CN110500645B - Optimized control method for improving unit bypass heat supply operation reliability - Google Patents
Optimized control method for improving unit bypass heat supply operation reliability Download PDFInfo
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Abstract
The invention relates to the technical field of automatic control of thermal power generating units, in particular to an optimal control method for improving the operation reliability of bypass heat supply of a unit, which comprises the following steps: when the heat supply thermal power unit is in a bypass heat supply mode, judging the fault of a unit bypass heat supply system by configuring the control logic of a Distributed Control System (DCS) of the heat supply thermal power unit; judging the flow of bypass heat supply steam, and performing chain protection action by combining the fault of a unit bypass heat supply system to ensure the safe and stable operation of the unit; adding automatic control logic to control the stability of the operation parameters of the unit bypass heating system; and querying historical operating data and design data of a distributed control system DCS of the heat supply thermal power generating unit, and setting each automatic control logic parameter. The invention can ensure the safety of the heat supply unit under the working condition of ensuring the heat supply quality, effectively reduce the labor intensity of operators and ensure that the control effect does not depend on the technical level of the operators; the real-time property is good, the field debugging process is simple, and the engineering realization is convenient.
Description
Technical Field
The invention relates to the technical field of automatic control of thermal power generating units, in particular to an optimal control method for improving the operation reliability of bypass heat supply of a unit.
Background
The operating characteristics of the heat supply unit and the operation mode of 'fixing electricity with heat' limit the adjusting capacity of the electric output, and cause the serious problem of wind/light abandonment. In order to improve the consumption capacity of new energy, the national energy agency puts forward clear requirements for carrying out thermal power flexibility transformation, and the method for improving the thermal power flexibility is divided into the following steps according to the unit type: the cogeneration unit performs thermoelectric decoupling to reduce the output of the unit when the peak heat load is generated, and the straight condensing unit performs unit transformation to realize deep peak regulation; the method is divided into the following steps according to the transformation mode: the external modification of the unit is provided with electric energy consumption devices such as an electric boiler, a storage battery and compressed air energy storage devices or heat storage devices such as a heat storage tank, and the internal modification of the unit is used for modifying a boiler combustion stabilizing system, a powder making system, a steam-water system and a thermal system. The heat supply through the bypass system of the unit is an effective way for improving the flexibility of the heat supply unit, the adjusting capacity of the heat supply unit can be greatly increased, after the heat supply is carried out through the bypass system of the unit, the safety problem of the unit is involved, a plurality of difficulties are brought to the control of the bypass system of the unit, and the chain protection control logic of the bypass heat supply of the unit needs to be optimized in a targeted manner.
In recent years, a plurality of domestic scholars research and discuss the problems related to the bypass system of the thermal power generating unit, for example, the feasibility analysis of the use of 100% bypass system for 350MW supercritical unit boiler direct heat supply of Hebei electric power technology, introduces a specific scheme of using 100% bypass system for boiler direct heat supply, compares the heat supply amount and the system arrangement with the traditional capacity bypass, and demonstrates the function of the 100% bypass system in the boiler direct heat supply. Chinese patent 'a complete thermoelectric decoupling steam extraction heat supply power station system and working method' patent application No. CN201710192352.5, provides a transformation scheme aiming at steam extraction heat supply of a steam turbine system of an intermediate reheating unit, and provides a complete thermoelectric decoupling steam extraction heat supply power station system and a working method. Chinese patent "utilize unit bypass heat supply to improve combined heat and power generation unit degree of depth peak regulation system and method" patent application No. CN201611166629.9, it proposes a system for utilizing unit bypass heat supply to improve combined heat and power generation unit degree of depth peak regulation, includes: the steam outlet of the boiler and the steam outlet of the boiler are communicated with a high-pressure cylinder, the steam exhaust of the high-pressure cylinder is heated by a boiler reheater and then is connected with an intermediate-pressure cylinder, the steam exhaust of the intermediate-pressure cylinder is connected with a low-pressure cylinder, the low-pressure cylinder is connected with a condenser, a high-pressure bypass system is connected out of a main steam pipeline and is connected to a reheating cooling section pipeline after being decompressed and cooled by a high-pressure bypass valve, the low-pressure bypass system steam bypass steam turbine intermediate-pressure cylinder is connected to the condenser after being decompressed and cooled by a low-pressure bypass valve, a high-side control valve of the high-pressure cylinder is connected in front of a steam extraction pipeline in parallel, a control valve.
The above documents and patents mainly describe the aspects of improving the deep peak shaving system of the cogeneration unit by using the unit bypass heat supply and the like by comparing the arrangement of the unit bypass system with the traditional capacity bypass, and providing a modification scheme for the steam extraction and heat supply of the steam turbine system of the intermediate reheating unit, but do not perform targeted research on the optimization control for improving the operation reliability of the unit bypass heat supply.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides an optimal control method for improving the operation reliability of unit bypass heat supply, and aims to solve the operation reliability control problem after the heat supply unit bypass system is transformed to supply heat, guarantee the safety of equipment and improve the deep peak regulation capability of the unit on the premise of meeting the heat supply requirement.
In order to achieve the purpose, the technical scheme adopted by the invention for solving the technical problem is as follows:
an optimization control method for improving the operation reliability of bypass heat supply of a unit comprises the following steps:
the first step is as follows: when the heat supply thermal power unit is in a bypass heat supply mode, judging the fault of a unit bypass heat supply system by configuring the control logic of a Distributed Control System (DCS) of the heat supply thermal power unit;
the second step is that: judging the flow of bypass heat supply steam, and performing chain protection action by combining the fault of a unit bypass heat supply system to ensure the safe and stable operation of the unit;
the third step: adding automatic control logic to control the stability of the operation parameters of the unit bypass heating system;
the fourth step: and querying historical operating data and design data of a distributed control system DCS of the heat supply thermal power generating unit, and setting parameters of each automatic control logic.
In the first step, the following judgment conditions of the bypass heat supply mode of the heat supply thermal power unit are met simultaneously, and the judgment conditions comprise:
(1) opening signals of all valves of the bypass heating system, all temperature measurement values, all pressure measurement values, all flow measurement values and unit actual power generation measurement values are displayed as good quality in a Distributed Control System (DCS) of the heat supply thermal power unit;
(2) the actual generating power measured value of the unit is lower than the value A1;
(3) and operating a bypass heating mode input button in a DCS operation picture of the distributed control system of the thermal power generating unit by a unit operator.
In the first step, the unit bypass heating system fault includes: the fault of the high-side regulating valve is mistakenly closed, the fault of the high-side regulating valve is mistakenly opened, the fault of the high-side regulating valve is stuck, the fault of the low-side regulating valve is mistakenly closed, the fault of the low-side regulating valve is mistakenly opened, the fault of the low-side regulating valve is stuck, the fault of the bypass temperature-reducing water cut-off and the fault of the heat supply network heater.
The value A1 ranges from 30% Pe to 50% Pe, Pe is rated power, the value B1 ranges from 350t/h to 450t/h, the value B2 ranges from 450t/h to 550t/h, the value C1 ranges from 2% to 5%, the value C2 ranges from 40% to 50%, the value C3 ranges from-2%/s to-1%/s, the value C4 ranges from-45 t/h/s to-40 t/h/s, the value D1 ranges from 55% to 60%, the value D2 ranges from 40% to 50%, the value D3 ranges from 1%/s to 2%/s, the value D4 ranges from 40t/h/s to 45t/h/s, the value E1 ranges from 2% to 5%, the value E2 ranges from 40% to 50%, the value E3 ranges from-2%/s to-1%/s, the value E4 ranges from-50 t/H/s to-45 t/H/s, the value F1 ranges from 55% to 60%, the value F2 ranges from 40% to 50%, the value F3 ranges from 1% s to 2% s, the value F4 ranges from 45t/H/s to 50t/H/s, the value G1 ranges from 15% to 20%, the value G2 ranges from 15% to 20%, the value H1 is the maximum temperature that can be tolerated by the pipeline material after a high bypass control valve and is 350 ℃, the value H2 is the maximum temperature that can be tolerated by the pipeline material after a high bypass control valve and is 20 ℃ below the maximum temperature that can be tolerated by the pipeline material after a low bypass control valve and is 330 ℃, the value H4 is the maximum temperature that can be tolerated by the pipeline material after a low bypass control valve and is 300 ℃, the value H5 is the maximum temperature that can be tolerated by the pipeline material after a low bypass control valve and is 20 ℃ below 280 ℃, and the value I1 ranges from, the value J1 ranges from 0 to 200 seconds, the value J2 ranges from 17 to 19Mpa for the subcritical unit, from 26 to 27Mpa for the supercritical unit, the value K1 ranges from 20 to 25%, the value L1 ranges from 1 to 5%/min, and the value L2 ranges from 5 to 20%/min.
In the second step, the size of the bypass heating steam flow is judged, and the method comprises the following steps:
(1) when the flow of the high-side heat supply steam is less than a value B1 or the flow of the low-side heat supply steam is less than a value B2, judging that the flow of the bypass heat supply steam is small;
(2) and when the flow of the high-side heat supply steam is greater than or equal to a value B1 or the flow of the low-side heat supply steam is greater than or equal to a value B2, judging that the flow of the bypass heat supply steam is large.
In the second step, judge the size of bypass heat supply steam flow, combine unit bypass heating system trouble to carry out chain protection action, the step is:
step 1: when judging bypass heat supply steam flow hour, the chain protection action after unit bypass heating system trouble takes place includes: when the high side regulating valve is in fault of being closed by mistake, the medium pressure regulating valve of the steam turbine is opened in a linkage manner, and the low side regulating valve is closed in a linkage manner; when the high side regulating valve is in fault of opening by mistake, the medium pressure regulating valve of the steam turbine is opened in a linkage manner, if the medium pressure regulating valve is fully opened, the low side regulating valve and the low side regulating valve are continuously opened and then reach the electric isolating door of the condenser so as to maintain the high discharge pressure to be stable; when the low-side regulating valve is in fault of being closed by mistake, the medium-pressure regulating valve of the steam turbine is opened in a linkage manner, the high-side regulating valve is closed in a linkage manner, when the low-side regulating valve is in fault of being opened by mistake, the low-side regulating valve is closed in a linkage manner and then reaches the electric isolating door of the heat supply network, and the high-side regulating valve is closed in a linkage manner so as to maintain the high discharge pressure to be stable; when the bypass temperature-reducing water is cut off, the high bypass adjusting valve and the low bypass adjusting valve are turned off, and the temperature-reducing water corresponding to the downstream heating surface is turned on; when the heat supply network heater fails, the high side regulating valve and the low side regulating valve are closed in a linkage manner; when any one of the unit bypass heating systems fails, the coordinated control system automatically switches the boiler main control to a manual mode, timing is started at the same time, and if the timing value is greater than J1 and the main steam pressure is higher than a value J2, the unit bypass heating system is triggered to fail RB, and the load is quickly reduced;
step 2: when judging bypass heat supply steam flow when big, the chain protection action after unit bypass heating system trouble takes place still includes including the chain protection action when the aforesaid is judged bypass heat supply steam flow hour: the coordination control system automatically switches the steam turbine master control into a manual mode, and a boiler pressure control valve PCV is opened in a linkage manner to trigger a unit bypass heating system fault RB;
and step 3: when the high side regulating valve is jammed and has a fault, the low side regulating valve is locked to act, and an alarm is given to prompt operating personnel; when the low side regulating valve is jammed and has a fault, the high side regulating valve is locked to act, and an alarm is given to prompt an operator.
The judging conditions that the fault of the high side regulating valve is turned off by mistake is as follows are all satisfied simultaneously, and the judging conditions comprise:
(1) the opening of the high bypass regulating valve is smaller than a value C1;
(2) the difference between the high bypass regulating valve instruction and the opening degree is larger than a value C2;
(3) the opening change rate of the high bypass regulating valve is greater than a value C3;
(4) the steam flow rate of change after the high side adjusting valve is larger than a value C4;
(5) the quality of the steam flow after the valve is adjusted by the high side is a non-defective point;
(6) the opening quality of the high bypass regulating valve is a non-defective point;
(7) the electric isolating door in front of the high-side regulating valve is not closed;
the judging conditions that the false opening fault of the high bypass regulating valve is as follows are all met at the same time, and the judging conditions comprise:
(1) the opening of the high bypass regulating valve is larger than a numerical value D1;
(2) the difference value between the opening of the high bypass regulating valve and the instruction is larger than a value D2;
(3) the opening change rate of the high bypass regulating valve is greater than a value D3;
(4) the steam flow rate of change after the high side adjusting valve is larger than a value D4;
(5) the quality of the steam flow after the valve is adjusted by the high side is a non-defective point;
(6) the opening quality of the high bypass regulating valve is a non-defective point;
(7) the electric isolating door in front of the high-side regulating valve is not closed;
the judging conditions that the fault of the low side regulating valve is turned off by mistake is as follows are all satisfied simultaneously, and the judging conditions comprise:
(1) the opening of the low bypass regulating valve is smaller than a value E1;
(2) the difference between the low bypass regulating valve instruction and the opening degree is larger than a value E2;
(3) the opening change rate of the low bypass regulating valve is greater than a value E3;
(4) the steam flow rate of change after the valve is adjusted by the low side bypass is larger than a value E4;
(5) the quality of the steam flow after the valve is adjusted by the low side is a non-defective point;
(6) the opening quality of the low bypass regulating valve is a non-defective point;
(7) the valve is adjusted at the lower side until the electric isolation door of the heat supply network is not closed;
the judging conditions that the fault of the low-side regulating valve is opened by mistake is as follows are all met at the same time, and the judging conditions comprise that:
(1) the opening of the low bypass regulating valve is larger than a numerical value F1;
(2) the difference value between the opening of the low bypass regulating valve and the command is larger than a value F2;
(3) the opening change rate of the low bypass regulating valve is greater than a value F3;
(4) the steam flow rate of change after the valve is adjusted by the low side valve is larger than a value F4;
(5) the steam flow behind the low side adjusting valve is not a dead point;
(6) the opening of the low bypass adjusting valve is not bad;
(7) the valve is adjusted at the lower side until the electric isolation door of the heat supply network is not closed;
the judgment condition of the high bypass regulating valve jamming fault is that the absolute value of the difference value between the high bypass regulating valve instruction and the opening degree is greater than a value G1, and the judgment condition of the low bypass regulating valve jamming fault is that the absolute value of the difference value between the low bypass regulating valve instruction and the opening degree is greater than a value G2;
the bypass desuperheating water-break fault is any one of the following judgment conditions, including:
(1) the steam temperature quality after the valve is adjusted by the high side is good and is greater than the value H1;
(2) the steam temperature quality after the high-side regulating valve is good and is greater than a value H2, and the pressure of the high-side desuperheating water is lower than a value H3;
(3) the steam temperature quality after the valve is adjusted by the low side is good and is greater than the value H4;
(4) the steam temperature quality after the low-side regulating valve is good and is greater than a value H5, and the pressure of the low-side desuperheating water is lower than a value H6;
the pressure of the high-side temperature-reducing water is lower than a value H3, the forming process is that the cold recompression is added with 0.5MPa, and the forming process of the low-side temperature-reducing water is lower than a value H6, the pressure of the low-side temperature-reducing water is added with 0.5MPa after the valve is adjusted;
and the fault judgment condition of the heat supply network heaters is that the steam inlet valve instruction and the opening of 2 heat supply network heaters in 4 heat supply network heaters are smaller than a value I1.
The action process of the unit bypass heating system fault RB is as follows: after the fault RB of the bypass heat supply system of the unit occurs, the coordinated control system switches the fuel main control mode into a manual mode, meanwhile, whether the number of the coal mills operated by the unit is larger than the number of 50% of rated power generation power is judged, if so, an instruction of tripping the coal mill at the uppermost layer is sent, and after 10 seconds of delay, a second coal mill is tripped until the number of the coal mills operated is not larger than the number of 50% of rated power generation power.
In the third step: the method is characterized in that automatic control logic is added, and the steps of controlling the stability of main operation parameters of the unit bypass heating system are as follows:
(1) a PID regulator of the high exhaust pressure of a turbine medium pressure regulating valve is added to control the high exhaust pressure of the turbine within a reasonable range, the set value of the PID regulator is a set value of the low limit of the high exhaust pressure, the regulation stage pressure of the turbine is calculated by a Distributed Control System (DCS) with a heat supply thermal power unit with a broken line function f1(x), the feedback value of the PID regulator is a measured value of the high exhaust pressure, the output value of the PID regulator is used as offset and is added with the original turbine medium pressure regulating valve instruction to form a final turbine medium pressure regulating valve instruction, and the range of the output value of the PID regulator is-K1-0%;
(2) increasing the switching rate limit control logic of the high bypass adjusting valve and the low bypass adjusting valve, wherein the switching rate limit of the high bypass adjusting valve and the low bypass adjusting valve is variable parameter control, when the unit is in a bypass heating mode, the value of the rate limit is L1, and when the unit is not in the bypass heating mode, the value of the rate limit is L2;
(3) and designing a switching sequence locking condition of the high-side regulating valve and the electric isolating door in front of the high-side regulating valve in a control logic, and ensuring that the electric isolating door in front of the high-side regulating valve is opened firstly and then the high-side regulating valve is opened, and the high-side regulating valve is not closed and does not allow the electric isolating door in front of the high-side regulating valve to be opened.
In the fourth step: the method comprises the following steps of inquiring historical operating data and design data of a distributed control system DCS of the heat supply thermal power generating unit and setting parameters of each automatic control logic:
(1) querying historical operating data of relevant parameters in a database of a DCS (distributed control system) historical control station of a distributed control system of a heat supply thermal power generating unit, and determining the range of normal values of the relevant parameters after eliminating abnormal data;
(2) determining the range of abnormal values of the relevant parameters according to the range of normal values of the relevant parameters and by combining design data;
(3) and determining the numerical value in each judgment condition according to the range of the normal numerical value and the range of the abnormal numerical value of the relevant parameter.
The invention has the advantages and beneficial effects that:
(1) when the heat supply thermal power unit is in a bypass heat supply mode, judging the fault of a unit bypass heat supply system by configuring the control logic of a Distributed Control System (DCS) of the heat supply thermal power unit; judging the flow of bypass heat supply steam, and performing chain protection action by combining the faults of the unit bypass heat supply system to ensure the safe and stable operation of the unit; adding automatic control logic to control the stability of main operation parameters of the bypass heating system; querying historical operation data and design data of a distributed control system DCS of the heat supply thermal power generating unit, and setting parameters of each automatic control logic; the safety of the heat supply unit under the working condition of ensuring the heat supply quality is guaranteed.
(2) The labor intensity of operators can be effectively reduced, and the control effect does not depend on the technical level of the operators.
(3) The real-time property is good, the field debugging process is simple, and the engineering realization is convenient.
Drawings
The invention will be described in further detail with reference to the drawings and specific embodiments for facilitating understanding and practicing of the invention by those of ordinary skill in the art, but it should be understood that the scope of the invention is not limited by the specific embodiments.
FIG. 1 is a logic diagram of the unit bypass heating system fault interlock protection of the present invention;
FIG. 2 is a logic diagram for the high discharge pressure control of the intermediate pressure regulator valve of the steam turbine of the present invention;
fig. 3 is a flow chart of the present invention.
Detailed Description
The invention discloses an optimization control method for improving the operation reliability of bypass heat supply of a unit, which is shown in figure 3, wherein figure 3 is a work flow block diagram of the invention and comprises the following steps:
the first step is as follows: when the heat supply thermal power unit is in a bypass heat supply mode, judging the fault of a unit bypass heat supply system by configuring the control logic of a Distributed Control System (DCS) of the heat supply thermal power unit;
the second step is that: judging the flow of bypass heat supply steam, and performing chain protection action by combining the fault of a unit bypass heat supply system to ensure the safe and stable operation of the unit;
the third step: adding automatic control logic to control the stability of the operation parameters of the unit bypass heating system;
the fourth step: querying historical operation data and design data of a distributed control system DCS of the heat supply thermal power generating unit, and setting parameters of each automatic control logic;
in the first step, the following judgment conditions of the bypass heat supply mode of the heat supply thermal power unit are met simultaneously, and the judgment conditions comprise:
(1) opening signals of all valves of the bypass heating system, all temperature measurement values, all pressure measurement values, all flow measurement values and unit actual power generation measurement values are displayed as good quality in a Distributed Control System (DCS) of the heat supply thermal power unit;
(2) the actual generating power measured value of the unit is lower than the value A1;
(3) the method comprises the following steps that unit operators operate a bypass heating mode input button in a DCS operation picture of a distributed control system of a thermal power generating unit;
in the second step, the size of the bypass heating steam flow is judged, and the method comprises the following steps:
(1) when the flow of the high-side heat supply steam is less than a value B1 or the flow of the low-side heat supply steam is less than a value B2, judging that the flow of the bypass heat supply steam is small;
(2) when the flow of the high-side heat supply steam is greater than or equal to a value B1 or the flow of the low-side heat supply steam is greater than or equal to a value B2, judging that the flow of the bypass heat supply steam is large;
in the first step, the unit bypass heating system fault includes: a fault of mistaken closing of the high-side regulating valve, a fault of mistaken opening of the high-side regulating valve, a fault of jamming of the high-side regulating valve, a fault of mistaken closing of the low-side regulating valve, a fault of mistaken opening of the low-side regulating valve, a fault of jamming of the low-side regulating valve, a fault of water cut-off of bypass temperature-reducing water and a fault of a heat supply network heater;
the judging conditions that the fault of the high side regulating valve is turned off by mistake is as follows are all satisfied simultaneously, and the judging conditions comprise:
(1) the opening of the high bypass regulating valve is smaller than a value C1;
(2) the difference between the high bypass regulating valve instruction and the opening degree is larger than a value C2;
(3) the opening change rate of the high bypass regulating valve is greater than a value C3;
(4) the steam flow rate of change after the high side adjusting valve is larger than a value C4;
(5) the quality of the steam flow after the valve is adjusted by the high side is a non-defective point;
(6) the opening quality of the high bypass regulating valve is a non-defective point;
(7) the electric isolating door in front of the high-side regulating valve is not closed;
the judging conditions that the false opening fault of the high bypass regulating valve is as follows are all met at the same time, and the judging conditions comprise:
(1) the opening of the high bypass regulating valve is larger than a numerical value D1;
(2) the difference value between the opening of the high bypass regulating valve and the instruction is larger than a value D2;
(3) the opening change rate of the high bypass regulating valve is greater than a value D3;
(4) the steam flow rate of change after the high side adjusting valve is larger than a value D4;
(5) the quality of the steam flow after the valve is adjusted by the high side is a non-defective point;
(6) the opening quality of the high bypass regulating valve is a non-defective point;
(7) the electric isolating door in front of the high-side regulating valve is not closed;
the judging conditions that the fault of the low side regulating valve is turned off by mistake is as follows are all satisfied simultaneously, and the judging conditions comprise:
(1) the opening of the low bypass regulating valve is smaller than a value E1;
(2) the difference between the low bypass regulating valve instruction and the opening degree is larger than a value E2;
(3) the opening change rate of the low bypass regulating valve is greater than a value E3;
(4) the steam flow rate of change after the valve is adjusted by the low side bypass is larger than a value E4;
(5) the quality of the steam flow after the valve is adjusted by the low side is a non-defective point;
(6) the opening quality of the low bypass regulating valve is a non-defective point;
(7) the valve is adjusted at the lower side until the electric isolation door of the heat supply network is not closed;
the judging conditions that the fault of the low-side regulating valve is opened by mistake is as follows are all met at the same time, and the judging conditions comprise that:
(1) the opening of the low bypass regulating valve is larger than a numerical value F1;
(2) the difference value between the opening of the low bypass regulating valve and the command is larger than a value F2;
(3) the opening change rate of the low bypass regulating valve is greater than a value F3;
(4) the steam flow rate of change after the valve is adjusted by the low side valve is larger than a value F4;
(5) the steam flow behind the low side adjusting valve is not a dead point;
(6) the opening of the low bypass adjusting valve is not bad;
(7) the valve is adjusted at the lower side until the electric isolation door of the heat supply network is not closed;
the judgment condition of the high bypass regulating valve jamming fault is that the absolute value of the difference value between the high bypass regulating valve instruction and the opening degree is greater than a value G1, and the judgment condition of the low bypass regulating valve jamming fault is that the absolute value of the difference value between the low bypass regulating valve instruction and the opening degree is greater than a value G2;
the bypass desuperheating water-break fault is any one of the following judgment conditions, including:
(1) the steam temperature quality after the valve is adjusted by the high side is good and is greater than the value H1;
(2) the steam temperature quality after the high-side regulating valve is good and is greater than a value H2, and the pressure of the high-side desuperheating water is lower than a value H3;
(3) the steam temperature quality after the valve is adjusted by the low side is good and is greater than the value H4;
(4) the steam temperature quality after the low-side regulating valve is good and is greater than a value H5, and the pressure of the low-side desuperheating water is lower than a value H6;
the fault judgment condition of the heat supply network heaters is that the steam inlet valve instructions and the opening degrees of 2 heat supply network heaters in 4 heat supply network heaters are all smaller than a value I1;
in the second step: judging the size of bypass heat supply steam flow, combining the above-mentioned unit bypass heating system trouble and carrying out chain protection action, the step of the safe and stable operation of assurance unit specifically is:
(1) when judging bypass heat supply steam flow hour, the chain protection action after unit bypass heating system trouble takes place includes: when the high side regulating valve is in fault of being closed by mistake, the medium pressure regulating valve of the steam turbine is opened in a linkage manner, and the low side regulating valve is closed in a linkage manner; when the high side regulating valve is in fault of opening by mistake, the medium pressure regulating valve of the steam turbine is opened in a linkage manner, if the medium pressure regulating valve is fully opened, the low side regulating valve and the low side regulating valve are continuously opened and then reach the electric isolating door of the condenser so as to maintain the high discharge pressure to be stable; when the low-side regulating valve is in fault of being closed by mistake, the medium-pressure regulating valve of the steam turbine is opened in a linkage manner, the high-side regulating valve is closed in a linkage manner, when the low-side regulating valve is in fault of being opened by mistake, the low-side regulating valve is closed in a linkage manner and then reaches the electric isolating door of the heat supply network, and the high-side regulating valve is closed in a linkage manner so as to maintain the high discharge pressure to be stable; when the bypass temperature-reducing water is cut off, the high bypass adjusting valve and the low bypass adjusting valve are turned off, and the temperature-reducing water corresponding to the downstream heating surface is turned on; when the heat supply network heater fails, the high side regulating valve and the low side regulating valve are closed in a linkage manner; when any one of the unit bypass heating systems fails, the coordinated control system automatically switches the boiler main control to a manual mode, timing is started at the same time, and if the timing value is greater than J1 and the main steam pressure is higher than a value J2, the unit bypass heating system is triggered to fail RB, and the load is quickly reduced;
(2) when judging bypass heat supply steam flow when big, the chain protection action after unit bypass heating system trouble takes place still includes including the chain protection action when the aforesaid is judged bypass heat supply steam flow hour: the coordination control system automatically switches the steam turbine master control into a manual mode, and a boiler pressure control valve PCV is opened in a linkage manner to trigger a unit bypass heating system fault RB;
(3) when the high side regulating valve is jammed and has a fault, the low side regulating valve is locked to act, and an alarm is given to prompt operating personnel; when the low side regulating valve is jammed and has a fault, the high side regulating valve is locked to act, and an alarm is given to prompt an operator.
The action process of the unit bypass heating system fault RB is as follows: after the fault RB of the bypass heat supply system of the unit occurs, the coordinated control system switches the fuel main control mode into a manual mode, meanwhile, whether the number of the coal mills operated by the unit is larger than the number of 50% of rated power generation power is judged, if so, an instruction of tripping the coal mill at the uppermost layer is sent, and after 10 seconds of delay, a second coal mill is tripped until the number of the coal mills operated is not larger than the number of 50% of rated power generation power.
In the third step: the method is characterized in that automatic control logic is added, and the steps of controlling the stability of main operation parameters of the unit bypass heating system are as follows:
(2) a PID regulator of the high exhaust pressure of a turbine medium pressure regulating valve is added to control the high exhaust pressure of the turbine within a reasonable range, the set value of the PID regulator is a set value of the low limit of the high exhaust pressure, the regulation stage pressure of the turbine is calculated by a Distributed Control System (DCS) with a heat supply thermal power unit with a broken line function f1(x), the feedback value of the PID regulator is a measured value of the high exhaust pressure, the output value of the PID regulator is used as offset and is added with the original turbine medium pressure regulating valve instruction to form a final turbine medium pressure regulating valve instruction, and the range of the output value of the PID regulator is-K1-0%;
(2) increasing the switching rate limit control logic of the high bypass adjusting valve and the low bypass adjusting valve, wherein the switching rate limit of the high bypass adjusting valve and the low bypass adjusting valve is variable parameter control, when the unit is in a bypass heating mode, the value of the rate limit is L1, and when the unit is not in the bypass heating mode, the value of the rate limit is L2;
(3) and designing a switching sequence locking condition of the high-side regulating valve and the electric isolating door in front of the high-side regulating valve in a control logic, and ensuring that the electric isolating door in front of the high-side regulating valve is opened firstly and then the high-side regulating valve is opened, and the high-side regulating valve is not closed and does not allow the electric isolating door in front of the high-side regulating valve to be opened.
In the fourth step: the method comprises the following steps of inquiring historical operating data and design data of a distributed control system DCS of the heat supply thermal power generating unit and setting parameters of each automatic control logic:
(2) querying historical operating data of relevant parameters in a database of a DCS (distributed control system) historical control station of a distributed control system of a heat supply thermal power generating unit, and determining the range of normal values of the relevant parameters after eliminating abnormal data;
(2) determining the range of abnormal values of the relevant parameters according to the range of normal values of the relevant parameters and by combining design data;
(3) determining the value in each judgment condition according to the range of the normal value and the range of the abnormal value of the relevant parameter;
the specific range of the numerical value A1 is 30% Pe to 50% Pe, Pe is rated power generation, the specific range of the numerical value B1 is 350t/h to 450t/h, the specific range of the numerical value B2 is 450t/h to 550t/h, the specific range of the numerical value C1 is 2% to 5%, the specific range of the numerical value C2 is 40% to 50%, the specific range of the numerical value C3 is-2%/s to-1%/s, the specific range of the numerical value C4 is-45 t/h/s to-40 t/h/s, the specific range of the numerical value D1 is 55% to 60%, the specific range of the numerical value D2 is 40% to 50%, the specific range of the numerical value D3 is 1%/s to 2%/s, the specific range of the numerical value D4 is 40t/h/s to 45t/h/s, the specific range of the numerical value E1 is 2% to 5%, a specific range of the value E2 is 40% to 50%, a specific range of the value E3 is-2%/s to-1%/s, a specific range of the value E4 is-50 t/H/s to-45 t/H/s, a specific range of the value F1 is 55% to 60%, a specific range of the value F2 is 40% to 50%, a specific range of the value F3 is 1%/s to 2%/s, a specific range of the value F4 is 45t/H/s to 50t/H/s, a specific range of the value G1 is 15% to 20%, a specific range of the value G2 is 15% to 20%, a specific range of the value H1 is a maximum temperature that can be allowed by the piping material after a high bypass adjustment valve, generally 350 ℃, a specific range of the value H2 is 20 ℃ lower than the maximum temperature that can be allowed by the piping material after a high bypass adjustment valve, generally 330 ℃, a specific range of the value H4 is a maximum temperature that can be allowed by the, generally 300 ℃, the value H5 is 20 ℃, generally 280 ℃, the value I1 specifically ranges from 2% to 5%, the value J1 specifically ranges from 0 second to 200 seconds, the value J2 specifically ranges from 17Mpa to 19Mpa of the subcritical unit, the value K1 specifically ranges from 20% to 25%, the value L1 specifically ranges from 1%/min to 5%/min, and the value L2 specifically ranges from 5%/min to 20%/min;
the pressure of the high-side temperature-reducing water is lower than a value H3, the specific forming process is that the cold recompression is added with 0.5MPa, and the specific forming process that the pressure of the low-side temperature-reducing water is lower than a value H6 is that the pressure is added with 0.5MPa after the valve is adjusted by the low side;
the core idea of the invention is that when the heat supply thermal power unit is in a bypass heat supply mode, the fault of the unit bypass heat supply system is judged by configuring the control logic of a distributed control system DCS of the heat supply thermal power unit; judging the flow of bypass heat supply steam, and performing chain protection action by combining the faults of the unit bypass heat supply system to ensure the safe and stable operation of the unit; adding automatic control logic to control the stability of main operation parameters of the bypass heating system; querying historical operation data and design data of a distributed control system DCS of the heat supply thermal power generating unit, and setting parameters of each automatic control logic; the safety of the heat supply unit under the working condition of ensuring the heat supply quality is guaranteed.
The invention discloses an algorithm logic diagram, namely an optimization control algorithm for improving the operation reliability of unit bypass heating, wherein the logic of unit bypass heating system fault interlock protection is shown in figure 1, and the logic of turbine medium-pressure regulating valve high-exhaust pressure control is shown in figure 2.
In fig. 1, a fault of mistakenly closing a high-side regulating valve, a fault of mistakenly opening a high-side regulating valve, a fault of mistakenly closing a low-side regulating valve, a fault of mistakenly opening a low-side regulating valve, a fault of water cut-off of bypass temperature-reducing water, a fault of a heat supply network heater, a bypass heat supply thermal power generating unit in a bypass heat supply mode, and a large bypass heat supply steam flow are obtained by logical judgment; and the main steam pressure is directly read from a DCS real-time database of the distributed control system of the heat supply thermal power generating unit.
In fig. 2, the turbine regulation stage pressure, the high exhaust pressure measurement value, and the original turbine medium pressure regulation valve instruction are directly read from the distributed control system DCS real-time database of the heat supply thermal power generating unit; f. of1(x) The distributed control system DCS is provided with a broken line function for the heat supply thermal power generating unit, the input of the broken line function is the pressure of a regulating stage of the steam turbine, the output is the set value of a PID regulator for regulating the high exhaust pressure of a valve of the medium pressure regulating valve of the steam turbine, f1(x) The parameters of (2) can be adjusted on line according to a real-time curve.
The optimization control of the bypass heat supply operation reliability of a hoisting unit of a certain 350MW heat supply unit is taken as an example, and the setting result of the algorithm parameters is introduced.
Overview of the unit: the unit boiler is an HG-1125/25.4-HM2 type supercritical boiler manufactured by Harbin boiler plant Limited liability company, and is a variable-pressure Bunsen direct current boiler with supercritical pressure, spiral pipe rings, a low NOx direct current pulverized coal burner, primary intermediate reheating, single hearth balanced ventilation, close-fitting sealing, solid slag discharging and all-steel framework, and a powder making system: each boiler is provided with 5 medium-speed coal mills, 4 boilers run, and 1 boiler is reserved; the steam turbine is an NC 350-24.2/0.4/566/556 type supercritical, primary intermediate reheating, double-cylinder double-steam-exhaust and steam-extraction condensing steam turbine produced by North steam North heavy steam turbine Limited liability company; the turbine of the unit adopts a two-stage serial bypass system device of a high-pressure bypass and a low-pressure bypass, the design capacity is 40 percent BMCR, the high-pressure bypass desuperheating water is taken from high-pressure feed water, and the low-pressure bypass desuperheating water is taken from condensed water.
The rated capacity of the unit is 350MW, and the parameter setting result is as follows: a value A1 of 175MW, a value B1 of 400t/H, a value B2 of 500t/H, a value C1 of 5%, a value C2 of 50%, a value C3 of-1%/s, a value C4 of-40 t/H/s, a value D1 of 60%, a value D2 of 50%, a value D3 of 1%/s, a value D4 of 40t/H/s, a value E1 of 5%, a value E2 of 50%, a value E3 of-1%/s, a value E4 of-50 t/H/s, a value F1 of 60%, a value F2 of 50%, a value F3 of 1%/s, a value F4 of 50t/H/s, a value G4 of 20%, a value H4 of 350 ℃, a value H4 of 330 ℃, a value H4 of 300 ℃, a value H4 of 120% J4, a value J4, the value J2 is 27MPa, the value K1 is 20%, the value L1 is 1%/min, the value L2 is 5%/min;
as shown in Table 1, Table 1 shows the setting of the control parameter of the set value of the PID regulator for the medium pressure regulating valve and the high exhaust pressure of the steam turbine.
In Table 1 with f1(x) Corresponding x is the pressure of a steam turbine regulating stage, the logical configuration of a control loop of the optimized control method for improving the reliability of the bypass heat supply operation of the unit is completed, the system is put into actual operation, and f is repeatedly set on line according to the operation curve of the unit1(x) A parameter; the field debugging process is simple, and engineering implementation is facilitated.
TABLE 1 broken line function f of distributed control system DCS of heat supply thermal power generating unit1(x) Control parameter tuning
| x(MPa) | 5.5 | 8.2 | 12.0 | 17.0 | 19.2 |
| f1(x)( MPa) | 1 | 1 | 2.2 | 3.7 | 4.25 |
Claims (8)
1. An optimization control method for improving the operation reliability of bypass heat supply of a unit is characterized by comprising the following steps: the method comprises the following steps:
the first step is as follows: when the heat supply thermal power unit is in a bypass heat supply mode, judging the fault of a unit bypass heat supply system by configuring the control logic of a Distributed Control System (DCS) of the heat supply thermal power unit;
the second step is that: judging the flow of bypass heat supply steam, and performing chain protection action by combining the fault of a unit bypass heat supply system to ensure the safe and stable operation of the unit;
the third step: adding automatic control logic to control the stability of the operation parameters of the unit bypass heating system;
the method comprises the following steps:
(1) a PID regulator of the high exhaust pressure of a turbine medium pressure regulating valve is added to control the high exhaust pressure of the turbine within a reasonable range, the set value of the PID regulator is a set value of the low limit of the high exhaust pressure, the regulation stage pressure of the turbine is calculated by a Distributed Control System (DCS) with a heat supply thermal power unit with a broken line function f1(x), the feedback value of the PID regulator is a measured value of the high exhaust pressure, the output value of the PID regulator is used as offset and is added with the original turbine medium pressure regulating valve instruction to form a final turbine medium pressure regulating valve instruction, and the range of the output value of the PID regulator is-K1-0%;
(2) increasing the switching rate limit control logic of the high bypass adjusting valve and the low bypass adjusting valve, wherein the switching rate limit of the high bypass adjusting valve and the low bypass adjusting valve is variable parameter control, when the unit is in a bypass heating mode, the value of the rate limit is L1, and when the unit is not in the bypass heating mode, the value of the rate limit is L2;
(3) designing a switching sequence locking condition of the high-side regulating valve and the electric isolating door in front of the high-side regulating valve in a control logic to ensure that the electric isolating door in front of the high-side regulating valve is opened firstly and then the high-side regulating valve is opened, and the electric isolating door in front of the high-side regulating valve is not allowed to be opened when the high-side regulating valve is not closed;
the fourth step: and querying historical operating data and design data of a distributed control system DCS of the heat supply thermal power generating unit, and setting parameters of each automatic control logic.
2. The optimal control method for improving the operational reliability of the bypass heating of the unit as claimed in claim 1, wherein the optimal control method comprises the following steps: in the first step, the following judgment conditions of the bypass heat supply mode of the heat supply thermal power unit are met simultaneously, and the judgment conditions comprise:
(1) opening signals of all valves of the bypass heating system, all temperature measurement values, all pressure measurement values, all flow measurement values and unit actual power generation measurement values are displayed as good quality in a Distributed Control System (DCS) of the heat supply thermal power unit;
(2) the actual generating power measured value of the unit is lower than the value A1;
(3) and operating a bypass heating mode input button in a DCS operation picture of the distributed control system of the thermal power generating unit by a unit operator.
3. The optimal control method for improving the operational reliability of the bypass heating of the unit as claimed in claim 1, wherein the optimal control method comprises the following steps: in the first step, the unit bypass heating system fault includes: the fault of the high-side regulating valve is mistakenly closed, the fault of the high-side regulating valve is mistakenly opened, the fault of the high-side regulating valve is stuck, the fault of the low-side regulating valve is mistakenly closed, the fault of the low-side regulating valve is mistakenly opened, the fault of the low-side regulating valve is stuck, the fault of the bypass temperature-reducing water cut-off and the fault of the heat supply network heater.
4. The optimal control method for improving the operational reliability of the bypass heating of the unit as claimed in claim 1, wherein the optimal control method comprises the following steps: in the second step, the size of the bypass heating steam flow is judged, and the method comprises the following steps:
(1) when the flow of the high-side heat supply steam is less than a value B1 or the flow of the low-side heat supply steam is less than a value B2, judging that the flow of the bypass heat supply steam is small;
(2) and when the flow of the high-side heat supply steam is greater than or equal to a value B1 or the flow of the low-side heat supply steam is greater than or equal to a value B2, judging that the flow of the bypass heat supply steam is large.
5. The optimal control method for improving the operational reliability of the bypass heating of the unit as claimed in claim 1, wherein the optimal control method comprises the following steps: in the second step, judge the size of bypass heat supply steam flow, combine unit bypass heating system trouble to carry out chain protection action, the step is:
step 1: when judging bypass heat supply steam flow hour, the chain protection action after unit bypass heating system trouble takes place includes: when the high side regulating valve is in fault of being closed by mistake, the medium pressure regulating valve of the steam turbine is opened in a linkage manner, and the low side regulating valve is closed in a linkage manner; when the high side regulating valve is in fault of opening by mistake, the medium pressure regulating valve of the steam turbine is opened in a linkage manner, if the medium pressure regulating valve is fully opened, the low side regulating valve and the low side regulating valve are continuously opened and then reach the electric isolating door of the condenser so as to maintain the high discharge pressure to be stable; when the low-side regulating valve is in fault of being closed by mistake, the medium-pressure regulating valve of the steam turbine is opened in a linkage manner, the high-side regulating valve is closed in a linkage manner, when the low-side regulating valve is in fault of being opened by mistake, the low-side regulating valve is closed in a linkage manner and then reaches the electric isolating door of the heat supply network, and the high-side regulating valve is closed in a linkage manner so as to maintain the high discharge pressure to be stable; when the bypass temperature-reducing water is cut off, the high bypass adjusting valve and the low bypass adjusting valve are turned off, and the temperature-reducing water corresponding to the downstream heating surface is turned on; when the heat supply network heater fails, the high side regulating valve and the low side regulating valve are closed in a linkage manner; when any one of the unit bypass heating systems fails, the coordinated control system automatically switches the boiler main control to a manual mode, timing is started at the same time, and if the timing value is greater than J1 and the main steam pressure is higher than a value J2, the unit bypass heating system is triggered to fail RB, and the load is quickly reduced;
step 2: when judging bypass heat supply steam flow when big, the chain protection action after unit bypass heating system trouble takes place still includes including the chain protection action when the aforesaid is judged bypass heat supply steam flow hour: the coordination control system automatically switches the steam turbine master control into a manual mode, and a boiler pressure control valve PCV is opened in a linkage manner to trigger a unit bypass heating system fault RB;
and step 3: when the high side regulating valve is jammed and has a fault, the low side regulating valve is locked to act, and an alarm is given to prompt operating personnel; when the low side regulating valve is jammed and has a fault, the high side regulating valve is locked to act, and an alarm is given to prompt an operator.
6. The optimal control method for improving the operational reliability of the bypass heating of the unit as claimed in claim 3, wherein the optimal control method comprises the following steps: the judging conditions that the fault of the high side regulating valve is turned off by mistake is as follows are all satisfied simultaneously, and the judging conditions comprise:
(1) the opening of the high bypass regulating valve is smaller than a value C1;
(2) the difference between the high bypass regulating valve instruction and the opening degree is larger than a value C2;
(3) the opening change rate of the high bypass regulating valve is greater than a value C3;
(4) the steam flow rate of change after the high side adjusting valve is larger than a value C4;
(5) the quality of the steam flow after the valve is adjusted by the high side is a non-defective point;
(6) the opening quality of the high bypass regulating valve is a non-defective point;
(7) the electric isolating door in front of the high-side regulating valve is not closed;
the judging conditions that the false opening fault of the high bypass regulating valve is as follows are all met at the same time, and the judging conditions comprise:
(1) the opening of the high bypass regulating valve is larger than a numerical value D1;
(2) the difference value between the opening of the high bypass regulating valve and the instruction is larger than a value D2;
(3) the opening change rate of the high bypass regulating valve is greater than a value D3;
(4) the steam flow rate of change after the high side adjusting valve is larger than a value D4;
(5) the quality of the steam flow after the valve is adjusted by the high side is a non-defective point;
(6) the opening quality of the high bypass regulating valve is a non-defective point;
(7) the electric isolating door in front of the high-side regulating valve is not closed;
the judging conditions that the fault of the low side regulating valve is turned off by mistake is as follows are all satisfied simultaneously, and the judging conditions comprise:
(1) the opening of the low bypass regulating valve is smaller than a value E1;
(2) the difference between the low bypass regulating valve instruction and the opening degree is larger than a value E2;
(3) the opening change rate of the low bypass regulating valve is greater than a value E3;
(4) the steam flow rate of change after the valve is adjusted by the low side bypass is larger than a value E4;
(5) the quality of the steam flow after the valve is adjusted by the low side is a non-defective point;
(6) the opening quality of the low bypass regulating valve is a non-defective point;
(7) the valve is adjusted at the lower side until the electric isolation door of the heat supply network is not closed;
the judging conditions that the fault of the low-side regulating valve is opened by mistake is as follows are all met at the same time, and the judging conditions comprise that:
(1) the opening of the low bypass regulating valve is larger than a numerical value F1;
(2) the difference value between the opening of the low bypass regulating valve and the command is larger than a value F2;
(3) the opening change rate of the low bypass regulating valve is greater than a value F3;
(4) the steam flow rate of change after the valve is adjusted by the low side valve is larger than a value F4;
(5) the steam flow behind the low side adjusting valve is not a dead point;
(6) the opening of the low bypass adjusting valve is not bad;
(7) the valve is adjusted at the lower side until the electric isolation door of the heat supply network is not closed;
the judgment condition of the high bypass regulating valve jamming fault is that the absolute value of the difference value between the high bypass regulating valve instruction and the opening degree is greater than a value G1, and the judgment condition of the low bypass regulating valve jamming fault is that the absolute value of the difference value between the low bypass regulating valve instruction and the opening degree is greater than a value G2;
the bypass desuperheating water-break fault is any one of the following judgment conditions, including:
(1) the steam temperature quality after the valve is adjusted by the high side is good and is greater than the value H1;
(2) the steam temperature quality after the high-side regulating valve is good and is greater than a value H2, and the pressure of the high-side desuperheating water is lower than a value H3;
(3) the steam temperature quality after the valve is adjusted by the low side is good and is greater than the value H4;
(4) the steam temperature quality after the low-side regulating valve is good and is greater than a value H5, and the pressure of the low-side desuperheating water is lower than a value H6;
the pressure of the high-side temperature-reducing water is lower than a value H3, the forming process is that the cold recompression is added with 0.5MPa, and the forming process of the low-side temperature-reducing water is lower than a value H6, the pressure of the low-side temperature-reducing water is added with 0.5MPa after the valve is adjusted;
and the fault judgment condition of the heat supply network heaters is that the steam inlet valve instruction and the opening of 2 heat supply network heaters in 4 heat supply network heaters are smaller than a value I1.
7. The optimal control method for improving the operational reliability of the bypass heating of the unit as claimed in claim 5, wherein the optimal control method comprises the following steps: the action process of the unit bypass heating system fault RB is as follows: after the fault RB of the bypass heat supply system of the unit occurs, the coordinated control system switches the fuel main control mode into a manual mode, meanwhile, whether the number of the coal mills operated by the unit is larger than the number of 50% of rated power generation power is judged, if so, an instruction of tripping the coal mill at the uppermost layer is sent, and after 10 seconds of delay, a second coal mill is tripped until the number of the coal mills operated is not larger than the number of 50% of rated power generation power.
8. The optimal control method for improving the operational reliability of the bypass heating of the unit as claimed in claim 1, wherein the optimal control method comprises the following steps: in the fourth step: the method comprises the following steps of inquiring historical operating data and design data of a distributed control system DCS of the heat supply thermal power generating unit and setting parameters of each automatic control logic:
(1) querying historical operating data of relevant parameters in a database of a DCS (distributed control system) historical control station of a distributed control system of a heat supply thermal power generating unit, and determining the range of normal values of the relevant parameters after eliminating abnormal data;
(2) determining the range of abnormal values of the relevant parameters according to the range of normal values of the relevant parameters and by combining design data;
(3) and determining the numerical value in each judgment condition according to the range of the normal numerical value and the range of the abnormal numerical value of the relevant parameter.
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