Electric heating system scheduling method for peak shaving based on gravity energy storage device

Abstract

A dispatching method for an electric-heat system based on peak shaving of a gravity energy storage device belongs to the field of electric-heat system regulation. The purpose of the present invention is to solve the problem that existing systems cannot accommodate large amounts of curtailed wind power. A total objective function is synthesized by combining a coal consumption objective function with the goal of minimizing the coal consumption of units and a low-carbon objective function with the goal of minimizing the carbon trading cost; under the total objective function, the dispatching of the electric-heat system is achieved by adjusting the power generation and power reception of the power system, the heat generation and heat reception of the thermal system, and the power generation and power reception of the gravity energy storage device. It is used for dispatching the electric-heat system.

Description

Technical Field

[0001] The present invention relates to the scheduling of electro-thermal systems and belongs to the field of electro-thermal system regulation. Background Art

[0002] At present, energy storage methods are generally divided into three main forms: chemical battery energy storage, physical energy storage, and power-to-fuel energy storage. Physical energy storage has received extensive attention from domestic and foreign scholars because it can participate well in power grid peak shaving and achieve the day-night transfer of electric energy. As one of the physical energy storage forms, the research on gravity energy storage technology is still in its initial stage. However, because it can achieve stepless adjustment of power in the generator or motor state and can be well applied to power grid system peak shaving, it has very broad development prospects.

[0003] Under this background, this patent proposes a scheduling model that uses gravity energy storage technology to participate in system peak shaving in an electro-thermal combined system. The operating characteristics of the thermal system, power system, and gravity energy storage device are fully considered in the model. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that existing systems cannot accommodate a large amount of curtailed wind power, and a scheduling method for electro-thermal systems based on peak shaving by gravity energy storage devices is proposed.

[0005] A scheduling method for electro-thermal systems based on peak shaving by gravity energy storage devices, the method comprising the following steps:

[0006] Step 1: Establish a coal consumption objective function with the minimum coal consumption of the unit as the goal and a low-carbon objective function with the minimum carbon trading cost as the goal. Perform fuzzy processing on the coal consumption objective function and the low-carbon objective function respectively to obtain the processed coal consumption objective function and the processed low-carbon objective function, and synthesize the processed coal consumption objective function and the processed low-carbon objective function into a total objective function;

[0007] Step 2: Establish the constraint conditions of the power system, the thermal system constraint conditions, and the gravity energy storage device constraint conditions. Adjust the power generation and power reception of the power system within the constraint conditions of the power system, adjust the heat generation and heat reception of the thermal system within the constraint conditions of the thermal system, and adjust the power generation and power reception of the gravity energy storage device within the constraint conditions of the gravity energy storage device. Through adjusting the power generation and power reception of the power system, the heat generation and heat reception of the thermal system, and the power generation and power reception of the gravity energy storage device under the total objective function, the scheduling of the electro-thermal system is realized.

[0008] Preferably, in step 2, a coal consumption objective function with the minimum coal consumption of the unit as the goal is established:

[0009]

[0010] where f 1is the total coal consumption of the system; T is the total dispatching period; is the coal consumption of the i-th thermal power unit in the r-th thermal power plant at time t; is the coal consumption of the i-th thermal power unit in the h-th thermal power plant at time t; R and H are the numbers of thermal power units and thermal power plants respectively; e 0 ~e 5 are the fitting parameters of the consumption characteristics of thermal power units; P t,r,i is the power generation of the i-th thermal power unit in the r-th thermal power plant at time t, is the thermal power of the i-th thermal power unit in the r-th thermal power plant, a 0 ~a 2 are the fitting parameters of the consumption characteristics of thermal power plants;

[0011] Establish a low-carbon objective function with the minimum carbon trading cost as the goal:

[0012]

[0013] In the formula, f 2 is the total carbon emissions of the system, is the molar number of carbon emissions of the system.

[0014] The beneficial effects of the present invention are:

[0015] The present application adds a gravity energy storage device. Due to the addition of the gravity energy storage device, by adjusting the power generation and power reception of the power system, the heat generation and heat reception of the thermal system, and the power generation and power reception of the gravity energy storage device under the total objective function, the gravity energy storage device can adjust the power generation and power reception in real time, continuously adjust the system, and make the system operate stably. And during the night period of the winter heating season, when the wind power is large and the thermal power units have too high a lower limit of their electric power output due to excessive heat load, the too high lower limit of the electric power output of the thermal power units leads to too low a grid connection space for wind power, resulting in wind power abandonment. After applying the gravity energy storage device, the electric load can be transferred in time, the electric load of the system can be increased during the night period of the heating season, giving more grid connection space for wind power, and thus better consuming the abandoned wind. Therefore, the gravity energy storage device can reduce the wind power abandonment problem of the electric-thermal combined system to a certain extent and improve the peak regulation difficulty of the system. The larger the capacity of the gravity energy storage device, the lower the wind power abandonment rate of the system. Description of the Drawings

[0016] Figure 1 is the flow chart of the dispatching method for the electric-thermal system based on the peak regulation of the gravity energy storage device. Detailed Embodiments

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0018] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but it is not limited to the present invention.

[0020] Specific Embodiment 1: In combination with Figure 1 To illustrate this embodiment, the dispatching method of the electric-heat system based on the peak regulation of the gravity energy storage device in this embodiment includes the following steps:

[0021] Step 1: Establish a coal consumption objective function with the minimum coal consumption of the unit as the goal and a low-carbon objective function with the minimum carbon trading cost as the goal. Fuzzify the coal consumption objective function and the low-carbon objective function respectively to obtain the processed coal consumption objective function and the processed low-carbon objective function, and synthesize the processed coal consumption objective function and the processed low-carbon objective function into a total objective function;

[0022] Step 2: Establish the constraint conditions of the power system, the constraint conditions of the thermal system, and the constraint conditions of the gravity energy storage device. Adjust the power generation and power reception of the power system within the constraint conditions of the power system, adjust the heat generation and heat reception of the thermal system within the constraint conditions of the thermal system, and adjust the power generation and power reception of the gravity energy storage device within the constraint conditions of the gravity energy storage device. Through adjusting the power generation and power reception of the power system, the heat generation and heat reception of the thermal system, and the power generation and power reception of the gravity energy storage device under the total objective function, the dispatching of the electric-heat system is realized.

[0023] In this embodiment, with the large-scale investment of thermal power units and the large-scale grid connection of wind turbines, the peak regulation difficulty of the power system becomes increasingly difficult. Therefore, a large number of peak shaving and valley filling devices are urgently needed to ensure the stable operation of the power system. As a device that can adjust its power generation and power reception in real time, the gravity energy storage device is an effective way to solve the peak regulation difficulty of the electric-heat combined system. Establish an optimal dispatching model of the electric-heat combined system considering the operating characteristics of the power system, the operating characteristics of the thermal system, and the system carbon trading cost and coal consumption as the objective function, and study the impact of the investment of the gravity energy storage device on the operating characteristics of the electric-heat combined system. The case analysis shows that the gravity energy storage device can reduce the problem of wind abandonment in the electric-heat combined system to a certain extent.

[0024] Embodiment 2: This embodiment further defines the dispatching method of the electric-heat system for peak shaving based on the gravity energy storage device described in Embodiment 1. In this embodiment, in step 2, a coal consumption objective function with the minimum coal consumption of the unit is established:

[0025]

[0026] In the formula, f 1 is the total coal consumption of the system; T is the total dispatching period; is the coal consumption of the i-th thermal power unit in the r-th thermal power plant at time t; is the coal consumption of the i-th thermal power unit in the h-th thermal power plant at time t; R and H are the numbers of thermal power units and thermal power units respectively; e 0 ~e 5 are the fitting parameters of the thermal power unit consumption characteristics; P t,r,i is the power generation power of the i-th thermal power unit in the r-th thermal power plant at time t, is the thermal power of the i-th thermal power unit in the r-th thermal power plant, a 0 ~a 2 are the fitting parameters of the thermal power unit consumption characteristics;

[0027] A low-carbon objective function with the minimum carbon trading cost is established:

[0028]

[0029] In the formula, f 2 is the total carbon emission of the system, is the number of moles of carbon emissions in the system.

[0030] Embodiment 3: This embodiment further defines the dispatching method of the electric-heat system for peak shaving based on the gravity energy storage device described in Embodiment 2. In this embodiment, in step 2, the processed coal consumption objective function is obtained:

[0031]

[0032] The processed low-carbon objective function is obtained:

[0033]

[0034] In the formula, F 1max , F 1min are the theoretically maximum and minimum power generation operation costs respectively; F 2max , F 2min are the theoretically maximum and minimum carbon trading costs respectively, u(f 1 ) is the processed coal consumption objective function; u(f 2) is the processed low-carbon objective function;

[0035] The total objective function F:

[0036] F = min{-min[u(f 1 ), u(f 2 )]}, Equation 5.

[0037] Specific Embodiment 4: This embodiment further limits the dispatching method of the electric-heat system based on the peak regulation of the gravity energy storage device described in Specific Embodiment 3. In this embodiment, the constraint conditions of the power system include the electric power balance constraint, the output constraint of thermal power units, the output constraint of heat and power units, and the output constraint of the unit climbing and sliding;

[0038] Electric power balance constraint:

[0039]

[0040] In the formula, is the electric power of the i-th heat and power unit in the r-th thermal power plant; is the electric power of the i-th thermal power unit in the h-th thermal power plant; is the electric power of the wind turbine unit; is the electric energy exchanged between the gravity energy storage device and the power grid, which is positive in the generator state and negative in the motor state; is the electric load power of the n-th load node; N is the number of electric load nodes; N r 、N h are the numbers of heat and power units in the r-th thermal power plant and the numbers of thermal power units in the h-th thermal power plant respectively;

[0041] Output constraint of thermal power units:

[0042]

[0043] In the formula, are the upper and lower limits of the electric power of the i-th thermal power unit in the h-th thermal power plant;

[0044] Output constraint of heat and power units:

[0045]

[0046]

[0047] In the formula, D t,r,i is the heating extraction rate of the i-th heat and power unit in the r-th thermal power plant; are the upper and lower limits of the heating extraction rate of the i-th heat and power unit in the r-th thermal power plant; are the upper and lower limits of the electric power of the i-th heat and power unit in the r-th thermal power plant; b L 、bH They are the heat - electricity ratio of the thermal power unit under back - pressure condition and the heat - electricity ratio of the thermal power unit under maximum condensing condition respectively;

[0048] Unit climbing and sliding output constraints:

[0049] P t - P t-1 ≤r up , Formula 10

[0050] P t - P t+1 ≤r down , Formula 12

[0051] Wherein, r up 、r down respectively represent the climbing and sliding power of the unit, P t is the electric power of any thermal power unit or thermal power plant at time t; P t-1 is the electric power of any unit at time t - 1.

[0052] In this embodiment, because of the electric energy interacted between the gravity energy storage device and the power grid in this application continuous regulation of the system is realized.

[0053] Specific Embodiment Five: This embodiment further limits the dispatching method of the heat - electricity system for peak - shaving based on the gravity energy storage device described in Specific Embodiment Three. In this embodiment, the constraints of the thermal system include heat - power balance constraint, heat - source constraint, and heat - load constraint;

[0054] Heat - power balance constraint:

[0055]

[0056] Wherein, is the heat power of the i - th thermal power unit of the r - th thermal power plant; is the heat - load power of the l - th heat - exchange station served by the r - th thermal power plant at time ; ΔQ t,r,p is the heat loss of the p - th pipeline in the heat network served by the r - th thermal power plant; M p is the number of pipelines in the heat network served by the r - th thermal power plant; L r is the number of heat - exchange stations served by the r - th thermal power plant; τ r,l is the transmission delay time for the heat of the r - th thermal power plant to reach the l - th heat - exchange station; is the heat - load loss power of the l - th heat - exchange station served by the r - th thermal power plant at time t + τ r,l ;

[0057] Heat - source constraint:

[0058]

[0059] In the formula, C P is the specific heat capacity of water; m t,r is the total heat supply pipeline flow of the r-th thermal power plant; are the supply water temperature and return water temperature at the heat source node of the r-th thermal power plant respectively;

[0060] Heat load constraint:

[0061]

[0062] In the formula, is the heat load carried by the l-th heat exchange station of the r-th thermal power plant; m t,r,l is the heat exchange water flow of the l-th heat exchange station of the r-th thermal power plant; are the supply water temperature and return water temperature of the l-th heat exchange station carried by the r-th thermal power plant respectively.

[0063] Specific implementation method six: This implementation method further limits the electric - heat system scheduling method based on peak - shaving of the gravity energy storage device described in the specific implementation method three. In this implementation method, the constraint conditions of the gravity energy storage device:

[0064]

[0065] In the formula, t 1 is the duration of a scheduling period; T is the number of scheduling periods; W 1 HE are the maximum stored electricity and the initial stored electricity of the gravity energy storage device respectively, is the electric energy interacted between the gravity energy storage device and the power grid;

[0066]

[0067]

[0068] In the formula, P mo,min is the lower limit of the electric power output in the state of the gravity energy storage motor, P al,min is the lower limit of the electric power output in the state of the generator of the gravity energy storage device, is the rated power of the gravity energy storage device.

[0069] Although the present invention has been described herein with reference to particular embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Accordingly, it should be understood that numerous modifications may be made to the exemplary embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the different dependent claims and the features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with separate embodiments may be used in other described embodiments.

Claims

1. A dispatching method for an electric-heat system based on peak shaving of a gravity energy storage device, characterized in that, the method comprises the following steps: Step 1: Establish a coal consumption objective function with the minimum coal consumption of the unit as the target and a low-carbon objective function with the minimum carbon trading cost as the target, perform fuzzy processing on the coal consumption objective function and the low-carbon objective function respectively, obtain the processed coal consumption objective function and the processed low-carbon objective function respectively, and synthesize the processed coal consumption objective function and the processed low-carbon objective function into a total objective function; Step 2: Establish the constraint conditions of the power system, the constraint conditions of the thermal system and the constraint conditions of the gravity energy storage device, adjust the power generation and power reception of the power system within the constraint conditions of the power system, adjust the heat generation and heat reception of the thermal system within the constraint conditions of the thermal system, adjust the power generation and power reception of the gravity energy storage device within the constraint conditions of the gravity energy storage device, and realize the dispatching of the electric-heat system by adjusting the power generation and power reception of the power system, the heat generation and heat reception of the thermal system, and the power generation and power reception of the gravity energy storage device under the total objective function; In Step 2, establish a coal consumption objective function with the minimum coal consumption of the unit as the target: where f 1 is the total coal consumption of the system; T is the total dispatching period; is the coal consumption of the i-th thermal power unit of the r-th thermal power plant in the t-th period; is the coal consumption of the i-th thermal power unit of the h-th thermal power plant in the t-th period; R and H are the numbers of thermal power units and thermal power units respectively; e 0 ~e 5 are the fitting parameters of the consumption characteristics of thermal power units; P t,r,i is the power generation of the i-th thermal power unit of the r-th thermal power plant in the t-th period, is the thermal power of the i-th thermal power unit of the r-th thermal power plant; a 0 ~a 2 are the fitting parameters of the consumption characteristics of thermal power units; Establish a low-carbon objective function with the minimum carbon trading cost as the target: where f 2 is the total carbon emissions of the system, is the molar number of carbon emissions of the system; In Step 2, obtain the processed coal consumption objective function: Obtain the processed low-carbon objective function: where F 1max and F 1min are the maximum and minimum power generation operating costs in theory; F 2max and F 2min are the maximum and minimum carbon trading costs in theory, u(f 1 ) is the processed coal consumption objective function; u(f 2 ) is the processed low-carbon objective function; Total objective function F: F = min{-min[u(f 1 ), u(f 2 )]}, Formula 5; The constraint conditions of the power system include electric power balance constraint, thermal power unit output constraint, heat and power unit output constraint and unit ramp rate output constraint; Electric power balance constraint: Wherein, is the electric power of the i-th thermal power generating unit of the r-th thermal power plant; is the electric power of the i-th thermal power generating unit of the h-th thermal power plant; P t CW is the electric power of the wind turbine generator set; P t HE is the electric energy interacted between the gravity energy storage device and the power grid, which is positive in the generator state and negative in the motor state; is the electric load power of the n-th load node; N is the number of electric load nodes; N r 、N h are respectively the number of thermal power generating units of the r-th thermal power plant and the number of thermal power generating units of the h-th thermal power plant; Thermal power unit output constraint: In the formula, are the upper and lower limits of the electric power of the i-th thermal power unit in the h-th thermal power plant; Heat and power unit output constraint: where D t,r,i is the heating extraction steam rate of the i-th thermal power generating unit in the r-th thermal power plant; are the upper and lower limits of the heating extraction steam rate of the i-th thermal power generating unit in the r-th thermal power plant; are the upper and lower limits of the electric power of the i-th thermal power generating unit in the r-th thermal power plant; b L and b H are the electric-to-heat ratios of the thermal power generating unit under backpressure condition and maximum condensing condition respectively; Unit ramp rate output constraint: P t -P t-1 ≤r up , Formula 10 P t -P t+1 ≤r down , Formula 12 where r up , r down represent the ramp-up and ramp-down power of the unit respectively, and P t is the electric power of any thermoelectric unit or thermal power unit at time t; P t-1 is the electric power of any unit at time t-1; The constraint conditions of the thermal system include heat power balance constraint, heat source constraint and heat load constraint; Heat power balance constraint: In the formula, is the thermal power of the i-th thermal power generating unit of the r-th thermal power plant; is the thermal load power of the l-th heat exchange station served by the r-th thermal power plant at time t + τ r,l ; ΔQ t,r,p is the heat loss of the p-th pipeline in the heat network served by the r-th thermal power plant; M p is the number of pipelines in the heat network served by the r-th thermal power plant; L r is the number of heat exchange stations served by the r-th thermal power plant; τ r,l is the transmission delay time for the heat of the r-th thermal power plant to reach the l-th heat exchange station; is the thermal load loss power of the l-th heat exchange station served by the r-th thermal power plant at time t + τ r,l ; Heat source constraint: where C P is the specific heat capacity of water; m t,r is the total flow rate of the heat supply pipeline of the r-th thermal power plant; are the supply water temperature and the return water temperature at the heat source node of the r-th thermal power plant, respectively; Heat load constraint: In the formula, is the heat load carried by the l-th heat exchange station of the r-th thermal power plant; m t,r,l is the heat exchange water flow of the l-th heat exchange station of the r-th thermal power plant; are respectively the supply water temperature and return water temperature of the l-th heat exchange station carried by the r-th thermal power plant; Constraint conditions of the gravity energy storage device: where t 1 is the duration of a scheduling period; T is the number of scheduling periods; W 1 HE are respectively the maximum stored electricity and the initial stored electricity of the gravity energy storage device, and P t HE is the electric energy interacted between the gravity energy storage device and the power grid; where P mo,min is the lower limit of the electrical output in the state of the gravity energy storage motor, and P al,min is the lower limit of the electrical output in the state of the generator of the gravity energy storage device, and [[ ]] is the rated power of the gravity energy storage device.

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