Safety evaluation method of clean energy direct current transmission system based on safety analogue simulation

Abstract

The invention discloses a safety simulation-based safety evaluation method for a clean energy direct-current power transmission system, and the method comprises the steps: collecting first data related to a direct-current power transmission line and a converter station and second data related to a new energy generator, and building a direct-current power transmission system model and a new energy load change model respectively; respectively inputting the first data and the second data set of a meteorological change set time period to a direct current power transmission system model and a new energy load change model to simulate the system to continuously obtain the first data and the second data of the time period; establishing a steady-state simulation model and a dynamic simulation model, setting parameters influencing system safety, operating the parameters, and obtaining simulation effects corresponding to parameter operation conditions through the steady-state simulation model and the dynamic simulation model; safety parameters in the simulation effect are collected for safety evaluation. According to the method, the safety evaluation of the clean energy direct-current power transmission system can be effectively and comprehensively realized.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current transmission, and in particular to a safety assessment method for a clean energy direct current transmission system based on safety simulation. Background Art

[0002] Direct current transmission technology is a technology that transmits electricity through direct current cables or power lines. It is mainly used for long-distance power transmission and connecting different power grids. Direct current transmission systems can reduce energy loss in long-distance transmission because direct current does not have the capacitance and inductance losses in alternating current. HVDC systems can better stabilize the power grid, especially when multiple regional power grids are interconnected, which can improve the dynamic response and power quality of the power grid. Application scenarios include: remote power generation sites, such as wind farms and solar farms, especially those far away from the load center; asynchronous grid connection, connecting grids of different frequencies or phases to achieve grid interconnection; urban and island power supply, power supply in cities or remote islands, key components include: converter station: the core of the direct current system, including converters, converting alternating current into direct current. Common conversion technologies include linear conversion and modular conversion; direct current cables or lines: used for actual power transmission, conductors, cable insulation and environmental factors should be considered during design.

[0003] When the existing DC transmission technology is used in the process of clean energy transmission, it is impossible to realize the safety assessment of the system and ensure the safe and stable operation of the DC transmission system. Summary of the invention

[0004] The purpose of the present invention is to solve the defects in the prior art and provide a safety assessment method for a clean energy direct current transmission system based on safety simulation, which can achieve effective and comprehensive safety assessment.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A safety assessment method for a clean energy direct current transmission system based on safety simulation, the clean energy direct current transmission system comprising a new energy generator, a direct current transmission line and a converter station, the safety assessment method comprising:

[0007] Collecting first data related to the DC transmission line and the converter station and second data related to the new energy generator, and establishing a DC transmission system model based on the first data and a new energy load change model based on the second data;

[0008] Inputting a first data set of a set period of meteorological change into a DC power transmission system model, and inputting a second data set of a set period of meteorological change into a new energy load change model, so as to simulate the system through the DC power transmission system model and the new energy load change model, and continuously obtaining the first data and the second data of the period;

[0009] Establishing a steady-state simulation model and a dynamic simulation model for safety simulation, setting parameters that affect system safety, wherein the parameters are derived from the first data and the second data, and obtaining simulation effects corresponding to parameter operation conditions by operating the parameters and using the steady-state simulation model and the dynamic simulation model;

[0010] Part of the data based on the first data and the second data is set as the safety parameter, and the standard value of the system-related safety parameter and the safety range based on the standard value are set, the safety parameters in the simulation effect are collected and compared with the standard value, and if the difference between the two is within the safety range, the system is evaluated as safe, and if it is outside the safety range, the system is evaluated as unsafe.

[0011] Further, the first data includes data of voltage, current, resistance, DC voltage, AC voltage, phase angle, power and impedance obtained from the system; the second data includes moment of inertia, mechanical input power, electrical power, rotor angular velocity and damping coefficient obtained from the new energy generator;

[0012] Among them, the formula of the converter station model is:

[0013]

[0014] Where V dc is the DC voltage, V ac is the AC voltage and θ is the phase angle.

[0015] The DC transmission system model is:

[0016]

[0017] In the formula, V is voltage, I is current, R is line resistance, and L is line inductance. is the rate of change of current with time;

[0018] The new energy load change model is:

[0019]

[0020] Where J is the moment of inertia of the rotor, T m is the mechanical input power, T e is the electrical power, D is the damping coefficient, and w is the rotor angular velocity.

[0021] Furthermore, the parameter that affects system safety is resistance. The resistance model of the effect of temperature on resistance when the weather changes is:

[0022] R T =R0[1+α(T-T0)]

[0023] In the formula, RT is the resistance at temperature T, R0 is the resistance at reference temperature T0, and α is the resistance temperature coefficient.

[0024] By operating the corresponding values ​​of the resistance parameters, the resistance change caused by the temperature change caused by the meteorological change is simulated, so that the DC power transmission system model simulates the first data and the second data of the corresponding time period.

[0025] Furthermore, the steady-state simulation model is a complex power matrix model and a power balance model based on power flow;

[0026] The steady-state simulation model is as follows:

[0027] S=V * I *

[0028] Where S is the complex power matrix, V * is the voltage matrix, I * is the conjugate matrix of current;

[0029] The power balance model is as follows:

[0030]

[0031] Where P i is the active power of node i, Q i is the reactive power of node i, x ij is the line impedance, θ is the voltage phase angle, v i is the voltage amplitude of node i, v j is the voltage amplitude at node j, x ij The impedance between node i and node j, θ j is the voltage phase angle at node j, θ i is the voltage phase angle at node i.

[0032] Furthermore, the dynamic simulation model is:

[0033]

[0034] In the formula, is the magnetic flux of the transformer, V is the input voltage, R is the winding resistance, I is the transformer current, and L is the self-inductance of the transformer.

[0035] The above safety parameters are the current, voltage and resistance in the first data, or the moment of inertia of the rotor in the second data.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] The present invention establishes a DC transmission system model and a new energy load change model by collecting relevant data, and uses the model to simulate parameter changes caused by simulated meteorological changes, so as to continuously obtain relevant data of the set time period of the meteorological changes, and establishes a steady-state simulation model and a dynamic simulation model, and obtains corresponding simulation effects through parameter operations, collects safety parameters in the simulation effects and compares them with set values, thereby realizing a safety assessment of the system.

[0038] The present invention can effectively realize the safety assessment of the DC power transmission system, and when performing the steady-state simulation model and the dynamic model simulation effect, the influence of meteorological changes on the safety parameters of the DC power transmission system is fully considered, so that the safety assessment is more comprehensive and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a flow chart of the steps of the present invention. DETAILED DESCRIPTION

[0040] The present invention is described in detail below with reference to specific embodiments.

[0041] like Figure 1 As shown, the present invention performs a safety assessment method for a clean energy DC transmission system based on safety simulation. The clean energy DC transmission system includes a new energy generator, a DC transmission line and a converter station. The new energy generator in this embodiment is a wind turbine generator, and the converter station adopts the following voltage model:

[0042]

[0043] Where V dc is the DC voltage, V ac is the AC voltage and θ is the phase angle.

[0044] The safety assessment method for the above-mentioned clean energy DC transmission system is as follows:

[0045] S1. Establish a DC power transmission system model and a new energy load change model and collect first data for simulating the operation of the DC power transmission system model and second data for simulating the operation of the new energy load change model.

[0046] Among them, the DC transmission system model is:

[0047]

[0048] In the formula, V is voltage, I is current, R is line resistance, and L is line inductance. is the rate of change of current with time.

[0049] The new energy load change model is:

[0050]

[0051] Where J is the moment of inertia of the rotor, T m is the mechanical input power, T e is the electrical power, D is the damping coefficient, and w is the rotor angular velocity.

[0052] Collecting first data related to the DC transmission line and the converter station for simulating the operation of the DC transmission system. The first data in this embodiment includes data of voltage, current, resistance, DC voltage, AC voltage, phase angle, power and impedance obtained from the system;

[0053] The second data related to the new energy generator is collected for simulating the change of the new energy load. The second data of this embodiment includes the moment of inertia, mechanical input power, electrical power, rotor angular velocity and damping coefficient obtained by the new energy generator.

[0054] S2. In order to better simulate the safety assessment of the system, this embodiment selects a time period when meteorological changes may have a greater impact on the system. Therefore, this step selects the first data of the meteorological change setting time period to be input into the DC power transmission system model, and the second data of the meteorological change setting time period to be input into the new energy load change model, so as to simulate the system through the DC power transmission system model and the new energy load change model, and continuously obtain the first data and the second data of the time period.

[0055] S3. Establish a steady-state simulation model and a dynamic simulation model based on safety simulation, set parameters that affect system safety, the parameters are derived from the first data and the second data, and obtain simulation effects corresponding to parameter operation conditions by operating the parameters and using the steady-state simulation model and the dynamic simulation model.

[0056] The parameter that affects the safety of the system is set as resistance. The resistance model of the effect of temperature on resistance when the weather changes is:

[0057] R T =R0[1+α(T-T0)]

[0058] In the formula, R T is the resistance at temperature T, R0 is the resistance at reference temperature T0, and α is the resistance temperature coefficient.

[0059] By operating the corresponding values ​​of the resistance parameters, the resistance change caused by the temperature change caused by the meteorological change is simulated, so that the DC power transmission system model simulates the first data and the second data of the corresponding time period.

[0060] The steady-state simulation model established above is a complex power matrix model and a power balance model based on power flow;

[0061] Among them, the steady-state simulation model is as follows:

[0062] S=V * I *

[0063] Where S is the complex power matrix, V * is the voltage matrix, I * is the conjugate matrix of current;

[0064] The power balance model is as follows:

[0065]

[0066] Where P i is the active power of node i, Q i is the reactive power of node i, x ij is the line impedance, θ is the voltage phase angle, v i is the voltage amplitude of node i, v j is the voltage amplitude at node j, x ij The impedance between node i and node j, θ j is the voltage phase angle at node j, θ i is the voltage phase angle at node i.

[0067] The dynamic simulation model established above is:

[0068]

[0069] In the formula, is the magnetic flux of the transformer, V is the input voltage, R is the winding resistance, I is the transformer current, and L is the self-inductance of the transformer;

[0070] By manipulating the changes in voltage and current, the steady state of the system power flow (complex power matrix S) and power balance are simulated.

[0071] S4. Set part of the data based on the first data and the second data as safety parameters, and set standard values ​​of the system-related safety parameters and a safety range based on the standard values. Collect the safety parameters in the simulation effect and compare them with the standard values. If the difference between the two is within the safety range, the system is evaluated as safe. If it is outside the safety range, the system is evaluated as unsafe.

[0072] The safety parameters of this embodiment are the current, voltage and resistance in the first data, or the moment of inertia of the rotor in the second data. For example, when the current is greater than a certain standard value and the value is beyond the safety range, it can be determined that the system has an unsafe assessment of a short circuit fault during this period. For another example, when there is a strong wind, the rotor angular velocity w may be too large, and the corresponding moment of inertia J of the rotor will also be too large. Excessive speed will cause damage to the engine. If the moment of inertia J is greater than a certain standard value and the value is beyond the safe range, an unsafe assessment of the generator rotor overspeed can be determined.

Claims

1. A safety assessment method for a clean energy direct current transmission system based on safety simulation, wherein the clean energy direct current transmission system comprises a new energy generator, a direct current transmission line and a converter station, characterized in that: The method comprises: Establishing a direct current transmission system model and a new energy load change model and collecting first data for simulating the operation of the direct current transmission system model and second data for simulating the operation of the new energy load change model; Inputting a first data set of a set period of meteorological change into a DC power transmission system model, and inputting a second data set of a set period of meteorological change into a new energy load change model, so as to simulate the system through the DC power transmission system model and the new energy load change model, and continuously obtaining the first data and the second data of the period; Establishing a steady-state simulation model and a dynamic simulation model for safety simulation, setting parameters that affect system safety, wherein the parameters are derived from the first data and the second data, and obtaining simulation effects corresponding to parameter operation conditions by operating the parameters and using the steady-state simulation model and the dynamic simulation model; Part of the data based on the first data and the second data is set as the safety parameter, and the standard value of the system-related safety parameter and the safety range based on the standard value are set, the safety parameters in the simulation effect are collected and compared with the standard value, and if the difference between the two is within the safety range, the system is evaluated as safe, and if it is outside the safety range, the system is evaluated as unsafe.

2. The security assessment method according to claim 1, characterized in that: The first data includes data of voltage, current, resistance, DC voltage, AC voltage, phase angle, power and impedance obtained from the system; the second data includes moment of inertia, mechanical input power, electrical power, rotor angular velocity and damping coefficient obtained from the new energy generator; The DC transmission system model is: In the formula, V is voltage, I is current, R is line resistance, and L is line inductance. is the rate of change of current with time; The new energy load change model is: Where J is the moment of inertia of the rotor, T m is the mechanical input power, T e is the electrical power, D is the damping coefficient, and w is the rotor angular velocity.

3. The safety assessment method according to claim 2, characterized in that: The parameter that affects the safety of the system is resistance. The resistance model of the effect of temperature on resistance when the weather changes is: R T =R0[1+α(T-T0)] In the formula, R T is the resistance at temperature T, R0 is the resistance at reference temperature T0, and α is the resistance temperature coefficient.

4. The safety assessment method according to claim 3, characterized in that: The steady-state simulation model is a complex power matrix model and a power balance model based on power flow; The steady-state simulation model is as follows: S=V*·I* in, S is the complex power matrix, V* is the voltage matrix, and I* is the conjugate matrix of the current; The power balance model is as follows: Where P i is the active power of node i, Q i is the reactive power of node i, x ij is the line impedance, θ is the voltage phase angle, v i is the voltage amplitude of node i, v j is the voltage amplitude at node j, x ij The impedance between node i and node j, θ j is the voltage phase angle at node j, θ i is the voltage phase angle at node i.

5. The safety assessment method according to claim 4, characterized in that: The dynamic simulation model is: In the formula, is the magnetic flux of the transformer, V is the input voltage, R is the winding resistance, I is the transformer current, and L is the self-inductance of the transformer.

6. The safety assessment method according to claim 5, characterized in that: The safety parameter is the current, voltage and resistance in the first data, or the moment of inertia of the rotor in the second data.

7. The safety assessment method according to claim 1, characterized in that: The voltage model of the converter station model is: Where V dc is the DC voltage, V ac is the AC voltage and θ is the phase angle.

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