阅读说明：本技术 一种适用于大规模交直流电网机电-电磁暂态混合仿真的接口定位方法 (Interface positioning method suitable for large-scale alternating current-direct current power grid electromechanical-electromagnetic transient hybrid simulation ) 是由 赵乐 熊雪君 冯煜尧 于 2021-07-19 设计创作，主要内容包括：本发明提出了一种适用于大规模交直流电网机电-电磁暂态混合仿真的接口定位方法,包含以下步骤：S1、基于无功功率注入法确定接口母线范围；S2、对所述S1中确定的接口母线范围内的所有母线进行阻频特性扫描并绘制阻频特性图；S3、分析所述S2中得到的各阶母线的阻频特性图,确定接口母线。本发明提出的一种适用于大规模交直流电网机电-电磁暂态混合仿真的接口定位方法,解决了目前大规模交直流电网机电-电磁暂态混合仿真接口定位无法量化描述或仅以换流器换流母线作为接口,所带来的仿真不准确的问题。(The invention provides an interface positioning method suitable for large-scale alternating current and direct current power grid electromechanical-electromagnetic transient hybrid simulation, which comprises the following steps of: s1, determining the interface bus range based on a reactive power injection method; s2, performing frequency resistance characteristic scanning on all buses in the interface bus range determined in the S1 and drawing a frequency resistance characteristic diagram; and S3, analyzing the frequency resistance characteristic diagram of the buses of each order obtained in the S2, and determining the interface bus. The invention provides an interface positioning method suitable for large-scale alternating current and direct current power grid electromechanical-electromagnetic transient hybrid simulation, which solves the problem of inaccurate simulation caused by the fact that the current large-scale alternating current and direct current power grid electromechanical-electromagnetic transient hybrid simulation interface positioning cannot be quantitatively described or only a converter bus is used as an interface.)

1. An interface positioning method suitable for large-scale alternating current and direct current power grid electromechanical-electromagnetic transient hybrid simulation is characterized by comprising the following steps of:

s1, determining the interface bus range based on a reactive power injection method;

s2, carrying out frequency resistance characteristic scanning on each-order bus in the interface bus range determined in the S1 and drawing a frequency resistance characteristic diagram;

and S3, analyzing the frequency resistance characteristic diagram of the buses of each order obtained in the S2, and determining the interface bus.

2. The method of claim 1, wherein the step S1 further comprises the following steps:

s11, injecting quantitative reactive power Q into the converter bus of the converter_inj；

S12, calculating the voltage deviation delta U of each-order bus of 1-n-order around the commutation bus;

the voltage of the 0-order bus is U when the current conversion bus is 0 order₀If the bus directly connected with the commutation bus is a 1-order bus, the voltage of the 1-order bus is U₁The voltage deviation of the 1 st order bus is Δ U₁＝U₁-U₀The bus directly connected with the 1-order bus is 2-order, and the voltage of the 2-order bus is U₂Then the voltage deviation of the 2 nd order bus is Δ U₂＝U₂-U₁By analogy, the voltage deviation of the i-order bus is DeltaU_i＝U_i-U_i-1Until the voltage deviation of the n-order bus is calculated to be delta U_n＝U_n-U_n-1；

And S13, calculating and comparing the reactive power and the voltage change rate of each-stage bus, and determining the range of the interface bus.

3. The method of claim 2, wherein the step S13 further comprises the following steps:

s131, calculating 1-n orderReactive power and rate of change of voltage of the bus of each stage, i.e.Wherein Q_injRepresents the reactive power, Δ U, injected at the converter bus of the converter in said step S11_iRepresents the voltage deviation, k, of the i-th order bus obtained in the step S12_iRepresenting the reactive power and voltage change rate of the i-order bus;

s132, comparing the reactive power and the voltage change rate of each-order bus obtained in the step S131, and comparing the reactive power and the voltage change rate k at the j-th order and the j + 1-th order buses_iWhen the change is not significant, i.e.Then, take the minimum j meeting the condition_minStep bus and maximum j satisfying the condition_maxThe step buses being respectively used as both ends of the interface bus range, i.e. j_min～j_maxThe step bus is a determined interface bus range.

4. The method of claim 3, wherein the step S2 further comprises the following steps:

s21, at each level of bus within the range of interface bus determined in the step S1, i.e. all j_min～j_maxRespectively injecting harmonic sources with increasing frequencies into buses of each order, and measuring the impedance of the system under different frequencies after stable operation;

s22, drawing j according to the impedance of the bus of each order obtained in the step S21 under different frequencies_min～j_maxAnd (3) a frequency resistance characteristic diagram of each step of bus.

5. The interface positioning method suitable for large-scale AC/DC power grid electromechanical-electromagnetic transient hybrid simulation of claim 4, wherein the detailed analysis of the step S3The following were used: for j obtained in the step S22_min～j_maxAnd comparing and analyzing the frequency resistance characteristic diagrams of the buses of all steps, and taking the bus with the minimum order as an interface bus when the frequency resistance characteristic curves between two adjacent steps of buses are overlapped by more than 85%.

6. The interface positioning method suitable for large-scale AC/DC power grid electromechanical-electromagnetic transient hybrid simulation according to claim 5, wherein in step S3, j is_min～j_maxIn each order of buses, when the overlap ratio of the frequency resistance characteristic curves of the mth order bus and the (m + 1) th order bus is more than 85%, the minimum mth order bus is taken as an interface bus, wherein m is [ j [ ]_min，j_max]An integer within the range.

Technical Field

The invention relates to the field of power system simulation, in particular to an interface positioning method suitable for large-scale alternating current and direct current power grid electromechanical-electromagnetic transient hybrid simulation.

Background

With more and more high-voltage direct-current power transmission systems, flexible direct-current power transmission systems and renewable energy sources such as wind power and photovoltaic power accessed into a power grid, the modern power grid becomes a large-scale alternating-current and direct-current interconnected power grid.

Simulation analysis is an important means for planning and operating the power system. Traditional digital simulation of power systems can be divided into electromechanical transient simulation and electromagnetic transient simulation. The electromechanical transient simulation step length is usually millisecond level, the calculation speed is high, the calculation scale can reach tens of thousands of nodes, but the accurate simulation of the power electronic device with quick response is difficult to carry out; the electromagnetic transient simulation step length is microsecond level, detailed modeling can be performed on large-scale power electronic devices, but the mathematical modeling is complex, the calculated amount is large, the scale is limited, and in the pure electromagnetic transient simulation process, a voltage source and an impedance are generally used for a large-system alternating-current part to perform equivalence on a Withanan model, but the equivalent model cannot reflect the dynamic characteristics of elements such as a generator and a speed regulator, and certain difference with a real system is inevitable, so that the simulation modeling accuracy is low. The electromechanical-electromagnetic transient hybrid simulation is a combination of electromechanical transient simulation and electromagnetic transient simulation, can accurately simulate equipment connected through a large-scale power electronic device, can consider the integral transient characteristics of a large-scale alternating current power grid, and becomes an important tool for researching the operation mechanism and characteristics of the large-scale alternating current and direct current power grid.

The electromechanical-electromagnetic transient hybrid simulation technology is proposed to date, electromechanical transient and electromagnetic transient interface positioning is always a hotspot and difficulty problem of hybrid simulation research, balancing needs to be carried out before accuracy and complexity of simulation realization, an alternating current-direct current distribution network (a current conversion bus of a current converter is taken as an interface position) and an alternating current-alternating current distribution network (a current conversion bus of the current converter extends to an alternating current side for a certain distance to be taken as an interface position) are generally available at present, the alternating current-direct current distribution network is relatively simple, but it can not accurately reflect the harmonic wave influence around the current conversion bus, the simulation precision is not high, the alternating-current and alternating-current networks are relatively complex, the harmonic influence of a converter bus can be considered to a certain extent, but the interface position is difficult to select, and a quantization method is not available at present.

Disclosure of Invention

The invention aims to provide an interface positioning method suitable for large-scale alternating current and direct current power grid electromechanical-electromagnetic transient hybrid simulation, and aims to solve the problem that simulation is inaccurate due to the fact that the current large-scale alternating current and direct current power grid electromechanical-electromagnetic transient hybrid simulation interface positioning cannot be quantitatively described or only a converter bus is used as an interface.

In order to achieve the above object, the present invention provides an interface positioning method suitable for large-scale ac/dc power grid electromechanical-electromagnetic transient hybrid simulation, the method is based on the electromagnetic transient simulation software RTDS and electromechanical transient simulation software PSS/E commonly used in the world, and uses the existing RTDS GTFPGA as the interface of the two simulation software, constructs the electromechanical-electromagnetic hybrid simulation platform of the large-scale ac/dc power grid, develops the interface positioning research of the large-scale ac/dc power grid electromechanical-electromagnetic transient hybrid simulation based on the platform, and comprises the following steps: s1, determining the interface bus range based on a reactive power injection method; s2, performing frequency resistance characteristic scanning on each-order bus in the range determined by the reactive power injection method and drawing a frequency resistance characteristic diagram; and S3, analyzing the frequency resistance characteristic diagram of the buses of each order obtained in the S2, and determining the interface bus.

In step S1, the method further includes the following steps: s11, injecting quantitative reactive power Q at the converter bus of the converter_inj(ii) a S12, calculating the voltage deviation delta U of each-order bus of 1-n orders around the commutation bus, and taking the commutation bus as 0 order, wherein the voltage of the 0 order bus is U₀The bus directly connected with the current conversion bus is a 1-order bus, and the voltage of the 1-order bus is U₁Then the voltage deviation of the 1 st order bus is Δ U₁＝U₁-U₀(ii) a The bus directly connected with the 1-order bus is 2-order, and the voltage of the 2-order bus is U₂Then the voltage deviation of the 2 nd order bus is Δ U₂＝U₂-U₁(ii) a By analogy, the voltage deviation of the i-order bus is Delta U_i＝U_i-U_i-1Until the voltage deviation of the n-order bus is calculated to be delta U_n＝U_n-U_n-1；

And S13, calculating and comparing the reactive power and the voltage change rate of each-stage bus, and determining the range of the interface bus.

The step S13 further includes the steps of: s131, calculating the reactive power and the voltage change rate of the 1-n-order buses, namely

Wherein Q is_injRepresents the reactive power, Δ U, injected at the converter bus of the converter in said step S11_iRepresents the voltage deviation, k, of the i-th order bus obtained in the step S12_iRepresenting the reactive power and voltage change rate of the i-order bus;

s132, comparing the change rate of the buses of each order from 1 to n, and determining the range of the interface buses;

comparing the reactive power of the bus of each step obtained in the step S131 with the voltage change rate k_iWhen the reactive power and the voltage change rate k of the j-th order and the j +1 th order buses are not obviously changed, namelyTaking the minimum j meeting the above condition_minStep generatrix and maximum of eligible j_maxThe step buses being respectively the ends of the range of interface buses, i.e. j_min～j_maxThe step bus is a determined interface bus range.

The step S2 further includes the steps of: at each step of the generatrix, i.e., all j, within the range determined in the step S1_min～j_maxRespectively injecting harmonic sources with increasing frequencies into buses of each order, and measuring the impedance of the system under different frequencies after stable operation;

s22, drawing j according to the impedance of each order of bus obtained in the step S21 under different frequencies_min～j_maxAnd (3) a frequency resistance characteristic diagram of each step of bus.

In step S3, the specific analysis is as follows for j_min～j_maxComparing and analyzing the frequency resistance characteristic diagrams of the buses of all orders, and taking the bus of the minimum order with little frequency resistance characteristic change as an interface bus; when j is_min～j_maxWhen the frequency resistance characteristic diagram of the m-th order bus and the m +1 th order bus has the contact ratio of more than 85%, the m-order bus with the minimum order is taken as an interface bus, wherein m is [ j [ ]_min，j_max]An integer within the range.

In summary, the invention provides an interface positioning method suitable for large-scale alternating current and direct current power grid electromechanical-electromagnetic transient hybrid simulation, and the method solves a series of problems that the position of the current large-scale alternating current and direct current power grid electromechanical-electromagnetic hybrid simulation interface cannot be quantitatively described or determined inaccurately, and a simulation result is possibly inaccurate, so that the safety and stability analysis is inaccurate, and the safety strategy is not properly formulated. The steps of the present invention will be further explained with reference to the accompanying drawings.

Drawings

Fig. 1 is a detailed flow diagram of an interface positioning method suitable for large-scale alternating current/direct current power grid electromechanical-electromagnetic transient hybrid simulation.

Detailed Description

The invention is based on the electromagnetic transient simulation software RTDS and electromechanical transient simulation software PSS/E commonly used in the world, and uses the existing RTDS GTFPGA as the interface of the RTDS and the PSS/E, constructs the electromechanical-electromagnetic hybrid simulation platform of the large-scale AC/DC interconnected power grid, the invention provides an interface positioning method suitable for the electromechanical-electromagnetic transient hybrid simulation platform of the large-scale AC/DC power grid, the specific steps are as follows:

s1, determining the interface bus range based on a reactive power injection method;

s11, injecting quantitative reactive power Q at the converter bus of the converter_inj；

S12, calculating the voltage deviation delta U of each-order bus of 1-n-order around the commutation bus;

using the current conversion bus as a 0-order bus, wherein the voltage of the 0-order bus is U₀The bus directly connected with the current conversion bus is a 1-order bus, and the voltage of the 1-order bus is U₁Then the voltage deviation of the 1 st order bus is Δ U₁＝U₁-U₀(ii) a The bus directly connected with the 1-order bus is a 2-order bus, and the voltage of the 2-order bus is U₂Then the voltage deviation of the 2 nd order bus is Δ U₂＝U₂-U₁(ii) a By analogy, the voltage deviation of the i-order bus is Delta U_i＝U_i-U_i-1Until the voltage deviation of the n-order bus is calculated to be delta U_n＝U_n-U_n-1；

S13, calculating and comparing the reactive power and the voltage change rate of each-order bus, and determining the range of the interface bus;

s131, calculating the reactive power and the voltage change rate of the 1-n-order buses, namely:

wherein Q is_injRepresenting reactive power, DeltaU, injected at a converter bus of a converter_iRepresenting the voltage deviation, k, of the i-th order bus_iRepresenting the reactive power and voltage change rate of the i-order bus;

s132, comparing the reactive power and the voltage change rate of the 1-n-order buses, and determining the range of the interface bus;

comparing the reactive power of the bus of each step obtained in step S131 with the voltage change rate k_iWhen the change of the reactive power and the voltage change rate of the j-th order and the j +1 th order buses is not obvious, namelyWhen it is takenMinimum j satisfying the above conditions_minStep generatrix and maximum of eligible j_maxThe step buses being respectively the ends of the range of interface buses, i.e. j_min～j_maxThe step bus is a determined interface bus range.

S2, performing frequency resistance characteristic scanning on all buses within the range determined by the reactive power injection method and drawing a frequency resistance characteristic diagram;

s21, all j within the interface bus determined in step S1_min～j_maxRespectively injecting harmonic sources with increasing frequencies into buses of each order, and measuring the impedance of the simulation platform at different frequencies by using a frequency-rejection response model in electromagnetic transient simulation software after stable operation;

s22, drawing j by using electromagnetic transient simulation software according to the impedance of each order of bus obtained in the step S21 under different frequencies_min～j_maxAnd (3) a frequency resistance characteristic diagram of each step of bus.

S3, analysis j_min～j_maxDetermining an interface bus according to the impedance frequency characteristic diagram of each order of bus;

for j obtained in step S2_min～j_maxComparing and analyzing the impedance characteristic diagrams of the buses of all orders, and taking the bus of the minimum order with small impedance characteristic change as an interface bus, namely when j is the bus_min～j_maxWhen the overlap ratio of the frequency resistance characteristic curves of the mth order bus and the (m + 1) th order bus in the order buses is more than 85%, the m order bus with the minimum order is taken as an interface bus, wherein m is [ j ]_min，j_max]An integer within the range. While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.