Novel coal power pulverizing equipment control system and control method

Abstract

The invention relates to the field of coal mill control methods, in particular to a novel electric coal pulverizing equipment control system and a control method thereof. The device is applied to a double-inlet and double-outlet mill. The system comprises a DCS control system, and a load coal level control unit, a speed control unit and a protection and linkage unit which are in communication connection with the DCS control system. According to the method, through DCS coordination, the optimal material level of the mill is accurately maintained by adopting a composite control strategy which takes differential pressure as a main part and takes an electric lug as an auxiliary part, and efficient and stepless regulation and energy-saving control of the rotating speed of a roller are realized by utilizing a variable-frequency permanent-magnet speed regulation system consisting of a frequency converter, a permanent-magnet synchronous motor and a speed reducer; and meanwhile, hierarchical safety protection and intelligent interlocking are realized based on a multi-sensor network deployed in key equipment. The problems that in the prior art, material level control is not accurate, energy consumption is high, safety protection is insufficient, and subsystem collaboration is poor are solved, the powder making efficiency can be improved, and long-term safe and stable operation of equipment is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of coal mill control methods, specifically a novel coal-fired power pulverizing equipment control system and its control method. Background Technology

[0002] In the traditional coal-fired power plant pulverizing field, the double-inlet, double-outlet ball mill is a key piece of equipment, tasked with grinding raw coal into pulverized coal that meets the combustion requirements of boilers. For a long time, the control of this type of equipment has relied on relatively independent and simple automation loops. For the core controlled variable of the amount of coal stored in the mill cylinder (material level), since level gauges cannot be directly installed, indirect monitoring methods are commonly used. The most common method is to use the pressure difference between the primary air header at the mill inlet and the outlet of the coarse powder separator to reflect the material level. The control system attempts to stabilize this pressure difference by adjusting the feeder speed. In addition, electric ears are often installed to listen to the sound of the steel balls striking each other inside the cylinder, serving as an empirical reference for the material level.

[0003] However, the existing control methods described above have some problems. First, in terms of load control, there is an over-reliance on a single differential pressure signal, which is easily affected by factors such as air volume and coal type, leading to lag and measurement inaccuracies. Electromagnetic sensors are typically only used as an aid to manual judgment and fail to be deeply integrated with the differential pressure signal at the control algorithm level to achieve rapid, automatic fine-tuning and safety boundary protection. This makes it difficult for the system to accurately maintain the optimal material level, resulting in large fluctuations in grinding efficiency and slow response under abnormal conditions such as coal blockage or coal shortage, which can easily lead to equipment failure or safety accidents. Second, in terms of drive and energy saving, traditional coal mills generally adopt a fixed-speed drive scheme of "asynchronous motor + reducer," or only perform frequency conversion modifications on auxiliary equipment such as fans and pumps. The main motor of the coal mill always runs at a constant speed, unable to flexibly adjust the cylinder speed according to boiler load and coal characteristics, resulting in a large amount of electrical energy being consumed in ineffective friction, impact, and heat generation, leading to persistently high system energy consumption. Even when frequency converters are introduced in some applications, simple V / F control is often used, resulting in slow dynamic response, low speed regulation accuracy, and an inability to achieve precise torque control. This makes it difficult to match the high inertia and fluctuating load conditions of coal mills, and the energy-saving potential is not fully realized. The monitoring and protection measures in existing systems are often isolated. Temperature, pressure, and vibration sensors are typically only equipped with simple upper-level alarms and hard-wired trips. There is a lack of intelligent correlation and logical judgment between various protection signals, making false trips or failures to trip easily possible. Early signs of lubrication system failures may not be effectively identified and warned in advance, and shutdown may only be triggered when serious equipment damage occurs. The timeliness and accuracy of protection actions are insufficient. Finally, the load control, speed drive, and safety monitoring subsystems in existing technologies are often isolated and lack unified coordination. Distributed control systems (DCS) mostly only achieve data collection and simple loop adjustment, failing to achieve adaptive optimization control based on multivariable coupling models. This makes it impossible for coal mill systems to automatically adjust control strategies when facing complex time-varying factors such as coal type changes, load adjustments, and equipment wear, making it difficult to maintain optimal overall operating efficiency and economy.

[0004] Therefore, there is an urgent need for a new type of intelligent control system for coal-fired power pulverizing equipment that can achieve precise load control, high-efficiency energy-saving drive, intelligent safety interlocking, and collaborative optimization of the operation of various subsystems. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a novel control system and method for coal-fired power pulverizing equipment. The system is centrally coordinated by a DCS and includes a load coal level control unit primarily based on differential pressure and secondarily on electric sensors; a variable frequency speed control unit composed of a frequency converter, a permanent magnet motor, and a reduction gear; and a protection unit based on multi-sensor hierarchical interlocking. The method, through coordinated control and parameter feedback, enables the mill to operate efficiently, energy-savingly, and safely at optimal material level and speed.

[0006] To achieve the above objectives, the present invention specifically adopts the following solution:

[0007] A novel control system for coal-fired power pulverizing equipment, applied to a double-inlet, double-outlet mill, the system comprising:

[0008] DCS control system;

[0009] The load coal level control unit is communicatively connected to the DCS control system and is used to monitor and control the amount of coal stored in the coal mill cylinder.

[0010] The speed control unit is communicatively connected to the DCS control system and is used to drive and precisely control the rotational speed of the coal mill drum.

[0011] The protection and interlocking unit is communicatively connected to the DCS control system and is used to monitor equipment operating parameters and perform protective actions when abnormalities occur.

[0012] The load coal level control unit, speed control unit, and protection and interlocking unit achieve adaptive control under the coordination of the DCS control system.

[0013] Furthermore, the load coal level control unit includes:

[0014] The differential pressure control module is used to measure the pressure difference between the primary air header at the inlet of the coal mill and the outlet of the separator, and uses this pressure difference as the main control signal to reflect the amount of coal stored in the cylinder;

[0015] The electric ear control module is used to monitor the noise intensity of the coal mill during operation and uses the noise signal as an auxiliary fine-tuning signal to reflect the amount of coal stored in the cylinder;

[0016] The DCS control system adjusts the feeder speed to maintain the material level based on the deviation between the differential pressure signal and the set value, and uses the electric ear signal to quickly fine-tune the coal feed rate and judge abnormal working conditions.

[0017] Furthermore, the speed control unit includes:

[0018] The frequency converter receives the speed command signal from the DCS control system and outputs control commands using a vector control algorithm.

[0019] A permanent magnet synchronous motor is electrically connected to the frequency converter and receives its drive commands;

[0020] The speed reducer connects the permanent magnet synchronous motor to the coal mill drum;

[0021] The frequency converter, permanent magnet synchronous motor and reduction mechanism are integrated into a variable frequency permanent magnet speed regulation system, which realizes stepless speed regulation of the coal mill drum speed.

[0022] Furthermore, the protection and interlocking unit includes multiple sensors deployed on the following components;

[0023] Temperature sensors deployed on the stator and bearings of the main motor are used to monitor the operating temperature; vibration sensors deployed on the main motor are used to monitor the operation or shutdown of the main motor.

[0024] Pressure sensors deployed on the oil lines of high and low pressure lubrication oil stations are used to monitor whether the lubrication oil pressure meets the requirements for equipment start-up and shutdown; temperature sensors and level sensors deployed on the lubrication oil tank are used to monitor oil temperature and oil level in the tank, respectively; differential pressure switches deployed on the lubrication oil station filter are used to monitor the filter clogging status.

[0025] The DCS control system is configured to receive signals from various sensors, and the DCS executes graded alarm or safety interlock logic based on preset thresholds.

[0026] Correspondingly, this invention provides an intelligent control method for coal-fired power pulverizing equipment, comprising the following steps: The method is executed under the coordination of a DCS control system, including the following steps:

[0027] The DCS control system receives the boiler main control command and outputs it as the output demand of the coal mill; based on the output demand and process optimization objectives, it generates and sends the speed command of the coal mill drum to the speed control unit, and at the same time generates the material level setpoint command to the load coal level control unit.

[0028] The frequency converter in the speed control unit receives the speed command and obtains the actual speed feedback of the permanent magnet synchronous motor. It uses a vector control algorithm for closed-loop regulation to drive the permanent magnet synchronous motor and drive the coal mill drum to run stably at the target speed through the reducer. The load coal level control unit works in a mode of differential pressure as the main factor and electric ears as the auxiliary factor to adjust the coal mill speed and coal storage capacity.

[0029] The protection and interlocking unit continuously collects temperature, pressure, liquid level, and vibration status parameters of the main motor, high and low pressure lubrication oil stations, and main bearing. When any parameter exceeds the preset safety threshold, it sends an interlocking signal to the DCS control system to trigger a graded alarm or emergency shutdown.

[0030] The DCS control system integrates actual differential pressure feedback, electro-optical signals, actual speed feedback, and parameters from various sensors to dynamically adjust the speed command and material level setpoint, ensuring that the coal mill system always operates at the optimal speed and material level in an energy-saving and efficient state under safe conditions.

[0031] Furthermore, the load coal level control unit works in a coordinated mode, primarily based on differential pressure and secondarily on electrical sensors, to adjust the coal machine speed and coal storage capacity. Specifically, this includes the following steps:

[0032] The actual pressure difference between the primary air header at the inlet of the coal mill and the outlet of the coarse powder separator is measured in real time and compared with the pressure difference setpoint corresponding to the material level setpoint from the DCS control system to generate the first coal feeder speed adjustment command.

[0033] The noise level of the coal mill is monitored in real time, and the speed adjustment command of the first coal feeder is quickly and finely adjusted. When the electric ear signal indicates a serious abnormality, the differential pressure control logic is exceeded and the safety interlock is triggered.

[0034] The integrated feeder speed adjustment command is output to control the feeder speed and adjust the coal feed rate, thereby maintaining a constant optimal coal storage level in the cylinder.

[0035] Furthermore, the execution of the vector control algorithm includes the following steps:

[0036] The speed setpoint ω* from the DCS control system is compared with the actual rotational speed ω fed back by the permanent magnet synchronous motor. The resulting speed error is sent to the speed regulator for processing. The output of the speed regulator is used as the torque current setpoint i_q*.

[0037] Current inner loop control and coordinate transformation yield direct-axis voltage setpoint V_d* and quadrature-axis voltage setpoint V_q*;

[0038] The direct-axis voltage setpoint V_d* and the quadrature-axis voltage setpoint V_q* are converted back to the two-phase voltages V_α and V_β in the stationary coordinate system by the inverse Park transformation.

[0039] The two-phase voltages V_α and V_β are used to generate six PWM drive signals through a space vector pulse width modulation module. These signals control the power switching devices of the inverter in the frequency converter, thereby generating the required three-phase sinusoidal voltage at the permanent magnet synchronous motor terminal and achieving independent and precise control of the motor torque and magnetic field.

[0040] Furthermore, the current inner loop control and coordinate transformation include the following steps:

[0041] The rotor flux position angle θ and amplitude Ψ of the permanent magnet synchronous motor are observed and calculated in real time using a flux linkage observer.

[0042] The detected three-phase motor currents are converted into direct-axis current i_d and quadrature-axis current i_q in a rotating coordinate system using the Park transformation.

[0043] The given current setpoint i_d* and the obtained torque current setpoint i_q* are compared with the feedback direct-axis current i_d and quadrature-axis current i_q, respectively. The resulting current errors are sent to the corresponding current regulators for processing, and voltage feedforward decoupling terms based on speed and motor parameters are added to output the direct-axis voltage setpoint V_d* and quadrature-axis voltage setpoint V_q* in the rotating coordinate system.

[0044] Furthermore, the protection and interlocking unit specifically performs the following steps:

[0045] The system synchronously collects signals from temperature sensors deployed on the main motor stator and bearings, vibration sensors on the main motor, pressure sensors on the high and low pressure lubricating oil circuits, temperature and level sensors on the lubricating oil tank, and differential pressure switch signals from the lubricating oil station filter.

[0046] The real-time values ​​of the collected sensor signals are compared with the preset alarm thresholds and trip thresholds to determine whether each monitoring point is in a normal, early warning, alarm, or trip state.

[0047] Tiered safety response execution: When any monitoring point parameter reaches the alarm threshold but does not reach the trip threshold, the DCS control system triggers an audible and visual alarm and records the event; when any monitoring point parameter reaches the trip threshold, or when multiple monitoring point parameters meet the preset interlocking logic conditions, the DCS control system immediately generates and issues an emergency shutdown command to control the relevant equipment to trip.

[0048] Furthermore, the interlocking logic conditions include at least one of the following:

[0049] The main motor bearing temperature and the main motor vibration signal both exceed their respective alarm thresholds.

[0050] The oil pressure in the high-pressure lubrication station is lower than the trip threshold, which directly constitutes a tripping condition.

[0051] If the lubricating oil level in the tank is lower than the low level threshold, it directly constitutes a tripping condition.

[0052] The execution of the protection and interlocking units enables the system to have a layered protection mechanism from early warning and alarm to emergency shutdown.

[0053] Compared with the prior art, the present invention has the following beneficial technical effects:

[0054] This invention improves the control accuracy and reliability of coal storage in the mill drum by adopting a composite load control strategy of "differential pressure as the main control and electric sensor as the auxiliary control". The differential pressure control module provides a stable and direct main adjustment signal to ensure that the material level is maintained within the set range; the electric sensor control module serves as a rapid-response auxiliary fine-tuning and safety monitoring means. It can not only make fine corrections to the coal feed rate under normal operating conditions, but also prioritize triggering safety interlocks when abnormal noise or vibration is detected. This effectively solves the problem of control failure or misjudgment that may be caused by a single signal source, thereby ensuring the continuous and stable pulverization process and preventing serious accidents that may be caused by coal blockage, coal interruption, or equipment mechanical failure.

[0055] This system achieves a shift from "constant speed operation" to "on-demand speed regulation" by providing wide-range, high-precision stepless adjustment of the coal mill drum speed. Since the drive power is approximately cubically related to the speed, shaft power consumption can be significantly reduced simply by appropriately lowering the speed when the boiler load changes or when processing different types of coal. Combined with the inherent high efficiency of the permanent magnet synchronous motor and the precise and rapid control of motor torque and magnetic field by the vector control algorithm within the frequency converter, various losses during light loads and transition processes are minimized. Actual operating data shows that this integrated speed regulation scheme can achieve a comprehensive energy saving rate of 15% to 30% for the coal mill system, resulting in significant economic benefits.

[0056] The system employs a hierarchical, multi-parameter collaborative intelligent protection and interlocking mechanism for safeguards. A sensor network deployed in key components such as the main motor, high and low pressure lubrication stations, filters, and main bearings continuously monitors multi-dimensional status information including temperature, pressure, liquid level, and vibration. The DCS control system not only sets multi-level thresholds for each parameter, including early warning, alarm, and tripping, but also incorporates logical judgments such as "AND" and "OR". Tripping is only triggered when both the main motor bearing temperature rise and vibration intensify simultaneously, effectively preventing false shutdowns caused by fluctuations in a single parameter. Conversely, low lubrication station liquid levels or severe filter blockage directly constitute tripping conditions, ensuring rapid protection in case of core lubrication and filtration failures. This hierarchical protection system achieves comprehensive safety management from early warning and process intervention to emergency shutdown.

[0057] The DCS control system not only receives boiler master control commands and breaks them down into specific speed and material level setpoints, but also integrates feedback data from differential pressure, electric ears, speed sensors, and various safety sensors in real time. Based on this information, the system can dynamically adjust control parameters and adaptively respond to complex operating conditions such as changes in coal type, steel ball wear, and equipment characteristic drift, ensuring that the coal mill always operates around the balance point of optimal grinding efficiency and minimum energy consumption. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the overall system structure according to a specific embodiment of the present invention;

[0059] Figure 2 This is a schematic diagram of sensor interaction according to a specific embodiment of the present invention;

[0060] Figure 3 This is a flowchart of a control method according to a specific embodiment of the present invention;

[0061] Figure 4 This is a schematic diagram of the speed control unit structure according to a specific embodiment of the present invention;

[0062] Figure 5 This is a schematic diagram of the load coal level control principle in a specific embodiment of the present invention;

[0063] Figure 6 This is a vector control algorithm model diagram of a specific embodiment of the present invention.

[0064] Numbers in the diagram:

[0065] 101. DCS Control System; 102. Load Coal Level Control Unit; 1021. Differential Pressure Control Module; 1022. Electric Ear Control Module; 103. Speed ​​Control Unit; 1031. Frequency Converter; 1032. Permanent Magnet Synchronous Motor; 1033. Reducer; 104. Protection and Interlock Unit; 1041. Sensors; 1041a. Temperature Sensor; 1041b. Vibration Sensor; 1041c. Pressure Sensor; 1041d. Temperature Sensor; 1041e. Liquid Level Sensor; 1041f. Differential Pressure Switch. Detailed Implementation

[0066] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0067] Please see Figure 1This specific embodiment provides a novel coal-fired power pulverizing equipment control system applied to a double-inlet, double-outlet mill. The system uses a DCS control system 101 as its core coordination hub and includes a load coal level control unit 102, a speed control unit 103, and a protection and interlocking unit 104, all connected to it in communication. The DCS control system 101 centrally monitors the entire system from the operator station in the central control room, receiving boiler main control commands and decomposing them into specific mill output requirements, speed setpoint commands, and material level setpoint commands. Simultaneously, the DCS 101 is responsible for the sequential start-up and shutdown logic of the mill system and automatically adjusts the feeder speed and hot / cold air damper opening through a PID control loop to ensure that key process parameters such as mill outlet temperature and inlet negative pressure remain stable at their set values.

[0068] Please see Figure 5 The load coal level control unit 102 adopts a composite control strategy of "differential pressure as the main factor and electric sensor as the auxiliary factor". Its differential pressure control module 1021 measures the pressure difference between the primary air header at the pulverizer inlet and the coarse powder separator outlet in real time, serving as the main control signal reflecting the amount of coal stored in the cylinder; the electric sensor control module 1022 monitors the intensity and spectrum of the pulverizer's operating noise through acoustic sensors. The DCS control system 101 generates the first feeder speed adjustment command based on the deviation between the actual differential pressure and the set value using a PID algorithm. The electric sensor signal is not only used for rapid fine-tuning of this command under normal operating conditions but can also serve as an independent basis for judging safety boundaries. The system performs comprehensive logical judgment on the differential pressure and electric sensor signals to cope with different operating conditions. The specific collaborative judgment logic is shown in the table below:

[0069]

[0070] Its control process follows a closed-loop logic: First, continuously monitor the real-time values ​​and trends of differential pressure and electric sensor signals; when the differential pressure deviates from the set range and the electric sensor does not alarm, the system calculates and outputs the feeder speed adjustment command based on the differential pressure deviation using a PID algorithm; throughout the adjustment process, monitor the electric sensor signal in real time, and if its value exceeds the safety threshold (e.g., vibration speed ≤ preset value mm / s), pause or intervene in the adjustment; finally, observe whether the system stabilizes to the target state.

[0071] Please see Figure 4 and Figure 6The speed control unit 103 is an integrated variable frequency permanent magnet speed regulation system consisting of a frequency converter 1031, a permanent magnet synchronous motor 1032, and a reducer 1033. It realizes the transformation of the coal mill drum speed from constant speed operation to on-demand speed regulation. The frequency converter 1031 receives the speed command signal from the DCS 101 and uses a vector control algorithm for high-precision drive. Its core performance indicators include: rated power of 800kW (matching the load), stepless speed regulation of output frequency from 0-50Hz, steady-state speed accuracy of ±0.1%, and support for Profibus-DP or Modbus TCP / IP communication with the DCS. The permanent magnet synchronous motor 1032 serves as the drive core, with a rated power of 800kW, a rated speed of 1500rpm, an efficiency >96%, and a protection rating of IP54 or higher. The reducer 1033 acts as a force regulator, with a reduction ratio of 30:1 (reducing the motor speed from 1500rpm to the required 50rpm for the grinding disc), a rated output torque ≥250kNm, and a transmission efficiency >97%.

[0072] The detailed steps of the vector control algorithm are as follows:

[0073] In the outer speed loop control, the speed setpoint ω* from the DCS control system 101 is compared with the actual rotational speed ω fed back by the permanent magnet synchronous motor 1032. The resulting speed error is sent to the speed regulator (usually a PI controller) for processing. The output of this speed regulator serves as the torque current setpoint i_q*, directly determining the magnitude of the electromagnetic torque that the motor needs to output.

[0074] In the inner current loop control, the rotor flux linkage position angle θ and amplitude Ψ of the permanent magnet synchronous motor 1032 are observed and calculated in real time using a flux linkage observer. Simultaneously, the detected three-phase motor currents are transformed into a rotating coordinate system oriented towards the rotor magnetic field direction using Park transformation, yielding the direct-axis current i_d and quadrature-axis current i_q. Next, the given direct-axis current setpoint i_d* (usually controlled to 0 to achieve maximum torque-to-current ratio control) and the previously obtained torque current setpoint i_q* are compared with the feedback direct-axis current i_d and quadrature-axis current i_q, respectively. The resulting current errors are fed into the corresponding current regulators (PI controllers) for processing. During processing, voltage feedforward decoupling terms -ω_e*L_s*i_q and ω_e*L_s*i_d, based on the electric angular velocity ω_e and the motor stator inductance parameter L_s, are added to eliminate the coupling effect between the d-axis and q-axis currents. Finally, the direct-axis voltage setpoint V_d* and quadrature-axis voltage setpoint V_q* in the rotating coordinate system are output.

[0075] The obtained direct-axis voltage setpoint V_d* and quadrature-axis voltage setpoint V_q* are converted back to the two-phase voltages V_α and V_β in the stationary coordinate system through the inverse Park transformation.

[0076] The two-phase voltages V_α and V_β are passed through the space vector pulse width modulation (SVPWM) module to generate six PWM drive signals, which are used to control the on / off switching of the IGBT power switching devices in the inverter 1031. This generates the required three-phase sinusoidal voltage waveform at the permanent magnet synchronous motor 1032, enabling independent, precise, and rapid control of the motor torque and magnetic field.

[0077] This system uses variable frequency speed control to allow stepless adjustment of the coal mill drum speed according to demand, rather than constant speed operation. Since the drive power is approximately cubic in relation to the speed, appropriately reducing the speed under low load can significantly reduce shaft power consumption. Combining the inherent high efficiency characteristics of the permanent magnet synchronous motor with the optimal control of the motor's operating state using vector control algorithms, various losses during light loads and transient processes are minimized, thereby achieving energy-saving effects, with an overall power saving rate of 15% to 30%.

[0078] Please see Figure 2 and Figure 3 The protection and interlocking unit 104 constructs a hierarchical, multi-parameter collaborative intelligent safety protection mechanism through a network of multi-sensor 1041 deployed in various key parts of the equipment. The DCS control system 101 continuously and synchronously collects these sensor signals and compares them in real time with preset alarm thresholds and trip thresholds, executing a graded safety response from early warning and alarm to emergency shutdown. Specific monitoring points, sensor configurations, and setpoints are shown in the table below:

[0079]

[0080]

[0081] The protection logic of this system is not a simple threshold trigger; the DCS control system 101 introduces intelligent interlocking logic judgment. For example, the system only triggers a high-level alarm or prepares for tripping when both conditions are met simultaneously (AND logic), effectively preventing false tripping caused by fluctuations in a single parameter. For conditions that directly endanger core safety, such as "high-pressure lubricating oil station oil pressure ≤ 15MPa" or "lubricating oil tank level ≤ low-low level," the tripping condition is directly established (OR logic), ensuring rapid and error-free emergency shutdown, achieving layered protection throughout the entire process from early warning and process intervention to emergency shutdown.

[0082] Please see Figures 1 to 6 The overall control flow of this system is as follows. Under the unified coordination and cyclic execution of the DCS control system 101, this flow achieves the adaptive, efficient, and safe operation of the coal mill system:

[0083] Step 1: The DCS control system 101 receives load commands from the boiler main control unit in real time and, combined with process information such as current coal characteristics and steel ball wear status, calculates the optimal output demand of the coal mill system. Based on this demand, the DCS 101 simultaneously generates two core setpoints: one is the target speed command for the coal mill drum, which is sent to the frequency converter 1031 in the speed control unit 103 via an analog signal (4-20mA); the other is the differential pressure setpoint command corresponding to the optimal material level, which is sent to the load coal level control unit 102.

[0084] Step Two: Upon receiving the speed command, the speed control unit 103 immediately starts. The frequency converter 1031 employs the vector control algorithm described above, using outer-loop speed PI regulation, inner-loop current PI regulation, and feedforward decoupling to drive the permanent magnet synchronous motor 1032 to quickly reach the target speed. The actual motor speed is fed back to the frequency converter 1031 in real time via an encoder, forming a high-precision closed-loop control to ensure the drum speed remains stable at the set value with an error of no more than ±0.1%. The reducer 1033 converts the high speed and low torque of the motor into the low speed and high torque required by the grinding disc, driving the coal mill drum.

[0085] Step 3: The load coal level control unit 102 operates in parallel to maintain the optimal coal storage level in the cylinder. It uses the actual pressure difference from the inlet to the separator outlet measured by the differential pressure control module 1021 as the main control signal, comparing it with the differential pressure setpoint issued by the DCS 101. The deviation is calculated using PID control to generate a basic feeder speed command. Simultaneously, the electric ear control module 1022 continuously monitors the cylinder noise. Under normal operating conditions, the electric ear signal rapidly fine-tunes the basic command to compensate for the lag in the differential pressure signal. The system performs real-time logical judgments based on the aforementioned "Differential Pressure-Electric Ear Coordinated Operating Condition Judgment Table." Once the electric ear signal indicates a "serious abnormality" (such as severely excessive noise), regardless of the differential pressure signal status, the system will immediately exceed the conventional adjustment logic, directly triggering the safety interlock in the protection and interlock unit 104, and entering the emergency response process.

[0086] Step Four: The protection and interlocking unit 104 operates independently and synchronously throughout the process. Various sensors 1041a-f, deployed at the main motor, high and low pressure lubrication stations, filters, and main bearings, continuously collect parameters such as temperature, pressure, vibration, and liquid level. The DCS control system 101 compares this real-time data with multi-level thresholds in the protection parameter setting table. When a parameter reaches the "alarm value," the DCS 101 triggers an audible and visual alarm and records it, alerting the operator to intervene. When a parameter reaches the "trip value" or meets the preset combined interlocking logic, such as when bearing temperature and vibration simultaneously exceed limits, the DCS 101 will unconditionally generate an emergency stop command, tripping related equipment and forming the system's final safety defense.

[0087] Step 5: The DCS control system 101, acting as the brain, continuously integrates the actual speed feedback from Step 2, the actual differential pressure and electro-optical signals from Step 3, and the status of all sensors from Step 4. Based on this multi-source information, the optimization algorithm within DCS101 dynamically evaluates the overall energy efficiency and safety margin of the system. For example, based on the actual grinding effect and motor current, it dynamically fine-tunes the speed command and material level setpoint to adapt to changes in coal type; or it provides early warnings of potential mechanical failures based on vibration trends. Through this continuous feedback and optimization, the entire coal mill system adaptively approaches the optimal speed and optimal material level—a highly efficient and energy-saving balance—while meeting boiler load requirements, and ensures that the entire process is under layered safety protection.

[0088] In summary, this specific implementation integrates the precise adaptive adjustment of the load coal level control unit 102, the efficient and energy-saving speed regulation of the speed control unit 103, and the intelligent hierarchical protection of the protection and interlocking unit 104 into a unified whole through centralized coordination and optimization of the DCS control system 101. The system can dynamically adjust the control strategy based on multi-source information feedback, ensuring that the coal mill operates safely, stably, and efficiently at its optimal operating point when dealing with complex conditions such as coal type changes, load fluctuations, and equipment wear.

Claims

1. A novel control system for coal-fired power pulverizing equipment, characterized in that, The system, applied to a dual-inlet, dual-outlet mill, includes: DCS control system (101); The load coal level control unit (102) is communicatively connected to the DCS control system (101) and is used to monitor and control the amount of coal stored in the coal mill cylinder. The speed control unit (103) is communicatively connected to the DCS control system (101) and is used to drive and precisely control the rotational speed of the coal mill drum. The protection and interlocking unit (104) is communicatively connected to the DCS control system (101) and is used to monitor equipment operating parameters and perform protection actions when abnormalities occur. The load coal level control unit (102), speed control unit (103), and protection and interlocking unit (104) achieve adaptive control under the coordination of the DCS control system (101).

2. The novel coal-fired power pulverizing equipment control system according to claim 1, characterized in that, The load coal level control unit (102) includes: The differential pressure control module (1021) is used to measure the differential pressure between the primary air header at the inlet of the coal mill and the outlet of the separator, and uses this differential pressure as the main control signal to reflect the amount of coal stored in the cylinder. The electric ear control module (1022) is used to monitor the noise intensity of the coal mill and use the noise signal as an auxiliary fine-tuning signal to reflect the amount of coal stored in the cylinder; The DCS control system (101) adjusts the speed of the coal feeder to maintain the material level based on the deviation between the differential pressure signal and the set value, and uses the electric ear signal to quickly fine-tune the coal feed rate and judge abnormal working conditions.

3. The novel coal-fired power pulverizing equipment control system according to claim 1, characterized in that, The speed control unit (103) includes: The frequency converter (1031) receives the speed command signal from the DCS control system (101) and outputs control commands using a vector control algorithm; A permanent magnet synchronous motor (1032) is electrically connected to the frequency converter (1031) and receives its drive commands; The speed reducer (1033) connects the permanent magnet synchronous motor (1032) to the coal mill drum; The frequency converter (1031), permanent magnet synchronous motor (1032) and reducer (1033) constitute an integrated frequency conversion permanent magnet speed regulation system, which realizes stepless speed regulation of the coal mill drum speed.

4. The novel coal-fired power pulverizing equipment control system according to claim 1, characterized in that, The protection and interlocking unit (104) includes multiple sensors (1041) deployed on the following components; Temperature sensors (1041a) deployed on the stator and bearings of the main motor are used to monitor the operating temperature; vibration sensors (1041b) deployed on the main motor are used to monitor the operation or shutdown of the main motor. Pressure sensors (1041c) deployed on the oil lines of high and low pressure lubrication stations are used to monitor whether the lubrication oil pressure meets the requirements for equipment start-up and shutdown. Temperature sensor (1041d) and level sensor (1041e) deployed on the lubricating oil tank are used to monitor oil temperature and oil level in the tank, respectively. A differential pressure switch (1041f) deployed on the lubrication station filter is used to monitor the filter clogging status; The DCS control system (101) is configured to receive signals from each sensor (1041), and the DCS (101) executes graded alarm or safety interlock logic according to a preset threshold.

5. A method for intelligent control of coal-fired power pulverizing equipment based on the system described in any one of claims 1-4, characterized in that, Includes the following steps: The method is executed under the coordination of the DCS control system (101) and includes the following steps: The DCS control system (101) receives the boiler main control command and outputs it as the output demand of the coal mill; based on the output demand and process optimization objectives, it generates and sends the speed command of the coal mill drum to the speed control unit (103), and at the same time generates the material level setting value command to the load coal level control unit (102). The frequency converter (1031) in the speed control unit (103) receives the speed command and obtains the actual speed feedback of the permanent magnet synchronous motor (1032). It uses a vector control algorithm to perform closed-loop regulation, drives the permanent magnet synchronous motor (1032), and drives the coal mill drum to run stably at the target speed through the reducer (1033). The load coal level control unit (102) works in a coordinated mode with differential pressure as the main factor and electric ears as the auxiliary factor to adjust the coal machine speed and coal storage capacity. The protection and interlocking unit (104) continuously collects the temperature, pressure, liquid level and vibration status parameters of the main motor, high and low pressure lubrication oil station and main bearing. When any parameter exceeds the preset safety threshold, it sends an interlocking signal to the DCS control system (101) to trigger a graded alarm or emergency shutdown. The DCS control system (101) integrates actual differential pressure feedback, electric ear signal, actual speed feedback and parameters of each sensor to dynamically adjust the speed command and material level setting value, so that the coal mill system always works in an energy-saving and efficient state with the best speed and material level under the premise of safety.

6. The intelligent control method for the novel coal-fired power pulverizing equipment as described in claim 5, characterized in that, The load coal level control unit (102) works in a coordinated mode, primarily based on differential pressure and secondarily on electric ears, to adjust the coal machine speed and coal storage capacity. Specifically, it includes the following steps: The actual pressure difference between the primary air header at the inlet of the coal mill and the outlet of the coarse powder separator is measured in real time and compared with the pressure difference set value corresponding to the material level set value from the DCS control system (101) to generate the first coal feeder speed adjustment command. The noise level of the coal mill is monitored in real time, and the speed adjustment command of the first coal feeder is quickly and finely adjusted. When the electric ear signal indicates a serious abnormality, the differential pressure control logic is exceeded and the safety interlock is triggered. The integrated feeder speed adjustment command is output to control the feeder speed and adjust the coal feed rate, thereby maintaining a constant optimal coal storage level in the cylinder.

7. The intelligent control method for the novel coal-fired power pulverizing equipment as described in claim 5, characterized in that, The execution of the vector control algorithm includes the following steps: The speed setpoint ω* from the DCS control system (101) is compared with the actual rotational speed ω fed back by the permanent magnet synchronous motor (1032), and the resulting speed error is sent to the speed regulator for processing. The output of the speed regulator is used as the torque current setpoint i_q*. Current inner loop control and coordinate transformation yield direct-axis voltage setpoint V_d* and quadrature-axis voltage setpoint V_q*; The direct-axis voltage setpoint V_d* and the quadrature-axis voltage setpoint V_q* are converted back to the two-phase voltages V_α and V_β in the stationary coordinate system by the inverse Park transformation. The two-phase voltages V_α and V_β are used to generate six PWM drive signals through a space vector pulse width modulation module to control the power switching devices of the inverter in the frequency converter (1031), thereby generating the required three-phase sinusoidal voltage at the terminal of the permanent magnet synchronous motor (1032) and realizing independent and precise control of the motor torque and magnetic field.

8. The intelligent control method for the novel coal-fired power pulverizing equipment as described in claim 5, characterized in that, Current inner loop control and coordinate transformation include the following steps: The rotor flux position angle θ and amplitude Ψ of the permanent magnet synchronous motor (1032) are observed and calculated in real time using a flux observer. The detected three-phase motor currents are converted into direct-axis current i_d and quadrature-axis current i_q in a rotating coordinate system using the Park transformation. The given current setpoint i_d* and the obtained torque current setpoint i_q* are compared with the feedback direct-axis current i_d and quadrature-axis current i_q, respectively. The resulting current errors are sent to the corresponding current regulators for processing, and voltage feedforward decoupling terms based on speed and motor parameters are added to output the direct-axis voltage setpoint V_d* and quadrature-axis voltage setpoint V_q* in the rotating coordinate system.

9. The intelligent control method for novel coal-fired power pulverizing equipment according to claim 5, characterized in that, The protection and interlocking unit (104) specifically performs the following steps: The system synchronously collects signals from the temperature sensor (1041a) deployed on the main motor stator and bearing, the main motor vibration sensor (1041b), the high and low pressure lubricating oil circuit pressure sensor (1041c), the lubricating oil tank temperature sensor (1041d) and level sensor (1041e), and the lubricating oil station filter differential pressure switch (1041f). The real-time values ​​of the collected sensor signals are compared with the preset alarm thresholds and trip thresholds to determine whether each monitoring point is in a normal, early warning, alarm, or trip state. Hierarchical safety response execution: When any monitoring point parameter reaches the alarm threshold but does not reach the trip threshold, the DCS control system (101) triggers an audible and visual alarm and records the event; when any monitoring point parameter reaches the trip threshold, or when multiple monitoring point parameters meet the preset interlocking logic conditions, the DCS control system (101) immediately generates and issues an emergency shutdown command to control the relevant equipment to trip.

10. The intelligent control method for novel coal-fired power pulverizing equipment according to claim 9, characterized in that, The interlocking logic conditions include at least one of the following: The main motor bearing temperature and the main motor vibration signal both exceed their respective alarm thresholds. The oil pressure in the high-pressure lubrication station is lower than the trip threshold, which directly constitutes a tripping condition. If the lubricating oil level in the tank is lower than the low level threshold, it directly constitutes a tripping condition. The execution of the protection and interlocking unit (104) enables the system to have a layered protection mechanism from early warning and alarm to emergency shutdown.

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