SFC control method of pumped storage power station based on Ethernet communication

Abstract

The invention provides a pumped storage power station SFC control method based on Ethernet communication, the control method is based on a control network structure of Ethernet communication, an LCU of each generator set is connected with a public LCU through a network A and a network B of a double-loop network, SFC control information of the LCU of each generator set is gathered to the public LCU, programming is carried out in a controller of the public LCU, information integration is completed, and the SFC control information of the LCU of each generator set is stored in the public LCU. The common LCU controls the SFC devices in a one-to-one mode, and state feedback signals of the SFC devices are transmitted to the common LCU and transmitted to the corresponding unit LCU through SFC selection marks. The use amount of bridging relays is reduced, control failure caused by unreliable relay contacts is reduced, and the pumping phase modulation starting success rate of the pumped storage unit can be improved. Fault diagnosis information can be transmitted to a power station computer monitoring system through communication and programming, faults can be quickly positioned, only communication physical channels and control programs need to be checked, tedious relay bridging loops do not need to be checked, fault removal is faster, and operation and maintenance are more reliable and convenient.

Description

Technical Field

[0001] The invention relates to the technical field of pumped storage power station control, and in particular to an SFC control method of a pumped storage power station based on Ethernet communication. Background Art

[0002] SFC (static frequency changer) is a very important starting device for pumped storage power plants. Considering the construction cost, usually one pumped storage power plant is equipped with 1-2 sets of SFC for pumping start of generator motors. The power plant computing and monitoring system controls the SFC to pump start any unit.

[0003] In the traditional design of a SFC controlling multiple units, a relay bridge method is used, using a large number of relays to switch different control signal inputs and outputs to complete the control start of the SFC. For example, if Unit 1 is selected to be started by SFC 1, Unit 1 will open the SFC start relay, which needs to expand 36 pairs of contacts for Unit 1 to transmit control signals and feedback signals to SFC 1. Any abnormal contact will cause the SFC to start the motor failure.

[0004] Taking the excitation current control as an example, in the traditional SFC startup process, the SFC and the excitation control the unit terminal voltage through the monitoring relay bridge method. The SFC compares the excitation current with the 4-20mA analog feedback from the excitation system, and the error signal is sent to the SFC voltage regulator. The SFC then outputs the excitation current set value. The excitation system controls the trigger pulse angle in the current closed-loop mode with reference to the set value, thereby controlling the unit terminal voltage. In the field application process, due to the control cable being too long, any abnormal or faulty contact of the bridge relay, the 4-20mA feedback between the SFC and the excitation will be slow or distorted, which will affect the response speed of the excitation system, causing the unit terminal voltage to be adjusted slowly and the unit terminal voltage to be unstable. In severe cases, the unit will fail to start. Summary of the invention

[0005] The present invention provides an SFC control method for a pumped storage power station based on Ethernet communication, which utilizes Ethernet communication to replace traditional relay bridging, thereby solving the problem of startup failure of relay bridging control caused by poor contact of relay contacts or excessive contact resistance.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: The invention discloses an SFC control method based on Ethernet communication for a pumped storage power station. The SFC control method is based on a control network of Ethernet communication. The control network includes a common LCU and the LCUs of each generator set. The LCUs of each generator set are connected to the common LCU through network A and network B of a double-loop network. Network A and network B are redundant with each other. The common LCU is connected to SFC No. 1 and SFC No. 2 devices. The SFC control information of the LCUs of each generator set is gathered to the common LCU. The controller of the common LCU is programmed to complete information integration. The common LCU controls the SFC device one-to-one. The status feedback signal of the SFC device is transmitted to the common LCU and transmitted to the corresponding unit LCU through the SFC selection mark.

[0007] The above SFC control process is: Step 1: When the water pump unit needs to be started as planned, the automatic generation controller AGC or the operator determines whether the SFC is selectable. If it is selectable, it enters Step 2. If it is not selectable, it exits to the initial state. Step 2, the automatic generation controller AGC or the operator selects the X-unit to be dragged by the Y-unit SFC device, where X is the unit number, Y is the SFC device number, and Y=1 or 2; Step 3, Unit X sends the SFC device selection information to the common LCU; Step 4, the public LCU sets the control information of unit X to SFC device Y as valid, and sets SFC device Y as unselectable; Step 5: Unit X starts according to the pumping phase adjustment process, and transmits the SFC control information to the public LCU in real time. The public LCU forwards the control information to the SFC device Y to drive Unit X to start; Step 6, determine whether the SFC driven unit meets the synchronous grid connection conditions, if so, go to Step 7; Step 7, the X unit LCU transmits the synchronous grid-connected information of increasing and decreasing magnetic field and increasing and decreasing speed to the public LCU, and the public LCU forwards the increase and decrease information to the SFC device; Step 8: Determine whether the pumping phase adjustment and grid connection of Unit X is successful. If so, proceed to Step 9; Step 9, Unit X exits and selects SFC Y, and the public LCU sets SFC Y as optional.

[0008] The logic of the above automatic generation controller AGC or the operator selecting the SFC device to drive is: When the LCU of unit X receives the command to select SFC device No. Y, the selection signal of the corresponding SFC device "SFC No. Y is selected by unit No. X" is set. When the startup is completed or the fault is exited, the selection signal of the corresponding SFC device "SFC No. Y is selected by unit No. X" is reset.

[0009] The above-mentioned common LCU receives the selection status signal of the SFC device of the unit and sets the selected SFC to be unselectable to prevent other units from selecting the SFC. The logic control is as follows: All "SFC No. 1 is selected by unit No. X" are controlled by "AND" operation after "NOT" operation, and the signal status of "SFC No. 1 is optional" is controlled by "AND" operation; All "SFC No. 2 is selected by unit No. X" are controlled by "AND" operation after "NOT" operation, and the signal status of "SFC No. 2 is optional" is controlled by "AND" operation.

[0010] The above-mentioned unit LCU integrates the control information of the SFC into a control word, that is, a 16-bit binary word.

[0011] The above-mentioned 16-bit control word is transmitted to the common LCU in real time. The common LCU outputs the control word to control the SFC system according to the SFC selection information. The SFC system transmits the real-time status information to the common LCU. The common LCU transmits the status information back to the corresponding unit LCU according to the SFC selection information.

[0012] The above-mentioned unit LCU transmits the excitation current to the common LCU in real time, and the common LCU outputs the excitation current to the SFC device according to the selection information of the SFC.

[0013] The present invention provides an SFC control method for a pumped storage power station based on Ethernet communication, which uses communication and programming to replace the traditional relay bridging circuit, thereby improving the information level of the automatic control system. It reduces the cable laying and related labor costs during the construction period. It reduces the use of bridging relays and reduces the control failure caused by unreliable relay contacts, which can improve the success rate of pumping phase adjustment start-up of the pumped storage unit. By using communication and programming, fault diagnosis information can be transmitted to the power station computer monitoring system, and the fault can be quickly located. It only needs to check the communication physical channel and control program, without checking the cumbersome relay bridging circuit, making troubleshooting faster and operation and maintenance more reliable and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 A network structure diagram of an Ethernet communication control SFC system of the present invention; Figure 2 A control flow chart of the Ethernet communication control SFC system of the present invention; Figure 3 A schematic diagram showing the logic of selecting the SFC signal to maintain for the LCU of the unit of the present invention; Figure 4 After the SFC of the present invention is selected, the SFC is set as an unselectable logic schematic diagram; Figure 5 A logical schematic diagram of the unit LCU of the present invention integrating SFC control information into a control word; Figure 6 A logic diagram of selecting a unit control word to output to SFC in the present invention; Figure 7 The unit is selected for the present invention to output the excitation current to the SFC. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following content will systematically and completely describe the specific technical solutions of the present invention in combination with the drawings provided according to the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0016] Example: A SFC control method based on Ethernet communication for a pumped storage power station. The SFC control method is based on a control network for Ethernet communication. The control network includes a common LCU and LCUs of each generator set. The LCUs of each generator set are connected to the common LCU through a network A and a network B of a double-loop network. The network A and the network B are mutually redundant. The common LCU is connected to a No. 1 SFC device and a No. 2 SFC device. SFC control information of the LCUs of each generator set is gathered to the common LCU. The controller of the common LCU is programmed to complete information integration. The common LCU controls the SFC device one-to-one. The state feedback signal of the SFC device is transmitted to the common LCU and transmitted to the corresponding unit LCU through an SFC selection mark.

[0017] The method of the present invention uses Ethernet communication technology and utilizes the power station computer monitoring system network to aggregate the SFC control information of the unit LCU to the public LCU, and completes the information integration by programming the controller of the public LCU. The public LCU controls the SFC system one-to-one. The state feedback signal of the SFC system is transmitted to the public, and is transmitted to the corresponding unit LCU through the SFC selection mark.

[0018] Network structure: Using the network of the monitoring system, this power station uses a double-ring network structure built with single-mode optical fiber. The A and B networks are redundant with each other. If a breakpoint occurs in any ring network, it can be quickly healed to ensure normal data communication and send out an alarm. The maintenance personnel can determine the fault point based on the alarm information and handle it quickly. The communication network diagram is as follows: Figure 1 shown.

[0019] Communication data: The unit LCU communicates control information and status information to the public LCU, which is integrated and transmitted to the SFC through programming. It is the input signal of the SFC and is transmitted from the unit LCU to the public LCU for controlling the SFC. It is marked with analog AI and digital DI. The SFC outputs control information and status information to the public LCU and then communicates it to the unit using the SFC. It is marked with analog AO and output DO, as shown in Table 1: Table 1: Exchange information table of the unit LCU and SFC control process

[0020] Control process: When the water pump unit needs to be started as planned, the AGC (automatic generation control) or the operator determines whether the SFC is selectable. The AGC or the operator selects the X unit to be driven by the Y SFC. The X unit sends the SFC selection information to the public LCU. The public LCU sets the control information of the X unit to the Y SFC as valid, and sets the Y SFC as unselectable to prevent other units from selecting the Y SFC to be driven. The X unit is started according to the pumping phase adjustment process, and the SFC control information is transmitted to the public LCU in real time. The public LCU forwards the control information to the Y SFC to drive the X unit to start. When the SFC-driven unit enters the quasi-synchronous condition, the X unit LCU transmits the synchronous grid-connected information such as increase and decrease of magnetism and increase and decrease of speed to the public LCU, and the public LCU forwards the increase and decrease information to the X SFC. After the standby unit is successfully pumped and phased and connected to the grid, the X unit exits the selection of the Y SFC, and the public LCU sets the Y SFC as selectable. The control process is as follows: Figure 2 shown.

[0021] Logic block diagram: 1) AGC or operator operates the unit to select SFC drag logic. The unit LCU remains in the selected state after receiving the command; Figure 3 As shown, the RS module in the figure is a reset priority RS trigger, and the unit LCU transmits the SFC selection status to the common LCU.

[0022] 2) The public LCU receives the SFC selection status signal of the unit and sets the selected SFC to be unselectable to prevent other units from selecting the SFC; Figure 4 As shown in the figure, the & module is a logic and function block. If any unit selects this SFC, the SFC optional state will be set to zero.

[0023] 3) The unit LCU integrates the SFC control information into a control word; e.g. Figure 5 As shown, the module BIT_TO_WORD is a function block for converting bit variables into word variables, which converts the switch control point into a control word.

[0024] 4) The control word is transmitted to the public LCU in real time. The public LCU outputs the control word to control the SFC system according to the SFC selection information; Figure 6 As shown, the module MUX_N is a multi-channel selection function block. When the input of one of the channels A1-A6 is 1, the corresponding IA1-IA6 output is used for SFC control.

[0025] 5) The unit LCU transmits the excitation current to the public LCU in real time, and the public LCU outputs the excitation current to the SFC system according to the SFC selection information; Figure 7 shown.

Claims

1. A SFC control method for a pumped storage power station based on Ethernet communication, characterized in that: The SFC control method is based on a control network of Ethernet communication. The control network includes a common LCU and the LCUs of each generator set. The LCUs of each generator set are connected to the common LCU through network A and network B of a dual-ring network. Network A and network B are redundant with each other. The common LCU is connected to SFC devices No. 1 and SFC devices No.

2. The SFC control information of the LCUs of each generator set is converged to the common LCU. The controller of the common LCU is programmed to complete information integration. The common LCU controls the SFC device one-to-one. The status feedback signal of the SFC device is transmitted to the common LCU and transmitted to the corresponding unit LCU through the SFC selection mark.

2. The SFC control method of a pumped storage power station based on Ethernet communication according to claim 1, characterized in that: The SFC control process is as follows: Step 1: When the water pump unit needs to be started as planned, the automatic generation controller AGC or the operator determines whether the SFC is selectable. If it is selectable, it enters Step 2. If it is not selectable, it exits to the initial state. Step 2, the automatic generation controller AGC or the operator selects the X-unit to be dragged by the Y-unit SFC device, where X is the unit number, Y is the SFC device number, and Y=1 or 2; Step 3, Unit X sends the SFC device selection information to the common LCU; Step 4, the public LCU sets the control information of unit X to SFC device Y as valid, and sets SFC device Y as unselectable; Step 5: Unit X starts according to the pumping phase adjustment process, and transmits the SFC control information to the public LCU in real time. The public LCU forwards the control information to the SFC device Y to drive Unit X to start; Step 6, determine whether the SFC driven unit meets the synchronous grid connection conditions, if so, go to Step 7; Step 7, the X unit LCU transmits the synchronous grid-connected information of increasing and decreasing magnetic field and increasing and decreasing speed to the public LCU, and the public LCU forwards the increase and decrease information to the SFC device; Step 8: Determine whether the pumping phase adjustment and grid connection of Unit X is successful. If so, proceed to Step 9; Step 9, Unit X exits and selects SFC Y, and the public LCU sets SFC Y as optional.

3. The SFC control method of a pumped storage power station based on Ethernet communication according to claim 2, characterized in that: The logic of the automatic generation controller AGC or the operator selecting the SFC device to drive is: When the LCU of unit X receives the command to select SFC device Y, the selection signal of the corresponding SFC device "SFC device Y is selected by unit X" is set. When the startup is completed or the fault is exited, the selection signal of the corresponding SFC device "SFC device Y is selected by unit X" is reset.

4. The SFC control method of a pumped storage power station based on Ethernet communication according to claim 3, characterized in that: The public LCU receives the selection status signal of the SFC device of the unit and sets the selected SFC to be unselectable to prevent other units from selecting the SFC. The logic control is as follows: All "No. 1 SFC is selected by No. X unit" are controlled by "and" operation after "not" operation, and "No. 1 SFC is optional" signal status is controlled by "and" operation; All "SFC No. 2 is selected by unit No. X" are controlled by "AND" operation after "NOT" operation and "SFC No. 2 is optional" signal status.

5. The SFC control method of a pumped storage power station based on Ethernet communication according to claim 4, characterized in that: The unit LCU integrates the control information of the SFC into a control word, namely a 16-bit binary word.

6. The SFC control method of a pumped storage power station based on Ethernet communication according to claim 5, characterized in that: The 16-bit control word is transmitted to the common LCU in real time. The common LCU outputs the control word to control the SFC system according to the SFC selection information. The SFC system transmits the real-time status information to the common LCU. The common LCU transmits the status information back to the corresponding unit LCU according to the SFC selection information.

7. The SFC control method of a pumped storage power station based on Ethernet communication according to claim 6, characterized in that: The unit LCU transmits the excitation current to the common LCU in real time, and the common LCU outputs the excitation current to the SFC device according to the selection information of the SFC.

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