Thermal load calculation method for guaranteeing heating safety of thermal generator set

Abstract

The invention provides a thermal load calculation method for guaranteeing the heating safety of a thermal power generating unit. The thermal load calculation method comprises the following steps: acquiring an instantaneous value standard signal of the heating flow of a single thermal power generating unit; the heating flow standard signal is smoothed, and a plurality of piecewise functions are set to convert the heating flow standard signal into an initial heat load signal in a piecewise mode; whether heating is conducted or not is judged according to the initial heat load signal; carrying out anti-fluctuation processing on the initial thermal load signal subjected to the conversion calculation; and adding the thermal load signal after the anti-wave processing and the electric load signal to obtain an actual load signal as a reference signal. The stability and accuracy of the thermal load signal of the northern thermal generator set in the winter heating period are guaranteed, the serious safety problem caused by the fact that all control loops of the set lose control due to large actual load fluctuation or inaccuracy in the heating period is avoided, and long-term stable operation of the heating set is guaranteed.

Description

Technical Field

[0001] The present invention provides a heat load calculation method for ensuring heating safety of a thermal power generating set, belongs to the technical field of power control, and particularly relates to heat load calculation and control of a thermal power generating set during a heating period. Background Art

[0002] At present, there is a rigid demand for winter heating in northern my country. The heating time in the northeast region of the three northern regions is usually from November 1st to April 1st of the following year, which lasts for 5 months. The heating time in North China is usually from November 15th to March 15th of the following year, which lasts for 4 months. The heating time in the northwest region is usually from October 15th to April 15th of the following year, which lasts for 6 months.

[0003] In order to ensure the overall heating efficiency, the main heat source for winter heating in northern cities is large thermal power plants. During the 4-6 months of heating in winter each year, the operating safety of large thermal power generating units in the north is not only related to the safety and stability of the local power system, but also to the heating of thousands of households in the vast northern region.

[0004] During the operation of thermal power generating units, the most important control parameter to ensure safety is the actual load. All parameter controls of the unit are based on the actual load as a reference benchmark and basic basis. During the non-heating period, the energy generated by the combustion of the boiler of the thermal power generating unit is used for power generation. The actual load signal is the electric load signal representing the power generation. All controls are based on the electric load signal, and the overall control is relatively simple. During the heating period, the energy generated by the combustion of the boiler of the thermal power generating unit is not only used for power generation, but also for heating. Compared with the non-heating period, the actual load signal is not only affected by the power generation output of the unit, but also by the heating output. Therefore, it must be recalculated. The actual load signal during the heating period must include not only the electric load signal representing the power generation, but also the thermal load signal representing the heating. The sum of the two is the actual load of the unit during the heating period. All unit monitoring and control methods are based on the sum of the electric load and the thermal load as a benchmark and basis to ensure the long-term safe and stable operation of the unit.

[0005] The current existing thermal load calculation method for thermal power units is to first obtain the instantaneous heating flow signal of a single thermal power unit, then divide the signal by a preset conversion coefficient, and then smooth the calculation result as the final thermal load signal, and finally add the thermal load signal and the electrical load signal as the reference signal for all control loops of the unit. The main disadvantage of this method is that it is prone to large signal deviations, and there is no judgment function for whether heating is on or not and no anti-fluctuation design. When the heating flow changes dramatically during the heating period, it will directly cause frequent fluctuations in the thermal load and actual load, seriously affecting the stability of all control loops related to the actual load of the unit, thereby seriously affecting the heating safety and power generation safety.

[0006] The current thermal load calculation method for thermal power units is mainly based on a simple heating flow multiplication coefficient. The calculated thermal load signal fluctuates greatly, and there is no heating judgment function and signal anti-fluctuation design. It is easy to cause frequent fluctuations in the actual load signal of the unit during the heating period or even signal distortion, seriously affecting the unit's operating safety and heating safety. Summary of the invention

[0007] In view of the problems existing in the above-mentioned prior art, the present invention proposes a heat load calculation method for ensuring the heating safety of a thermal power generating set, which solves the problem of frequent fluctuations or even signal distortion of the actual load signal of the set during the heating period in the prior art.

[0008] The present invention provides a heat load calculation method for ensuring heating safety of a thermal power generating set, and the technical solution comprises the following steps:

[0009] Step 1, obtaining a standard signal of the instantaneous value of the heating flow of a single thermal power unit;

[0010] Step 2, smoothing the above heating flow standard signal, and converting the heating flow standard signals of different intervals into initial heat load signals;

[0011] Step 3, determining whether the initial heat load signal is in heating mode or not, if heating mode is in heating mode, the initial heat load signal is converted and calculated; if not heating mode is in heating mode, the initial heat load signal is set to zero;

[0012] Step 4, performing speed and amplitude limiting to prevent fluctuations on the initial heat load signal for the conversion calculation, so that the heat load signal maintains the current value unchanged;

[0013] Step 5, adding the heat load signal after the wave protection processing to the electric load signal to obtain the actual load signal, and using the actual load signal as the reference signal used by all control loops of the unit.

[0014] In the step 2, the heating flow standard signal is smoothed by the lead-lag function module, and the time constant is set to a lag of 3-5 seconds.

[0015] In step 3, the actual opening feedback signal of the heating quick-closing valve and the heating flow signal are introduced to determine whether the heating is actually put into operation. If it is, the initial heat load is calculated normally. If it is not, the initial heat load signal is reset to zero.

[0016] Furthermore, in step 3, when the opening of the quick-closing valve is greater than 10% and the heating flow rate is higher than 30 t / h, the heating input is determined.

[0017] In step 4, when the initial heat load signal is subjected to speed limiting and anti-fluctuation processing, the change rate of the initial heat load signal is limited, and the rate limit value is 0.0167 / s.

[0018] In step 4, the heat load signal is adjusted and corrected in real time through the gain and offset adjustment of the gain function block itself, the final heat load signal is limited, and the output of 80MW after the limit adjustment is set as the final heat load signal.

[0019] In the step 4, a logical judgment is set that the absolute change of the initial heat load signal before and after the speed limit exceeds 10MW and then a delay of 10 seconds, a logical judgment is made that the heating flow signal has not had a bad quality condition, and a logical judgment is made that the thermal power unit has not had a load change condition for more than 300 seconds. When the three logical judgments are established at the same time, the initial heat load signal proceeds to the next step of calculation normally to form a heat load signal, otherwise the initial heat load signal maintains the current value unchanged.

[0020] A computer device comprising:

[0021] A processor; and a memory configured to store machine-readable instructions, which, when executed by the processor, execute the above-mentioned heat load calculation method for ensuring heating safety of a thermal power generating set.

[0022] A storage medium stores a computer program, wherein the computer program is executed by a processor to implement the above-mentioned heat load calculation method for ensuring heating safety of a thermal power generating set.

[0023] The beneficial effects of the present invention are:

[0024] 1. It avoids the large deviation caused by the traditional method of using a single coefficient for conversion, and adopts multiple piecewise functions to correspond the heat load values ​​of different flow sections, thereby improving the calculation accuracy of the heat load.

[0025] 2. The conditions for determining whether to heat are set. Normal calculation of heat load is performed during heating period, and heat load value is directly reset to zero during non-heating period, thus avoiding calculation errors of traditional methods during non-heating period.

[0026] 3. Aiming at the common working conditions where the heating flow changes dramatically, a heat load fluctuation prevention function is designed. The actual load signals used in all automatic control loops and manual control loops will not fluctuate frequently at the same time when the heat load changes in a small range, thus ensuring the safety and stability of the unit during the heating period.

[0027] 4. A heat load retention function is designed when the heating flow signal is broken to avoid abnormal fluctuations in the heat load and actual load when there is a problem with the heating flow signal, affecting the normal operation of all relevant control circuits of the unit, thereby effectively ensuring the power generation safety and heating safety of the unit.

[0028] 5. The speed limit and amplitude limit functions of the heat load are designed to facilitate the calibration and adjustment of the heat load signal according to objective conditions at any time when the unit is running. At the same time, the amplitude limit function can also avoid excessive fluctuations in the heat load signal itself when the heating flow signal exceeds the limit.

[0029] 6. A variable load holding function is designed. When the electric load rises or falls, the thermal load signal remains unchanged for a period of time, avoiding the simultaneous changes of the electric load and the thermal load in the same period of time, reducing the control disturbance of the unit, and being beneficial to the heating safety of the unit.

[0030] In summary, the present invention adopts a variety of measures to jointly ensure the stability and accuracy of the heat load signal of the northern thermal power generating units during the winter heating period, so that all control loops of the units will not lose control during the heating period due to large fluctuations or inaccuracies in the actual load, thereby preventing serious safety problems. The long-term stable operation of the heating units is ensured, thereby effectively ensuring that the rigid people's livelihood needs for winter heating in the northern region are met. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The figure is a flow chart of the method of the present invention.

[0032] Figure 2 This is a control logic diagram of an embodiment of the present invention for calculating the thermal load and actual load of a 600MW thermal power unit put into actual operation.

[0033] Figure 2 Among them, 11, lead-lag function module, 12, signal conversion function module, 13, first analog output switching function module, 14, first high value monitoring function module, 15, second high value monitoring function module, 16, logic and function module, 17-analog constant function module, 18, second analog output switching function module, 19, rate limiting function module, 20, subtraction function module, 21, absolute value function module, 22, third high value monitoring function module, 23, delayed closing function module, 24, quality judgment function module, 25, first inversion function module, 26, second inversion function module, 27, delayed closing function module, 28, logic and function module, 29, gain function module, 30, addition function module. DETAILED DESCRIPTION

[0034] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0035] Example 1

[0036] like Figure 1-2 As shown, a heat load calculation method for ensuring heating safety of a thermal power generating set comprises the following steps:

[0037] Step 1, obtaining a standard signal of the instantaneous value of the heating flow of a single thermal power unit;

[0038] Step 2, in the ICC software system of the unit control system engineer station, introduce the heating flow signal, use the lead-lag function module 11 to smooth the heating flow standard signal, and set a time constant of 3-5 seconds.

[0039] Step 3, smooth the above heating flow standard signal, and convert the heating flow standard signal of different intervals into the initial heat load signal according to the proportional coefficient of 40:1 for 300MW thermal power generating set and 50:1 for 600MW thermal power generating set, as shown in Table 1. The proportional coefficients of all intervals can be fine-tuned after the unit is heating to improve the signal accuracy.

[0040] Input(t / h) 0 100 240 300 400 500 Output(MW) 0 20 50 62.5 85 105

[0041] Table 1

[0042] Step 4, introduce the heating quick-closing valve opening feedback signal and the heating flow signal, through the first high-value monitoring function module 14, the second high-value monitoring function module 15 and the logic and function module 16, when the quick-closing valve opening is greater than 10% and the heating flow is higher than 30t / h at the same time, the heating input is determined by the program.

[0043] Step 5, calling the first analog output switching function module 13, so that when heating is put into operation, the initial heat load signal is normally used for the next calculation, and when heating is not put into operation, the heat load signal is directly switched to 0t / h set in the analog constant function module 17.

[0044] Step 6, calling the rate limiting function module 19 to limit the change rate of the initial heat load signal, and the rate limiting value is 0.0167 / s.

[0045] Step 7, calling the subtraction function module 20, the absolute value function module 21, the third high value monitoring function module 22, and the delayed closing function module 23, introducing the initial heat load signal and the initial heat load signal after speed limit, and realizing the logical judgment of delaying 10 seconds after the absolute change of the initial heat load signal before and after speed limit exceeds 10MW.

[0046] Step 8, introducing the heating flow signal, calling the quality judgment function module 24 and the first negation function module 25, and forming a logical judgment that the heating flow signal has no bad quality situation.

[0047] Step 9, introducing a load change signal, calling the second negation function module 26 and the delayed closing function module 27, and forming a logical judgment that the thermal power unit has not experienced a load change for more than 300 seconds.

[0048] Step 10, calling the logic and function module 28 and the second analog output switching function module 18, to realize that when the logic judgments of step 7, step 8, and step 9 are simultaneously established, the initial heat load signal normally performs the next step calculation to form a heat load signal, otherwise the initial heat load signal maintains the current value unchanged.

[0049] Step 11, call the gain function module 29, and through the gain and offset adjustment of the gain function module itself, fine-tune and correct the thermal load signal at any time to adapt to the actual needs of the unit control, and limit the final thermal load signal, setting 80MW as the thermal load signal output by the gain function module 29.

[0050] Step 12, introduce the electric load signal, call the addition function module 30, add the thermal load signal and the electric load signal to form an actual load signal, which is called by all control loops of the unit and added to the common display screen of the operator for monitoring at any time.

[0051] A computer device comprising:

[0052] A processor; and a memory configured to store machine-readable instructions, which, when executed by the processor, execute the above-mentioned heat load calculation method for ensuring heating safety of a thermal power generating set.

[0053] A storage medium stores a computer program, wherein the computer program is executed by a processor to implement the above-mentioned heat load calculation method for ensuring heating safety of a thermal power generating set.

[0054] Example 2

[0055] Figure 2 This is a control logic diagram for calculating the thermal load and actual load of a 600MW thermal power unit put into actual operation. In the figure, the analog connection lines are solid lines and the digital connection lines are dotted lines.

[0056] Lead-lag function module 11, used for smoothing the input analog signal;

[0057] The signal conversion function module 12 is used to convert the input heating flow signal into an electrical load signal;

[0058] The first analog output switching function module 13, when the upper left dotted line is set to 1, the "YES" input terminal is output, and when the upper left dotted line is set to 0, the "NO" input terminal is output;

[0059] The first high value monitoring function module 14 sets the digital output to 1 when the analog input value is higher than 10%;

[0060] The second high value monitoring function module 15, when the analog input value is higher than 30t / h, the digital output is set to 1;

[0061] Logic and function module 16, when all digital quantity input values ​​are 1, the digital quantity output is set to 1, otherwise the digital quantity output is set to 0;

[0062] Analog constant function module 17, set a constant value online, the value range is a positive or negative floating point number less than 65535, and can also be 0;

[0063] The second analog output switching function module 18, when the dotted line in the upper left corner is set to 1, the "YES" input terminal is output, otherwise the output maintains the current value;

[0064] The rate limiting function module 19 sets a set rate online. When the change rate of the analog input value exceeds the set rate in seconds, the instantaneous change of the analog output value will not exceed the set rate;

[0065] Subtraction function module 20, the analog output value is equal to the difference between the analog input value at the positive end and the analog input value at the negative end;

[0066] Absolute value function module 21, the analog output value is equal to the absolute value of the analog input value;

[0067] The third high value monitoring function module 22 sets the digital output to 1 when the analog input value is higher than 10MW;

[0068] Delayed closing function module 23, when the digital input is set to 1, the digital output is delayed for 10 seconds and then set to 1;

[0069] The quality judgment function module 24 sets the digital output to 1 when the analog input signal has bad quality;

[0070] The first negation function module 25 sets the digital quantity output to 1 when the digital quantity input is set to 0, and sets the digital quantity output to 0 when the digital quantity input is set to 1;

[0071] The second negation function module 26 sets the digital quantity output to 1 when the digital quantity input is set to 0, and sets the digital quantity output to 0 when the digital quantity input is set to 1;

[0072] Delay closing function module 27, when the digital input is set to 1, the digital output is delayed for 300 seconds and then set to 1;

[0073] Logic and function module 28, when all digital input values ​​are 1, the digital output is set to 1, otherwise the output is set to 0;

[0074] Gain function module 29, used to limit and correct the upper and lower amplitudes of the input heat load signal;

[0075] Addition function module 30, the analog output value is equal to the algebraic sum of the two analog input values.

[0076] Innovations of the present invention:

[0077] The calculation method of the present invention has a heating judgment function. When the unit is not heating, the heat load signal is directly reset to zero, the signal accuracy is improved, and the automatic switching of the actual load between the non-heating period and the heating period within the annual range is realized, thereby ensuring the heating safety and power generation safety of the unit from the aspect of signal effectiveness.

[0078] The present invention has an anti-fluctuation function. When the heat load signal changes greatly, such as the heating flow of a 600MW unit exceeds 50t / h, which is equivalent to an equivalent electric load change of more than 10MW, the heat load is allowed to continue to be calculated. Otherwise, the current heat load value is kept unchanged. This function greatly improves the stability of the heat load signal and the actual load signal, and improves the stability of all control loops of the unit that use the actual load signal, thereby ensuring the control safety of the thermal power generating unit during the winter heating period.

[0079] The present invention carries out a judgment process of the variable load of the unit. The thermal load signal remains unchanged within 300 seconds after the electric load is increased or decreased, thereby avoiding the unstable operation of the unit caused by large fluctuations or even distortion of the actual load signal when the electric load and the thermal load change at the same time in the same time period, which is beneficial to the heating safety of the unit.

[0080] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprising a reference structure" do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0081] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0082]

[0083] Table 2

Claims

1. A heat load calculation method for ensuring heating safety of thermal power generating units, characterized in that The following steps are involved: Step 1, obtaining a standard signal of the instantaneous value of the heating flow of a single thermal power unit; Step 2, smoothing the above heating flow standard signal, and converting the heating flow standard signals of different intervals into initial heat load signals; Step 3, determining whether the initial heat load signal is in heating mode or not, if heating mode is in heating mode, the initial heat load signal is converted and calculated; if not heating mode is in heating mode, the initial heat load signal is set to zero; Step 4, performing speed and amplitude limiting to prevent fluctuations on the initial heat load signal for the conversion calculation, so that the heat load signal maintains the current value unchanged; Step 5, adding the heat load signal after the wave protection processing to the electric load signal to obtain the actual load signal, and using the actual load signal as the reference signal used by all control loops of the unit.

2. A heat load calculation method for ensuring heating safety of a thermal power generating set according to claim 1, characterized in that In the step 2, the heating flow standard signal is smoothed by the lead-lag function module, and the time constant is set to a lag of 3-5 seconds.

3. A heat load calculation method for ensuring heating safety of a thermal power generating set according to claim 1, characterized in that In the step 2, the heating flow standard signal is converted into an initial heat load signal according to the ratio coefficient of 40:1 for 300MW thermal power generating set and 50:1 for 600MW thermal power generating set.

4. A heat load calculation method for ensuring heating safety of a thermal power generating set according to claim 1, characterized in that In step 3, the actual opening feedback signal of the heating quick-closing valve and the heating flow signal are introduced to determine whether the heating is actually put into operation. If it is, the initial heat load is calculated normally. If it is not, the initial heat load signal is reset to zero.

5. A heat load calculation method for ensuring heating safety of a thermal power generating set according to claim 4, characterized in that In the step 3, when the opening of the quick-closing valve is greater than 10% and the heating flow rate is higher than 30t / h, the heating input is determined.

6. A heat load calculation method for ensuring heating safety of a thermal power generating set according to claim 1, characterized in that In step 4, when the initial heat load signal is subjected to speed limiting and anti-fluctuation processing, the change rate of the initial heat load signal is limited, and the rate limit value is 0.0167 / s.

7. A heat load calculation method for ensuring heating safety of a thermal power generating set according to claim 1, characterized in that In step 4, the heat load signal is adjusted and corrected in real time through the gain and offset adjustment of the gain function block itself, the final heat load signal is limited, and the output of 80MW after the limit adjustment is set as the final heat load signal.

8. A heat load calculation method for ensuring heating safety of a thermal power generating set according to claim 1 or 7, characterized in that In the step 4, a logical judgment is set that the absolute change of the initial heat load signal before and after the speed limit exceeds 10MW and then a delay of 10 seconds, a logical judgment is made that the heating flow signal has not had a bad quality condition, and a logical judgment is made that the thermal power unit has not had a load change condition for more than 300 seconds. When the three logical judgments are established at the same time, the initial heat load signal proceeds to the next step of calculation normally to form a heat load signal, otherwise the initial heat load signal maintains the current value unchanged.

9. A computer device comprising: processor; as well as A memory configured to store machine-readable instructions, which, when executed by the processor, execute the heat load calculation method for ensuring heating safety of a thermal power generator set as described in any one of claims 1-7.

10. A storage medium storing a computer program, wherein the computer program is executed by a processor according to the method for calculating the heat load for ensuring heating safety of a thermal power generating set as claimed in any one of claims 1 to 7.

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