

[0030] The gas boiler output model is:

[0031] H MT (t) = η MT G MT (t) LHV;

[0032] Where: H MT (t) is the output thermal power of the gas boiler during period t, η MT is the gas-to-heat conversion efficiency of the gas boiler, G MT (t) is the fuel consumption of the gas boiler during period t;

[0033] The output model of electric boiler is:

[0034] H EB (t) = η EB P EB (t);

[0035] Where: H EB (t) is the output thermal power of the electric boiler during period t, η EB is the electric-to-heat conversion efficiency, P EB (t) is the input power of the electric boiler during period t;

[0036] The output model of the power-to-gas equipment is:

[0037]

[0038] Where: G EG (t) is the gas supply of the power-to-gas device during period t; η EG is the power-to-gas efficiency of the power-to-gas equipment, P EG (t) is the input power of the power-to-gas device during period t;

[0039] Energy storage equipment includes electricity storage equipment, heat storage equipment and gas storage equipment, and the output model is unified as follows:

[0040]

[0041] Where: i∈{ESS, HSS, GSS}, ESS represents electricity storage equipment, HSS represents heat storage equipment, GSS represents gas storage equipment; E i (t) is the energy stored in the corresponding energy storage device in time period t, P cha，i (t) and P dis，i(t) are the charging power and discharging power of the corresponding energy storage device in time period t, σ i is the self-consumption rate of the corresponding energy storage device, η cha，i and η dis,i are the charging efficiency and discharging efficiency of the corresponding energy storage equipment respectively.

[0042] As a further improvement of the method for optimizing the operation of the electricity-heat-gas integrated energy system:

[0043] (1) The power network balance relationship model is:

[0044]

[0045] Where: P load (t) is the electric load demand of the electricity-heat-gas integrated energy system in period t, which is a specified value; P buy (t) is the power purchased from the main grid by the electricity-heat-gas integrated energy system during period t, which is the decision value; P WT，k (t), P PV，k (t), P GFT，k (t) and P FC，k (t) are the outputs of the kth distributed wind turbine, the kth distributed photovoltaic power generation device, the gas turbine of the kth cogeneration unit and the kth fuel cell in period t, respectively, and are the decision values; P EB，k (t), P EG，k (t) are the power consumption of the k-th electric boiler and the k-th power-to-gas equipment in period t, respectively, which are calculated by the output decision value and output model of the corresponding equipment; P cha，k (t) and P dis，k (t) are the charging power and discharging power of the kth power storage device in period t, respectively, and are the decision values; C e is the load reduction, is the decision value; N wt 、N pv 、N gft 、N fc 、N ess 、N eb and N eg They are the number of distributed wind turbines, distributed photovoltaic power generation devices, gas turbines, fuel cells, power storage devices, electric boilers and power-to-gas devices;

[0046] (2) The thermal network balance relationship model is:

[0047]

[0048] Where: H load (t) is the heat load demand of the electricity-heat-gas integrated energy system during period t, which is a specified value; H buy(t) is the external heat purchased by the electricity-heat-gas integrated energy system in period t, which is the decision value; N mt 、N whb and N h are the number of gas boilers, waste heat boilers of cogeneration units and gas storage equipment; H MT，k (t), H WHB，k (t) and H EB，k (t) are the output thermal powers of the k-th gas boiler, the waste heat boiler of the k-th cogeneration unit and the k-th electric boiler during period t, respectively, and are the decision values; H cha，k (t) and H dis，k (t) are the heat storage power and heat release power of the kth heat storage device in period t, which are the decision values; C h is the heat load reduction, is the decision value;

[0049] (3) The natural gas network balance relationship model is:

[0050]

[0051] Where: G load (t) is the gas load demand of the electricity-heat-gas integrated energy system in period t, which is a specified value; G buy (t) is the natural gas purchase volume in period t, which is the decision value; N g is the number of gas storage equipment; G EG，k (t) is the natural gas supply of the kth power-to-gas equipment; G FC，k (t), G MT，k (t) and G GFT，k (t) are the natural gas consumption of the kth fuel cell, the kth gas boiler and the gas turbine of the kth cogeneration unit in period t, respectively, which are calculated by the output decision value and output model of the corresponding equipment; G cha，k (t) and G dis，k (t) is the gas filling and deflation volume of the k-th gas storage device in period t, which is the decision value; C g is the natural gas load reduction, and is the decision value.

[0052] As a further improvement of the optimization operation method of the electricity-heat-gas integrated energy system, the objective function of the optimization model is specifically:

[0053]

[0054] Among them, F1 is the total operating cost of the electricity-heat-gas integrated energy system in the target operating cycle, and is the minimum and maximum total operating cost in an operating cycle specified according to historical data; F2 is the total reduction of the electricity-heat-gas integrated energy system in the target operating cycle, and are the minimum and maximum total reductions that the electricity-heat-gas integrated energy system can accept; λ1 and λ2 are weight values, both of which are greater than 0 and λ1+λ2=1.

[0055] As a further improvement of the optimized operation method of the electricity-heat-gas integrated energy system, the total operation cost F1 is calculated as follows:

[0056]

[0057] Where T is the total number of time periods in the target operation cycle, and C(t) is the total operating cost of time period t:

[0058] C(t)=C E (t)+C H (t)+C G (t);

[0059] In the formula, C E (t), C H (t) and C G (t) are the operating costs of the power network, heat network and natural gas network during period t respectively.

[0060] As a further improvement of the method for optimizing the operation of the electricity-heat-gas integrated energy system:

[0061] The operation cost of the power network in period t is calculated as follows:

[0062] C E (t) = C M，E (t)+C B，E (t)

[0063]

[0064] C B，E (t) = P buy (t)·P E (t)

[0065] Where: C M，E (t) and C B，E (t) are the operation and maintenance cost and electricity purchase cost of the power network in period t; N is the number of power output equipment in the power network, which includes distributed wind turbines, distributed photovoltaic power generation devices, gas turbines of cogeneration units, fuel cells and power storage devices; C n，e is the operation and maintenance cost per unit output of the nth power output equipment; P n (t) is the output of the nth power output equipment in period t, which is the decision value; P E (t) is the electricity price during period t;

[0066] The operation cost of the heating network in period t is calculated as follows:

[0067]

[0068] Where: C M，H (t) and C B，H (t) are the operation and maintenance cost and heat purchase cost of the thermal network in period t; L is the number of thermal network output equipment, which includes gas boilers, waste heat boilers of cogeneration units, electric boilers and gas storage equipment; C l，e is the operation and maintenance cost per unit output of the first thermal network output equipment; H n (t) is the output thermal power of the first thermal network output device in period t; P H (t) is the heat selling price in time period t;

[0069] The operating cost of the natural gas network during period t is calculated as:

[0070]

[0071] Where: C M，G (t) and C B，G (t) are the operation and maintenance cost and gas purchase cost of the natural gas network in period t; K is the number of natural gas network output equipment, which includes: power-to-gas equipment and gas storage equipment; C k，g G is the unit gas transmission operation and maintenance cost of the k-th natural gas network output equipment; n (t) is the natural gas supply of the kth natural gas network output device in period t; P G (t) is the natural gas price.

[0072] As a further improvement of the optimized operation method of the electricity-heat-gas integrated energy system, the total reduction amount F2 is calculated as follows:

[0073]

[0074] Where T is the total number of time periods in the target operation cycle, and L(t) is the load reduction in time period t:

[0075] L(t)=ω e C e +ω h C h +ω g C g ;

[0076] In the formula, C e , C h and C gare the reduction in electricity load, heat load and natural gas load respectively; ω e ,ω h and ω g are the weights representing the importance of electric load, heat load and natural gas load, all of which are greater than 0 and ω e +ω h +ω g =1.

[0077] As a further improvement of the method for optimizing the operation of the electric-heat-gas integrated energy system, the specific process of step 2 is as follows:

[0078] Step 2-1: Extract data points of several operation cycles from historical data. Each data point includes the consumption value and output value of each device in the corresponding operation cycle, the total operation cost of the energy system Cost, and the electric load reduction amount C e , Heat load reduction C h and natural gas load reduction C g ; At the same time, the operating status label corresponding to each data point is extracted, and the operating status label includes: normal, voltage over limit, air pressure over limit and power overload;

[0079] Step 2-2: Cluster all data points using the K-Means method, and specify the number of clusters K as 4;

[0080] Step 2-3: Count the running status labels of the data points in each category, take the running status label with the largest number as the label of the category, and then remove the data points in each category whose running status labels are inconsistent with the category labels to achieve data point screening;

[0081] Step 2-4: For each category, calculate the weight value corresponding to each category according to the following steps:

[0082] Step 2-4-1, weight value ω e ,ω h ,ω g , λ1 and λ2 are assigned initial values, ω e ,ω h and ω g are greater than 0 and ω e +ω h +ω g =1, λ1 and λ2 are both greater than 0 and λ1+λ2=1; set the number of iterations to 0;

[0083] Step 2-4-2, set the objective function:

[0084]

[0085] Step 2-4-3: Substitute the values ​​of all data points in the current classification into the above objective function, and then calculate the average value of the obtained obj Iteration number +1;

[0086] Step 2-4-4, determine whether the number of iterations reaches a preset threshold, if it reaches it, end step 2-4, otherwise execute step 2-4-5;

[0087] Step 2-4-5, to make the average Minimum is the goal, and the weight value ω is updated through the gradient descent method. e ,ω h ,ω g , λ1 and λ2, then jump to step 2-4-3;

[0088] In step 3, before solving the problem, the rotation speed of the distributed wind turbine generator set and the total solar radiation on the photovoltaic surface in each period of the target operation cycle are specified according to the weather forecast data, and then a set of optimal operation configurations are solved. The optimal operation configuration includes: the output of each device in each period, the charging and discharging power of each energy storage device in each period, the purchase amount of electricity, heat and natural gas in each period, and the reduction amount of electric load, heat load and natural gas load.

[0089] As a further improvement of the optimization operation method of the electric-heat-gas integrated energy system, the optimization model also includes control constraints:

[0090] (1) Equipment output constraints:

[0091]

[0092] Where: P n (t) is the output of the nth device in period t; are the maximum output value and minimum output value of the nth device respectively;

[0093] (2) Energy storage equipment constraints:

[0094]

[0095] Where: P cha，i and P dis，i are the charging power and discharging power of the i-th energy storage device at any time period, β cha，i and β dis，i are the maximum charging rate and discharging rate of the i-th energy storage device respectively; C i is the rated storage capacity of the i-th energy storage device; and are the maximum load state and minimum load state of the i-th energy storage device respectively; E i(t) is the energy stored in the i-th energy storage device in time period t; E i (0) and E i (T) are the storage energy at the beginning and the end of the operation cycle of the i-th energy storage device;

[0096] (3) Distributed generation output constraints:

[0097]

[0098] Where: P WT (t) is the output power of the distributed wind turbine generator set during period t, P PV (t) is the output power of the distributed photovoltaic power generation device during period t, and are the maximum outputs of distributed wind turbines and distributed photovoltaic power generation devices respectively;

[0099] (4) Interaction power constraints between the integrated energy system and the main power grid:

[0100]

[0101] Where: P buy (t) is the power purchased from the main grid by the electricity-heat-gas integrated energy system during period t, It is the maximum allowable power purchase power of the interconnection line between the electricity-heat-gas integrated energy system and the power grid.

[0102] Compared with the prior art, the present invention has the following beneficial effects:

[0103] 1. The optimization model in the present invention comprehensively considers the two objectives of minimum cost and minimum load reduction, thereby taking into account both cost and load demand and realizing efficient energy integration of power network, heat network and natural gas network.

[0104] 2. When generating the output configuration, the present invention first selects the corresponding historical data according to the state of the system to obtain the optimal weight value, and then solves the model based on the optimal weight value to ensure that the obtained output configuration matches the current characteristics of the system.

[0105] 3. In the process of solving the weight value, the historical data is further screened through the clustering method, making the weight value more representative and improving the accuracy of the calculation result. BRIEF DESCRIPTION OF THE DRAWINGS

[0106] Figure 1 This is the architecture diagram of the electricity-heat-gas integrated energy system. DETAILED DESCRIPTION

[0107] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0108] A method for optimizing operation of an electric-heat-gas integrated energy system, comprising:

[0109] Step 1: Build an optimization model.

[0110] The optimization model includes output models of various types of equipment in the electricity-heat-gas integrated energy system and an energy network balance relationship model of the electricity-heat-gas integrated energy system.

[0111] like Figure 1 , the equipment in the electric-heat-gas integrated energy system includes: distributed power generation devices, fuel cells, gas boilers, combined heating and power (CHP) units, electric boilers, power to gas (P2G) equipment, power storage equipment, heat storage equipment and gas storage equipment. Among them, the electric load is provided by the distributed power generation devices, fuel cells, combined heat and power units and power storage equipment connected to the power network, the heat load is provided by the gas boilers, combined heat and power units, electric boilers and heat storage equipment connected to the thermal network, and the gas load is provided by the combined heat and power units, power to gas and gas storage equipment connected to the natural gas network. The distributed power generation devices include distributed wind turbines and distributed photovoltaic power generation devices, and may also include other power generation equipment.

[0112] The output models of each device are:

[0113] (1) Distributed power generation equipment.

[0114] (1-1) Distributed wind turbine generator sets are mainly composed of wind turbines (WT), and their output model is:

[0115]

[0116] Where: w is the speed of the distributed wind turbine generator set during period t, P WT (t) is the output power of the distributed wind turbine generator set in period t, in kWh, w1, w cutout and w r are the cut-in speed, cut-off speed and rated speed of the distributed wind turbine generator set (related to the specifications of the wind turbine), P nom is the rated output power of the distributed wind turbine generator set, k1 and k2 are the linear coefficients of the distributed wind turbine installed power.

[0117] (1-2) Distributed photovoltaic power generation devices are mainly composed of photovoltaic arrays (PV). The overall solar radiation directly determines the output power. Its output model is:

[0118]

[0119] Where: P PV (t) is the output power of the distributed photovoltaic power generation device during period t, Y PV is the rated capacity of distributed photovoltaic power generation, I S The rated solar radiation that the photovoltaic surface can withstand is related to the photovoltaic manufacturing material. In this embodiment, it is set to 1000W / m 2 , I T is the total solar radiation on the photovoltaic surface during period t (in kWh / m 2 ), f PV It is the attenuation factor, which covers the factors that affect the function of photovoltaic panels, such as high temperature, line loss, etc.

[0120] (2) Coupling equipment

[0121] (2-1) The cogeneration unit is the core energy flow coupling device in the electricity-heat-gas integrated energy system. It includes a gas-fired turbine (GFT) and a waste heat boiler (WHB). Its output model is:

[0122]

[0123] Where: P GFT (t) and H GFT (t) are the output electric power and thermal power of the gas turbine during period t, G GFT (t) is the fuel consumption of the gas turbine during period t, H WHB (t) is the output thermal power of the waste heat boiler during period t, η GFT，e and η GFT，h are the electrical conversion efficiency and thermal conversion efficiency of the gas turbine, respectively, WHB is the conversion efficiency of the waste heat boiler, and LHV is the lower heating value of natural gas.

[0124] (2-2) Fuel cells can directly convert the chemical energy of natural gas into electrical energy with high power generation efficiency. Its output model is:

[0125] P FC (t) = η FC LHV·G FC (t);

[0126] Where: P FC(t) is the output power of the fuel cell during period t, η FC is the power generation efficiency of the fuel cell during period t, G FC (t) is the fuel consumption of the fuel cell during period t.

[0127] (2-3) Gas boilers generate heat energy by consuming natural gas, and their output model is:

[0128] H MT (t) = η MT G MT (t) LHV;

[0129] Where: H MT (t) is the output thermal power of the gas boiler during period t, η MT is the gas-to-heat conversion efficiency of the gas boiler, G MT (t) is the fuel consumption of the gas boiler during period t.

[0130] (2-4) Electric boilers are typical electric-thermal coupling devices that generate heat energy by consuming electrical energy. Their output model is:

[0131] H EB (t) = η EB P EB (t);

[0132] Where: H EB (t) is the output thermal power of the electric boiler during period t, η EB is the electric-to-heat conversion efficiency, P EB (t) is the input power of the electric boiler during period t.

[0133] (2-5) When the wind and solar power are abandoned in the electricity-heat-gas integrated energy system, the surplus wind power and photovoltaic power can be converted into natural gas by turning on the power-to-gas equipment and injected into the natural gas network for storage and transportation. The output model of the power-to-gas equipment is:

[0134]

[0135] Where: G EG (t) is the gas supply of the power-to-gas device during period t; η EG is the power-to-gas efficiency of the power-to-gas equipment, P EG (t) is the input power of the power-to-gas device during period t.

[0136] (2-6) Energy storage equipment includes electricity storage equipment, heat storage equipment and gas storage equipment, and the output model is unified as follows:

[0137]

[0138] Where: i∈{ESS, HSS, GSS}, ESS represents electricity storage equipment, HSS represents heat storage equipment, GSS represents gas storage equipment; E i (t) is the energy stored in the corresponding energy storage device in time period t, P cha，i (t) and P dis，i (t) are the charging power and discharging power of the corresponding energy storage device in time period t, σ i is the self-consumption rate of the corresponding energy storage device, η cha，i and η dis,i are the charging efficiency and discharging efficiency of the corresponding energy storage equipment respectively.

[0139] The energy network balance relationship model includes an electric power network balance relationship model, a thermal network balance relationship model and a natural gas network balance relationship model:

[0140] (1) Power network balance relationship model

[0141] The electricity load in the electricity-heat-gas integrated energy source mainly comes from the main grid, distributed wind turbines, distributed photovoltaic generators, fuel cells, cogeneration units and power storage equipment. If it is insufficient, it will be purchased from the main grid. At the same time, the electricity load reduction variable C is introduced. e , the model is:

[0142]

[0143] Where: P load (t) is the electric load demand of the electricity-heat-gas integrated energy system in period t, which is a specified value; P buy (t) is the power purchased from the main grid by the electricity-heat-gas integrated energy system during period t, which is the decision value; P WT，k (t), P PV，k (t), P GFT，k (t) and P FC，k (t) are the outputs of the kth distributed wind turbine, the kth distributed photovoltaic power generation device, the gas turbine of the kth cogeneration unit and the kth fuel cell in period t, respectively, and are the decision values; P EB，k (t), P EG，k (t) are the power consumption of the k-th electric boiler and the k-th power-to-gas equipment in period t, respectively, which are calculated by the output decision value and output model of the corresponding equipment; P cha，k (t) and P dis，k (t) are the charging power and discharging power of the kth power storage device in period t, respectively, and are the decision values; C e is the load reduction, is the decision value; N wt 、N pv、 N gft 、N fc 、N ess、N eb and N eg They are the number of distributed wind turbines, distributed photovoltaic power generation devices, gas turbines, fuel cells, energy storage equipment, electric boilers and power-to-gas equipment.

[0144] (2) Thermal network balance relationship model

[0145] In the electric-heat-gas integrated energy system, the heat load demand mainly comes from gas boilers, electric boilers, cogeneration units and heat storage equipment. If it is insufficient, it will be purchased from the external network. At the same time, the heat load reduction variable C is introduced. h , the model is:

[0146]

[0147] Where: H load (t) is the heat load demand of the electricity-heat-gas integrated energy system during period t, which is a specified value; H buy (t) is the external heat purchased by the electricity-heat-gas integrated energy system in period t, which is the decision value; N mt 、N whb and N h are the number of gas boilers, waste heat boilers of cogeneration units and gas storage equipment; H MT，k (t), H WHB，k (t) and H EB，k (t) are the output thermal powers of the k-th gas boiler, the waste heat boiler of the k-th cogeneration unit and the k-th electric boiler during period t, respectively, and are the decision values; H cha，k (t) and H dis，k (t) are the heat storage power and heat release power of the kth heat storage device in period t, which are the decision values; C h is the heat load reduction, and is the decision value.

[0148] (3) Natural gas network balance relationship model

[0149] The gas load demand in the electricity-heat-gas integrated energy system mainly comes from the natural gas network, gas boilers, fuel cells, cogeneration units, power-to-gas equipment and gas storage equipment. If it is insufficient, it will be purchased from the external network. At the same time, the gas load reduction variable C is introduced. g , the model is:

[0150]

[0151] Where: G load (t) is the gas load demand of the electricity-heat-gas integrated energy system in period t, which is a specified value; G buy (t) is the natural gas purchase volume in period t, which is the decision value; N g is the number of gas storage equipment; G EG，k(t) is the natural gas supply of the kth power-to-gas equipment; G FC，k (t), G MT，k (t) and G GFT，k (t) are the natural gas consumption of the kth fuel cell, the kth gas boiler and the gas turbine of the kth cogeneration unit in period t, respectively, which are calculated by the output decision value and output model of the corresponding equipment; G cha，k (t) and G dis，k (t) is the gas filling and deflation volume of the k-th gas storage device in period t, which is the decision value; C g is the natural gas load reduction, and is the decision value.

[0152] The objective function of the optimization model includes a cost term and a load reduction term, and the calculation of the objective function involves a decision value and a weight value of the optimization model.

[0153] The specific objective function is:

[0154]

[0155] Among them, F1 is the total operating cost of the electricity-heat-gas integrated energy system in the target operating cycle, and is the minimum and maximum total operating cost in an operating cycle specified according to historical data; F2 is the total reduction of the electricity-heat-gas integrated energy system in the target operating cycle, and are the minimum and maximum total reductions that the electricity-heat-gas integrated energy system can accept. λ1 and λ2 are weight values, both of which are greater than 0 and λ1+λ2=1.

[0156] Furthermore, the total operating cost F1 is calculated as follows:

[0157]

[0158] Where T is the total number of time periods in the target operation cycle, and C(t) is the total operating cost of time period t:

[0159] C(t)=C E (t)+C H (t)+C G (t);

[0160] In the formula, C E (t), C H (t) and C G (t) are the operating costs of the power network, heat network and natural gas network during period t respectively.

[0161] Specifically, the operation cost of the power network in period t is calculated as follows:

[0162] C E (t) = C M，E (t)+C B，E (t)

[0163]

[0164] C B，E (t) = P buy (t)·P E (t)

[0165] Where: C M，E (t) and C B，E (t) are the operation and maintenance cost and electricity purchase cost of the power network in period t; N is the number of power output equipment in the power network, which includes distributed wind turbines, distributed photovoltaic power generation devices, gas turbines of cogeneration units, fuel cells and power storage devices; C n，e is the operation and maintenance cost per unit output of the nth power output equipment; P n (t) is the output of the nth power output equipment in period t, which is the decision value; P E (t) is the electricity selling price in period t.

[0166] The operation cost of the heating network in period t is calculated as follows:

[0167]

[0168] Where: C M，H (t) and C B，H (t) are the operation and maintenance cost and heat purchase cost of the thermal network in period t; L is the number of thermal network output equipment, which includes gas boilers, waste heat boilers of cogeneration units, electric boilers and gas storage equipment; C l，e is the operation and maintenance cost per unit output of the first thermal network output equipment; H n (t) is the output thermal power of the first thermal network output device in period t; P H (t) is the hot selling price in period t.

[0169] Specifically, the operation cost of the natural gas network in period t is calculated as follows:

[0170]

[0171] Where: C M，G (t) and C B，G (t) are the operation and maintenance cost and gas purchase cost of the natural gas network in period t; K is the number of natural gas network output equipment, which includes: power-to-gas equipment and gas storage equipment; C k，gG is the unit gas transmission operation and maintenance cost of the k-th natural gas network output equipment; n (t) is the natural gas supply of the kth natural gas network output device in period t; P G (t) is the natural gas price.

[0172] Furthermore, the total reduction F2 is calculated as:

[0173]

[0174] Where T is the total number of time periods in the target operation cycle, and L(t) is the load reduction in time period t:

[0175] L(t)=ω e C e +ω h C h +ω g C g ;

[0176] In the formula, C e , C h and C g are the reduction in electricity load, heat load and natural gas load respectively; ω e ,ω h and ω g are the weights representing the importance of electric load, heat load and natural gas load, all of which are greater than 0 and ω e +ω h +ω g =1.

[0177] The optimization model also includes control constraints:

[0178] (1) Equipment output constraints

[0179] The output of all devices in the system must meet the upper and lower output constraints, as follows:

[0180]

[0181] Where: P n (t) is the output of the nth device in period t; They are the maximum output value and minimum output value of the nth device respectively.

[0182] (2) Energy storage equipment constraints

[0183] To ensure sufficient energy storage during the dispatch cycle, the energy storage in the energy storage device needs to be within the upper and lower limits of the device capacity:

[0184]

[0185] Where: Pcha，i and P dis，i are the charging power and discharging power of the i-th energy storage device at any time period, β cha，i and β dis，i are the maximum charging rate and discharging rate of the i-th energy storage device respectively; C i is the rated storage capacity of the i-th energy storage device; and are the maximum load state and minimum load state of the i-th energy storage device respectively; E i (t) is the energy stored in the i-th energy storage device in time period t; E i (0) and E i (T) are the storage capacities at the beginning and the end of the operation cycle of the i-th energy storage device.

[0186] (3) Distributed generation output constraints:

[0187]

[0188] Where: P WT (t) is the output power of the distributed wind turbine generator set during period t, P PV (t) is the output power of the distributed photovoltaic power generation device during period t, and They are the maximum outputs of distributed wind turbines and distributed photovoltaic power generation devices respectively.

[0189] (4) Interaction power constraints between the integrated energy system and the main power grid:

[0190]

[0191] Where: P buy (t) is the power purchased from the main grid by the electricity-heat-gas integrated energy system during period t, It is the maximum allowable power purchase power of the interconnection line between the electricity-heat-gas integrated energy system and the power grid.

[0192] Step 2: Determine the weight value in the objective function under different operating conditions.

[0193] The specific process is:

[0194] Step 2-1: Extract data points of several operation cycles from historical data. Each data point includes the consumption value and output value of each device in the corresponding operation cycle, the total operation cost of the energy system Cost, and the electric load reduction amount C e , Heat load reduction C h and natural gas load reduction C gAt the same time, the operation status label corresponding to each data point is extracted, and the operation status label includes: normal, voltage over limit, air pressure over limit and power overload.

[0195] Step 2-2: Cluster all data points using the K-Means method, and specify the number of clusters K as 4.

[0196] Step 2-3: Count the running status labels of the data points in each category, take the running status label with the largest number as the label of the category, and then remove the data points in each category whose running status labels are inconsistent with the category labels to achieve data point screening. The purpose is to ensure that the weight value obtained later is more representative and improve the accuracy of the calculation.

[0197] Step 2-4: For each category, calculate the weight value corresponding to each category according to the following steps:

[0198] Step 2-4-1, weight value ω e ,ω h ,ω g , λ1 and λ2 are assigned initial values; the number of iterations is set to 0.

[0199] Step 2-4-2, set the objective function:

[0200]

[0201] Step 2-4-3: Substitute the values ​​of all data points in the current classification into the above objective function, and then calculate the average value of the obtained obj Iteration count +1.

[0202] Step 2-4-4: Determine whether the number of iterations reaches a preset threshold. If so, end step 2-4; otherwise, execute step 2-4-5.

[0203] Step 2-4-5, to make the average Minimum is the goal, and the weight value ω is updated through the gradient descent method. e ,ω h ,ω g , λ1 and λ2, then jump to step 2-4-3.

[0204] At this point, the weight values ​​corresponding to different operating states can be determined.

[0205] Step 3: Select the weight value in the corresponding objective function according to the current actual operating status of the electricity-heat-gas integrated energy system, then solve the model, and control the operation of the electricity-heat-gas integrated energy system in the next operating cycle according to the optimal operating configuration obtained.

[0206] Specifically, before solving the problem, the rotation speed of distributed wind turbines in each period of the target operating cycle and the total solar radiation on the photovoltaic surface are specified according to the weather forecast data, and then the Cplex optimization software is called to solve a set of optimal operating configurations. The optimal operating configuration includes: the output of each device in each period, the charging and discharging power of each energy storage device in each period, the purchase amount of electricity, heat and natural gas in each period, and the reduction of electric load, heat load and natural gas load.

[0207] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. The scope of the present invention is defined by the claims rather than the above description.

Claims

1. A method for optimizing the operation of an electric-heat-gas integrated energy system, characterized in that the steps include: Step 1: Build an optimization model; The optimization model includes output models of various types of equipment in the electric-heat-gas integrated energy system and an energy network balance relationship model of the electric-heat-gas integrated energy system; the energy network balance relationship model includes an electric power network balance relationship model, a thermal network balance relationship model and a natural gas network balance relationship model; The objective function of the optimization model includes a cost term and a load reduction term, and the calculation of the objective function involves a decision value and a weight value of the optimization model; Step 2: Determine the weight value in the objective function under different operating conditions; Step 3: Select the weight value in the corresponding objective function according to the current actual operating status of the electricity-heat-gas integrated energy system, then solve the model, and control the operation of the electricity-heat-gas integrated energy system in the next operating cycle according to the optimal operating configuration obtained.

2. The method for optimizing operation of an electric-heat-gas integrated energy system according to claim 1, characterized in that: The equipment in the electric-heat-gas integrated energy system includes: distributed power generation devices, fuel cells, gas boilers, cogeneration units, electric boilers, power-to-gas equipment, power storage equipment, heat storage equipment and gas storage equipment; The electric load is provided by distributed power generation devices, fuel cells, cogeneration units and power storage equipment connected to the power grid; the thermal load is provided by gas boilers, cogeneration units, electric boilers and heat storage equipment connected to the thermal network; and the gas load is provided by cogeneration units, power-to-gas equipment and gas storage equipment connected to the natural gas network. The distributed power generation device includes a distributed wind turbine and a distributed photovoltaic power generation device; The combined heat and power unit includes a gas turbine and a waste heat boiler.

3. The method for optimizing operation of an electric-heat-gas integrated energy system according to claim 2, characterized in that: The output model of distributed wind turbine generator is: Where: w is the speed of the distributed wind turbine generator set during period t, P WT (t) is the output power of the distributed wind turbine generator set during period t, w1, w cutout and w r are the cut-in speed, cut-off speed and rated speed of the distributed wind turbine generator set, P nom is the rated output power of the distributed wind turbine generator set, k1 and k2 are the linear coefficients of the distributed wind turbine installed power; The output model of distributed photovoltaic power generation device is: Where: P PV (t) is the output power of the distributed photovoltaic power generation device during period t, Y PV is the rated capacity of distributed photovoltaic power generation, I S It is the rated solar radiation that the photovoltaic surface can withstand, which is related to the photovoltaic manufacturing materials. T is the total solar radiation on the photovoltaic surface during period t, f PV is the attenuation factor; The output model of the combined heat and power unit is: Where: P GFT (t) and H GFT (t) are the output electric power and thermal power of the gas turbine during period t, G GFT (t) is the fuel consumption of the gas turbine during period t, H WHB (t) is the output thermal power of the waste heat boiler during period t, η GFT,e and η GFT,h are the electrical conversion efficiency and thermal conversion efficiency of the gas turbine, respectively, WHB is the conversion efficiency of the waste heat boiler, LHV is the lower heating value of natural gas; The fuel cell output model is: P FC (t)=η FC LHV·G FC (t); Where: P FC (t) is the output power of the fuel cell during period t, η FC is the power generation efficiency of the fuel cell during period t, G FC (t) is the fuel consumption of the fuel cell during period t; The gas boiler output model is: H MT (t)=η MT G MT (t)LHV; Where: H MT (t) is the output thermal power of the gas boiler during period t, η MT is the gas-to-heat conversion efficiency of the gas boiler, G MT (t) is the fuel consumption of the gas boiler during period t; The output model of electric boiler is: H EB (t)=η EB P EB (t); Where: H EB (t) is the output thermal power of the electric boiler during period t, η EB is the electric-to-heat conversion efficiency, P EB (t) is the input power of the electric boiler during period t; The output model of the power-to-gas equipment is: Where: G EG (t) is the gas supply of the power-to-gas device during period t; η EG is the power-to-gas efficiency of the power-to-gas equipment, P EG (t) is the input power of the power-to-gas device during period t; Energy storage equipment includes electricity storage equipment, heat storage equipment and gas storage equipment, and the output model is unified as follows: Where: i∈{ESS,HSS,GSS}, ESS represents the electric storage equipment, HSS represents the heat storage equipment, GSS represents the gas storage equipment; E i (t) is the energy stored in the corresponding energy storage device in time period t, P cha,i (t) and P dls,i (t) are the charging power and discharging power of the corresponding energy storage device in time period t, σ i is the self-consumption rate of the corresponding energy storage device, η cha,i and η dis,i are the charging efficiency and discharging efficiency of the corresponding energy storage equipment respectively.

4. The method for optimizing operation of an electric-heat-gas integrated energy system according to claim 3, characterized in that: (1) The power network balance relationship model is: Where: P load (t) is the electric load demand of the electricity-heat-gas integrated energy system in period t, which is a specified value; P buy (t) is the power purchased from the main grid by the electricity-heat-gas integrated energy system during period t, which is the decision value; P WT,k (t), P PV,k (t), P GFT,k (t) and P FC,k (t) are the outputs of the kth distributed wind turbine, the kth distributed photovoltaic power generation device, the gas turbine of the kth cogeneration unit and the kth fuel cell in period t, respectively, and are the decision values; P EB,k (t), P EG,k (t) are the power consumption of the k-th electric boiler and the k-th power-to-gas equipment in period t, respectively, which are calculated by the output decision value and output model of the corresponding equipment; P cha,k (t) and P dis,k (t) are the charging power and discharging power of the kth power storage device in period t, respectively, and are the decision values; C e is the load reduction, is the decision value; N wt 、N pv 、N gft 、N fc 、N ess 、N eb and N eg They are the number of distributed wind turbines, distributed photovoltaic power generation devices, gas turbines, fuel cells, power storage devices, electric boilers and power-to-gas devices; (2) The thermal network balance relationship model is: Where: H load (t) is the heat load demand of the electricity-heat-gas integrated energy system during period t, which is a specified value; H buy (t) is the external heat purchased by the electricity-heat-gas integrated energy system in period t, which is the decision value; N mt 、N whb and N h are the number of gas boilers, waste heat boilers of cogeneration units and gas storage equipment; H MT,k (t), H WHB,k (t) and H EB,k (t) are the output thermal powers of the k-th gas boiler, the waste heat boiler of the k-th cogeneration unit and the k-th electric boiler during period t, respectively, and are the decision values; H cha,k (t) and H dis,k (t) are the heat storage power and heat release power of the kth heat storage device in period t, which are the decision values; C h is the heat load reduction, is the decision value; (3) The natural gas network balance relationship model is: Where: G load (t) is the gas load demand of the electricity-heat-gas integrated energy system in period t, which is a specified value; G buy (t) is the natural gas purchase volume in period t, which is the decision value; N g is the number of gas storage equipment; G EG,k (t) is the natural gas supply of the kth power-to-gas equipment; G FC,k (t), G MT,k (t) and G GFT,k (t) are the natural gas consumption of the kth fuel cell, the kth gas boiler and the gas turbine of the kth cogeneration unit in period t, respectively, which are calculated by the output decision value and output model of the corresponding equipment; G cha,k (t) and G dis,k (t) is the gas filling and deflation volume of the k-th gas storage device in period t, which is the decision value; C g is the natural gas load reduction, and is the decision value.

5. The method for optimizing operation of an electric-heat-gas integrated energy system according to claim 4, characterized in that: The objective function of the optimization model is as follows: Among them, F1 is the total operating cost of the electricity-heat-gas integrated energy system in the target operating cycle, and is the minimum and maximum total operating cost in an operating cycle specified according to historical data; F2 is the total reduction of the electricity-heat-gas integrated energy system in the target operating cycle, and are the minimum and maximum total reductions that the electricity-heat-gas integrated energy system can accept; λ1 and λ2 are weight values, both of which are greater than 0 and λ1+λ2=1.

6. The method for optimizing operation of an electric-heat-gas integrated energy system according to claim 5, characterized in that: The total operating cost F1 is calculated as: Where T is the total number of time periods in the target operation cycle, and C(t) is the total operating cost of time period t: C(t)=C E (t)+G H (t)+C G (t); In the formula, C E (t), C H (t) and C G (t) are the operating costs of the power network, heat network and natural gas network during period t respectively.

7. The method for optimizing operation of an electric-heat-gas integrated energy system according to claim 6, characterized in that: The operation cost of the power network in period t is calculated as follows: C E (t)=C M,E (t)+C B,E (t) C B,E (t)=P buy (t)·P E (t) Where: C M,E (t) and C B,E (t) are the operation and maintenance cost and electricity purchase cost of the power network in period t; N is the number of power output devices in the power network, including distributed wind turbines, distributed photovoltaic power generation devices, gas turbines of cogeneration units, fuel cells and power storage devices; C n,e is the operation and maintenance cost per unit output of the nth power output equipment; P n (t) is the output of the nth power output equipment in period t, which is the decision value; P E (t) is the electricity price during period t; The operation cost of the heating network in period t is calculated as follows: Where: C M,H (t) and C B,H (t) are the operation and maintenance cost and heat purchase cost of the thermal network in period t; L is the number of thermal network output equipment, which includes gas boilers, waste heat boilers of cogeneration units, electric boilers and gas storage equipment; C l,e is the operation and maintenance cost per unit output of the first thermal network output equipment; H n (t) is the output thermal power of the first thermal network output device in period t; P H (t) is the heat selling price in period t; The operating cost of the natural gas network during period t is calculated as: Where: C M,G (t) and C B,G (t) are the operation and maintenance cost and gas purchase cost of the natural gas network in period t; K is the number of natural gas network output equipment, which includes: power-to-gas equipment and gas storage equipment; C k,g G is the unit gas transmission operation and maintenance cost of the k-th natural gas network output equipment; n (t) is the natural gas supply of the kth natural gas network output device in period t; P G (t) is the natural gas price.

8. The method for optimizing operation of an electric-heat-gas integrated energy system according to claim 6, characterized in that: The total reduction F2 is calculated as: Where T is the total number of time periods in the target operation cycle, and L(t) is the load reduction in time period t: L(t) = ω e C e +ω h C h +ω g C g ; In the formula, C e , C h and C g are the reduction in electricity load, heat load and natural gas load respectively; ω e ,ω h and ω g are the weights representing the importance of electric load, heat load and natural gas load, all of which are greater than 0 and ω e +ω h +ω g =1.

9. The method for optimizing operation of an electric-heat-gas integrated energy system according to claim 5, characterized in that: The specific process of step 2 is: Step 2-1: Extract data points of several operation cycles from historical data. Each data point includes the consumption value and output value of each device in the corresponding operation cycle, the total operation cost of the energy system Cost, and the electric load reduction amount C e , Heat load reduction C h and natural gas load reduction C g ; At the same time, the operating status label corresponding to each data point is extracted, and the operating status label includes: normal, voltage over limit, air pressure over limit and power overload; Step 2-2: Cluster all data points using the K-Means method, and specify the number of clusters K as 4; Step 2-3: Count the running status labels of the data points in each category, take the running status label with the largest number as the label of the category, and then remove the data points in each category whose running status labels are inconsistent with the category labels to achieve data point screening; Step 2-4: For each category, calculate the weight value corresponding to each category according to the following steps: Step 2-4-1: For the weight value ω e ,ω h ,ω g , λ1 and λ2 are assigned initial values, ω e ,ω h and ω g are greater than 0 and ω e +ω h +ω g =1, λ1 and λ2 are both greater than 0 and λ1+λ2=1; set the number of iterations to 0; Step 2-4-2, set the objective function: Step 2-4-3: Substitute the values ​​of all data points in the current classification into the above objective function, and then calculate the average value of the obtained obj Iteration number +1; Step 2-4-4, determine whether the number of iterations reaches a preset threshold, if it reaches it, end step 2-4, otherwise execute step 2-4-5; Step 2-4-5, to make the average Minimum is the goal, and the weight value ω is updated through the gradient descent method. e ,ω h ,ω g , λ1 and λ2, then jump to step 2-4-3; In step 3, before solving the problem, the rotation speed of the distributed wind turbine generator set and the total solar radiation on the photovoltaic surface in each period of the target operation cycle are specified according to the weather forecast data, and then a set of optimal operation configurations are solved. The optimal operation configuration includes: the output of each device in each period, the charging and discharging power of each energy storage device in each period, the purchase amount of electricity, heat and natural gas in each period, and the reduction amount of electric load, heat load and natural gas load.

10. The method for optimizing operation of an electric-heat-gas integrated energy system according to any one of claims 1 to 9, characterized in that: The optimization model also includes control constraints: (1) Equipment output constraints: Where: P n (t) is the output of the nth device in period t; are the maximum output value and minimum output value of the nth device respectively; (2) Energy storage equipment constraints: Where: P cha,i and P dis,i are the charging power and discharging power of the i-th energy storage device at any time period, β cha,i and β dis,i are the maximum charging rate and discharging rate of the i-th energy storage device respectively; C i is the rated storage capacity of the i-th energy storage device; and are the maximum load state and minimum load state of the i-th energy storage device respectively; E i (t) is the energy stored in the i-th energy storage device in time period t; E i (0) and E i (T) are the storage energy at the beginning and the end of the operation cycle of the i-th energy storage device; (3) Distributed generation output constraints: Where: P WT (t) is the output power of the distributed wind turbine generator set during period t, P PV (t) is the output power of the distributed photovoltaic power generation device during period t, and are the maximum outputs of distributed wind turbines and distributed photovoltaic power generation devices respectively; (4) Interaction power constraints between the integrated energy system and the main power grid: Where: P buy (t) is the power purchased from the main grid by the electricity-heat-gas integrated energy system during period t, It is the maximum allowable power purchase power of the interconnection line between the electricity-heat-gas integrated energy system and the power grid.

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