Method and system for determining electric load adjustment interval of low-vacuum heat supply unit
Technical Field
The disclosure relates to the technical field of peak shaving of thermoelectric units, in particular to a method and a system for determining an electric load adjustment interval of a low-vacuum heat supply unit.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The low-vacuum heat supply technology of the thermal power generating unit is characterized in that steam expansion is reduced and the backpressure of a condenser is improved by reducing the last stages of blades of a steam turbine. Thereby raising the temperature of the outlet water of the circulating water and directly introducing the circulating water into a heat supply technology of heat exchange of a heat supply network. The low-vacuum heat supply of the steam turbine set can fully utilize the latent heat of vaporization of steam, thereby greatly reducing the heat consumption rate of the set. Taking a 135MW stage steam turbine as an example, the heat consumption rate of the low vacuum heat supply unit is about 3700kJ/kWh, and the heat consumption rate of the condensing type unit of the same type is more than 8000 kJ/kWh.
Based on good economic benefits of the low-vacuum heat supply unit, the low-vacuum unit basically maintains rated power operation at the present stage and does not participate in peak shaving of the power grid. On the other hand, with the continuous perfection of the extra-high voltage transmission network, the trans-regional transmission capacity of electric power is continuously increased, meanwhile, the proportion of wind power generation, photovoltaic power generation, nuclear power generation and various novel energy power generation is continuously increased, and the peak load regulation pressure of the power grid is huge. The requirement of power grid peak regulation is difficult to meet only by a straight condensing thermal power generating unit and a condensing thermal power generating unit, and the low-vacuum thermal power generating unit is inevitably involved in peak regulation.
Because the low-vacuum heat supply unit generally maintains basic power operation, the current research aiming at the low-vacuum heat supply unit mostly focuses on the aspects of economy and safety, and peak-shaving operation calculation research is lacked. In order to meet the increasingly severe peak regulation requirements, the peak regulation capability of the low vacuum unit needs to be calculated quickly and accurately. Therefore, it is necessary to research the electric load adjustment capability of the low-vacuum heat supply unit and establish an accurate calculation model.
The electric load adjustment interval of the low-vacuum heat supply unit refers to the variation range from the lowest to the highest of the unit electric loads meeting basic heat supply requirements, however, the inventor of the present disclosure finds that the general low-vacuum heat supply unit bears higher heat load and has smaller electric load variation range, and the electric load of the heat supply unit is calculated by generally adopting a comprehensive heat balance calculation method in the prior art, so that the parameters are more and the calculation is complicated.
Disclosure of Invention
In order to solve the defects of the prior art, the invention provides a method and a system for determining an electric load adjustment interval of a low vacuum heat supply unit.
In order to achieve the purpose, the following technical scheme is adopted in the disclosure:
the first aspect of the disclosure provides a method for determining an electric load adjustment interval of a low-vacuum heat supply unit.
A method for determining an electric load adjustment interval of a low-vacuum heat supply unit comprises the following steps:
obtaining a main steam flow correction coefficient according to a preset main steam flow and the main steam flow under a reference working condition, and iteratively obtaining an enthalpy drop correction coefficient and a regenerative steam extraction coefficient according to steam discharge parameter data;
obtaining the total heat supply quantity of the current working condition according to the heat regeneration steam extraction coefficient, the preset main steam flow and the preset heat supply steam extraction flow;
when the total heat supply of the current working condition is larger than the preset heat supply demand, obtaining the electric load according to the obtained main steam flow correction coefficient and the steam enthalpy drop correction coefficient, or correcting the preset main steam flow and the preset heat supply extraction steam flow value until the total heat supply is larger than the heat supply demand;
and calculating the electric loads under different preset main steam flow rates and preset steam extraction flow rates, and taking the range between the maximum electric load and the minimum electric load of the unit as the electric load adjustment interval of the low-vacuum heat supply unit.
The second aspect of the disclosure provides a system for determining an electric load adjustment interval of a low-vacuum heating unit.
A low vacuum heat supply unit electrical load adjustment interval determining system comprises:
a correction coefficient calculation module configured to: obtaining a main steam flow correction coefficient according to a preset main steam flow and the main steam flow under a reference working condition, and iteratively obtaining an enthalpy drop correction coefficient and a regenerative steam extraction coefficient according to steam discharge parameter data;
a total heat supply amount calculation module configured to: obtaining the total heat supply quantity of the current working condition according to the heat regeneration steam extraction coefficient, the preset main steam flow and the preset heat supply steam extraction flow;
an electrical load calculation module configured to: when the total heat supply of the current working condition is larger than the preset heat supply demand, obtaining the electric load according to the obtained main steam flow correction coefficient and the steam enthalpy drop correction coefficient, or correcting the preset main steam flow and the preset heat supply extraction steam flow value until the total heat supply is larger than the heat supply demand;
an electrical load interval determination module configured to: and calculating the electric loads under different preset main steam flow rates and preset steam extraction flow rates, and taking the range between the maximum electric load and the minimum electric load of the unit as the electric load adjustment interval of the low-vacuum heat supply unit.
A third aspect of the present disclosure provides a medium having a program stored thereon, the program, when executed by a processor, implementing the steps in the determination method of the electric load adjustment interval of the low vacuum heating unit according to the first aspect of the present disclosure.
A fourth aspect of the present disclosure provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor, where the processor executes the program to implement the steps in the method for determining the electric load adjustment interval of the low vacuum heat supply unit according to the first aspect of the present disclosure.
Compared with the prior art, the beneficial effect of this disclosure is:
1. the method, the system, the medium and the electronic equipment are based on a simplified thermal balance calculation and iterative correction method, the correction coefficient of key parameters is introduced, and the electric load adjustment interval of the low-vacuum heat supply unit under the premise of meeting the heat supply requirement is calculated, so that related personnel can calculate in real time and predict the variation range of the electric load of the unit under different heat supply requirements in advance, and the peak regulation limit of the unit is accurately determined.
2. According to the method, the system, the medium and the electronic equipment, the calculation efficiency can be greatly improved on the premise of ensuring the accuracy by comparing the reference working conditions and introducing the correction coefficient of the key parameter to calculate the electrical load.
3. The method, the system, the medium and the electronic equipment introduce the flow correction coefficient and the enthalpy drop correction coefficient aiming at the characteristic of small change amplitude of low-vacuum heating electric load, and greatly simplify the calculation process on the premise of ensuring the accuracy of the calculation result.
4. The method, the system, the medium and the electronic equipment disclosed by the disclosure have the advantages that the calculation parameters involved in calculating the electric load of the low-vacuum heat supply unit are few, the calculation parameters are the key parameters for unit operation, and the calculation parameters can be extracted from various information systems in operation of a power plant. The method is suitable for realizing online calculation by combining an informatization technology; in addition, the method and the device adopt a hypothesis-iteration computing thought, can realize off-line computation, and are suitable for power generation load prediction analysis and power generation scheduling planning.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
Fig. 1 is a schematic flow chart of a method for determining an electrical load adjustment interval of a low vacuum heating unit according to embodiment 1 of the present disclosure.
Detailed Description
The present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict.
Example 1:
as shown in fig. 1, an embodiment 1 of the present disclosure provides a method for determining an electrical load adjustment interval of a low vacuum heating unit, including the following steps:
obtaining a main steam flow correction coefficient according to a preset main steam flow and the main steam flow under a reference working condition, and iteratively obtaining an enthalpy drop correction coefficient and a regenerative steam extraction coefficient according to steam discharge parameter data;
obtaining the total heat supply quantity of the current working condition according to the heat regeneration steam extraction coefficient, the preset main steam flow and the preset heat supply steam extraction flow;
when the total heat supply of the current working condition is larger than the preset heat supply demand, obtaining the electric load according to the obtained main steam flow correction coefficient and the steam enthalpy drop correction coefficient, or correcting the preset main steam flow and the preset heat supply extraction steam flow value until the total heat supply is larger than the heat supply demand;
and calculating the electric loads under different preset main steam flow rates and preset steam extraction flow rates, and taking the range between the maximum electric load and the minimum electric load of the unit as the electric load adjustment interval of the low-vacuum heat supply unit.
The detailed steps are as follows:
s1: and determining the calculation data of the unit reference working condition.
And selecting a design rated working condition as a calculation reference working condition, and determining the unit power, the main steam flow, the main steam enthalpy value, the exhaust steam enthalpy value, the water supply enthalpy value, the condensed water enthalpy value and the heating steam extraction flow under the reference working condition.
S2: and determining the heat supply amount of the exhausted steam and the enthalpy drop correction coefficient of the unit based on the iterative calculation of the steam exhaust parameters.
S2.1: assuming the exhaust temperature, in this embodiment, the turbine exhaust is considered as wet steam with a dryness of 0.93, and the exhaust pressure and the exhaust enthalpy are calculated according to the properties of water and steam.
S2.2: and (4) neglecting the supercooling degree of the condensed water, and calculating the enthalpy of the condensed water. In the embodiment, the condensed water is considered as saturated water under the exhaust steam pressure, and the enthalpy of the condensed water is calculated according to the properties of water and water vapor.
S2.3: and calculating the total regenerative steam extraction share. The total regenerative steam extraction fraction alpha is defined as the ratio of the regenerative steam extraction flow to the main steam flow, and is expressed by the following formula
Wherein D isReThe flow rate is the regenerative extraction flow rate, t/h; dmThe main steam flow is t/h.
The regenerative steam extraction is mainly used for heating condensed water, and the regenerative steam extraction amount can be calculated according to the enthalpy rise of the condensed water. When the working condition is changed, the total portion of the regenerative extraction steam is calculated by the following formula:
wherein, delta H'w,ΔHwThe enthalpy of water supply is increased under a rated working condition and a variable working condition respectively, and alpha' and alpha are regenerative steam extraction shares under the rated working condition and the variable working condition respectively.
S2.4: and calculating the steam discharge flow of the unit, wherein the steam discharge flow can be calculated according to the following formula:
D′p=D′m(1-a′)-De
wherein, D'mAssuming a main steam flow, DeThe flow rate of heating extraction steam.
S2.5: and (3) calculating the temperature rise of circulating water, wherein the external heat supply quantity of the unit through the low-vacuum circulating water can be calculated according to the following formula:
Q=DEx(hEx-hn)
in the formula, hExThe enthalpy of the unit exhaust steam is kJ/kg; h isnThe enthalpy of the condensed water is kJ/kg.
Based on the condenser heat balance, the circulating water temperature rise can be calculated as follows:
in the formula, RhThe constant pressure specific heat capacity of water is 4.1868 kJ/(kg.K); dcwCirculating water flow rate, kg/s.
S2.6: and calculating the exhaust steam temperature. The condenser end difference t can be calculated according to the following formula:
in the formula, Ac is the heat exchange area of the condenser, m2(ii) a K is the heat exchange coefficient.
The exhaust temperature was calculated as follows:
ts=ts+Δt+t
s2.7: and comparing whether the calculated exhaust steam temperature is equal to the assumed exhaust steam temperature or not, and if not, taking the calculated temperature as a new assumed temperature to carry out iterative calculation until the calculated exhaust steam temperature is equal to the assumed exhaust steam temperature.
S3: and determining the total heat supply and the power generation power of the unit by iteratively optimizing the main steam flow and the steam extraction heat supply flow.
S3.1: calculating a main steam flow correction coefficient K according to the assumed main steam flow and the calculated exhaust steam parameterQAnd enthalpy drop correction factor KΔH:
Wherein D is0The main steam flow is the reference working condition; Δ H, Δ H0The enthalpy drop of the main steam is calculated and the enthalpy drop of the main steam is reference.
S3.2: and calculating the heat supply load and the power generation load of the low-vacuum heat supply unit.
Heat supply Q of the unitsFor heat supply Q and heat supply Q of extraction steam of uniteAnd (3) the sum:
Qs=Q+Qe=Q+De(he-hn)
wherein h iseThe enthalpy of heating steam extraction of the unit is kJ/kg.
Heat supply Q of the unitsShould not be less than the heating demand given by the heating companies.
The low vacuum power generation capacity can be calculated by the following formula:
P=KQKΔHP0-De(hhe-hEx)
wherein, KQIs a main steam flow correction coefficient, KΔHFor the correction coefficient of the total enthalpy drop of the steam, P0Rated power of the unit, DheFlow rate of heat supply extraction steam hheEnthalpy of heat supply extraction, hExIs the exhaust enthalpy.
S3.3: the numerical value of the assumed main steam flow and the steam extraction flow of the unit is changed, on the premise of meeting the heat supply requirement, the electric power of the unit is changed, the maximum electric power and the minimum electric power of the unit are obtained, and the power range between the two limit powers is the electric load adjustment interval of the low-vacuum heat supply unit.
Taking a certain C121-13.24/0.8/535/535 type low-vacuum heat supply unit as an example, in order to meet the heat supply requirement, the heat supply amount of the unit is more than 600GJ/h, the load stable operation of about 100MW is always maintained in the actual operation, and the peak regulation of a power grid is not participated.
According to the calculation method, the first step is to collect the datum working condition data of the unit:
the power generation power is 121.58MW, the main steam flow rate is 428t/h, the exhaust steam flow rate is 322.59t/h, the main steam enthalpy is 3532kJ/kg, the water supply enthalpy is 1058.4kJ/, and the circulating water flow rate is 7680 t/h.
And secondly, iteratively calculating the heat supply amount of exhausted steam and the enthalpy drop correction coefficient of the unit.
An iterative calculation program for calculating heat supply based on the exhaust steam temperature is compiled, the exhaust steam pressure is calculated to be 0.02MPa, the exhaust steam enthalpy is 2609kJ/kg, the condensation water enthalpy is 251.9kJ/kg, the main steam flow is 348t/h, the steam extraction coefficient is 0.307, the exhaust steam flow is 166.1t/h, the exhaust steam heat supply is 391GJ/h, the circulating water temperature is 12.18 ℃, the exhaust steam temperature is calculated to be 60.18 ℃, the calculated temperature is substituted into the assumed temperature, and the cyclic iteration is carried out, so that the exhaust steam temperature is finally determined to be 60.17 ℃, the exhaust steam heat supply is 391.6GJ/h, and the enthalpy drop correction coefficient is 1.012.
Thirdly, adjusting the main steam flow and the extraction heat supply flow to determine the total heat supply and the generating power of the unit
When the main steam flow is 348t/h, the flow coefficient is 0.813, the heating extraction flow is 75t/h, the total heating load is calculated to be 590.67GJ/h, and the power generation power is 91.82 MW. The main steam flow and the heating extraction steam amount are continuously corrected, and the maximum electric load of the unit can be calculated to be 115MW and the minimum electric load can be calculated to be 88MW by utilizing the automatic calculation function of a calculation program.
The unit is subjected to a load capacity test in a heat supply state in 2019, and the test result shows that the electric load adjustment interval of the unit is 85.5-114.5MW under the condition of meeting the heat supply requirement, and is consistent with the calculation result. The patent shows that the method has higher calculation precision.
Example 2:
the embodiment 2 of the present disclosure provides a system for determining an electrical load adjustment interval of a low vacuum heat supply unit, including:
a correction coefficient calculation module configured to: obtaining a main steam flow correction coefficient according to a preset main steam flow and the main steam flow under a reference working condition, and iteratively obtaining an enthalpy drop correction coefficient and a regenerative steam extraction coefficient according to steam discharge parameter data;
a total heat supply amount calculation module configured to: obtaining the total heat supply quantity of the current working condition according to the heat regeneration steam extraction coefficient, the preset main steam flow and the preset heat supply steam extraction flow;
an electrical load calculation module configured to: when the total heat supply of the current working condition is larger than the preset heat supply demand, obtaining the electric load according to the obtained main steam flow correction coefficient and the steam enthalpy drop correction coefficient, or correcting the preset main steam flow and the preset heat supply extraction steam flow value until the total heat supply is larger than the heat supply demand;
an electrical load interval determination module configured to: and calculating the electric loads under different preset main steam flow rates and preset steam extraction flow rates, and taking the range between the maximum electric load and the minimum electric load of the unit as the electric load adjustment interval of the low-vacuum heat supply unit.
The working method of the system is the same as the method for determining the electric load adjustment interval of the low vacuum heat supply unit provided in embodiment 1, and details are not repeated here.
Example 3:
the embodiment 3 of the present disclosure provides a medium, on which a program is stored, where the program, when executed by a processor, implements the steps in the method for determining the electric load adjustment interval of the low vacuum heating unit according to the embodiment 1 of the present disclosure, where the steps are:
obtaining a main steam flow correction coefficient according to a preset main steam flow and the main steam flow under a reference working condition, and iteratively obtaining an enthalpy drop correction coefficient and a regenerative steam extraction coefficient according to steam discharge parameter data;
obtaining the total heat supply quantity of the current working condition according to the heat regeneration steam extraction coefficient, the preset main steam flow and the preset heat supply steam extraction flow;
when the total heat supply of the current working condition is larger than the preset heat supply demand, obtaining the electric load according to the obtained main steam flow correction coefficient and the steam enthalpy drop correction coefficient, or correcting the preset main steam flow and the preset heat supply extraction steam flow value until the total heat supply is larger than the heat supply demand;
and calculating the electric loads under different preset main steam flow rates and preset steam extraction flow rates, and taking the range between the maximum electric load and the minimum electric load of the unit as the electric load adjustment interval of the low-vacuum heat supply unit.
The detailed steps are the same as the method for determining the electric load adjustment interval of the low vacuum heat supply unit provided in embodiment 1, and are not described again here.
Example 4:
the embodiment 4 of the present disclosure provides an electronic device, which includes a memory, a processor, and a program stored in the memory and capable of running on the processor, where the processor executes the program to implement the steps in the method for determining the electric load adjustment interval of the low vacuum heat supply unit according to embodiment 1 of the present disclosure, where the steps are as follows:
obtaining a main steam flow correction coefficient according to a preset main steam flow and the main steam flow under a reference working condition, and iteratively obtaining an enthalpy drop correction coefficient and a regenerative steam extraction coefficient according to steam discharge parameter data;
obtaining the total heat supply quantity of the current working condition according to the heat regeneration steam extraction coefficient, the preset main steam flow and the preset heat supply steam extraction flow;
when the total heat supply of the current working condition is larger than the preset heat supply demand, obtaining the electric load according to the obtained main steam flow correction coefficient and the steam enthalpy drop correction coefficient, or correcting the preset main steam flow and the preset heat supply extraction steam flow value until the total heat supply is larger than the heat supply demand;
and calculating the electric loads under different preset main steam flow rates and preset steam extraction flow rates, and taking the range between the maximum electric load and the minimum electric load of the unit as the electric load adjustment interval of the low-vacuum heat supply unit.
The detailed steps are the same as the method for determining the electric load adjustment interval of the low vacuum heat supply unit provided in embodiment 1, and are not described again here.
As will be appreciated by one skilled in the art, embodiments of the present disclosure may be provided as a method, system, or computer program product. Accordingly, the present disclosure may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present disclosure may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.
The present disclosure is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the disclosure. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, and various modifications and changes may be made to the present disclosure by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.