Comprehensive energy system load recovery method based on management and storage characteristics

Abstract

The invention discloses an integrated energy system load recovery method based on management and storage characteristics, and the method comprises the steps: constructing a load recovery strategy generation model which comprises an energy supply model, an equivalent energy storage model and an energy balance model; an objective function of the load recovery strategy generation model is a weighted sum of an electrical load loss ratio, a thermal load loss ratio and a natural gas load loss ratio; determining an optimal weight value in the target function; and based on the weight optimal value, solving a load recovery strategy generation model by taking the minimum objective function as an optimization objective, taking the solved decision value as a recovery strategy of a post-disaster scheduling period, and controlling the electric-thermal-gas integrated energy system to work in a post-disaster recovery stage according to the recovery strategy. According to the method, the energy storage effect of the heat supply pipe network and the natural gas pipe network is fully considered, the three energy sources of electricity, heat and gas are fully transferred, the utilization efficiency of the heat energy and the gas energy is improved, and emergency response and rapid recovery of the system are promoted.

Description

Technical Field

[0001] The invention relates to a post-disaster load recovery method for an energy system. Background Art

[0002] In recent years, the energy sector has continuously increased the development and utilization of Integrated Electricity-Heat-Gas System (IEHGS), aiming to achieve complementarity and mutual assistance among multiple energy systems and ensure the safe and reliable operation of IEHGS.

[0003] However, in recent years, frequent large-scale power outages and other faults caused by extreme disasters have brought unprecedented challenges to the integrated energy system. In a large power outage, the system loses the energy supply of the main power supply, resulting in internal power imbalance and threatening the safe operation of the system. To meet this challenge, the integrated energy system adopts a load recovery strategy, which ensures uninterrupted power supply to key loads through the island operation mode to reduce the impact of large-scale power outages on production and life.

[0004] With the large-scale access of gas-to-electricity equipment such as cogeneration units and gas turbines, the connection between the power grid and the gas grid has become increasingly close. In the integrated energy system, electricity is transmitted and stored through transmission lines and battery energy storage systems, while natural gas and hot water are transported through pipelines, and gas tanks and heat storage tanks are also used as backup energy sources. In response to the problem of power loss load caused by distribution network failures under extreme disasters, existing technologies mostly focus on the analysis of the multi-energy synergy mechanism of integrated energy and the energy coupling characteristics. However, existing technologies often ignore the energy storage role of the system's thermal network and natural gas network, resulting in the failure to fully utilize gas and heat resources during post-disaster recovery, affecting the overall load recovery efficiency of the integrated energy system. Summary of the invention

[0005] The present invention proposes a load recovery method for an integrated energy system based on pipe storage characteristics, the purpose of which is to solve the problem of low efficiency of post-disaster load recovery caused by the ineffective performance of the energy storage function of the thermal network and the natural gas network.

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

[0007] A method for restoring load of an integrated energy system based on pipe storage characteristics, characterized in that the steps include:

[0008] Step 1: Construct a load recovery strategy generation model;

[0009] The load recovery strategy generation model includes an energy supply model, an equivalent energy storage model and an energy balance model;

[0010] The decision values ​​of the load recovery strategy generation model include the output power of each power supply device in each time period, the output power of each heating device, the charge and discharge control amount of each energy storage device, and the discharge control amount of the equivalent energy storage device, as well as the demand for electric load, heat load and natural gas load in each time period;

[0011] The objective function of the load recovery strategy generation model is the weighted sum of the electric load loss ratio, the thermal load loss ratio and the natural gas load loss ratio;

[0012] Step 2: Determine the optimal value of the weight in the objective function;

[0013] Step 3: Based on the optimal weight value and taking the minimum objective function as the optimization goal, the load recovery strategy generation model is solved, and the decision value obtained is used as the recovery strategy for a scheduling cycle after the disaster. The electricity-heat-gas integrated energy system is controlled according to this recovery strategy to work in the post-disaster load recovery stage.

[0014] As a further improvement of the integrated energy system load recovery method based on pipeline storage characteristics, the energy supply model includes an electricity supply model, a heat supply model and a natural gas supply model.

[0015] As a further improvement of the integrated energy system load restoration method based on pipe storage characteristics, the power supply model includes:

[0016] Fuel cell power supply model:

[0017]

[0018] Where: is the output power of the fuel cell during period t, η FC is the power generation efficiency of the fuel cell, is the fuel consumption of the fuel cell during period t; LHV is the lower heating value of natural gas; is the start / stop state of the fuel cell during period t, which takes the value of 1 or 0, 1 means on, and 0 means off;

[0019] Power supply model of combined heat and power unit:

[0020]

[0021] Where: is the output power of the gas turbine during period t; is the fuel consumption of the gas turbine during period t; η GFT,e is the electricity conversion efficiency of the gas turbine; LHV is the lower heating value of natural gas; is the start / stop state of the gas turbine during period t, which takes the value of 1 or 0, 1 represents start, and 0 represents shutdown;

[0022] The combined heat and power unit power supply model also includes the following constraints:

[0023]

[0024] Where: are the upper and lower limits of the gas turbine output power respectively; R u , R d are the upper and lower limits of the gas turbine's ramp-up power, respectively;

[0025] Power supply model of power storage equipment;

[0026] The power supply model of the storage device includes the following constraints:

[0027]

[0028]

[0029] Where: are the charging power and discharging power of the energy storage device in period t respectively; are the upper limit of charging power and the upper limit of discharging power of the power storage device respectively; η ESS,cha , η ESS,dis E are the charging efficiency and discharging efficiency of the energy storage device respectively; ESS The energy storage capacity of the power storage device; is the state of charge of the power storage device during period t; are the upper and lower limits of the state of charge of the power storage device respectively; σ ESS is the self-consumption rate of the energy storage device; Δt is the duration of a scheduling period.

[0030] As a further improvement of the integrated energy system load recovery method based on pipe storage characteristics, the heat supply model includes:

[0031] Heat supply model of cogeneration unit:

[0032]

[0033] Where: are the thermal output power of the gas turbine of the cogeneration unit during period t; is the output thermal power of the waste heat boiler of the cogeneration unit during period t; is the fuel consumption of the gas turbine during period t; is the output power of the gas turbine during period t; η GFT,h is the heat conversion efficiency of the gas turbine; η WHB is the heat conversion efficiency of the waste heat boiler; is the start / stop state of the gas turbine during period t, which takes the value of 1 or 0, 1 represents start, and 0 represents shutdown; is the start / stop status of the waste heat boiler during period t, which can be 1 or 0, 1 means start, 0 means shutdown; LHV is the lower heating value of natural gas;

[0034] Gas boiler heat supply model:

[0035]

[0036] Where: is the output thermal power of the gas boiler during period t, η GB is the gas-to-heat conversion efficiency of the gas boiler, is the fuel consumption of the gas boiler during period t; is the start / stop status of the gas boiler during period t, which takes 1 or 0, 1 means on, 0 means off; LHV is the lower heating value of natural gas;

[0037] Electric boiler heat supply model:

[0038]

[0039] Where: is the output thermal power of the electric boiler during period t, η WB is the electric-to-heat conversion efficiency, is the input power of the electric boiler during period t; The start / stop status of the electric boiler, which can be 1 or 0, 1 means start, 0 means stop;

[0040] Thermal supply model of thermal storage equipment:

[0041]

[0042]

[0043] Where: is the energy state of the heat storage device during period t; HES is the self-consumption heat rate of the heat storage equipment; are the heat storage power and heat release power of the heat storage device in period t respectively; η HES,cha , η HES,dis are the heat storage efficiency and heat release efficiency of the heat storage equipment respectively; E HES is the rated capacity of the heat storage equipment; are the upper and lower limits of the energy state of the heat storage device, respectively; are the maximum heat storage power and maximum heat release power of the heat storage equipment respectively; Δt is the duration of a scheduling period.

[0044] As a further improvement of the integrated energy system load recovery method based on pipeline storage characteristics, the natural gas supply model includes:

[0045] Natural gas supply constraints:

[0046] L min ≤L t ≤L max ;

[0047] Where: L t is the flow rate of gas source in the natural gas pipeline during period t, in m 3 / s;L max , L min is the upper and lower limits of the gas source flow rate;

[0048] Gas pressure constraints:

[0049] p i,min ≤p i,t ≤p i,max ;

[0050] Where: p i,t is the pressure of natural gas supply node i during period t; p i,max 、p i,min are the upper and lower limits of the pressure at node i;

[0051] Gas flow constraints:

[0052]

[0053] Where: L ij,t is the steady-state flow of natural gas pipeline ij in period t, where pipeline ij refers to the pipeline with nodes i and j at both ends; K ij It is the conversion parameter between pipeline pressure and flow; s ij is the symbol function; p i,t 、p j,t is the pressure of nodes i and j in period t;

[0054] Gas storage equipment supply model:

[0055]

[0056] 0≤υ t ≤ξ t ≤1;

[0057] Where: is the total gas storage volume of the gas storage equipment in period t, in m 3 ; are respectively the air intake and air output of the gas storage device during period t, in m 3 / s; Δt is the duration of a scheduling period; are the maximum air intake and maximum air output of the gas storage equipment; v t , tis an integer variable from 0 to 1, representing the gas inlet and outlet conditions of the gas storage device during period t, v t 0 means no air intake, 1 means air intake, t 0 means no air is released, 1 means air is released.

[0058] As a further improvement of the integrated energy system load recovery method based on pipeline storage characteristics, the equivalent energy storage model includes a natural gas pipeline energy storage model and a thermal pipeline energy storage model;

[0059] The thermal pipeline energy storage model is:

[0060]

[0061]

[0062] Where: is the energy state of the equivalent heat storage device during period t; σ hl is the self-consumption heat rate of the equivalent heat storage equipment; is the heat release power of the equivalent energy storage device in period t, is the decision value; η hl,dis is the energy release efficiency of the equivalent energy storage device; is the initial energy storage capacity of the thermal pipeline when it is equivalent to an energy storage device due to the impact of extreme disasters during period u; is the maximum heat release power of the equivalent heat storage device; Δt is the duration of a scheduling period;

[0063] Initial energy storage capacity of equivalent energy storage equipment The calculation method and safety constraints are as follows:

[0064]

[0065]

[0066] Where: C p is the specific heat capacity of water; m u is the flow rate of the thermal pipeline in period u; are the outlet temperatures of the water supply pipe and the return pipe of the thermal pipeline in time period u respectively; are the pipe inlet temperatures of the water supply pipe and the return pipe of the thermal pipe section in time period u respectively; are the upper and lower limits of water supply temperature respectively; are the upper and lower limits of return water temperature respectively;

[0067] The natural gas pipeline energy storage model is:

[0068]

[0069] Where: is the total gas storage volume of the equivalent gas storage equipment during period t; is the gas output of the equivalent gas storage equipment in period t, is the decision value; Δt is the duration of a scheduling period; is the maximum gas output of the equivalent gas storage equipment; ξ t 0 means no air is released, 1 means air is released;

[0070] Assume that the urban integrated energy system is affected by an extreme disaster during period u. The total gas storage capacity of the equivalent gas storage equipment when the disaster occurs is The calculation method is:

[0071]

[0072] Where: L u is the pipeline flow in period u; Δt is the duration of a scheduling period.

[0073] As a further improvement of the integrated energy system load recovery method based on pipeline storage characteristics, the energy balance model includes an electric power balance model, a thermal balance model and a natural gas balance model.

[0074] As a further improvement of the load recovery method of the integrated energy system based on pipe storage characteristics, the power balance model is:

[0075]

[0076] Where: K FC , K CHP , K ESS , K EB They are the number of fuel cells, cogeneration units, power storage equipment and electric boilers in the city's integrated energy system; They are the output power of the kth fuel cell during period t, the output power of the gas turbine of the kth cogeneration unit during period t, the discharge power of the kth power storage device during period t, the input power of the kth electric boiler during period t, and the charging power of the kth power storage device during period t, all of which are decision values; is the electricity load demand of the urban integrated energy system in period t after the disaster, and is the decision value;

[0077] The thermodynamic balance model is:

[0078]

[0079] Where: K CHP , K GB , K EB , K HES , K h_pipeThey are the number of cogeneration units, gas boilers, electric boilers, heat storage equipment and equivalent heat storage equipment in the city's integrated energy system; They are the output thermal power of the gas turbine of the kth cogeneration unit during period t, the output thermal power of the waste heat boiler of the kth cogeneration unit during period t, the output thermal power of the kth gas boiler during period t, the output thermal power of the kth electric boiler during period t, the heat release power of the kth heat storage device during period t, the heat release power of the kth equivalent heat storage device during period t and the heat storage power of the kth heat storage device during period t, all of which are decision values; is the heat load demand of the urban integrated energy system during period t after the disaster, and is the decision value;

[0080] The natural gas balance model is:

[0081]

[0082] Where: K GES , K g_pipe , K Fc , K chP , K GB They are the number of gas storage equipment, equivalent gas storage equipment, fuel cells, cogeneration units and gas boilers in the integrated energy system; They are the fuel consumption of the kth fuel cell in period t, the fuel consumption of the gas turbine of the kth cogeneration unit in period t, the fuel consumption of the kth gas boiler in period t, and the thermal storage power of the kth gas storage device in period t, all of which are decision values; and They are the gas output of the k-th gas storage device in period t, the gas output of the k-th equivalent gas storage device in period t, and the gas intake of the k-th gas storage device in period t, all of which are decision values; is the natural gas load demand of the urban comprehensive energy system in period t after the disaster, and is the decision value.

[0083] As a further improvement of the integrated energy system load restoration method based on pipe storage characteristics, the objective function of the load restoration strategy generation model is specifically:

[0084]

[0085] Where: are the proportion of electricity, heat and natural gas load loss respectively; e , h , g are the weights representing the importance of electricity, heat and natural gas loads respectively; are the electricity, heat and natural gas load demands in period t during the post-disaster dispatch cycle, respectively; They are respectively the electricity, heat and natural gas load demands in period t in the last normal operation scheduling cycle before the disaster; T is the number of time periods in a scheduling cycle.

[0086] As a further improvement of the integrated energy system load recovery method based on pipe storage characteristics, the specific process of step 2 is:

[0087] Step 2-1: weight λ e , h , g Assign an initial value and set the number of iterations to 0;

[0088] Step 2-2, construct the objective function obj:

[0089]

[0090] Where: They are the proportion of electricity, heat and natural gas load losses during historical post-disaster recovery;

[0091] Step 2-3: Select N groups of post-disaster recovery historical data, substitute them into the objective function obj respectively, and record the function value of the objective function obj corresponding to the nth group of post-disaster recovery historical data as obj n , find the average value And increase the number of iterations by 1;

[0092] Step 2-4: Determine whether the current number of iterations has reached the preset value. If it has reached the preset value, the current weight λ e , h , g The values ​​of are taken as their respective optimal values, otherwise, execute steps 2-5;

[0093] Step 2-5: Average value The maximum is the goal, and the weight λ is updated by gradient descent method. e , h , g The value of , then jump to step 2-3;

[0094] At this point, the weight λ can be determined e , h , g The optimal value of .

[0095] Compared with the prior art, the present invention has the following beneficial effects:

[0096] The present invention not only takes into account the coupling characteristics between the power system, thermal system and natural gas system within the urban electricity-heat-gas integrated energy system, but also fully considers the energy storage function of the thermal pipeline network and the natural gas pipeline network, enriches the energy supply means of the emergency recovery strategy, realizes the full mobilization of the three energy sources of electricity, heat and gas, improves the utilization efficiency of thermal energy and gas energy, and promotes the emergency response and rapid recovery of the system. DETAILED DESCRIPTION

[0097] The technical solution of the present invention is described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0098] A method for restoring load of an integrated energy system based on pipe storage characteristics, comprising the following steps:

[0099] Step 1: Construct a load recovery strategy generation model.

[0100] The load recovery strategy generation model includes an energy supply model, an equivalent energy storage model and an energy balance model. The decision values ​​of the load recovery strategy generation model include the output power of each power supply device in each time period, the output power of each heating device, the charge and discharge control amount of each energy storage device and the discharge control amount of the equivalent energy storage device, and also include the demand of electric load, heat load and natural gas load in each time period.

[0101] (1) Energy supply model.

[0102] The urban integrated energy system is a system composed of multiple energy forms such as electricity, heat, and gas, including power systems, thermal systems, and natural gas systems. Its characteristic is the coupling between energy subgrids. Different energy subgrids in the urban integrated energy system are closely integrated through coupling equipment such as combined heating and power (CHP) units, gas boilers, and electric boilers.

[0103] The energy supply model includes an electricity supply model, a heat supply model and a natural gas supply model:

[0104] (1.1) Power supply model.

[0105] The power system receives power from the main power grid, and also includes power supply from fuel cells and CHP units within the system.

[0106] (1.1.1) Fuel cell power supply model.

[0107] The fuel cell power supply model is:

[0108]

[0109] Where: is the output power of the fuel cell during period t, η FC is the power generation efficiency of the fuel cell, is the fuel consumption of the fuel cell in period t; LHV is the lower heating value of natural gas, which is 9.7 (kW·h) / (N·m 3 ); The start / stop state of the fuel cell during period t, which takes the value 1 or 0, 1 means on, and 0 means off.

[0110] (1.1.2) Power supply model of cogeneration unit.

[0111] The gas turbine in the CHP unit consumes natural gas and converts it into electrical energy to supply energy to the power system.

[0112] The power supply model of the combined heat and power unit is:

[0113]

[0114] Where: is the output power of the gas turbine during period t; is the fuel consumption of the gas turbine during period t; η GFT,e is the electricity conversion efficiency of the gas turbine; LHV is the lower heating value of natural gas; It is the start / stop status of the gas turbine during period t, and takes the value 1 or 0, where 1 indicates start and 0 indicates shutdown.

[0115] The combined heat and power unit power supply model also includes the following constraints:

[0116]

[0117] Where: are the upper and lower limits of the gas turbine output power respectively; R u , R d They are the upper and lower limits of the gas turbine's climbing power respectively.

[0118] (1.1.3) Electricity supply model of energy storage equipment.

[0119] Energy storage plays a vital role in balancing energy supply and demand, alleviating fluctuations, and improving the reliability of energy systems. During the post-disaster load recovery phase, energy storage equipment can provide backup power and ensure uninterrupted power supply to loads.

[0120] The power supply model of the storage device includes the following constraints:

[0121]

[0122]

[0123] Where: are the charging power and discharging power of the energy storage device in period t respectively; are the upper limit of charging power and the upper limit of discharging power of the power storage device respectively; η ESS,cha , η ESS,dis E are the charging efficiency and discharging efficiency of the energy storage device respectively; ESS The energy storage capacity of the power storage device; is the state of charge of the power storage device during period t; are the upper and lower limits of the state of charge of the power storage device respectively; σ ESS is the self-consumption rate of the energy storage device; Δt is the duration of a scheduling period.

[0124] (1.2) Heat supply model.

[0125] The thermal system is mainly composed of three parts: heat source, heat network and heat load, wherein the heat source includes combined heat and power unit (CHP unit), gas boiler and electric boiler. The present invention assumes that the heat transfer medium in the heat network is hot water.

[0126] (1.2.1) Heat supply model of cogeneration unit.

[0127] In industrial production, the gas turbine of the cogeneration unit will produce a large amount of high-temperature wastewater and waste gas. The waste heat boiler in the cogeneration unit collects this waste heat through a specific device to achieve energy reuse.

[0128] The heat supply model of the cogeneration unit is as follows:

[0129]

[0130] Where: are the thermal output power of the gas turbine of the cogeneration unit during period t; is the output thermal power of the waste heat boiler of the cogeneration unit during period t; is the fuel consumption of the gas turbine during period t; is the output power of the gas turbine during period t; η GFT,h is the heat conversion efficiency of the gas turbine; η WHB is the heat conversion efficiency of the waste heat boiler; is the start / stop state of the gas turbine during period t, which takes the value of 1 or 0, 1 represents start, and 0 represents shutdown; It is the start and stop status of the waste heat boiler during period t, and takes 1 or 0, 1 means start, and 0 means shutdown; LHV is the lower heating value of natural gas.

[0131] (1.2.2) Gas boiler heat supply model:

[0132]

[0133] Where: is the output thermal power of the gas boiler during period t, η GB is the gas-to-heat conversion efficiency of the gas boiler, is the fuel consumption of the gas boiler during period t; It is the start and stop status of the gas boiler during period t, and takes 1 or 0, 1 means on, and 0 means off; LHV is the lower heating value of natural gas.

[0134] (1.2.3) Electric boiler heat supply model:

[0135]

[0136] Where: is the output thermal power of the electric boiler during period t, η EB is the electric-to-heat conversion efficiency, is the input power of the electric boiler during period t; The start and stop status of the electric boiler, which can be 1 or 0, 1 means on, and 0 means off.

[0137] (1.2.4) Thermal supply model of heat storage equipment:

[0138]

[0139]

[0140] Where: is the energy state of the heat storage device during period t; HES is the self-consumption heat rate of the heat storage equipment; are the heat storage power and heat release power of the heat storage device in period t respectively; η HES,cha , η HES,dis are the heat storage efficiency and heat release efficiency of the heat storage equipment respectively; E HES is the rated capacity of the heat storage equipment; are the upper and lower limits of the energy state of the heat storage device, respectively; are the maximum heat storage power and maximum heat release power of the heat storage equipment respectively; Δt is the duration of a scheduling period.

[0141] (1.3) Natural gas supply model.

[0142] (1.3.1) The natural gas supply model includes natural gas supply constraints:

[0143] L min ≤L t ≤L max ;

[0144] Where: L t is the flow rate of gas source in the natural gas pipeline during period t, in m 3 / s;Lmax , L min It is the upper and lower limits of the gas source flow rate.

[0145] (1.3.2) The natural gas supply model also includes a gas pressure constraint:

[0146] p i,min ≤p i,t ≤p i,max ;

[0147] Where: p i,t is the pressure of natural gas supply node i during period t; p i,max 、p i,min are the upper and lower limits of the pressure at node i.

[0148] (1.3.3) The natural gas supply model also includes gas flow constraints. The flow is only related to the pressure at both ends of the pipeline and flows from the high-pressure node to the low-pressure node. Therefore, the flow of natural gas in the pipeline has the following relationship:

[0149]

[0150] Where: L ij,t is the steady-state flow of natural gas pipeline ij in period t, where pipeline ij refers to the pipeline with nodes i and j at both ends; K ij It is the conversion parameter between pipeline pressure and flow; s ij is the symbol function; p i,t 、p j,t is the pressure of node i and node j in period t.

[0151] (1.3.4) Similar to the power system and thermal system, the gas storage equipment in the natural gas system can provide energy supply in time after an extreme disaster occurs to restore the operation of the power system and thermal system. The gas storage equipment supply model is as follows:

[0152]

[0153] Where: is the total gas storage volume of the gas storage equipment in period t, in m 3 ; are respectively the air intake and air output of the gas storage device during period t, in m 3 / s; Δt is the duration of a scheduling period; are the maximum air intake and maximum air output of the gas storage equipment; v t , t is an integer variable from 0 to 1, representing the gas inlet and outlet conditions of the gas storage device during period t, v t 0 means no air intake, 1 means air intake,t 0 means no air is released, 1 means air is released.

[0154] (2) Equivalent energy storage model.

[0155] After an extreme disaster occurs, it may cause a large-scale power outage, heating outage and other emergencies. The city's integrated energy system will be forced to operate in an isolated mode, completely disconnected from the external power grid, heat network, and natural gas network. The power system cannot store electricity in the transmission line, but the hot water and natural gas stored in some mid- and downstream pipelines will not be lost immediately when the heat source and gas source are disconnected due to the existence of switch valves and timely closure. Therefore, the well-preserved mid- and downstream pipelines can serve as emergency heat and gas storage equipment, providing the city with necessary energy support until normal supply is restored.

[0156] After a pipeline node failure occurs, the valves are closed, so that each section of the thermal pipeline and the natural gas pipeline are isolated, so each section of the pipeline can be equivalent to an energy storage device. At this time, a mobile pump is used to promote the flow of hot water in the thermal pipeline, and a mobile compressor is used to promote the flow of natural gas in the natural gas pipeline. Hot water or natural gas can be transported to adjacent pipelines that have not failed for energy supply, and the energy supply output can be controlled by the valves on the pipelines.

[0157] It should be noted that during the load recovery process of the integrated energy system, when thermal pipelines and gas pipelines are used as emergency energy storage equipment, there is only an energy release process, but no energy charging process.

[0158] The equivalent energy storage model includes a natural gas pipeline energy storage model and a thermal pipeline energy storage model.

[0159] (2.1) Thermal pipeline energy storage model.

[0160] After the disaster occurs, the natural gas pipeline is regarded as an equivalent heat storage device, and its model is:

[0161]

[0162]

[0163] Where: is the energy state of the equivalent heat storage device during period t; σ hl is the self-consumption heat rate of the equivalent heat storage equipment; is the heat release power of the equivalent energy storage device in period t, is the decision value; η hl,dis is the energy release efficiency of the equivalent energy storage device; is the initial energy storage capacity of the thermal pipeline when it is equivalent to an energy storage device due to the impact of extreme disasters during period u; is the maximum heat release power of the equivalent heat storage device; Δt is the duration of a scheduling period.

[0164] Initial energy storage capacity of equivalent energy storage equipment The calculation method and safety constraints are as follows:

[0165]

[0166] Where: C p is the specific heat capacity of water; m u is the flow rate of the thermal pipeline in period u; are the outlet temperatures of the water supply pipe and the return pipe of the thermal pipeline in time period u respectively; are the pipe inlet temperatures of the water supply pipe and the return pipe of the thermal pipe section in time period u respectively; are the upper and lower limits of water supply temperature respectively; They are the upper and lower limits of return water temperature respectively.

[0167] (2.2) Natural gas pipeline energy storage model.

[0168] After the disaster occurs, the natural gas pipeline is regarded as an equivalent gas storage device, and its model is:

[0169]

[0170]

[0171]

[0172] Where: is the total gas storage volume of the equivalent gas storage equipment during period t; is the gas output of the equivalent gas storage equipment in period t, is the decision value; Δt is the duration of a scheduling period; is the maximum gas output of the equivalent gas storage equipment; ξ t 0 means no air is released, 1 means air is released.

[0173] Assume that the urban integrated energy system is affected by an extreme disaster during period u. The total gas storage capacity of the equivalent gas storage equipment when the disaster occurs is The calculation method is:

[0174]

[0175] Where: K u is the pipeline flow in period u; Δt is the duration of a scheduling period.

[0176] (3) Energy balance model.

[0177] The energy balance model includes an electricity balance model, a thermal balance model and a natural gas balance model.

[0178] (3.1) Power balance model.

[0179] The power supply of the urban integrated energy system power system mainly comes from fuel cells, cogeneration units and power storage equipment, which jointly meet the city's power load demand. Under normal operation, the shortfall is supplied by the external network. However, after extreme disasters, the integrated energy system will change to an isolated operation mode, and the power balance relationship will change to:

[0180]

[0181] Where: K FC , K CHP , K ESS , K EB They are the number of fuel cells, cogeneration units, power storage equipment and electric boilers in the city's integrated energy system; They are the output power of the kth fuel cell during period t, the output power of the gas turbine of the kth cogeneration unit during period t, the discharge power of the kth power storage device during period t, the input power of the kth electric boiler during period t, and the charging power of the kth power storage device during period t, all of which are decision values; is the electricity load demand of the urban comprehensive energy system in period t after the disaster, and is the decision value.

[0182] (3.2) Thermodynamic equilibrium model.

[0183] The heat supply of the urban integrated energy system thermal system mainly comes from gas boilers, electric boilers, cogeneration units and heat storage equipment, which jointly meet the city's heat load demand. During normal operation, the shortfall is supplied by the external heat network. Under extreme disasters, the power balance relationship will change after considering the equivalent heat storage equipment:

[0184]

[0185] Where: K CHP , K GB , K EB , K HES , K h_pipe They are the number of cogeneration units, gas boilers, electric boilers, heat storage equipment and equivalent heat storage equipment in the city's integrated energy system; They are the output thermal power of the gas turbine of the kth cogeneration unit during period t, the output thermal power of the waste heat boiler of the kth cogeneration unit during period t, the output thermal power of the kth gas boiler during period t, the output thermal power of the kth electric boiler during period t, the heat release power of the kth heat storage device during period t, the heat release power of the kth equivalent heat storage device during period t and the heat storage power of the kth heat storage device during period t, all of which are decision values; is the heat load demand of the urban comprehensive energy system during period t after the disaster, and is the decision value.

[0186] (3.3) Natural gas balance model.

[0187] The natural gas supply of the urban integrated energy system mainly comes from the external gas network and gas storage equipment, which meets the gas load demand of the city. During normal operation, the insufficient amount will be supplied by the external network. Under extreme disasters, its energy balance relationship will be transformed into:

[0188]

[0189] Where: K GES , K g_pipe , K FC , K CHP , K GB They are the number of gas storage equipment, equivalent gas storage equipment, fuel cells, cogeneration units and gas boilers in the integrated energy system; They are the fuel consumption of the kth fuel cell in period t, the fuel consumption of the gas turbine of the kth cogeneration unit in period t, the fuel consumption of the kth gas boiler in period t, and the thermal storage power of the kth gas storage device in period t, all of which are decision values; and They are the gas output of the k-th gas storage device in period t, the gas output of the k-th equivalent gas storage device in period t, and the gas intake of the k-th gas storage device in period t, all of which are decision values; is the natural gas load demand of the urban comprehensive energy system in period t after the disaster, and is the decision value.

[0190] The objective function of the load recovery strategy generation model is the weighted sum of the electric load loss ratio, the thermal load loss ratio and the natural gas load loss ratio.

[0191] The specific objective function is:

[0192]

[0193]

[0194] Where: are the proportion of electricity, heat and natural gas load loss respectively; e , h , g are the weights representing the importance of electricity, heat and natural gas loads respectively; are the electricity, heat and natural gas load demands in period t during the post-disaster dispatch cycle, respectively; They are respectively the electricity, heat and natural gas load demands in period t in the last normal operation scheduling cycle before the disaster; T is the number of time periods in a scheduling cycle.

[0195] Step 2: Determine the optimal value of the weight in the objective function.

[0196] The specific process is:

[0197] Step 2-1: weight λ e , h , g Assign an initial value and set the number of iterations to 0.

[0198] Step 2-2, construct the objective function obj:

[0199]

[0200] Where: They are respectively the proportion of electricity, heat and natural gas load losses during historical post-disaster recovery.

[0201] Step 2-3: Select N groups of post-disaster recovery historical data, substitute them into the objective function obj respectively, and record the function value of the objective function obj corresponding to the nth group of post-disaster recovery historical data as obj n , find the average value And increase the number of iterations by 1.

[0202] Step 2-4: Determine whether the current number of iterations has reached the preset value. If it has reached the preset value, the current weight λ e , h , g The values ​​of are taken as their respective optimal values, otherwise, execute steps 2-5.

[0203] Step 2-5: Average value The maximum is the goal, and the weight λ is updated by gradient descent method. e , h , g value, then skip to step 2-3.

[0204] At this point, the weight λ can be determined e , h , g The optimal value of .

[0205] Step 3: Based on the optimal weight value and taking the minimum objective function as the optimization goal, the load recovery strategy generation model is solved, and the decision value obtained is used as the recovery strategy for a scheduling cycle after the disaster. The electricity-heat-gas integrated energy system is controlled according to this recovery strategy during the post-disaster recovery phase.

[0206] Generally speaking, a scheduling cycle includes 24 hours, and one hour is considered as a time period. In this embodiment, the solution process is performed by Cplex optimization software.

[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 restoring load of an integrated energy system based on pipe storage characteristics, characterized in that the steps include: Step 1: Construct a load recovery strategy generation model; The load recovery strategy generation model includes an energy supply model, an equivalent energy storage model and an energy balance model; The decision values ​​of the load recovery strategy generation model include the output power of each power supply device in each time period, the output power of each heating device, the charge and discharge control amount of each energy storage device, and the discharge control amount of the equivalent energy storage device, as well as the demand for electric load, heat load and natural gas load in each time period; The objective function of the load recovery strategy generation model is the weighted sum of the electric load loss ratio, the thermal load loss ratio and the natural gas load loss ratio; Step 2: Determine the optimal value of the weight in the objective function; Step 3: Based on the optimal weight value and taking the minimum objective function as the optimization goal, the load recovery strategy generation model is solved, and the decision value obtained is used as the recovery strategy for a scheduling cycle after the disaster. The electricity-heat-gas integrated energy system is controlled according to this recovery strategy during the post-disaster recovery phase.

2. The method for restoring the load of an integrated energy system based on pipe storage characteristics according to claim 1, characterized in that: The energy supply model includes an electricity supply model, a heat supply model and a natural gas supply model.

3. The integrated energy system load recovery method based on pipe storage characteristics according to claim 2, characterized in that: The power supply models include: Fuel cell power supply model: Where: is the output power of the fuel cell during period t, η FC is the power generation efficiency of the fuel cell, is the fuel consumption of the fuel cell during period t; LHV is the lower heating value of natural gas; is the start / stop state of the fuel cell during period t, which takes the value of 1 or 0, 1 means on, and 0 means off; Power supply model of combined heat and power unit: Where: is the output power of the gas turbine during period t; is the fuel consumption of the gas turbine during period t; η GFT,e is the electricity conversion efficiency of the gas turbine; LHV is the lower heating value of natural gas; is the start / stop state of the gas turbine during period t, which takes the value of 1 or 0, 1 represents start, and 0 represents shutdown; The combined heat and power unit power supply model also includes the following constraints: Where: are the upper and lower limits of the gas turbine output power respectively; R u , R d are the upper and lower limits of the gas turbine's ramp-up power, respectively; Power supply model of power storage equipment; The power supply model of the storage device includes the following constraints: Where: are the charging power and discharging power of the energy storage device in period t respectively; are the upper limit of charging power and the upper limit of discharging power of the power storage device respectively; η ESS,cha , η ESS,diS E are the charging efficiency and discharging efficiency of the energy storage device respectively; ESS The energy storage capacity of the power storage device; is the state of charge of the power storage device during period t; are the upper and lower limits of the state of charge of the power storage device respectively; σ ESS is the self-consumption rate of the energy storage device; Δt is the duration of a scheduling period.

4. The method for restoring the load of an integrated energy system based on pipe storage characteristics according to claim 3, characterized in that: The heat supply model includes: Heat supply model of cogeneration unit: Where: are the thermal output power of the gas turbine of the cogeneration unit during period t; is the output thermal power of the waste heat boiler of the cogeneration unit during period t; is the fuel consumption of the gas turbine during period t; is the output power of the gas turbine during period t; η GFT,h is the heat conversion efficiency of the gas turbine; η WHB is the heat conversion efficiency of the waste heat boiler; is the start / stop state of the gas turbine during period t, which takes the value of 1 or 0, 1 represents start, and 0 represents shutdown; is the start / stop status of the waste heat boiler during period t, which takes 1 or 0, 1 means start, 0 means shutdown; LHV is the lower heating value of natural gas; Gas boiler heat supply model: Where: is the output thermal power of the gas boiler during period t, η GB is the gas-to-heat conversion efficiency of the gas boiler, is the fuel consumption of the gas boiler during period t; is the start / stop status of the gas boiler during period t, which takes the value of 1 or 0, 1 means start, and 0 means shutdown; LHV is the lower heating value of natural gas; Electric boiler heat supply model: Where: is the output thermal power of the electric boiler during period t, η EB is the electric-to-heat conversion efficiency, is the input power of the electric boiler during period t; The start / stop status of the electric boiler, which can be 1 or 0, 1 means start, 0 means stop; Thermal supply model of thermal storage equipment: Where: is the energy state of the heat storage device during period t; HES is the self-consumption heat rate of the heat storage equipment; are the heat storage power and heat release power of the heat storage device in period t respectively; η HES,cha , η HES,diS are the heat storage efficiency and heat release efficiency of the heat storage equipment respectively; E HES is the rated capacity of the heat storage equipment; are the upper and lower limits of the energy state of the heat storage device, respectively; are the maximum heat storage power and maximum heat release power of the heat storage equipment respectively; Δt is the duration of a scheduling period.

5. The integrated energy system load recovery method based on pipe storage characteristics according to claim 4, characterized in that: The natural gas supply model includes: Natural gas supply constraints: L min ≤L t ≤L max ; Where: L t is the flow rate of gas source in the natural gas pipeline during period t, in m 3 / s;L max , L min is the upper and lower limits of the gas source flow rate; Gas pressure constraints: pi,min≤pi,t≤pi,max; Where: p i，t is the pressure of natural gas supply node i during period t; p i,max 、p i,min are the upper and lower limits of the pressure at node i; Gas flow constraints: Where: L ij，t is the steady-state flow of natural gas pipeline ij in period t, where pipeline ij refers to the pipeline with nodes i and j at both ends; K ij It is the conversion parameter between pipeline pressure and flow; s ij is a symbolic function; pi, t, p j ,t is the pressure of node i and node j in period t; Gas storage equipment supply model: 0≤υ t ≤ξ t ≤1; Where: is the total gas storage volume of the gas storage equipment in period t, in m 3 ; are respectively the air intake and air output of the gas storage device during period t, in m 3 / s; Δt is the duration of a scheduling period; are the maximum air intake and maximum air output of the gas storage equipment respectively; t , t is an integer variable from 0 to 1, representing the gas inlet and outlet conditions of the gas storage device during period t, υ t 0 means no air intake, 1 means air intake, t 0 means no air is released, 1 means air is released.

6. The method for restoring the load of an integrated energy system based on pipe storage characteristics according to claim 5, characterized in that: The equivalent energy storage model includes a natural gas pipeline energy storage model and a thermal pipeline energy storage model; The thermal pipeline energy storage model is: Where: is the energy state of the equivalent heat storage device during period t; σ hl is the self-consumption heat rate of the equivalent heat storage equipment; is the heat release power of the equivalent energy storage device in period t, is the decision value; η hl，dis is the energy release efficiency of the equivalent energy storage device; is the initial energy storage capacity of the thermal pipeline when it is equivalent to an energy storage device due to the impact of extreme disasters during period u; is the maximum heat release power of the equivalent heat storage device; Δt is the duration of a scheduling period; Initial energy storage capacity of equivalent energy storage equipment The calculation method and safety constraints are as follows: Where: C p is the specific heat capacity of water; m u is the flow rate of the thermal pipeline in period u; are the outlet temperatures of the water supply pipe and the return pipe of the thermal pipeline in time period u respectively; are the pipe inlet temperatures of the water supply pipe and the return pipe of the thermal pipe section in time period u respectively; are the upper and lower limits of water supply temperature respectively; are the upper and lower limits of return water temperature respectively; The natural gas pipeline energy storage model is: 0≤ξ t ≤1; Where: is the total gas storage volume of the equivalent gas storage equipment during period t; is the gas output of the equivalent gas storage equipment in period t, is the decision value; Δt is the duration of a scheduling period; is the maximum gas output of the equivalent gas storage equipment; ξ t 0 means no air is released, 1 means air is released; Assume that the urban integrated energy system is affected by an extreme disaster during period u. The total gas storage capacity of the equivalent gas storage equipment when the disaster occurs is The calculation method is: Where: L u is the pipeline flow in period u; Δt is the duration of a scheduling period.

7. The method for restoring the load of an integrated energy system based on pipe storage characteristics according to any one of claims 1 to 6, characterized in that: The energy balance model includes an electricity balance model, a thermal balance model and a natural gas balance model.

8. The method for restoring load of an integrated energy system based on pipe storage characteristics according to claim 7, characterized in that: The power balance model is: Where: K FC , K CHP , K ESS , K EB They are the number of fuel cells, cogeneration units, power storage equipment and electric boilers in the city's integrated energy system; They are the output power of the kth fuel cell during period t, the output power of the gas turbine of the kth cogeneration unit during period t, the discharge power of the kth power storage device during period t, the input power of the kth electric boiler during period t, and the charging power of the kth power storage device during period t, all of which are decision values; is the electricity load demand of the urban integrated energy system in period t after the disaster, and is the decision value; The thermodynamic balance model is: Where: K CHP , K GB , K EB , K HES , K h_pipe They are the number of cogeneration units, gas boilers, electric boilers, heat storage equipment and equivalent heat storage equipment in the city's integrated energy system; They are the output thermal power of the gas turbine of the kth cogeneration unit during period t, the output thermal power of the waste heat boiler of the kth cogeneration unit during period t, the output thermal power of the kth gas boiler during period t, the output thermal power of the kth electric boiler during period t, the heat release power of the kth heat storage device during period t, the heat release power of the kth equivalent heat storage device during period t and the heat storage power of the kth heat storage device during period t, all of which are decision values; is the heat load demand of the urban integrated energy system during period t after the disaster, and is the decision value; The natural gas balance model is: Where: K GES , K g_pipe , K FC , K CHP , K GB They are the number of gas storage equipment, equivalent gas storage equipment, fuel cells, cogeneration units and gas boilers in the integrated energy system; They are the fuel consumption of the kth fuel cell in period t, the fuel consumption of the gas turbine of the kth cogeneration unit in period t, the fuel consumption of the kth gas boiler in period t, and the thermal storage power of the kth gas storage device in period t, all of which are decision values; and They are the gas output of the k-th gas storage device in period t, the gas output of the k-th equivalent gas storage device in period t, and the gas intake of the k-th gas storage device in period t, all of which are decision values; is the natural gas load demand of the urban comprehensive energy system in period t after the disaster, and is the decision value.

9. The method for restoring the load of an integrated energy system based on pipe storage characteristics according to claim 8, characterized in that: The objective function of the load recovery strategy generation model is as follows: Where: are the proportion of electricity, heat and natural gas load loss respectively; e , h , g are the weights representing the importance of electricity, heat and natural gas loads respectively; are the electricity, heat and natural gas load demands in period t during the post-disaster dispatch cycle, respectively; They are respectively the electricity, heat and natural gas load demands in period t in the last normal operation scheduling cycle before the disaster; T is the number of time periods in a scheduling cycle.

10. The integrated energy system load recovery method based on pipe storage characteristics according to claim 9, characterized in that: The specific process of step 2 is: Step 2-1: weight λ e , h , g Assign an initial value and set the number of iterations to 0; Step 2-2, construct the objective function obj: Where: They are the proportion of electricity, heat and natural gas load losses during historical post-disaster recovery; Step 2-3: Select N groups of post-disaster recovery historical data, substitute them into the objective function obj respectively, and record the function value of the objective function obj corresponding to the nth group of post-disaster recovery historical data as obj n , find the average value And increase the number of iterations by 1; Step 2-4: Determine whether the current number of iterations has reached the preset value. If it has reached the preset value, the current weight λ e , h , g The values ​​of are taken as their respective optimal values, otherwise, execute steps 2-5; Step 2-5: Average value The maximum is the goal, and the weight λ is updated by gradient descent method. e , h , g The value of , then jump to step 2-3; At this point, the weight λ can be determined e , h , g The optimal value of .

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