A safety evaluation method for a clean energy direct current transmission system based on safety simulation modeling

Abstract

The application discloses a safety evaluation method for a clean energy direct current transmission system based on safety simulation and analog, and the safety evaluation method comprises the following steps: collecting first data related to a direct current transmission line and a converter station and second data related to a new energy generator, respectively establishing a direct current transmission system model and a new energy load change model; inputting the first data and the second data of a meteorological change setting period into the direct current transmission system model and the new energy load change model, so as to simulate the system constantly obtaining the first data and the second data of the period; establishing a steady-state simulation model and a dynamic simulation model, setting parameters affecting the safety of the system, obtaining simulation effects corresponding to the parameter operation conditions by operating the parameters and through the steady-state simulation model and the dynamic simulation model; collecting safety parameters in the simulation effects to perform safety evaluation. The method can effectively and comprehensively realize safety evaluation of the clean energy direct current transmission system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of direct current transmission, in particular to a safety evaluation method for a clean energy direct current transmission system based on safety simulation. BACKGROUND

[0002] Direct current transmission technology is a technology that transmits power through direct current cables or power lines, 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 has no capacitance and inductance loss 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 plants such as wind farms and solar power plants, especially in places far from load centers; asynchronous grid connection, connecting power grids of different frequencies or phases to achieve power 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 the converter that converts alternating current to direct current, common conversion technologies include linear conversion and modular conversion; direct current cable or line: used for actual power transmission, taking into account conductor, cable insulation and environmental factors.

[0003] The existing direct current transmission technology cannot achieve safety evaluation of the system when applied in the process of clean energy transmission, and cannot ensure the safe and stable operation of the direct current transmission system. SUMMARY

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

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] A safety evaluation 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 evaluation method comprising:

[0007] Collecting first data related to the direct current transmission line and the converter station and second data related to the new energy generator, establishing a direct current 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 meteorological change setting period into the direct current transmission system model and a second data set of the meteorological change setting period into the new energy load change model to simulate the system through the direct current transmission system model and the new energy load change model, and continuously obtain the first data and the second data of the period.

[0009] A steady-state simulation model and a dynamic simulation model based on safety simulation are established, parameters affecting system safety are set, the parameters are derived from the first data and the second data, and simulation effects corresponding to the operating conditions of the parameters are obtained by operating the parameters and through the steady-state simulation model and the dynamic simulation model;

[0010] Part of the data in the first data and the second data is set as a safety parameter, and a standard value of the system-related safety parameter and a safety range based on the standard value are set, the safety parameter in the simulation effect is 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 the difference is outside the safety range, the system is evaluated as unsafe.

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

[0012] The formula of the converter station model is:

[0013]

[0014] In the formula, V dc is the direct current voltage, V ac is the alternating current voltage, and θ is the phase angle.

[0015] The formula of the direct current transmission system model is:

[0016]

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

[0018] The formula of the new energy load change model is

[0019]

[0020] In the formula, 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] Further, the parameter affecting system safety is resistance, and the resistance model of the influence of temperature on resistance when the weather changes is:

[0022] R T = R0[1+α(T-T0)]

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

[0024] By operating the corresponding value of the resistance parameter, the resistance change caused by the temperature change due to the weather change is simulated, so that the first data and the second data of the corresponding period generated by the DC power transmission system model simulation are generated.

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

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

[0027] S = V * ·I *

[0028] Wherein, S is a complex power matrix, V * is a voltage matrix, I * is the conjugate matrix of current.

[0029] The power balance model is as follows:

[0030]

[0031] In the formula, P i is the active power of node i, Q i is the reactive power of node i, x ij is the line impedance, theta is the voltage phase angle, v i is the voltage amplitude of node i, v j is the voltage amplitude of node j, x ij is the impedance between node i and node j, theta j is the voltage phase angle of node j, theta i is the voltage phase angle of node i.

[0032] Further, 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 parameter is 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 application has the following advantages:

[0037] The application establishes a direct current transmission system model and a new energy load change model by collecting relevant data, simulates parameter changes caused by simulated meteorological changes by using the model, thereby continuously obtaining relevant data of the meteorological change setting time period, and establishes a steady-state simulation model and a dynamic simulation model, obtains corresponding simulation effects by parameter operation, compares safety parameters in the simulation effects with setting values, and thereby realizes safety evaluation of the system.

[0038] The application can effectively realize safety evaluation of the direct current transmission system, and when simulating effects of the steady-state simulation model and the dynamic model, fully considers the influence of meteorological changes on safety parameters of the direct current transmission system, so that the safety evaluation is more comprehensive and accurate. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The step flowchart of the application. DETAILED DESCRIPTION

[0040] The application will be described in detail below in combination with specific embodiments.

[0041] As shown in the figure, the application is based on a safety simulation to evaluate the safety of a clean energy direct current transmission system, which includes a new energy generator, a direct current transmission line and a converter station, the new energy generator of the embodiment is a wind power generator, and the converter station adopts the following voltage model: Figure 1

[0042]

[0043] In the formula, V is a direct current voltage, V is an alternating current voltage, and θ is a phase angle. dc ac

[0044] The safety evaluation method of the above clean energy direct current transmission system is as follows:

[0045] S1, a direct current transmission system model and a new energy load change model are established, and first data for simulating running the direct current transmission system model and second data for simulating running the new energy load change model are collected.

[0046] The direct current transmission system model is as follows:

[0047]

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

[0049] The new energy load change model is as follows:

[0050] ​​​​

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

[0052] First data related to DC transmission lines and converter stations are collected to simulate the operation of the DC transmission system. In this embodiment, the first data includes data on voltage, current, resistance, DC voltage, AC voltage, phase angle, power, and impedance obtained from the system.

[0053] Secondary data related to the new energy generator is collected to simulate the operation of the new energy load changes. In this embodiment, the secondary data includes the moment of inertia, mechanical input power, electrical power, rotor angular velocity and damping coefficient obtained from the new energy generator.

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

[0055] S3. Establish a steady-state simulation model and a dynamic simulation model for safety simulation, set parameters that affect system safety, the parameters are derived from the first data and the second data, and obtain the simulation effect corresponding to the parameter operation conditions by manipulating the parameters and through the steady-state simulation model and the dynamic simulation model.

[0056] The parameter affecting system safety is set as resistance, and the resistance model for the effect of temperature on resistance during meteorological changes is as follows:

[0057] R T =R0[1+α(T-T0)]

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

[0059] By manipulating the corresponding values ​​of the resistance parameters, the resistance change caused by temperature changes due to meteorological changes is simulated, resulting in the first and second data for the corresponding time period generated by the DC transmission system model.

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

[0061] The steady-state simulation model is as follows:

[0062] S = V * · I *

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

[0064] The power balance model is as follows:

[0065]

[0066] In the formula, 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 of node j, x ij is the impedance between node i and node j, θ j is the voltage phase angle of node j, θ i is the voltage phase angle of 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 operating the changes of voltage and current, the steady state (complex power matrix S) and power balance of system power flow are simulated.

[0071] S4, set the safety parameter based on part of the first data and the second data, and set the standard value of the system related safety parameter and the safety range based on the standard value, collect the safety parameter in the simulation effect and compare it with the standard value, 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.

[0072] The safety parameter of the embodiment is 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 exceeds the safety range, it can be determined that the system has a short circuit fault and is unsafe. For another example, when a weather occurs with excessive 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. The excessive speed will cause damage to the engine, and when And the moment of inertia J is greater than a certain standard value, and the value exceeds the safe range, the unsafe assessment of the generator rotor overspeed can be determined.

Claims

1. A safety assessment method for a clean energy DC transmission system based on safety simulation, wherein the clean energy DC transmission system includes a new energy generator, a DC transmission line, and a converter station, characterized in that, The method includes: Establish a DC transmission system model and a new energy load change model, and collect the first data for simulating the DC transmission system model and the second data for simulating the new energy load change model. The first dataset of meteorological changes for a set period is input into the DC transmission system model, and the second dataset of meteorological changes for a set period is input into the new energy load change model, so as to simulate the system through the DC transmission system model and the new energy load change model, and continuously obtain the first and second data for the set period. Establish a steady-state simulation model and a dynamic simulation model for safety simulation, set parameters that affect system safety, the parameters are derived from first data and second data, and obtain the simulation effect corresponding to the parameter operation conditions by manipulating the parameters and through the steady-state simulation model and the dynamic simulation model; A safety parameter is set based on a portion of the first and second data. Standard values ​​and safety ranges based on the standard values ​​are set for the relevant safety parameters of the system. The safety parameters in the simulation results are collected and compared with the standard values. If the difference between the two is within the safety range, the system is evaluated as safe. If the difference is outside the safety range, the system is evaluated as unsafe.

2. The safety assessment method according to claim 1, characterized in that, The first data includes voltage, current, resistance, DC voltage, AC voltage, phase angle, power, and impedance data 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 as follows: In the formula, V is the voltage, I is the current, R is the line resistance, and L is the line inductance. The rate of change of current over time; The new energy load change model is as follows: In the formula, J is the moment of inertia of the rotor, and T m T is the mechanical input power. e Where 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 affecting system safety is resistance. The resistance model for the effect of temperature on resistance during meteorological changes is as follows: R T =R0[1+α(T-T0)] In the formula, R T R is the resistance at temperature T, R0 is the resistance at reference temperature T0, and α is the temperature coefficient of resistance.

4. The safety assessment method according to claim 3, characterized in that, The steady-state simulation model is a complex power matrix model based on power flow and a power balance model; 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: In the formula, P i Let Q be the active power at node i. i Let x be the reactive power of node i. ij Here, θ is the line impedance, θ is the voltage phase angle, and v i Let v be the voltage magnitude at node i. j Let x be the voltage magnitude at node j. ij The impedance between node i and node j, θ j Let θ be the voltage phase angle at node j. i Let be the voltage phase angle at node i.

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

6. The safety assessment method according to claim 5, characterized in that, The safety parameters are 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 as follows: In the formula, V dc V is a DC voltage. ac Let θ be the AC voltage and θ be the phase angle.

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