A fast fuzzy control system and control method for auxiliary start and stop of thermal power unit

Abstract

The present invention discloses a rapid fuzzy control system and control method for auxiliary start and stop of thermal power units. The present invention comprises a unit heat storage capacity calculation module, an auxiliary start and stop performance simulation calculation module, an auxiliary start and stop performance analysis and decision module, and an auxiliary start and stop performance rapid fuzzy control module; the unit heat storage capacity calculation module is used to calculate the current heat storage regulation capacity of the boiler and the unit heat recovery system according to the change of the operating parameters during the unit load change process; the auxiliary start and stop performance simulation calculation module is used to calculate the comprehensive performance index of the unit auxiliary start and stop in real time according to the calculation formula of the unit auxiliary start and stop comprehensive performance index provided by the network dispatcher; the auxiliary start and stop performance analysis and decision module is used to analyze the main factors affecting the unit auxiliary start and stop performance; the auxiliary start and stop performance adopts fuzzy set theory to quickly adjust the boiler load instruction and the steam turbine load instruction in real time. The present invention can effectively improve the comprehensive performance of the auxiliary start and stop of thermal power units.

Description

Technical Field

[0001] The invention belongs to the technical field of coal-fired power generation, and in particular relates to a rapid fuzzy control system and a control method for auxiliary start and stop of a thermal power unit. Background Art

[0002] As the proportion of renewable energy power generation in the power grid gradually increases, the load of renewable energy power generation is greatly affected by environmental factors such as weather, and there are many uncontrolled factors in the power generation load, which leads to a greater impact on the frequency of the power grid and affects the stability of the power grid operation. Compared with renewable energy power generation, coal-fired power has better peak-shaving and start-stop performance. In this case, improving the auxiliary start-stop performance of thermal power units has become one of the main ways to maintain the stable operation of the power grid. It can be foreseen that the auxiliary start-stop transformation of thermal power units will continue to receive attention from various power grid companies in the next few years. In terms of economy, a series of subsidy policies for auxiliary start-stop of thermal power units will be introduced to encourage thermal power plants to complete the transformation of the optimization control of auxiliary start-stop of units, thereby greatly improving the comprehensive performance of auxiliary start-stop of each thermal power unit, and maintaining the stable operation of the power grid under the condition of continuous increase in renewable energy power generation load. The active optimization control transformation of auxiliary start-stop of units in thermal power plants is of great significance to maintaining the stable operation of the power grid. Summary of the invention

[0003] The purpose of the present invention is to provide a fast fuzzy control system and control method for auxiliary start and stop of thermal power units, which adopts fast fuzzy control technology to improve the comprehensive performance of auxiliary start and stop of thermal power units in response to the actual needs of the auxiliary start and stop market of thermal power units.

[0004] Technical solution: To achieve the above-mentioned invention object, the present invention adopts the following technical solution:

[0005] A fast fuzzy control system for auxiliary start and stop of thermal power units, comprising a unit heat storage capacity calculation module, an auxiliary start and stop performance simulation calculation module, an auxiliary start and stop performance analysis and decision module and an auxiliary start and stop performance fast fuzzy control module; the unit heat storage capacity calculation module is used to calculate the current heat storage regulation capacity of the boiler and the unit heat recovery system according to the changes in the operating parameters during the unit load change process, and provide the boundary conditions of load control for the subsequent unit fast fuzzy control; the auxiliary start and stop performance simulation calculation module is used to calculate the comprehensive performance index Kp of the unit auxiliary start and stop in real time according to the calculation formula of the unit auxiliary start and stop comprehensive performance index provided by the network dispatcher; the auxiliary start and stop performance analysis and decision module is used to analyze the main factors affecting the unit auxiliary start and stop performance, and provide selectable adjustment variables and decision basis for the auxiliary start and stop fuzzy control; the auxiliary start and stop performance is based on the calculated unit heat storage capacity, the simulated calculation value of the auxiliary start and stop performance and the factors affecting the unit auxiliary start and stop performance, and adopts fuzzy set theory to quickly adjust the boiler load command and the steam turbine load command in real time.

[0006] A method for performing fast fuzzy control of auxiliary start and stop of thermal power generation units using the above-mentioned fast fuzzy control system for auxiliary start and stop of thermal power generation units comprises the following steps:

[0007] Step 1. The unit heat storage capacity calculation module automatically calculates the current heat storage regulation capacity of the boiler and the unit heat recovery system according to the changes in the operating parameters during the unit load change process, and sends the calculation results to the auxiliary start-stop performance fast fuzzy control module;

[0008] Step 2. The auxiliary start-stop performance simulation calculation module calculates the comprehensive performance index Kp of the auxiliary start-stop of the unit in real time according to the calculation formula of the comprehensive performance index of the auxiliary start-stop of the unit provided by the network dispatcher, and sends the calculation result to the auxiliary start-stop performance fast fuzzy control module;

[0009] Step 3. The auxiliary start-stop performance analysis decision module analyzes the main factors affecting the auxiliary start-stop performance of the unit, and provides selectable adjustment variables and decision-making basis for the auxiliary start-stop fuzzy control.

[0010] Step 4. The auxiliary start-stop performance fast fuzzy control module uses fuzzy set theory to quickly adjust the boiler load command and the steam turbine load command in real time based on the calculated unit heat storage capacity, the simulated calculation value of the auxiliary start-stop performance and the factors affecting the unit's auxiliary start-stop performance.

[0011] Furthermore, the specific method for the unit heat storage capacity calculation module in step 1 to automatically calculate the heat storage regulation capacity currently possessed by the boiler and the unit heat recovery system according to the changes in the operating parameters during the unit load change process is: within the load regulation range of the unit, that is, within the rated load range of 50-100%, 5 load points are evenly selected, namely, load 55%, load 65%, load 75%, load 85%, and load 95%, and firstly, the calculation formula for the unit heat storage capacity is determined at each load point:

[0012]

[0013] r=1…5

[0014] Among them, ΔN E is the power change, ΔP T is the main steam pressure change, ΔT sp is the change in steam superheat, ΔN Er,max is the maximum heat storage capacity of the unit under load r, that is, the maximum allowable load change, Δu Tr,max It is the maximum allowable change of the turbine regulating valve under the load r condition.

[0015] Furthermore, the auxiliary start-stop performance simulation calculation module in step 2 calculates the comprehensive performance index Kp of the auxiliary start-stop of the unit in real time according to the calculation formula of the comprehensive performance index of the auxiliary start-stop of the unit provided by the network dispatcher, which is specifically expressed as:

[0016]

[0017] In the formula, is the comprehensive auxiliary start-stop performance index of unit i; D is the auxiliary start-stop performance index of the jth AGC instruction of unit i; +i,j The forward start-stop mileage of the jth AGC instruction of unit i; n is the number of times unit i is called by AGC during operation.

[0018] Beneficial effects: Compared with the prior art, the present invention is based on the calculated heat storage capacity of the unit, the simulated calculated value of the auxiliary start-stop performance and the main factors affecting the auxiliary start-stop performance of the unit, and adopts relevant fuzzy set theories such as fast fuzzy reasoning and fuzzy decision-making to quickly adjust the boiler load command and the steam turbine load command in real time to achieve optimal control of the auxiliary start-stop performance of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of a control system of the present invention. DETAILED DESCRIPTION

[0020] In order to make the technical problem to be solved, the technical solution and the beneficial effects of the present invention more clear, a detailed description is given below in conjunction with the accompanying drawings and specific embodiments.

[0021] The present invention discloses a quick fuzzy control system for auxiliary start and stop of thermal power generation units. Figure 1 As shown, the control system includes a unit heat storage capacity calculation module, an auxiliary start-stop performance simulation calculation module, an auxiliary start-stop performance analysis and decision module, and an auxiliary start-stop performance fast fuzzy control module.

[0022] The unit heat storage capacity calculation module automatically calculates the current heat storage regulation capacity of the boiler and the unit heat recovery system according to the changes in the main operating parameters during the unit load change process, providing the boundary conditions of load control for the subsequent unit fast fuzzy control.

[0023] The calculation formula of the heat storage capacity of the unit can be obtained through the following process: within the load regulation range of the unit, that is, within the rated load range of (50-100)% (without considering the deep peak regulation of the unit), 5 load points are evenly selected, namely load 1 (55%), load 2 (65%), load 3 (75%), load 4 (85%), and load 5 (95%). First, the calculation formula of the heat storage capacity of the unit is determined at each load point:

[0024]

[0025] r=1…5

[0026] Among them, ΔN E is the power change, ΔP T is the main steam pressure change, ΔT sp is the change in steam superheat. ΔN Er,max is the maximum heat storage capacity of the unit under load r (i.e. the maximum allowable load change), Δu Tr,max It is the maximum allowable change of the turbine regulating valve under the load r condition.

[0027] The auxiliary start-stop performance simulation calculation module is based on the calculation formula of the unit auxiliary start-stop comprehensive performance index provided by the network dispatcher, and the comprehensive performance index Kp of the unit auxiliary start-stop is calculated in real time, which is specifically expressed as:

[0028]

[0029] In the formula, is the comprehensive auxiliary start-stop performance index of unit i; D is the auxiliary start-stop performance index of the jth AGC instruction of unit i; +i,j The forward start-stop mileage of the jth AGC instruction of unit i; n is the number of times unit i is called by AGC during operation.

[0030] The auxiliary start-stop performance analysis and decision module analyzes the main factors affecting the auxiliary start-stop performance of the unit, and provides selectable adjustment variables and decision-making basis for the auxiliary start-stop fuzzy control.

[0031] The auxiliary start-stop performance fast fuzzy control module is based on the calculated unit heat storage capacity, the simulated calculated value of the auxiliary start-stop performance and the main factors affecting the unit's auxiliary start-stop performance, and adopts fuzzy set theory to quickly adjust the boiler load command and the steam turbine load command in real time.

[0032] Taking the auxiliary start-stop control of units in Jiangsu Province as an example, the performance index control range of auxiliary start-stop is between (2.0, 5.5), and the performance deviation e(k) and change rate De(k) of auxiliary start-stop are fuzzified. The performance deviation e(k) varies in the range of (-1.0, 2.5), and e(k) can be described by a set of fuzzy linguistic variables, namely positive large (PB, 1.5 ~ 2.5), positive medium (PM, 0.5 ~ 1.5), positive small (PS, 0.2 ~ 0.5), zero (ZO, -0.1 ~ +0.2), negative small (NS, -0.1 ~ -0.2), negative medium (NB, -0.2 ~ -0.5), and negative large (NB, -0.5 ~ -1.0). The variation range of De(k) is set to [-0.1, +0.2], and the same method can be used to fuzzify it.

[0033] Similarly, the correction amount of boiler load command and steam turbine load command can also be described by a set of fuzzy quantifiers. The correction amount of boiler load command can be expressed as the correction amount of boiler coal feed command. The agreed range of change of coal feed command correction amount is (-50t / h, +50t / h). Then the fuzzy quantifier of boiler load command correction amount can be positive large (PB, 30~50), positive middle (PM, 10~30), positive small (PS, 2~10), zero (ZO, -2~+2), negative small (NS, -2~-10), negative middle (NB, -10~-30), negative large (NB, -30~-50). Assuming that the range of variation of the steam turbine load command correction is (-5%, +5%), the fuzzy quantifiers of the steam turbine load command correction can be positive large (PB, 3~5), positive middle (PM, 1~3), positive small (PS, 0.2~1), zero (ZO, -0.2~+0.2), negative small (NS, -0.2~-1), negative middle (NB, -1~-3), and negative large (NB, -3~-5).

[0034] Furthermore, the fuzzy reasoning of the boiler load command and the steam turbine load command correction amount is to obtain the fuzzy quantifiers of the boiler load command and the steam turbine load command correction amount based on the fuzzy quantifier reasoning of the performance deviation e(k) and the change rate De(k) of the auxiliary start and stop. Generally, a fuzzy query table can be used to obtain the query result. In this embodiment, the fuzzy query table of the boiler load command and the steam turbine load command correction amount is shown in Table 1:

[0035] Table 1 Fuzzy query table of boiler load command and turbine load command correction

[0036]

[0037] Preferably, the correction amounts of the boiler load command and the steam turbine load command are calculated and obtained by using a traditional defuzzification method, that is, the correction amounts of the boiler coal feed rate command and the steam turbine throttle opening command are obtained.

[0038] The above embodiments are only preferred embodiments of the present invention, which are only used to more clearly illustrate the method of the present invention, and are not intended to impose any other form of limitation on the present invention. It should be pointed out that for general technology in the field, any obvious changes made thereto without departing from the principle and spirit of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for fast fuzzy control of auxiliary start and stop of thermal power units, characterized in that: The method comprises the following steps: Step 1. The unit heat storage capacity calculation module automatically calculates the current heat storage regulation capacity of the boiler and the unit heat recovery system according to the changes in the operating parameters during the unit load change process, and sends the calculation results to the auxiliary start-stop performance fast fuzzy control module; The specific method of the unit heat storage capacity calculation module in step 1 to automatically calculate the heat storage regulation capacity of the boiler and the unit heat recovery system according to the changes in the operating parameters during the unit load change process is: within the load regulation range of the unit, that is, within the rated load range of 50-100%, 5 load points are evenly selected, namely, load 55%, load 65%, load 75%, load 85%, and load 95%, and first determine the calculation formula of the unit heat storage capacity at each load point: Among them, ΔNE is the power change, ΔPT is the main steam pressure change, ΔTsp is the steam superheat change, ΔNEr,max is the maximum heat storage capacity of the unit under load r, that is, the maximum allowable load change, and ΔuTr,max is the maximum allowable change of the turbine valve under load r. Step 2. The auxiliary start-stop performance simulation calculation module calculates the comprehensive performance index Kp of the auxiliary start-stop of the unit in real time according to the calculation formula of the comprehensive performance index of the auxiliary start-stop of the unit provided by the network dispatcher, and sends the calculation result to the auxiliary start-stop performance fast fuzzy control module; The auxiliary start-stop performance simulation calculation module in step 2 is based on the calculation formula of the unit auxiliary start-stop comprehensive performance index provided by the network dispatcher, and the comprehensive performance index Kp of the unit auxiliary start-stop is calculated in real time, which is specifically expressed as: In the formula, is the comprehensive auxiliary start-stop performance index of unit i; is the auxiliary start-stop performance index of the jth AGC instruction of unit i; D+i,j is the positive start-stop mileage of the jth AGC instruction of unit i; n is the number of times unit i is called by AGC during operation; Step 3. The auxiliary start-stop performance analysis and decision module analyzes the main factors affecting the auxiliary start-stop performance of the unit, and provides selectable adjustment variables and decision-making basis for the auxiliary start-stop fuzzy control; Step 4. The auxiliary start-stop performance fast fuzzy control module uses fuzzy set theory to quickly adjust the boiler load command and the steam turbine load command in real time based on the calculated unit heat storage capacity, the simulated calculation value of the auxiliary start-stop performance and the factors affecting the unit's auxiliary start-stop performance.

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