Semi-physical simulation system and simulation method considering network-related protection check

Abstract

The invention discloses a semi-physical simulation system and simulation method considering grid-related protection check, and belongs to the technical field of grid-related protection, and the method comprises the steps: an analogue simulation operation unit builds a simulation model, outputs an electrical semaphore, receives a control voltage, and obtains an excitation voltage through a regulation link, thereby controlling the terminal voltage of a generator; the excitation control device receives an electrical semaphore, converts the electrical semaphore into a control semaphore, and transmits the control semaphore to the analogue simulation operation unit, wherein the control semaphore comprises a control voltage; the generator-transformer set protection device receives the electrical semaphore, the excitation voltage and the excitation current and calculates an actual electrical constant value when the analogue simulation operation unit has a fault, compares the actual electrical constant value with a preset value, and judges whether to execute generator-transformer set protection action or not. According to the method, the problem that simulation of the matching relation between generator-transformer unit protection and excitation limitation in grid-related protection checking by existing pure digital simulation is unreasonable and unreliable is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of network-related protection, and in particular relates to a semi-physical simulation system and a simulation method taking network-related protection verification into account. Background Art

[0002] With the large-scale grid connection of new energy sources, the power system faces a more complex operating environment, and the problem of reactive power is becoming increasingly prominent. This not only affects the voltage stability of the power grid, but also puts higher requirements on the operation of the generator set. In this context, the demagnetization leading phase operation capability of large-capacity generator sets becomes particularly critical, but the generator leading depth in the existing leading phase test is often insufficient and difficult to meet the requirements of the power grid standards. This not only limits the operating flexibility of the generator set, but may also lead to the setting of the protection setting value is not scientific and reasonable, which in turn affects the reliability of the coordination between the grid-related protection and restrictions and the actual power grid.

[0003] In order to meet this challenge, it is necessary to accurately check the coordination setting of protection and restriction before unknown risk operation. At present, most of the commonly used power system stability simulation programs at home and abroad adopt pure digital simulation verification methods, but this method is not reliable and accurate enough when simulating the unreasonable coordination relationship between the generator-transformer group protection and the excitation limitation and the action behavior of the grid-related protection. Therefore, there is an urgent need for a semi-physical research platform to study and verify these problems more accurately, so as to improve the reliability of system operation. Summary of the invention

[0004] The purpose of the present invention is to provide a semi-physical simulation system and simulation method taking into account grid-related protection verification, so as to solve the problem that the coordination relationship between generator-transformer group protection and excitation limitation in grid-related protection verification simulated by existing pure digital simulation is unreasonable and unreliable.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, a semi-physical simulation system for network-related protection verification includes: a simulation operation unit, a signal acquisition and interface unit, and a physical test unit, wherein the simulation operation unit is connected to the physical test unit via the signal acquisition and interface unit, and the physical test unit includes a generator-transformer group protection device and an excitation control device; A simulation operation unit is used to establish a simulation model and output an electrical signal, receive the control voltage fed back by the excitation control device and obtain the excitation voltage from the control voltage through a regulating link, thereby controlling the generator terminal voltage; An excitation control device, used for receiving the electrical signal and converting it into a control signal, and then transmitting the control signal to the simulation operation unit, wherein the control signal includes a control voltage; The generator-transformer group protection device is used to receive the electrical signal quantity, excitation voltage and excitation current and calculate the actual electrical constant when the simulation operation unit is set to fail, compare the actual electrical constant with a preset value, and execute the generator-transformer group protection action when the actual electrical constant exceeds the range of the preset value.

[0006] In some implementations, the simulation operation unit includes a simulation host and host computer software, the host computer software runs in the simulation host, and the host computer software establishes a single-machine-infinite system simulation model.

[0007] In some embodiments, the signal acquisition and interface unit includes an AI / AO interface device and a DI / DO interface device, the AI / AO interface device is connected to the simulation host, the excitation control device and the generator-transformer group protection device, and the DI / DO interface device is connected to the simulation host, the excitation control device and the generator-transformer group protection device.

[0008] In some implementations, the electrical signal quantities include: generator terminal voltage, stator current, switch position, generator frequency, etc.

[0009] In some embodiments, the signal acquisition and interface unit further includes a power amplifier for receiving the generator terminal voltage and stator current, and outputting three-phase AC voltage and three-phase AC current to the excitation control device and the generator-transformer group protection device.

[0010] In some implementations, the control signal quantity further includes a PID adjustment instruction, a trip signal, and a channel switching signal.

[0011] In a second aspect, a simulation method of a semi-physical simulation system taking into account network protection verification is based on the semi-physical simulation system described in the claims, comprising the following steps: A simulation model is established in the simulation operation unit, and initialization power flow parameters are configured to provide an initial operation state for the simulation operation unit. The simulation operation unit outputs the generator terminal voltage, stator current, switch position and generator frequency to the excitation control device and the generator-transformer group protection device through the simulation model; The excitation control device obtains the control voltage through internal control according to the generator terminal voltage, stator current, switch position and generator frequency, and the control voltage obtains the excitation voltage and excitation current through the links in the simulation model; The generator-transformer group protection device calculates according to the generator terminal voltage, stator current, switch position, generator frequency, excitation voltage and excitation current to obtain an actual electrical set value, compares the actual electrical set value with a preset value to obtain a comparison result, and determines whether to execute the generator-transformer group protection action according to the comparison result.

[0012] In some implementations, the step of obtaining the excitation voltage and the excitation current through the links in the simulation model by controlling the voltage specifically includes the following steps: The control voltage outputs an excitation voltage through the SCR link in the simulation model, and the excitation voltage supplies power to the generator, thereby generating an excitation current.

[0013] In some embodiments, the following steps are also included: if the actual electrical setting exceeds the range of preset values, the generator-transformer group protection device performs the generator-transformer group protection action; if the actual electrical setting does not exceed the range of preset values, the generator-transformer group protection device does not perform the generator-transformer group protection action.

[0014] In some embodiments, the following steps are also included: before the excitation control device is operated, an excitation model is configured in the simulation operation unit to perform excitation control, and when the grid-connected unit operates stably, the excitation model is switched to the excitation control device.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a semi-physical simulation system taking into account grid-related protection verification, including a simulation operation unit, a signal acquisition and interface unit, and a physical test unit, wherein the physical test unit includes a generator-transformer group protection device and an excitation control device, wherein the excitation control device receives an electrical signal quantity and converts it into a control signal quantity, and then transmits the control signal quantity to the simulation operation unit, wherein the control signal quantity includes a control voltage; when the simulation operation unit sets a fault, the generator-transformer group protection device receives the electrical signal quantity, the excitation voltage, and the excitation current, and calculates the actual electrical constant value, compares the actual electrical constant value with a preset value, and when the actual electrical constant value exceeds the range of the preset value, the generator-transformer group protection action is executed. The present invention can reliably verify the coordination relationship between the generator-transformer group protection and the excitation limit to ensure the correct action behavior of the grid-related protection, and improve the safety and reliability of the system operation.

[0016] Furthermore, the present invention configures a single-machine-infinite system simulation model in the host computer software, and can adjust the initialization power flow parameters as needed, so that the entire semi-physical simulation system can adapt to different test requirements and improve the pertinence and accuracy of the test.

[0017] Furthermore, the signal acquisition and interface unit includes AI / AO (analog input / analog output) interface device and DI / DO (digital input / digital output) interface device, as well as power amplifier, which can accurately collect and process electrical signal quantities such as generator terminal voltage, stator current, switch position, and control signal quantities such as control voltage and PID adjustment instructions. It ensures that the system can reflect the operation status of the power grid in real time and accurately, and provide reliable input signals for the generator-transformer protection device and excitation control device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A block diagram of a semi-physical simulation system structure taking into account network-related protection verification provided in Example 1; Figure 2 A signal transmission principle diagram of a semi-physical simulation system taking into account network-related protection verification provided in Example 1; Figure 3 A verification flow chart of a semi-physical simulation system taking into account network protection verification provided in Example 1. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings, and the described content is intended to explain the present invention rather than to limit it.

[0020] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or are inherent to these processes, methods, systems, products or apparatus.

[0021] Embodiment 1 In order to realize the semi-physical simulation of grid-related protection verification and fully realize the verification of the coordination between excitation limitation and generator-transformer group protection, such as Figure 1 As shown, this embodiment provides a semi-physical simulation system taking into account network-related protection verification, including: a simulation operation unit A1, a signal acquisition and interface unit A2, and a physical test unit A3, which are connected through signal cables to form a closed loop. A simulation model is built in the simulation operation unit A1, and the required analog signals and digital signals are provided to the physical test unit A3 through the signal acquisition and interface unit A2. After the link adjustment of the physical test unit A3, the required digital and analog signals are obtained and fed back to the simulation operation unit A1, thereby forming a closed-loop semi-physical simulation environment.

[0022] The simulation operation unit A1 includes a simulation host A11 and a host computer software A12. The host computer software A12 is used to establish a single-machine-infinite system simulation model, including a generator model, a transformer model, a π-type line model, and an infinite power supply model. The generator model also includes a voltage regulator model, a speed regulator model, and a PSS model. The required model elements and the connection relationship between the elements are established in the host computer software, the parameters of each element are input, the dynamic curve monitoring and variable control modules are set, the initial power flow parameters are input, and the initial operation state is provided for the simulation system, and then the simulation can be started.

[0023] The initial power flow parameter settings in the simulation model established by the host computer software A12 include establishing the voltage effective value and voltage phase angle of each bus node in the single-machine-infinite system simulation model.

[0024] The signal acquisition and interface unit A2 includes an AI / AO interface device A22 and a DI / DO interface device A23. Through the interface and signal transmission of the system, the simulation operation unit A1 provides the required generator terminal voltage Ut, stator current It, excitation current If, generator frequency f, switch position and other analog and digital signals to the excitation control device A32 and the generator-transformer group protection device A31. The functional board of the simulation host A11 physical interface box includes analog input AI, analog output AO, digital input DI and digital output DO. Each board has multiple interfaces for realizing the conversion function of digital and analog signals, which can be connected with the AI / AO interface device A22 and the DI / DO interface device A23 to realize signal transmission. The power amplifier A21 receives the analog quantities such as the terminal voltage Ut and stator current It calculated by the simulation host, and outputs the three-phase AC voltage and three-phase AC current and other AC quantities through the interface and sends them to the excitation control device A32 and the generator-transformer group protection device A31.

[0025] The physical test unit A3 includes an excitation control device A32 and a generator-transformer group protection device A31. Both devices include a power module, a CPU / FPGA / DSP module, an input module, an output module, a communication module and an AC module. The excitation control device A32 receives the digital and analog quantities such as the generator terminal voltage Ut, the stator current It, the excitation current If, the switch position, etc. transmitted by the simulation operation unit A1. The excitation control device A32 returns the output control voltage Uc, PID adjustment instructions, tripping signals, channel switching signals, etc. analog and digital quantities to the simulation operation unit A1, and obtains the excitation voltage Uf and other analog and digital quantities through the model adjustment link of the simulation operation system A1. The generator-transformer group protection device A31 receives the digital and analog quantities such as the generator terminal voltage, stator current, main switch position, etc. sent by the simulation operation unit A1, and the analog and digital quantities such as the excitation voltage Uf and excitation current If sent by the excitation control device, and performs the protection action by calculating and comparing with the preset values.

[0026] The semi-physical simulation system can also realize pure digital dynamic simulation, provide switching between the excitation model and the excitation control device A32, and select the excitation model channel to select the pure digital dynamic simulation. Select the control process of the excitation model in the host computer software A12, and after the simulated grid-connected unit transition is stable, it can be switched to the excitation control device A32, that is, the semi-physical simulation operation mode.

[0027] The SCR (Silicon Controlled Rectifier) ​​in the simulation operation unit A1 is characterized by a first-order lag link that describes the rectifier characteristics. This link is represented by a transfer function Indicates that is the complex variable of the Laplace transform, is the time constant. Calculate the channel ratio of the physical interface box of the simulation host A11, and input the relevant ratio parameters in the host computer software A12. The physical interface module is configured with 6 input signals and 1 output signal. The input signals include: the instantaneous voltage of the machine-end voltage phase A, the instantaneous voltage of the machine-end voltage phase B, the instantaneous voltage of the machine-end voltage phase C, the ratio K1; the stator phase current of the generator phase A, the stator phase current of the generator phase B, the stator phase current of the generator phase C, the ratio K2; the output signal: the excitation control voltage Uc, the ratio K3.

[0028] The transformation ratio calculation process is as follows:

[0029] The machine-end voltage channel of the excitation control device A32 takes 57.74V as the rated phase voltage of the equipment, then 100V is the rated line voltage of the equipment, and the rated working reference voltage is the rated line voltage of the generator, that is, 10.5kV.

[0030] The stator current channel transformer of the excitation control device A32 is 1200 / 1, 1A is the rated phase current of the equipment, and the rated working reference current is the rated phase current of the generator, that is, 1000A.

[0031] The excitation control voltage Uc is the analog output of the excitation control device. The output type can be set to ±10V on the device. The gain can be adjusted as needed to meet the range of the analog input module of the simulation host.

[0032] In the semi-physical simulation system for network-related protection verification provided in this embodiment, the generator-transformer group protection device can understand the operating status of the system in real time by receiving signals from the excitation control device and the generator system. These signals include the generator terminal voltage, stator current, excitation voltage and excitation current, etc., which provide the protection device with key information for determining whether a fault has occurred in the system. Through precise signal acquisition and processing, the protection device can more accurately determine the fault information and thus perform the correct protection action.

[0033] Embodiment 2 like Figure 3 As shown, this embodiment provides a simulation method of a semi-physical simulation system taking into account network-related protection verification: S1: Before conducting the semi-physical simulation test, perform the correct wiring operation on the physical device to ensure that all connections meet the test requirements. Connect the simulation host A11, physical device, power amplifier A21 and other related physical equipment through the interface device using cables and signal lines. In addition, configure the fixed values ​​of the physical device in the host computer software A12, build the simulation model and define the variables that interface with the physical device; configure the initialization flow parameters to provide the starting state for the simulation test, and ensure that the simulation test can start under the correct steady-state conditions.

[0034] S2: After completing the preparation work such as wiring and software modeling, the power modules of each device are powered on to ensure that all the power modules of the equipment are powered on correctly. Then start the simulation system. During the startup process, closely monitor the startup status of the system and the system prompt information; Specifically, the simulation operation unit outputs the generator terminal voltage, stator current, switch position and generator frequency to the excitation control device and the generator-transformer group protection device through the simulation model.

[0035] S3: The excitation control device A32 and the generator-transformer protection device A31 receive signals from the generator system, such as the generator terminal voltage, stator current, excitation voltage and excitation current. After receiving the electrical signals such as the generator terminal voltage, stator current, switch position and generator frequency, the excitation control device A32 converts them into control voltages through the internal control link and outputs them to the host computer software A12. In the host computer software, these control voltage signals are further processed and finally output as excitation voltages through the SCR link, thereby controlling the generator terminal voltage.

[0036] S4: When a fault is set in the simulation model built by the host computer software, the generator-transformer group protection device A31 receives the signal output from the excitation control device. These signal quantities are key information for judging the fault condition of the system. The generator-transformer group protection device calculates according to the received signal quantity and compares it with the preset constant value to determine whether the generator-transformer group protection action needs to be executed; Specifically, the generator-transformer group protection device calculates according to the generator terminal voltage, stator current, switch position, generator frequency, excitation voltage and excitation current to obtain an actual electrical set value, compares the actual electrical set value with a preset value to obtain a comparison result, and determines whether to execute the generator-transformer group protection action according to the comparison result. If the actual electrical set value exceeds the range of the preset value, the generator-transformer group protection device executes the generator-transformer group protection action; if the actual electrical set value does not exceed the range of the preset value, the generator-transformer group protection device does not execute the generator-transformer group protection action.

[0037] In addition, before the excitation control device is operated, an excitation model is configured in the simulation operation unit to perform excitation control, and when the grid-connected unit operates stably, the excitation model is switched to the excitation control device.

[0038] This embodiment also provides a case of the coordination of excitation limitation and generator-transformer group protection related to the grid-related protection that can be verified, as follows: For example, if the prime mover suddenly increases power and causes the generator to demagnetize and trip, when setting the accident, this embodiment adjusts the speed regulator output through the load given instruction to simulate the sudden increase in prime mover power, and monitors the action of excitation limitation and generator-transformer group protection. If the excitation current continues to decrease during the process, the reactive power of the unit continues to decrease, and the reactive low excitation limitation is actuated, the low excitation protection is actuated, and the unit trips due to demagnetization, it means that the logical sequence of the limitation and protection actions is correct, and the comparison of the action process and time is within the specified error range, which means that the coordination of low excitation limitation and demagnetization protection is reasonable. On the contrary, if the sequence and timing of the excitation limitation and protection actions are incorrect under the above-mentioned serious fault setting, the verification result is that the coordination of low excitation limitation and demagnetization protection is unreasonable.

[0039] The method of this embodiment helps to enhance the reliability and stability of the power system operation. When a fault or abnormality occurs in the system, the generator-transformer group protection device can quickly detect the fault signal and determine whether a protection action needs to be performed according to the preset set value. At the same time, the excitation control device can quickly respond to changes in the system by adjusting the excitation voltage and excitation current to maintain the stable operation of the generator. This coordination relationship enables the system to recover stability more quickly when facing a fault and reduce the impact of the fault on the system; in addition, through simulation tests in the simulation system, the coordination strategy between the generator-transformer group protection and the excitation limit can be optimized. During the simulation process, various fault scenarios and different excitation control strategies can be simulated to observe their effects on system stability and protection action. Based on these simulation results, the set values ​​and excitation control strategies of the protection device can be adjusted to achieve better protection effects and higher system stability.

[0040] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the specific implementation modes of the present invention can still be modified or replaced by equivalents, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A semi-physical simulation system taking into account network protection verification, characterized in that: include: A simulation operation unit, a signal acquisition and interface unit and a physical test unit, wherein the simulation operation unit is connected to the physical test unit via the signal acquisition and interface unit, and the physical test unit includes a generator-transformer group protection device and an excitation control device; A simulation operation unit is used to establish a simulation model and output an electrical signal, receive the control voltage fed back by the excitation control device and obtain the excitation voltage and excitation current from the control voltage through a regulating link, thereby controlling the generator terminal voltage; An excitation control device, used for receiving the electrical signal and converting it into a control signal, and then transmitting the control signal to the simulation operation unit, wherein the control signal includes a control voltage; The generator-transformer group protection device is used to receive the electrical signal quantity, excitation voltage and excitation current and calculate the actual electrical constant value when the simulation operation unit is set to fail, and compare the actual electrical constant value with a preset value. When the actual electrical constant value exceeds the range of the preset value, the generator-transformer group protection action is executed, and the electrical signal quantity includes the generator terminal voltage.

2. A semi-physical simulation system taking into account network protection verification according to claim 1, characterized in that: The simulation operation unit comprises a simulation host and upper computer software. The upper computer software runs in the simulation host and establishes a single-machine-infinite system simulation model.

3. A semi-physical simulation system taking into account network protection verification according to claim 2, characterized in that: The signal acquisition and interface unit includes an AI / AO interface device and a DI / DO interface device, the AI / AO interface device is connected to the simulation host, the excitation control device and the generator-transformer group protection device, and the DI / DO interface device is connected to the simulation host, the excitation control device and the generator-transformer group protection device.

4. A semi-physical simulation system taking into account network protection verification according to claim 1, characterized in that: The electrical signal quantities also include: stator current, switch position and generator frequency.

5. A semi-physical simulation system taking into account network protection verification according to claim 4, characterized in that: The signal acquisition and interface unit also includes a power amplifier for receiving the generator terminal voltage and stator current, and outputting three-phase AC voltage and three-phase AC current to the excitation control device and the generator-transformer group protection device.

6. A semi-physical simulation system taking into account network protection verification according to claim 1, characterized in that: The control signal quantity also includes PID adjustment instructions, trip signals and channel switching signals.

7. A simulation method for a semi-physical simulation system taking into account network protection verification, characterized in that: The semi-physical simulation system according to any one of claims 1 to 6 comprises the following steps: The preset values ​​of the physical device are configured in the simulation operation unit, and a simulation model is established. At the same time, the initialization power flow parameters are configured to provide an initial operation state for the simulation operation unit. The simulation operation unit outputs the generator terminal voltage, stator current, switch position and generator frequency to the excitation control device and the generator-transformer group protection device through the simulation model. The excitation control device obtains a control voltage through internal control according to the generator terminal voltage, stator current, switch position and generator frequency, and the control voltage obtains the excitation voltage and excitation current through the simulation model; The generator-transformer group protection device calculates according to the generator terminal voltage, stator current, switch position, generator frequency, excitation voltage and excitation current to obtain an actual electrical set value, compares the actual electrical set value with a preset value to obtain a comparison result, and determines whether to execute the generator-transformer group protection action according to the comparison result.

8. The simulation method according to claim 7, characterized in that: The step of controlling the voltage to obtain the excitation voltage and the excitation current through the simulation model specifically includes the following steps: The control voltage outputs an excitation voltage through the SCR link in the simulation model, and the excitation voltage generates the excitation current accordingly.

9. The simulation method according to claim 7, characterized in that: The following steps are also included: If the actual electrical setting exceeds the range of the preset value, the generator-transformer group protection device performs the generator-transformer group protection action; if the actual electrical setting does not exceed the range of the preset value, the generator-transformer group protection device does not perform the generator-transformer group protection action.

10. The simulation method according to claim 7, characterized in that: The method also includes the following steps: before the excitation control device is operated, an excitation model is configured in the simulation operation unit to perform excitation control; when the grid-connected unit operates stably, the excitation model is switched to the excitation control device.

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