Energy storage device assisted AGC thermal power generating unit frequency modulation and peak regulation control system and method

Abstract

The invention discloses an energy storage device assisted AGC thermal power generating unit frequency modulation and peak regulation control system and method. Comprising an EMS power grid dispatching master station, an RTU, a DCS set decentralized control system, an MCS analog quantity control system, an FSSS hearth safety monitoring system, a DEH steam turbine digital electro-hydraulic control system, an EMS'energy storage controller, a super capacitor, a lithium battery and a liquid battery. According to the energy storage device-assisted AGC thermal power generating unit frequency modulation and peak regulation control system and method, a new hybrid energy storage system is added on the basis of an existing thermal power generating unit to assist in bringing into a thermal power generating unit AGC system, when a power grid needs load lifting and frequency modulation, the hybrid energy storage device is preferentially used for performing corresponding actions, and the characteristics of high regulation speed, short response time and high regulation precision of the device are utilized; and frequent starting, stopping and action of auxiliary equipment and a main steam control valve of the thermal power generating unit caused by responding to an AGC instruction are replaced, equipment abrasion is reduced, the service life of the main equipment and the auxiliary equipment is prolonged, and the failure rate is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of frequency and peak regulation of thermal power generation, and in particular to a frequency and peak regulation control system and method for an AGC thermal power unit assisted by an energy storage device. Background Art

[0002] The predictability of wind power, solar power and other new energy sources is relatively poor. The wind and solar power generation curve does not match the power load curve. At the same time, the controllability of new energy generation is relatively poor, and the primary frequency regulation contribution is limited. For the adjustment of the power grid, the higher the wind and solar power grid load, the more difficult it is to adjust the power grid. How to ensure the rapid development of the power grid while ensuring the technical indicators of the power grid frequency, voltage, etc. will also become an important technical problem.

[0003] At present, the AGC control principle of thermal power units is as follows: the power grid dispatching center sends the target load to the main analog control system (MCS) in the form of 4-20mA analog current through the RTU. After receiving this command signal, the main analog control system (MCS) adapts it to the operating status and load capacity of the machine and boiler, and further issues an action command to coordinate the machine and boiler, which acts on the boiler regulation system (FSSS) and steam turbine regulation (DEH) respectively, so as to ensure that the actual power of the thermal power unit follows the power grid AGC command. In order to achieve the above goals, the unit control system repeatedly adjusts the fuel and air volume of the boiler, and the regulating valve of the steam turbine quickly returns, resulting in large fluctuations in the boiler air volume, coal volume, steam pressure and temperature, thereby aggravating the wear and aging of the boiler heating surface and greatly reducing the service life of the steam turbine regulating valve. Summary of the invention

[0004] The technical problem to be solved by the present invention is to solve the problem that the unit control system repeatedly adjusts the fuel and air volume of the boiler, and the regulating valve of the turbine performs rapid reversal, resulting in large fluctuations in the boiler air volume, coal volume, steam pressure and temperature, thereby aggravating the wear and aging of the boiler heating surface and significantly reducing the service life of the turbine regulating valve. In order to solve the above problems, a control system and method for frequency and peak regulation of AGC thermal power units assisted by an energy storage device are provided.

[0005] The object of the present invention is achieved in the following manner: An energy storage device-assisted AGC thermal power unit frequency modulation and peak shaving control system, including an energy storage controller 7, an energy storage device, and a power conversion system (PCS) for the energy storage; the energy storage controller 7 is communicatively connected to the MCS analog control system 4. After the MCS analog control system 4 receives the target load issued by the EMS power grid dispatching master station 1, it makes it adapt to the operating status and load capacity of the boiler-turbine unit and the energy storage, and issues instructions for the coordinated operation of the boiler-turbine unit and the energy storage, which act on the DEH turbine digital electro-hydraulic control system 6, the boiler regulation system, and the energy storage controller respectively; the energy storage controller 7 is respectively connected to the energy storage device and the PCS of the energy storage converter. The energy storage device includes a supercapacitor 8, a lithium battery 9, and a liquid battery 10; both the supercapacitor 8 and the lithium battery 9 are connected to the high-voltage auxiliary power system through the PCS of the energy storage converter and are led to the outlet of the steam turbine generator through the high-voltage plant transformer; the liquid battery 10 is led to the in-plant 220 kV or 500 kV step-up bus through the PCS of the energy storage converter and a step-up transformer.

[0006] A control method for the energy storage device-assisted AGC thermal power unit frequency modulation and peak shaving control system described above, the method includes the following steps: S1. The energy storage device-assisted AGC thermal power unit frequency modulation and peak shaving control system is only put into operation when the DCS unit distributed control system and the AGC system of the thermal power unit are put into operation; S2. During power grid frequency modulation, the target value follows the sum of the turbine load and the power generation load of the supercapacitor 8. When the frequency modulation ends, the energy storage load is automatically set to 0; S3. When there is a peak shaving instruction within 2 hours in the power grid, start the combination of the supercapacitor 8 and the lithium battery 9, and set a certain time difference. First, put the supercapacitor 8 into operation, and then the lithium battery 9; S4. During peak shaving for more than 2 hours, start the combination of the supercapacitor 8 and the liquid battery 10, and set a time difference. First, put the supercapacitor 8 into operation, and then the liquid battery 10.

[0007] After the energy storage controller receives the peak shaving instruction from the power grid, it first judges the adjustment depth: If the adjustment instruction is greater than 20 WM and the time 0.5 < h < 2, judge whether the energy of the lithium battery 9 meets the instruction. If it meets, the lithium battery enters the discharge mode. If it does not meet, judge whether the energy of the supercapacitor 8 meets the instruction. If the energy of the supercapacitor meets the requirement, the supercapacitor enters the discharge mode to supplement the difference between the unit output and the AGC instruction. If it does not meet, the unit adjusts its output; If the adjustment instruction is greater than 2 WM and less than 20 WM and the time is less than 0.5 hours, the supercapacitor 8 and the lithium battery 9 are jointly adjusted. First, judge whether the energy of the supercapacitor meets the instruction. If it meets, the supercapacitor enters the discharge mode. If it does not meet, judge whether the energy of the lithium battery meets the instruction. If the lithium battery power meets the requirement, the lithium battery enters the discharge mode to supplement the difference between the unit output and the AGC instruction; If the adjustment instruction is less than 2WM and the time is less than 5 minutes, the supercapacitor 8 takes priority in the adjustment mode to determine whether the energy of the supercapacitor 8 meets the instruction. If it does, the supercapacitor enters the discharge mode to supplement the difference between the unit output and the AGC instruction. If it does not, the battery management system BMS is used to determine whether the battery energy meets the instruction. If the battery energy meets, the lithium battery enters the discharge mode to supplement the difference between the unit output and the AGC instruction. If the battery energy does not meet, the unit adjusts the output.

[0008] The beneficial effects of the present invention are as follows: a hybrid energy storage system is added to assist in incorporating the AGC system of the thermal power unit on the basis of the existing thermal power unit. When the power grid needs to raise or lower the load frequency modulation, the hybrid energy storage device is preferentially used to perform corresponding actions. The device is used to adjust the speed quickly, the response time is short, and the adjustment accuracy is high. The auxiliary equipment and the main steam regulating valve of the thermal power unit caused by responding to the AGC instruction are replaced. Frequent start and stop, action, and reduction of equipment wear, increase the service life of the main and auxiliary equipment, reduce the failure rate, reduce the difficulty of desulfurization and denitration control of the unit and the amount of ammonia spraying, and reduce the nitrogen oxides emitted by the unit; reduce the frequent and drastic changes in boiler operating parameters, smooth the air distribution, reduce the wear of boiler tubes, and extend the safe operation time of the boiler. The supercapacitor reaction time is less than 10ms, the lithium battery duration is 1-2h, and the liquid battery duration is more than 2h. Utilizing the fast reaction characteristics of the supercapacitor, it is preferentially enabled in frequency modulation and peak modulation, and then the lithium battery, liquid battery, etc. are started in sequence according to the load. The present invention utilizes the fast charging characteristics of the supercapacitor to solve the dead zone of AGC frequency modulation assessment, and improves the disadvantages of boiler system lag on AGC frequency modulation by integrating the energy storage system. It can significantly reduce the frequency of steam turbine valves and extend the life of equipment, while significantly improving the fit between power generation and target load curves. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is the AGC instruction control block diagram of the present invention; Figure 2 The AGC principle diagram of the present invention is shown below; Figure 3 It is a schematic diagram of the operation strategy of the energy storage controller of the present invention; Figure 4 This is a logic diagram of frequency and peak regulation of hybrid energy storage of ultracapacitor, lithium battery and flow battery of the present invention.

[0010] In the figure, 1-EMS power grid dispatching main station, 2-RTU telecontrol terminal unit, 3-DCS unit distributed control system, 4-MCS analog control system, 5-FSSS furnace safety monitoring system, 6-DEH steam turbine digital electro-hydraulic control system, 7-energy storage controller, 8-supercapacitor, 9-lithium battery, 10-liquid battery. DETAILED DESCRIPTION

[0011] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0012] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same technical meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0013] like Figure 1 and Figure 2 As shown, an energy storage device assists AGC thermal power unit frequency regulation and peak regulation control system, including an EMS power grid dispatching master station 1, an FSSS furnace safety monitoring system 5, and a DEH steam turbine digital electro-hydraulic control system 6; the EMS power grid dispatching master station 1 is connected to a DCS unit distributed control system 3 through an RTU telecontrol terminal unit 2, the DCS unit distributed control system 3 is connected to an MCS analog control system 4, and the MCS analog control system 4 is respectively connected to the FSSS furnace safety monitoring system 5 and the DEH steam turbine digital electro-hydraulic control system 6; it also includes an energy storage controller 7, an energy storage device, Energy storage converter PCS; the energy storage controller 7 is connected to the MCS analog control system 4 for communication, and the energy storage controller 7 controls the charging and discharging of the energy storage device; the EMS power grid dispatching master station 1 sends the target load to the MCS analog control system 4 in the form of 4-20mA analog current via the RTU remote terminal unit 2. After receiving this instruction, the MCS analog control system 4 adapts it to the operating status and load capacity of the machine, boiler and energy storage, and sends instructions for the coordinated action of the machine, boiler and energy storage, which act on the DEH steam turbine digital electro-hydraulic control system 6, boiler regulation system and energy storage controller 7 respectively.

[0014] The energy storage controller 7 is connected to the energy storage device and the energy storage converter PCS respectively. The energy storage device includes a super capacitor 8, a lithium battery 9 and a liquid battery 10; the super capacitor 8 and the lithium battery 9 are connected to the high-voltage plant power system through the energy storage converter PCS, and are led to the outlet of the steam turbine generator through the high-voltage plant transformer; the liquid battery 10 is led to the 220kV or 500kV boost bus in the plant through the energy storage converter PCS and the boost transformer. Since the grid metering point of the thermal power unit is on the side of the output line of the boost station, the online power is indirectly regulated by the charging and discharging of the energy storage in the station. For example, when the active power demand on the user side increases, the grid frequency will be reduced, and the mechanical adjustment speed of the traditional thermal power unit is slow. At this time, the energy storage device power is quickly released through this system to supplement the power demand, thereby increasing the grid frequency and achieving the purpose of frequency regulation. On the contrary, when the power consumption is low at night, the power generation is more than the power consumption, resulting in excess power and increased grid voltage. On the one hand, the output of the power supply side can be reduced, but the adjustment range is limited. At this time, the excess electricity can be stored in the long-term energy storage device to maintain the balance between power generation and power consumption, and reduce the abandonment of light to achieve the purpose of peak regulation.

[0015] In the embodiment of the present invention, the signal transmission of the energy storage device in the whole process of assisting the AGC thermal power unit frequency and peak regulation control system is bidirectional.

[0016] The power grid dispatching master station EMS in the frequency and peak regulation control system includes an AGC coordination control module and an AVC coordination control module, and the energy storage energy management system automatically receives dispatching instructions or locally stored planning curves, combines thermal power generation load, energy storage system data, power grid data and grid connection indicators, and adopts a safe, economical and optimized control strategy. By adjusting the energy storage inverter PCS, it effectively controls the active and reactive output of the battery group, forming a complete control system for active power and voltage / reactive power.

[0017] The energy storage device-assisted AGC thermal power unit frequency and peak regulation system is divided into an energy storage device layer, a coordination control layer and a station control layer. The station control layer includes an EMS power grid dispatching master station for energy storage system monitoring data management; and the coordination control layer includes an MCS analog control system for executing coordinated control and energy management strategies and calculating PCS instructions. The energy storage device layer includes an energy storage controller for executing scheduling commands for energy storage and uploading energy storage system operation information.

[0018] A control method for using an energy storage device to assist an AGC thermal power unit frequency and peak regulation control system, the method comprising the following steps: S1. The energy storage device assists the AGC thermal power unit frequency and peak regulation control system only when the DCS unit distributed control system and the thermal power unit AGC system are put into operation; S2. When the power grid performs frequency regulation, the target value follows the sum of the steam turbine load and the power generation load of the supercapacitor 8. When the frequency regulation ends, the energy storage load is automatically set to 0; S3. When there is a peak shaving instruction within 2 hours in the power grid, start the combination of the supercapacitor 8 and the lithium battery 9, and set a certain time difference. First, the supercapacitor 8 is put into operation, and then the lithium battery 9; S4. When performing peak shaving for more than 2 hours, start the combination of the supercapacitor 8 and the liquid battery 10, and set a time difference. First, the supercapacitor 8 is put into operation, and then the liquid battery 10.

[0019] As Figure 4 shown, the logic diagram of frequency regulation and peak shaving for the hybrid energy storage of the supercapacitor, lithium battery and liquid battery of the present invention. After the energy storage controller receives the peak shaving instruction from the power grid, it first judges the adjustment depth: If the adjustment instruction is greater than 20WM and the time 0.5 < h < 2, judge whether the energy of the lithium battery 9 meets the instruction. If it meets, the lithium battery enters the discharge mode. If it does not meet, judge whether the energy of the supercapacitor 8 meets the instruction. If the energy of the supercapacitor meets the requirement, the supercapacitor enters the discharge mode to supplement the difference between the unit output and the AGC instruction. If it does not meet, the unit adjusts the output; If the adjustment instruction is greater than 2WM and less than 20WM and the time is less than 0.5 hours, the supercapacitor 8 and the lithium battery 9 are jointly adjusted. First, judge whether the energy of the supercapacitor meets the instruction. If it meets, the supercapacitor enters the discharge mode. If it does not meet, judge whether the energy of the lithium battery meets the instruction. If the lithium battery power meets the requirement, the lithium battery enters the discharge mode to supplement the difference between the unit output and the AGC instruction; If the adjustment instruction is less than 2WM and the time is less than 5 minutes, the supercapacitor priority adjustment mode is adopted. Judge whether the capacitor energy meets the instruction. If it meets, the supercapacitor enters the discharge mode to supplement the difference between the unit output and the AGC instruction. If it does not meet, use the battery management system (BMS) of the battery body to judge whether the battery energy meets the instruction. If the battery energy meets the requirement, the lithium battery enters the discharge mode to supplement the difference between the unit output and the AGC instruction. If the battery energy does not meet the requirement, the unit adjusts the output.

[0020] In summary, the present invention adds a hybrid energy storage system to assist in incorporating the AGC system of the thermal power unit on the basis of the existing thermal power unit. When the power grid needs to increase or decrease the load and adjust the frequency, the hybrid energy storage device is given priority to perform corresponding actions, and the characteristics of the device such as fast adjustment speed, short response time, and high adjustment accuracy are used to replace the frequent start and stop and action of the auxiliary equipment and main steam regulating valve of the thermal power unit caused by responding to the AGC command, thereby reducing equipment wear, increasing the service life of the main and auxiliary equipment, and reducing the failure rate, reducing the difficulty of controlling the desulfurization and denitrification of the unit and the use of ammonia injection, and reducing the nitrogen oxides emitted by the unit; reducing the frequent and drastic changes in the boiler operating parameters, smoothly distributing air, reducing the wear of the boiler tubes, and extending the safe operation time of the boiler. The supercapacitor reaction time is less than 10ms, the lithium battery lasts for 1-2h, and the liquid battery lasts for more than 2h. By utilizing the fast response characteristics of supercapacitors, they are enabled first in frequency and peak regulation, and then lithium batteries, liquid batteries, etc. are started in sequence according to the load, providing a new and effective control scheme for AGC frequency regulation of traditional thermal power units. The present invention utilizes the fast charging characteristics of supercapacitors to solve the dead zone of AGC frequency regulation assessment, and can improve the disadvantages of boiler system lag on AGC frequency regulation by integrating the energy storage system, which can significantly reduce the frequency of steam turbine valves and extend the life of equipment. At the same time, it can significantly improve the fit between power generation and target load curves.

[0021] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, which should also be regarded as the scope of protection of the present invention.

Claims

1. An energy storage device assisted AGC thermal power unit frequency regulation and peak regulation control system, characterized in that: It includes an energy storage controller (7), an energy storage device, and a power conversion system (PCS) for energy storage; the energy storage controller (7) is communicatively connected to the MCS analog control system (4). After the MCS analog control system (4) receives the target load issued by the EMS grid dispatching master station (1), it makes it adapt to the operating status and load capacity of the boiler-turbine unit and the energy storage, and issues instructions for the coordinated operation of the boiler-turbine unit and the energy storage, which act on the DEH turbine digital electro-hydraulic control system (6), the boiler regulation system, and the energy storage controller respectively; the energy storage controller (7) is respectively connected to the energy storage device and the power conversion system (PCS) for energy storage. The energy storage device includes a supercapacitor (8), a lithium battery (9), and a liquid battery (10); both the supercapacitor (8) and the lithium battery (9) are connected to the high-voltage auxiliary power system through the power conversion system (PCS) for energy storage and are led to the outlet of the steam turbine generator through the high-voltage plant transformer; the liquid battery (10) is led to the in-plant 220 kV or 500 kV step-up bus through the power conversion system (PCS) for energy storage and a step-up transformer.

2. A control method for using the energy storage device according to claim 1 to assist an AGC thermal power unit in frequency and peak regulation control system, characterized in that: The method includes the following steps: S1. The frequency modulation and peak shaving control system of the energy storage device assisting the AGC thermal power unit is only put into operation when the DCS unit distributed control system and the AGC system of the thermal power unit are put into operation. S2. During grid frequency modulation, the target value follows the sum of the turbine load and the power generation load of the supercapacitor (8). When the frequency modulation ends, the energy storage load is automatically set to 0. S3. When there is a peak shaving instruction within 2 hours in the grid, start the combination of the supercapacitor (8) and the lithium battery (9), and set a certain time difference. First, put the supercapacitor (8) into operation, and then the lithium battery (9). S4. During peak shaving for more than 2 hours, start the combination of the supercapacitor (8) and the liquid battery (10), and set a time difference. First, put the supercapacitor (8) into operation, and then the liquid battery (10).

3. The control method according to claim 2, characterized in that: After receiving the peak shaving instruction from the grid, the energy storage controller first judges the regulation depth: If the regulation instruction is greater than 20 WM and 0.5 < h < 2, judge whether the energy of the lithium battery (9) meets the instruction. If it meets, the lithium battery enters the discharge mode. If it does not meet, judge whether the energy of the supercapacitor (8) meets the instruction. If the energy of the supercapacitor meets the requirement, the supercapacitor enters the discharge mode to supplement the difference between the unit output and the AGC instruction. If it does not meet, the unit adjusts its output. If the regulation instruction is greater than 2 WM and less than 20 WM and the time is less than 0.5 hours, the supercapacitor (8) and the lithium battery (9) are jointly regulated. First, judge whether the energy of the supercapacitor meets the instruction. If it meets, the supercapacitor enters the discharge mode. If it does not meet, judge whether the energy of the lithium battery meets the instruction. If the lithium battery's charge meets the requirement, the lithium battery enters the discharge mode to supplement the difference between the unit output and the AGC instruction. If the adjustment command is less than 2WM and the time is less than 5 minutes, the supercapacitor (8) takes priority in the adjustment mode to determine whether the energy of the supercapacitor (8) meets the command. If it does, the supercapacitor enters the discharge mode to supplement the difference between the unit output and the AGC command. If it does not, the battery management system BMS is used to determine whether the battery energy meets the command. If the battery energy meets the command, the lithium battery enters the discharge mode to supplement the difference between the unit output and the AGC command. If the battery energy does not meet the command, the unit adjusts the output.

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