A reverse fast coordinated control method based on DCS system of coal-fired generator sets

Abstract

A reverse rapid coordinated control method based on the DCS system of a coal-fired generator set maintains the control logic structure of the DCS system, dynamically revising the control parameters and setpoints of the regulated objects to implement reverse regulation control logic. The setpoints for the main steam pressure on the turbine side and the boiler side are dynamically calculated based on the real-time main steam pressure deviation. The turbine and boiler side load commands are issued based on the nonlinear function output by the variable load ratios of the turbine and boiler sides. The setpoints for the primary air pressure and mill cylinder pressure are based on the nonlinear function output by the variable load command on the boiler side. The PID control parameters of the turbine and boiler main controls are functions related to the main steam pressure deviation, and the magnitude of the PID control parameters for the turbine and boiler main controls are opposite to each other. This system improves the K value of the unit, requires minimal investment, requires less maintenance, and has rapid returns.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-fired power generation, in particular to a reverse rapid coordinated control method based on a DCS system of a coal-fired generator set. Background Art

[0002] To maintain grid stability, existing technology relies on primary frequency regulation. However, its contribution is relatively limited and cannot meet the needs of deep frequency regulation. Therefore, the power grid has introduced a deep auxiliary frequency regulation system. By issuing auxiliary frequency regulation commands to each unit with good regulation performance, the grid frequency can be quickly stabilized. Units participating in auxiliary frequency regulation can benefit from this, and the level of benefits depends primarily on the unit's comprehensive performance K value. The winning bid rules for grid-assisted frequency regulation require that each generator set can quickly adapt to changes in grid load demand. These are mainly composed of three indicators: regulation rate K1, response rate K2, and regulation accuracy K3. The comprehensive performance K value is K=0.5*K1+0.25*K1+0.25*K3. For the same regulation range, a higher K value indicates better coordinated control performance of the unit, and the higher the winning bid profit in the auxiliary frequency regulation system, thereby achieving revenue generation.

[0003] Traditional coordinated control methods for increasing the K value of a unit currently have two main approaches: installing an energy storage system or an external auxiliary control system. Energy storage systems offer the best results, but they require significant investment and are typically implemented through partnerships where profits are shared with investors. External systems are primarily promoted by scientific research institutions, but their core technology resides in external equipment, which coordinates control with the unit through communication. This makes maintenance difficult, and any issues require on-site intervention by the manufacturer.

[0004] The power grid requires units to respond quickly to load changes, with high load variation rates and regulation accuracy. Traditional coordinated control systems use a fixed load variation rate in the same direction to control the turbine and boiler control units. The feedforward control variables of these traditional control systems typically use load commands or related variables, but fail to consider the direction of change in key parameters, often resulting in counterproductive effects. For example, when the unit is loaded, the main steam pressure is significantly higher. The turbine control unit increases the load to eliminate the pressure deviation, while the boiler control unit continues to adjust the combustion system according to a fixed load variation rate. This results in a delayed elimination of the pressure deviation, causing the load deviation to increasingly deviate from the command. The opposite situation occurs when the load is reduced. Second, the combustion control system does not integrate the magnitude and direction of the current deviation in the unit's key parameters to adjust the control parameters. Consequently, pressure deviations cannot be quickly eliminated in auxiliary frequency regulation mode, and the integrated K value does not meet the minimum bid-winning requirements. Therefore, an intelligent integrated feedforward control system is needed to coordinate the combustion control system to adapt to frequent unit load variations. The power grid requires that the units respond quickly when changing loads, and have high load change rates and regulation accuracy. In addition, the characteristics of auxiliary frequency regulation are that the direction and magnitude of load command changes are very frequent. Traditional coordinated control systems find it difficult to adapt to such changes. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a reverse rapid coordinated control method based on the DCS system of a coal-fired generator set, which has the characteristics of improving the K value of the unit, low investment, low maintenance and fast returns.

[0006] To achieve the above technical objectives, the adopted technical solution is: a reverse rapid coordinated control method based on the DCS system of a coal-fired generator set, which maintains the control logic structure of the DCS system of the coal-fired generator set unchanged, dynamically modifies the control adjustment parameters and the set values ​​of the adjustment objects, and realizes the reverse adjustment control logic. The specific implementation method is as follows:

[0007] The main steam pressure set value is divided into the turbine-side main steam pressure set value and the boiler-side main steam pressure set value. A nonlinear function of the rate of the main steam pressure set values ​​on the turbine side and the boiler side corresponding to the main steam pressure deviation is constructed. The main steam pressure deviation is obtained by subtracting the main steam pressure from the turbine-side main steam pressure set value. The rate of the turbine-side main steam pressure set value and the rate of the boiler-side main steam pressure set value are opposite in magnitude. The turbine-side main steam pressure set value and the boiler-side main steam pressure set value are dynamically calculated according to the set value rate corresponding to the real-time changing main steam pressure deviation;

[0008] The load instructions are divided into engine-side load instructions and furnace-side load instructions. A nonlinear function of the engine-side and furnace-side variable load rate outputs is constructed, which is composed of the main steam pressure deviation corresponding to the engine-side and furnace-side variable load rates. The engine-side and furnace-side variable load rates corresponding to the main steam pressure deviation are opposite in magnitude. The engine-side and furnace-side load instructions are issued according to the nonlinear function of the engine-side and furnace-side variable load rate outputs.

[0009] The set values ​​of primary air pressure and coal mill cylinder pressure adopt the nonlinear function output by the furnace side variable load instruction;

[0010] The PID adjustment parameters of the turbine master control and the boiler master control are functions related to the main steam pressure deviation. The PID adjustment parameters of the turbine master control and the boiler master control corresponding to the main steam pressure deviation are opposite in size.

[0011] The PID adjustment parameters described in the present invention include integral time Ti and proportional coefficient Kp.

[0012] A reverse rapid coordinated control method based on the DCS system of a coal-fired power generation unit is characterized by: also including rapid load variation logic, specifically implemented by constructing a machine-side rapid load variation rate function related to the size of the unit's AGC instruction, and restoring to the machine-side load variation rate output nonlinear function after the unit's AGC instruction issues an N-second pulse.

[0013] A reverse rapid coordinated control method based on the DCS system of a coal-fired generator set also includes a primary air pressure set value increase rate control. The specific implementation method is that the primary air pressure set value rate of change is a function value related to the furnace side main pressure deviation. The furnace side main pressure deviation is obtained by subtracting the main steam pressure from the furnace side main steam pressure set value. When the load is increased, the primary air pressure set value rate of change increases with the increase of the furnace side main pressure deviation. When the load is reduced, the primary air pressure set value rate of change decreases with the increase of the furnace side main pressure deviation.

[0014] A reverse fast coordinated control system based on a DCS system of a coal-fired power generation unit also includes a primary air intelligent feedforward logic. The specific process is to construct a primary air pressure set value feedforward function f(x)1 corresponding to the primary air pressure of the furnace side load deviation when the load is increased, construct a primary air pressure set value feedforward function f(x)2 corresponding to the primary air pressure of the furnace side load deviation when the load is reduced, construct a primary air pressure set value feedforward function f(x)3 corresponding to the primary air pressure of the furnace side main pressure deviation when the load is increased, and construct a primary air pressure set value feedforward function f(x)4 corresponding to the primary air pressure of the furnace side main pressure deviation when the load is reduced. The primary air intelligent feedforward f(x) is obtained from three situations:

[0015] a. When the load is reduced or increased, and the main steam pressure on the machine side is higher than the set value of the main steam pressure on the machine side, the output is obtained by f(x)1+f(x)3;

[0016] b. When the load is increased or decreased, if the main steam pressure on the machine side is lower than the set value of the main steam pressure on the machine side, the output is obtained by f(x)2+f(x)4;

[0017] c. When the absolute value of the machine-side load deviation is less than 3MW at the end of the variable load, and the absolute value of the machine-side main pressure deviation is greater than 0.3MPa, the current value is kept unchanged and output is obtained.

[0018] The beneficial effects of the present invention are as follows: the present method adopts a flexible and variable load rate, which not only takes into account the magnitude of the main steam pressure deviation and the length of the load instruction change, but also the direction of the deviation. When the load is increased, the variable load rate is increased if the pressure is high, and when the load is reduced, the variable load rate is reduced if the pressure is high, and vice versa. At the same time, it is also necessary to consider that the steam turbine master control and the boiler master control cannot be adjusted at the same rate. When the pressure deviation is large, a reverse control strategy is used to coordinate the control to achieve stable control parameters of the unit and reduce the deviation. Ultimately, the purpose of fast unit load response, high variable load rate and adjustment accuracy, and significantly improved unit K value is achieved, and the problem of low battery capacity in the energy storage system is solved, which can extend the life of the battery in the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the logic diagram of this method;

[0020] Figure 2 The graph of variable load rate f(x)1 on the load adding opportunity side;

[0021] Figure 3 The load rate f(x)2 curve diagram for the load reduction opportunity side;

[0022] Figure 4 This is the logic block diagram of the unit load instruction;

[0023] Figure 5 This is the curve of the main pressure setting value rate f(x)1 on the load-adding timing side;

[0024] Figure 6 This is the main pressure setting value rate f(x)2 curve diagram of the load reduction timing side;

[0025] Figure 7 This is the rate curve of the furnace side main pressure setting value when adding load;

[0026] Figure 8 This is the rate curve of the furnace side main pressure setting value when the load is reduced;

[0027] Figure 9 This is the logic block diagram of the main steam pressure setting value;

[0028] Figure 10 This is the Ti change curve of the turbine coordination PID when the load is added;

[0029] Figure 11 This is the Ti change curve of the turbine coordination PID when the load is reduced;

[0030] Figure 12 This is the Kp change curve of the turbine coordination PID when the load is added;

[0031] Figure 13 This is the Kp change curve of the turbine coordination PID when the load is reduced;

[0032] Figure 14 This is the Ti change curve of the boiler coordination PID when the load is added;

[0033] Figure 15 This is the Ti change curve of the boiler coordination PID when the load is reduced;

[0034] Figure 16 This is the Kp change curve of the boiler coordination PID when the load is added;

[0035] Figure 17 This is the Kp change curve of the boiler coordination PID when the load is reduced;

[0036] Figure 18 It is the fast load rate f(x) curve;

[0037] Figure 19 This is the logic diagram for fast load change control;

[0038] Figure 20 This is the primary air set value rate curve when the load is added;

[0039] Figure 21 This is the primary air set value rate curve when the load is reduced;

[0040] Figure 22 It is the curve diagram of the primary wind pressure feedforward function f(x)1 when the load is added;

[0041] Figure 23 This is the curve of the primary wind pressure feedforward function f(x)2 during load reduction;

[0042] Figure 24 The graph of the primary wind pressure feedforward function f(x)3 when the load is added;

[0043] Figure 25 The graph of the primary wind pressure feedforward function f(x)4 during load reduction;

[0044] Figure 26 This is the primary wind intelligent feedforward logic diagram;

[0045] Figure 27 This is the coordinated control trend curve of the 330MW unit. DETAILED DESCRIPTION

[0046] A reverse fast coordinator control method (RFCCS) based on the DCS system of coal-fired generator sets is mainly composed of two parts, namely reverse regulation control logic and fast load change logic. The reverse regulation control logic can be used alone or in combination with the fast load change logic to improve the performance of the unit. The logic block diagram of RFCCS is shown in the figure. Figure 1 shown.

[0047] 1. RFCCS is modified on the basis of the original coordinated control system, keeping the original control logic structure unchanged, and dynamically correcting the control parameters and the set values ​​of the control objects. The adjustment rates of the turbine and boiler sides are opposite, that is, the adjustment rate of the steam turbine master control is fast, and the adjustment rate of the boiler master control is slow, or the adjustment rate of the steam turbine master control is fast, and the adjustment rate of the boiler master control is slow, and finally achieve synchronization, which is called reverse regulation. Reverse regulation mainly involves the unit load instruction logic ( Figure 4 )、Main steam pressure setting value logic( Figure 9 ), PID adjustment parameters (proportional coefficient Kp and integral time Ti) ( Figures 10-17 ).

[0048] 2. The second component is the rapid load change logic, which consists of the rapid load change control logic ( Figure 19 ) and primary wind intelligent feedforward logic ( Figure 26 The rapid load-variation control logic primarily sets a high load-variation ratio during load changes, allowing the unit to reach 0.5% of the rated load within 10 seconds, improving the unit's response rate. The primary air intelligent feedforward logic, generated by combining unit load deviations and main steam pressure deviations, coordinates combustion system regulation, quickly replenishing the heat consumed by the turbine's rapid load changes.

[0049] Terminology Notes:

[0050] 1) Main steam pressure setpoint: A sliding pressure curve converted from the unit load command through a function. Within the RFCCS, this is divided into the generator-side main steam pressure setpoint and the boiler-side main steam pressure setpoint.

[0051] 2) Main steam pressure deviation: the difference between the main steam pressure setting value and the main steam pressure.

[0052] 3) Boiler feedforward: It is used to control the rapid output instructions of each subsystem of the coal-fired regulation system (pulverizing system, air supply system, induced draft system, primary air system, etc.).

[0053] 4) Unit load command: This command is generated by rate-limiting the unit load target value. Traditional coordinated control systems use the same rate-limited unit load command on both the generator and furnace sides. However, RFCCS uses separate unit load commands for the generator and furnace sides, each with different rates, for the generator-side and furnace-side master controls, respectively.

[0054] 1. The reverse regulation control logic consists of three parts:

[0055] 1) Variable load rate: The variable load rate is related to the main steam pressure deviation and the direction of load change. A nonlinear function of the variable load rate output of the engine side and boiler side is constructed, which is composed of the variable load rates of the engine side and boiler side corresponding to the main steam pressure deviation.

[0056] a. The variable load rate is changed from a manually set value to a function related to the main steam pressure deviation, such as Figure 2 、 Figure 3As shown, the rate is (1.5-10) MW / min. Taking the generator side of a 330MW unit as an example, when the main steam pressure is higher than the set value and greater than 0.3 MPa during load increase, the rate becomes (7-10) MW / min. When the main steam pressure is lower than the set value and exceeds 0.3 MPa, the variable load rate becomes (7-1.5) MW / min. When the main steam pressure deviation is (-0.3-0.3) MPa, the variable load rate is 7 MW / min. The magnitude of the variable load rates for the generator side and the boiler side corresponding to the main steam pressure deviation is opposite. That is, the function when the generator side is loaded is the same as the function when the boiler side is unloaded, and the function when the generator side is unloaded is the same as the function when the boiler side is loaded.

[0057] ① Select the RB action rate when RB is in action (the original value remains unchanged);

[0058] ② When the turbine control is locked, select the rate as 0MW / min;

[0059] ③ When the operator activates the load command hold function, the rate is selected as 0MW / min;

[0060] ④ The operator can change the load rate, but the main steam pressure deviation cannot be modified when it is (-0.3~0.3)MPa. The modification is valid when it exceeds the range of (-0.3~0.3)MPa, but when the main steam pressure deviation returns to (-0.3~0.3)MPa, it will automatically switch to the variable load rate curve function value.

[0061] The variable load rate curve on the machine side is composed of the variable load rate curve f(x)1 when the load is added and the variable load rate curve f(x)2 when the load is reduced, as shown in Figure 2 、 Figure 3 As shown in the figure, the horizontal axis is the difference between the main steam pressure set value on the machine side and the main steam pressure SP-PV (main steam pressure deviation), and the vertical axis is the variable load rate MW / min.

[0062] Figure 2 Note: When the generator side is loaded, the variable load rate is generated by converting the difference between the main steam pressure set value and the main steam pressure (-1 to 1) MPa into the corresponding variable load rate output (10 to 1.5) MW / min nonlinear function {(-1, 10), (-0.5, 8), (-0.3, 7.5), (0, 7), (0.3, 6.5), (0.5, 3), (1, 1.5)}. If it exceeds this range, the endpoint value will be used.

[0063] Figure 3Note: The generation of the variable load rate during load reduction is achieved by converting the difference between the main steam pressure set value and the main steam pressure (-1 to 1) MPa into the corresponding variable load rate output (10 to 1.5) MW / min nonlinear function {(-1, 1.5), (-0.5, 3), (-0.3, 6.5), (0, 7), (0.3, 7.5), (0.5, 3), (8, 10)}.

[0064] b. The unit load instruction (divided into the unit load instruction on the generator side and the unit load instruction on the furnace side according to different uses) is obtained by limiting the unit load target value by rate, and is different when the load is increased or decreased, such as Figure 4 As shown, the machine side load command and the furnace side load command output nonlinear functions according to the machine side and furnace side variable load rate to issue corresponding commands.

[0065] Figure 4 illustrate:

[0066] ① The main steam pressure set value SP (1) and the main steam pressure measurement value PV (2) on the machine side are processed by the subtraction function block (3) to output the load-on function f(x)1 (4) and the load-off function f(x) (5);

[0067] ② The rate of the variable load rate on the machine side is selected by the selection function block (6) when the load is increased, and is selected by the selection function block (7) when the load is reduced. The AGC instruction (11) is processed by the rate limiting function block (10) to obtain the machine side unit load instruction (14);

[0068] ③ The rate of the furnace side load change is selected by the selection function block (8) when the load is increased, and is selected by the selection function block (9) when the load is reduced (4). The AGC instruction (13) is processed by the rate limiting function block (12) to obtain the furnace side unit load instruction (15).

[0069] ④ The load instruction rate coordinated to the boiler master control adopts the opposite function of the steam turbine master control, that is, the load increase rate on the turbine side is the load reduction rate on the boiler side, and vice versa.

[0070] c. Correlation function of the furnace side load instruction after the set values ​​of primary air pressure and mill cylinder pressure are changed to variable load rate.

[0071] 2) Main steam pressure setpoint rate:

[0072] ① The main steam pressure set value rate used by the steam turbine master control (machine side) is changed to a function value related to the size of the main steam pressure deviation, and the function is different when adding and reducing the load. When the main steam pressure deviation (SP-PV) is negative during load addition, the rate increases, otherwise the rate decreases, and the opposite is true when reducing the load.

[0073] The main steam pressure setting value on the machine side and the main steam pressure setting value on the boiler side are opposite in size. The main steam pressure setting value on the machine side and the main steam pressure setting value on the boiler side are dynamically calculated according to the real-time main steam pressure deviation. The main steam pressure setting value rate curve includes four function curves: the main steam pressure setting value rate on the machine side when adding load, the main steam pressure setting value rate on the machine side when reducing load, the main steam pressure setting value rate on the boiler side when adding load, and the main steam pressure setting value rate on the boiler side when reducing load. Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 shown.

[0074] Figure 5 Note: The horizontal axis is the difference between the machine-side main steam pressure set value and the main steam pressure SP-PV, and the vertical axis is the main steam pressure set value rate MPa / s. The main steam pressure set value rate on the machine side when loading is applied is generated by converting the main steam pressure deviation (-1~1)MPa into the corresponding machine-side main steam pressure set value rate output (0.005~0)MPa / s nonlinear function {(-1, 0.005), (-0.5, 0.004), (-0.3, 0.0035), (0, 0.003), (0.3, 0.0025), (0.5, 0.002), (1, 0)}.

[0075] Figure 6 Note: The horizontal axis is the difference between the machine-side main steam pressure set value and the main steam pressure SP-PV, and the vertical axis is the main steam pressure set value rate MPa / s. The main steam pressure set value rate on the machine-side during load reduction is generated by converting the main steam pressure deviation (-1 to 1) MPa into the corresponding machine-side main steam pressure set value rate output (0 to 0.005) MPa / s nonlinear function {(-1, 0), (-0.5, 0.002), (-0.3, 0.0025), (0, 0.003), (0.3, 0.0035), (0.5, 0.004), (1, 0.005)}.

[0076] ② The main steam pressure set value rate used by the boiler master control (furnace side) is changed to a function value related to the main steam pressure deviation, and the function is different when adding and reducing the load. When the main steam pressure deviation is large (SP-PV) and negative when the load is added, the rate becomes smaller, otherwise the rate increases. The opposite is true when the load is reduced. Figure 7 、 Figure 8 .

[0077] Figure 7Note: The horizontal axis is the difference between the machine side main steam pressure set value and the main steam pressure SP-PV, and the vertical axis is the main steam pressure set value rate MPa / s. When the load is added, the main steam pressure set value rate of the boiler side is generated by converting the main steam pressure deviation (-1~1) MPa into the corresponding boiler side main steam pressure set value rate output (0~0.005) MW / min nonlinear function {(-1, 0), (-0.5, 0.002), (-0.3, 0.0025), (0, 0.003), (0.3, 0.0035), (0.5, 0.004), (1, 0.005)}.

[0078] Figure 8 Note: The horizontal axis is the difference between the machine side main steam pressure set value and the main steam pressure SP-PV, and the vertical axis is the main steam pressure set value rate MPa / s. The main steam pressure set value rate of the boiler side during load reduction is generated by converting the main steam pressure deviation (-1~1)MPa into the corresponding boiler side main steam pressure set value rate output (0.005~0)MPa / s nonlinear function {(-1, 0.005), (-0.5, 0.004), (-0.3, 0.0035), (0, 0.003), (0.3, 0.0025), (0.5, 0.002), (1, 0)}.

[0079] ③ The speed of the main pressure setting value on the machine side and the furnace side is exactly opposite. The main steam pressure setting value on the machine side and the main steam pressure setting value on the furnace side are opposite in size. This is mainly due to the characteristics of auxiliary frequency regulation. The load instruction changes frequently, sometimes changing 1-3 times in one minute. If the speed of the machine side and the furnace side is the same, it will cause greater pressure fluctuations. The specific process is as follows Figure 9 shown.

[0080] Figure 9 illustrate:

[0081] ① The main steam pressure set value SP (1) and the main steam pressure measurement value PV (2) on the machine side are processed by the subtraction function block (3) to output the load-on function f(x)1 (4) and the load-off function f(x) (5);

[0082] ② The rate of the main steam pressure setting value on the machine side is selected by the selection function block (6) when the load is increased, and is selected by the selection function block (7) when the load is reduced. The main steam pressure target value (11) is processed by the rate limiting function block (10) to obtain the main steam pressure setting value on the machine side (14);

[0083] ③ The rate of the furnace side main steam pressure set value is selected by the selection function block (8) when the load is increased (5), and is selected by the selection function block (9) when the load is reduced (4). The main steam pressure target value (13) is processed by the rate limiting function block (12) to obtain the furnace side pressure set value (15).

[0084] 3) Steam turbine master control and boiler coordination PID parameters:

[0085] The PID adjustment parameters of the turbine master control and the boiler master control are functions related to the main steam pressure deviation, and the speed is opposite, that is, the turbine master control adjustment is fast and the boiler master control adjustment is slow, and vice versa. This can prevent the main steam pressure deviation from being too large during reverse load change.

[0086] ① The integral time of the turbine coordinated PID regulation is changed to a function related to the main steam pressure deviation, and the integral time is changed according to the load change direction and the size of the main steam pressure deviation. When the load is increased, the pressure is high (the main steam pressure is higher than the main steam pressure setting value), and the integral time is short. When the load is reduced, the pressure is high (the main steam pressure is higher than the main steam pressure setting value), and the integral time becomes longer. The integral time value is a function value related to the main steam pressure deviation, which is (6~10)s. When the load is reduced, the pressure is low, and the opposite is true. Figure 10 、 Figure 11 .

[0087] Figure 10 Note: The horizontal axis is the difference between the set value of the main steam pressure on the turbine side and the main steam pressure SP-PV, and the vertical axis is the integral time Ti (unit: s). When the load is added, the integral time Ti of the coordinated PID adjustment of the turbine is generated by converting the main steam pressure deviation (-1 to 1) MPa into the corresponding integral time Ti output of the coordinated PID adjustment of the turbine (6 to 30) s nonlinear function {(-1, 6), (-0.5, 7), (-0.3, 8), (0, 10), (0.3, 15), (0.5, 20), (1, 30)}.

[0088] Figure 11 Note: The horizontal axis is the difference between the turbine side main steam pressure set value and the main steam pressure SP-PV, and the vertical axis is the integral time Ti (unit: s). The integral time Ti of the turbine coordinated PID regulation during load reduction is generated by converting the main steam pressure deviation (-1 to 1) MPa into the corresponding turbine coordinated PID regulation integral time Ti output (30˜6) nonlinear function {(-1, 30), (-0.5, 20), (-0.3, 15), (0, 10), (0.3, 8), (0.5, 7), (1, 6)}.

[0089] ② The proportional coefficient Kp of the turbine coordinated PID regulation is changed to a function related to the main steam pressure deviation, and the proportional coefficient is changed according to the load change direction and the magnitude of the main steam pressure deviation. When the load is increased, the pressure is high, and the larger the Kp is, while when the load is reduced, the pressure is high, and the smaller the Kp is. The original value is a function value related to the main steam, which is 0.25~0.35. When the main steam pressure is low during load reduction, the opposite is true. Figure 12 、 Figure 13 shown.

[0090] Figure 12Note: The horizontal axis is the difference between the main steam pressure set value on the turbine side and the main steam pressure SP-PV, and the vertical axis is the proportional coefficient Kp. When the load is added, the proportional coefficient Kp of the turbine coordinated PID regulation is generated by converting the main steam pressure deviation (-1~1) MPa into the corresponding proportional coefficient Kp output of the turbine coordinated PID regulation (0.45~0.15) nonlinear function {(-1, 0.45), (-0.5, 0.35), (-0.3, 0.32), (0, 0.3), (0.3, 0.25), (0.5, 0.2), (1, 0.15)}.

[0091] Figure 13 Note: The horizontal axis is the difference between the turbine side main steam pressure set value and the main steam pressure SP-PV, and the vertical axis is the proportional coefficient Kp. The proportional coefficient Kp of the turbine coordinated PID adjustment when the load is reduced is generated by converting the main steam pressure deviation (-1~1) MPa into the corresponding proportional coefficient Kp output (0.15~0.45) of the turbine coordinated PID adjustment, which is a nonlinear function {(-1, 0.15), (-0.5, 0.2), (-0.3, 0.25), (0, 0.3), (0.3, 0.32), (0.5, 0.35), (1, 0.45)}.

[0092] ③ The integral time of the boiler coordinated PID adjustment is changed to a function related to the main steam pressure deviation, and the integral time Ti is changed according to the load change direction and the size of the pressure deviation. When the load is increased, the pressure is high and the integral time is long, while when the load is reduced, the pressure is high and the integral time becomes short. The integral time value is a function value related to the main steam pressure deviation, which is (6~10)s. When the load is reduced, the pressure is low and the opposite is true. Figure 14 、 Figure 15 .

[0093] Figure 14 Note: The horizontal axis is the difference between the machine-side main steam pressure set value and the main steam pressure SP-PV, and the vertical axis is the integral time Ti (unit: s). When the load is added, the integral time Ti of the boiler coordinated PID adjustment is generated by converting the main steam pressure deviation (-1~1)MPa into the corresponding integral time Ti output of the steam turbine coordinated PID adjustment (30~6)s nonlinear function {(-1, 30), (-0.5, 20), (-0.3, 15), (0, 10), (0.3, 8), (0.5, 7), (1, 6)}.

[0094] Figure 15Note: The horizontal axis is the difference between the main steam pressure set value on the turbine side and the main steam pressure SP-PV, and the vertical axis is the integral time Ti (unit: s). The integral time Ti of the boiler coordinated PID adjustment during load reduction is generated by converting the deviation (-1 to 1) MPa between the main steam pressure set value and the main steam pressure into the corresponding integral time Ti output (6 to 30) of the turbine coordinated PID adjustment, which is a nonlinear function (-1, 6, -0.5, 7, -0.3, 8, 0, 10, 0.3, 15, 0.5, 20, 1, 30).

[0095] ④ The proportional coefficient Kp of the boiler coordinated PID regulation is changed to a function related to the main steam pressure deviation, and the proportional coefficient is changed according to the load change direction and the size of the main steam pressure deviation. When the load is increased, the pressure is high and the Kp is smaller, while when the load is reduced, the pressure is high and the Kp is larger. The proportional coefficient value is a function value related to the main steam pressure deviation, which is 0.25~0.35. When the load is reduced, the pressure is low and the opposite is true. Figure 16 、 Figure 17 .

[0096] Figure 16 Note: The horizontal axis is the difference between the main steam pressure set value on the turbine side and the main steam pressure SP-PV, and the vertical axis is Kp. When the load is added, the proportional coefficient Kp of the boiler coordinated PID adjustment is generated by converting the main steam pressure deviation (-1~1) MPa into the corresponding proportional coefficient Kp output of the turbine coordinated PID adjustment (0.15~0.45) nonlinear function {(-1, 0.15), (-0.5, 0.2), (-0.3, 0.25), (0, 0.3), (0.3, 0.32), (0.5, 0.35), (1, 0.45)}.

[0097] Figure 17 Note: The horizontal axis is the difference between the turbine side main steam pressure set value and the main steam pressure SP-PV, and the vertical axis is Kp. The proportional coefficient Kp of the boiler coordinated PID adjustment during load reduction is generated by converting the main steam pressure deviation (-1 to 1) MPa into the corresponding proportional coefficient Kp output of the turbine coordinated PID adjustment (0.45 to 0.15) nonlinear function {(-1, 0.45), (-0.5, 0.35), (-0.3, 0.32), (0, 0.3), (0.3, 0.25), (0.5, 0.2), (1, 0.15)}.

[0098] 2. Rapid load change logic:

[0099] The rapid load change logic is composed of the rapid load rate logic ( Figure 19 ) and primary wind intelligent feedforward logic ( Figure 26 )composition.

[0100] 1) Rapid load rate change: When the load changes, the load change rate is the function corresponding to the load instruction (50~80) MW / min, and the normal load rate function value is restored after only 4 seconds of pulse ( Figure 2 or Figure 3 ), the purpose is to quickly change the unit load to ±0.5%Pe (unit rated load) to obtain a higher K1 value. K1 can basically reach 0.96 (the upper limit is 1). The rate when changing load is changed to the function corresponding to the load instruction to take into account the safety of the steam turbine valve. When the load is high, the amplitude of the rapid valve action should be small, so the rate is low. When the load is low, the rate is also low. This is mainly because the main steam pressure is low at low load. Too fast will easily lead to excessive valve action amplitude and large main steam pressure fluctuations. The rapid load change rate is such as Figure 18 shown.

[0101] Figure 18 Note: The horizontal axis is the unit AGC command (MW), and the vertical axis is the variable load rate (MW / min). The rapid variable load rate curve during load variation is generated by converting the unit AGC command (0~350) MW into the corresponding rapid variable load rate output nonlinear function {(0, 50), (150, 50), (200, 60), (250, 80), (280, 70), (300, 60), (350, 50)}.

[0102] Figure 19 illustrate:

[0103] ① The AGC instruction (1) is sent to the subtraction function block (2) through the delay function block (3) for subtraction, and the difference is sent to the high and low limit function block (4). The high limit output function block (4) outputs the high limit to the pulse function block (5), and the low limit output function block (4) outputs the low limit to the pulse function block (6);

[0104] ② The pulse function block (5) has two outputs after 4 seconds of pulse generation. The first output is sent to the selection function block (11) as the selection condition of the selection switch (11), and the second output is sent to the OR gate function block (15).

[0105] ③ During the first 4 seconds of load addition, the fast-changing load rate function f(x)(9) is selected by the selection switch (11). After the 4-second pulse, the machine-side load rate (10) is selected by the selection switch (11) and sent to the rate limiting function block (16) as the load instruction rate during load addition.

[0106] ④ The pulse function block (6) has two outputs after 4 seconds of pulse generation. The first output is sent to the selection function block (9) as the selection condition of the selection switch (9), and the second output is sent to the OR gate function block (12).

[0107] ⑤ During the first 4 seconds of load shedding, the fast-changing load rate function f(x)(7) is selected by the selection switch (9). After the 4-second pulse, the machine-side load shedding rate (8) is selected by the selection switch (9) and sent to the rate limiting function block (12) as the load instruction rate during load shedding.

[0108] ⑥AGC instruction (1) is sent to selection function block (14) after passing through rate limiting function block (12). When the rapid load change condition is met (i.e., the output of OR gate function (15) is "1", and after passing through NOT gate function block, it outputs "0"), selection function block (14) selects the rapid load change instruction output by rate limiting function block (12). When the rapid load change condition disappears (i.e., the output of OR gate function (15) is "0", and after passing through NOT gate function block, it outputs "1"), selection function block (14) selects the machine side load instruction (13) input by rate limiting function block (12). The output of selection function block (14) finally forms the machine side load constant (17).

[0109] 2) Using primary air intelligent feedforward logic, comprehensively considering the direction and size of the current unit's main parameters and load command changes, it automatically determines whether to increase or decrease the primary air pressure and value in advance, and references this intelligent feedforward signal to the combustion control system, including PID feedforward inputs such as mill capacity air control, air supply volume control, furnace pressure control, coal feed volume control, cooling water control, and reheating smoke damper control, so that the combustion system can quickly adapt to changes in unit load. This intelligent feedforward logic replaces the calorific value correction logic and is fast and accurate. Figure 26 (The parameters in the figure can be adjusted according to the capacity and characteristics of different units.) The primary air pressure set value is increased with variable rate control, and the variable rate is a function of the main pressure deviation. Figure 20 、 Figure 21 ).

[0110] A: Primary air pressure setting value increases variable rate control

[0111] Figure 20 Note: The horizontal axis is the difference between the furnace side main steam pressure set value and the main steam pressure (MPa), and the vertical axis is the primary air pressure set value change rate (kPa / s). When the load is added, the primary air pressure set value change rate is generated by converting the furnace side main pressure deviation (-1~1)MPa into the corresponding primary air pressure set value rate output (0.002~0.0065)kPa / s nonlinear function {(-1, 0.002), (-0.5, 0.0032), (-0.3, 0.0037), (0, 0.0045), (0.3, 0.0053), (0.5, 0.0057), (1, 0.0065)}.

[0112] Figure 21Note: The horizontal axis is the boiler side main steam pressure set value and the main steam pressure deviation (MPa), and the vertical axis is the primary air pressure set value change rate (kPa / s). The primary air pressure set value change rate during load reduction is generated by converting the boiler side main pressure deviation (-1~1)MPa into the corresponding primary air pressure set value rate output (0.0065~0.002)kPa / s nonlinear function {(-1, 0.0065), (-0.5, 0.0057), (-0.3, 0.0053), (0, 0.0045), (0.3, 0.0037), (0.5, 0.0032), (1, 0.002)}.

[0113] B: Primary air intelligent feedforward logic

[0114] Figure 22 Note: The horizontal axis is the difference between the furnace side load command and the unit load (SP-PV) (MW), and the vertical axis is the primary air pressure (kPa). When the load is added, the primary air pressure set value feedforward function f(x)1 is generated by converting the difference between the furnace side load command and the unit load (furnace side load deviation) (0~100) MW into the corresponding primary air pressure set value feedforward output (0.15~0.4) kPa nonlinear function {(0, 0.15), (30, 0.23), (50, 0.28), (100, 0.4)}.

[0115] Figure 23 Note: The horizontal axis is the difference between the furnace side load command and the unit load (SP-PV) (MW), and the vertical axis is the primary air pressure kPa. The primary air pressure set point feedforward function f(x)2 during load reduction is generated by converting the furnace side load deviation (-100~0)MW into the corresponding primary air pressure set point feedforward output (0.15~0.4)kPa nonlinear function {(-100, 0.4), (-50, 0.28), (-30, 0.23), (0, 0.15)}.

[0116] Figure 24 Note: The horizontal axis is the difference between the boiler side main steam pressure set value and the main steam pressure (MPa), and the vertical axis is the primary air pressure (kPa). When the load is added, the primary air pressure set value feedforward function f(x)3 is generated by converting the difference between the boiler side main steam pressure set value and the main steam pressure (furnace side main pressure deviation) (0~1) MPa into the corresponding primary air pressure set value feedforward output (0.15~0.5) kPa nonlinear function {(0, 0.15), (0.3, 0.25), (0.5, 0.3), (1, 0.5)}.

[0117] Figure 25Note: The horizontal axis is the boiler side main steam pressure set value and the main steam pressure deviation (MPa), and the vertical axis is the primary air pressure (kPa). The generation of the primary air pressure set value feedforward function f(x)4 during load reduction is achieved by converting the boiler side main pressure deviation (-1~0)MPa into the corresponding primary air pressure set value feedforward output (-0.5~-0.15)kPa nonlinear function {(-1, -0.5), (-0.3, 0.3), (-0.25, -0.25), (0, -0.15)}.

[0118] 1) The primary wind intelligent feedforward mainly consists of four functions, f(x)1, f(x)2, f(x)3, and f(x)4. When the load is increased, the output feedforward is y1=f(x)1+f(x)3, and when the load is reduced, the output feedforward is y2=f(x)2+f(x)4. The output y1 or y2 is selected according to the current operating conditions of the unit, such as Figure 22 、 Figure 23 、 Figure 24 、 Figure 25 .

[0119] Figure 26 illustrate:

[0120] ① The furnace side load command SP (1) and the unit load PV (2) are output through the subtraction function block (3) to output the load-on function f(x)1 (4) and the load-off function f(x)2 (5). (4) and (5) are output to the selection switch (13) after passing through the adder (6);

[0121] ② The boiler side main steam pressure set value SP (7) and the main steam pressure measurement value PV (8) are output through the subtraction function block (9) to output the load-on function f(x)3 (10) and the load-off function f(x)4 (11). (10) and (11) are output to the selection switch (13) after passing through the adder (12);

[0122] ③ When the load is increased, the primary wind feedforward quantity is obtained by adding (4) and (5) through the adder (6); when the load is reduced, the primary wind feedforward quantity is obtained by adding (10) and (11) through the adder (12);

[0123] ④ The primary wind intelligent feedforward function f(x)(19) is derived from three cases.

[0124] a. When the load is reduced or increased, if the main steam pressure on the machine side is higher than the set value of the main steam pressure on the machine side, (14) selects (12) by selecting function block (13);

[0125] b. When the load is increased or decreased, if the main steam pressure on the machine side is lower than the set value of the main steam pressure on the machine side, (15) selects (6) by selecting function block (16);

[0126] c. When the absolute value of the machine-side load deviation at the end of the variable load is lower than the machine-side load setting value, and the absolute value of the furnace-side main pressure deviation is greater than the furnace-side pressure deviation setting value, (18) selects the switch (17) to perform a self-holding output (19).

[0127] 2) The primary air intelligent feedforward function can replace the regulation feedforward of the entire combustion system, but it needs to be converted into a feedforward suitable for each regulation system through a function.

[0128] 3. Implementation and Effect of the Plan

[0129] (1) Implementation of the plan:

[0130] 1) Configure the control logic offline. Considering the possibility of anomalies during debugging, the newly added control logic is connected to the old logic by switching the switch. After the configured control logic is verified to be correct, it is downloaded to the corresponding controller. After downloading, if the DCS has online simulation capabilities, the correctness of the logic and the size of the values ​​are first simulated to verify whether they are appropriate to prevent anomalies during debugging.

[0131] 2) Before debugging, all parameters should be set close to the original size, preferably smaller rather than larger. After commissioning, they should be modified according to the debugging data until the main parameters of the unit do not fluctuate significantly.

[0132] 3) After the unit has been put into RFCCS operation for a period of time, and there are no abnormalities in the main operating parameters of the unit, apply for the auxiliary frequency regulation comprehensive performance K value test.

[0133] 4) If the K value is not ideal, analyze the historical trend every day, identify the problem, and adjust the corresponding parameters. After the adjustment, if you can achieve continuous winning bids, no major adjustments are needed.

[0134] (2) Effect:

[0135] 1) After the RFCCS was put into use, the main operating parameters of the unit did not show any abnormalities, and the unit operation became more stable, such as Figure 27 Trend description: The unit load varies from (232-314) MW. Within 55 minutes, the load changes 35 times. During this period, the maximum deviation between the main steam pressure and the main steam pressure set value is 0.36MPa, and the main steam temperature fluctuates by about 2°.

[0136] 2) The most significant feature of the rapid load change logic is that when the unit reverses load, the time between a load command and the next command, which previously took 8-12 seconds, now takes only 3 seconds. Before the RFCCS system was implemented, the unit's load response rate was slow, with a K2 value of only around 0.65. With the RFCCS system, this has increased to 0.96 (with an upper limit of 1).

[0137] 3) After the 330MW unit was put into RFCCS operation, the average daily K value increased from 0 to 0.78, and the highest hourly K value was recorded at 1.9. One 330MW unit operated for 33 days and earned a total of RMB 687,000, with the highest single-day profit being RMB 76,000.

[0138] 4) The combined regulation of RFCCS and energy storage systems significantly improves the performance of auxiliary frequency regulation. The K value increased from 1.2 to 1.72, an increase of about 40.8%. The highest single-day winning bid amount increased from the original 167,000 yuan to 229,400 yuan, an increase of 33.5%. At the same time, it solves the problem of low battery capacity in the energy storage system and can extend the life of the energy storage system battery.

[0139] 5) Revenue from auxiliary frequency regulation from the RFCCS system in 2022: One 330MW unit operated RFCCS independently for four months, generating a total revenue of 3.0773 million yuan. The RFCCS, operated in conjunction with the energy storage system for over nine months, generated a total revenue of 21.4907 million yuan. 6) After stable operation, the system achieved continuous winning bids, featuring low investment, minimal maintenance, and rapid returns.

Claims

1. A reverse rapid coordinated control method based on the DCS system of a coal-fired generator set, characterized by: Keep the control logic structure of the DCS system of the coal-fired generator set unchanged, dynamically modify the control parameters and the set values ​​of the control objects, and realize the reverse regulation control logic. The specific implementation method is as follows: The main steam pressure set value is divided into the turbine-side main steam pressure set value and the boiler-side main steam pressure set value. A nonlinear function of the rate of the main steam pressure set values ​​on the turbine side and the boiler side corresponding to the main steam pressure deviation is constructed. The main steam pressure deviation is obtained by subtracting the main steam pressure from the turbine-side main steam pressure set value. The rate of the turbine-side main steam pressure set value and the rate of the boiler-side main steam pressure set value are opposite in magnitude. The turbine-side main steam pressure set value and the boiler-side main steam pressure set value are dynamically calculated according to the set value rate corresponding to the real-time changing main steam pressure deviation; The load instructions are divided into engine-side load instructions and furnace-side load instructions. A nonlinear function of the engine-side and furnace-side variable load rate outputs is constructed, which is composed of the main steam pressure deviation corresponding to the engine-side and furnace-side variable load rates. The engine-side and furnace-side variable load rates corresponding to the main steam pressure deviation are opposite in magnitude. The engine-side and furnace-side load instructions are issued according to the nonlinear function of the engine-side and furnace-side variable load rate outputs. The set values ​​of primary air pressure and coal mill cylinder pressure adopt the nonlinear function output by the furnace side variable load instruction; The PID adjustment parameters of the turbine master control and the boiler master control are functions related to the main steam pressure deviation. The PID adjustment parameters of the turbine master control and the boiler master control corresponding to the main steam pressure deviation are opposite in size.

2. The reverse rapid coordinated control method based on the DCS system of a coal-fired power generation unit according to claim 1, characterized in that: The PID adjustment parameters include the integral time Ti and the proportional coefficient Kp.

3. The reverse rapid coordinated control method based on the DCS system of a coal-fired power generation unit according to claim 1, characterized in that: It also includes fast load change logic, which is specifically implemented by constructing a machine-side fast load change rate function related to the size of the unit AGC instruction, and restoring to the machine-side load change rate output nonlinear function after the unit AGC instruction sends an N-second pulse.

4. The reverse rapid coordinated control method based on the DCS system of a coal-fired power generation unit according to claim 1, characterized in that: It also includes the control of the rate of increase of the primary air pressure set value. The specific implementation method is that the rate of change of the primary air pressure set value is a function value related to the main pressure deviation on the furnace side. The main pressure deviation on the furnace side is obtained by subtracting the main steam pressure from the main steam pressure set value on the furnace side. When the load is increased, the rate of change of the primary air pressure set value increases with the increase of the main pressure deviation on the furnace side. When the load is reduced, the rate of change of the primary air pressure set value decreases with the increase of the main pressure deviation on the furnace side.

5. The reverse rapid coordinated control method based on the DCS system of a coal-fired power generation unit according to claim 1, characterized in that: It also includes primary air intelligent feedforward logic. The specific process is to construct a primary air pressure set value feedforward function f(x)1 corresponding to the primary air pressure of the furnace side load deviation when the load is increased, construct a primary air pressure set value feedforward function f(x)2 corresponding to the primary air pressure of the furnace side load deviation when the load is reduced, construct a primary air pressure set value feedforward function f(x)3 corresponding to the primary air pressure of the furnace side main pressure deviation when the load is increased, and construct a primary air pressure set value feedforward function f(x)4 corresponding to the primary air pressure of the furnace side main pressure deviation when the load is reduced. The primary air intelligent feedforward f(x) is derived from three situations: a. When the main steam pressure on the machine side is higher than the set value of the main steam pressure on the machine side, it is output as f(x)1+f(x)3; b. When the main steam pressure on the machine side is lower than the set value of the main steam pressure on the machine side, it is output as f(x)2+f(x)4; c. When the absolute value of the machine-side load deviation is less than 3MW at the end of the variable load, and the absolute value of the machine-side main pressure deviation is greater than 0.3MPa, the current value is kept unchanged and output is obtained.

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