Method for detecting stability improvement of power system based on electromechanical electromagnetic hybrid simulation

Abstract

The invention discloses a method for detecting stability improvement of a power system based on electromechanical electromagnetic hybrid simulation, and relates to the field of power system stability evaluation. An existing detection method is low in detection precision and low in efficiency. Dividing a region containing to-be-evaluated newly-built equipment from the power system model as an electromagnetic subnet model, and taking the rest part as an electromechanical network model; according to the electromagnetic subnet model and the electromechanical network model, constructing an electromechanical and electromagnetic hybrid simulation model; in an electromagnetic subnet electromagnetic model of the electromechanical electromagnetic hybrid simulation model, selecting one line from lines except for the maintenance line as a fault line, setting a fault for the fault line, simulating the set electromechanical electromagnetic hybrid simulation model, and obtaining dynamic response data under the condition that whether newly-built equipment to be evaluated exists or not; and comparing the dynamic response data under the condition that whether the new equipment to be evaluated exists or not so as to detect the stability improvement condition of the power system after the new equipment to be evaluated is put into operation. The method is used for detecting whether power system stability is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system stability evaluation. BACKGROUND

[0002] With the development of economic society, the scale of power system continues to expand, and the grid structure becomes increasingly complex. In particular, the high proportion of renewable energy access and the widespread application of high-voltage direct current transmission have posed unprecedented challenges to the safe and stable operation of the power grid. Under this background, through the construction of power transmission lines, the installation of static synchronous compensators and other power grid reinforcement projects to improve system stability has become a routine measure in power grid planning and operation.

[0003] However, how to scientifically, accurately and quantitatively evaluate the actual effect of these power grid reinforcement projects with huge investment has always been a technical problem faced by the industry. The existing evaluation methods mainly have the following limitations and deficiencies:

[0004] 1. The precision and efficiency of the simulation model are difficult to balance, resulting in distorted evaluation results:

[0005] Traditional power system stability analysis generally relies on electromechanical transient simulation programs. Although such programs can efficiently simulate the electromechanical fluctuation process of large-scale power grids, they lack precision in simulating power electronic devices with fast, nonlinear dynamic characteristics such as direct current converter stations and static synchronous compensators, and cannot accurately reflect the real transient process under fault conditions (such as commutation failure, controller interaction, etc.).

[0006] While full electromagnetic transient simulation can achieve high-precision simulation, it consumes a huge amount of computing resources and is difficult to apply to scanning analysis of multiple operating modes of large-scale power grids.

[0007] Therefore, the existing technology cannot accurately evaluate the stability of regional power grids containing complex power electronic devices at a reasonable computational cost, resulting in deviations between the predicted effect of new devices and the actual situation.

[0008] 2. Single evaluation dimension, lack of systematic quantitative index system:

[0009] Existing evaluation methods mainly focus on qualitative or rough quantitative analysis of a specific stability problem (such as voltage level), and fail to form a comprehensive evaluation system covering multiple dimensions such as voltage stability, power supply reliability and transmission capacity.

[0010] Especially, there is a lack of direct and quantifiable definition and measurement of "stability improvement effect". For example, only a vague conclusion of "stability is improved" can be given, and specific questions such as "how many milliseconds can the new line shorten the voltage recovery time after failure?" or "how many megawatts of load shedding can the static synchronous compensator avoid?" cannot be accurately answered. This leads to a lack of solid data support for project decision-making, and it is difficult to accurately measure the investment benefit of the project.

[0011] 3. The operation condition is not well considered, and the real effect under the most unfavorable condition cannot be reflected:

[0012] The existing effect evaluation is mostly carried out under the normal operation mode of "full wiring", and the system performance under the expected weak mode such as key line or equipment maintenance is generally ignored.

[0013] The structure of the power grid is weakened and the stability margin is reduced under the maintenance mode, which is the moment when the safety risk is the highest and the new device needs to play a supporting role. Ignoring the test of such working conditions may lead to overly optimistic evaluation conclusions, which cannot expose the potential risks of the system under extreme conditions, and thus cannot provide a comprehensive basis for the optimization of operation control strategies.

[0014] In summary, the existing technology lacks an analysis method that can balance simulation accuracy and efficiency, and can quantitatively analyze the improvement effect of power grid strengthening projects in voltage stability, power supply reliability, and transmission capacity under multiple typical and maintenance conditions. This defect directly affects the scientificity of power grid investment decision-making, the accuracy of planning schemes, and the effectiveness of operation strategies. SUMMARY

[0015] The purpose of the present application is to solve the problems of low detection accuracy and low efficiency of existing detection methods, and a method for detecting power system stability improvement based on electromechanical electromagnetic hybrid simulation is proposed.

[0016] The method for detecting power system stability improvement based on electromechanical electromagnetic hybrid simulation includes the following contents:

[0017] Step 1: Divide the region containing the new device to be evaluated from the power system model as an electromagnetic subnetwork model, and the remaining part as an electromechanical network model;

[0018] Step 2: According to the electromagnetic subnetwork model and the electromechanical network model, an electromechanical electromagnetic hybrid simulation model is constructed;

[0019] Step 3: In the electromagnetic subnetwork electromagnetic model of the electromechanical electromagnetic hybrid simulation model, select a line from the lines other than the maintenance line as the fault line, set the fault line after the fault, and simulate the set electromechanical electromagnetic hybrid simulation model to obtain dynamic response data with or without the new device to be evaluated.

[0020] Step 4, compare the dynamic response data with and without the new construction device to be evaluated, so as to detect the power system stability improvement after the new construction device to be evaluated is put into operation.

[0021] Preferably, in step 4, the dynamic response data with and without the new construction device to be evaluated are compared, specifically:

[0022] Compare whether the transient overvoltage during fault, the steady-state voltage drop during fault, the voltage recovery speed after fault removal, and the difference between the steady-state voltage after fault removal and the steady-state voltage before fault of the bus on both sides of the fault line, the bus on both sides of the maintenance line, the 500KV bus, and the converter station bus with the new construction device to be evaluated are reduced compared with those without the new construction device to be evaluated, if yes, it is determined that the new construction device improves the voltage stability of the power system, if not, it is determined that the new construction device does not improve the voltage stability of the power system.

[0023] Preferably, step 4 further comprises: comparing whether the minimum cut load amount with the new construction device to be evaluated is reduced compared with that without the new construction device to be evaluated, if yes, it is determined that the new construction device improves the power supply reliability of the power system, if not, it is determined that the new construction device does not improve the power supply reliability of the power system.

[0024] Preferably, step 4 further comprises: comparing whether the DC power receiving capacity with the new construction device to be evaluated is increased compared with that without the new construction device to be evaluated, if yes, it is determined that the new construction device improves the DC power receiving capacity of the power system, if not, it is determined that the new construction device does not improve the DC power receiving capacity of the power system.

[0025] Preferably, selecting a line from the lines other than the maintenance line refers to selecting a line that meets the preset impact, a 500kV line, a single-loop line of a ring network, or a regional power transmission line.

[0026] Preferably, the fault is a three-phase ground short-circuit fault occurring at 2% of the line, lasting for 160ms, and then the line is disconnected at 1% and 99% of the line to simulate the relay protection device cutting off the fault line.

[0027] The beneficial effects of the present application are:

[0028] The present application divides the key area containing the new construction device into an electromagnetic sub-network for high-precision simulation, and retains the external large-scale power grid as an electromechanical model, which fundamentally overcomes the limitations of a single simulation model. This method can accurately capture the transient response of fast dynamic elements such as DC converter stations and static synchronous compensators, and maintain the fast calculation ability of the whole network, thereby providing a real and reliable data basis for effect evaluation, ensuring the accuracy and engineering applicability of the evaluation conclusion.

[0029] The application first quantifies the promotion effect as specific and measurable core indexes such as "voltage drop depth and recovery time", "reduction or elimination of minimum load shedding amount" and "promotion of direct current power upper limit". This innovation enables the value of power grid strengthening project to be measured and compared with clear numerical values, completely changes the previous evaluation mode relying on vague expressions such as "improvement", and provides direct and solid data support for project investment decision, scheme comparison and benefit assessment.

[0030] The application defines a complete and standardized technical path from mode selection, model construction and fault setting to effect quantification. The standardized process ensures that the evaluation results of the same project at different design stages or different projects in the same region are highly comparable, greatly improves the efficiency and quality of analysis work, and is conducive to large-scale promotion and application of the technology in the field of power grid planning and operation. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A flowchart of the method for detecting promotion of power system stability based on electromechanical electromagnetic hybrid simulation. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0033] It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict. The application will be further described below with reference to the drawings and specific embodiments, but is not limited to the application.

[0034] Embodiment:

[0035] The method for detecting promotion of power system stability based on electromechanical electromagnetic hybrid simulation includes the following contents:

[0036] Step 1, dividing a region containing new devices to be evaluated from a power system model as an electromagnetic subnetwork model, and the remaining part as a mechanical network model;

[0037] Step 2, constructing an electromechanical electromagnetic hybrid simulation model according to the electromagnetic subnetwork model and the mechanical network model;

[0038] Step 3, in the electromagnetic sub-network electromagnetic model of the electromechanical-electromagnetic hybrid simulation model, a line other than the maintenance line is selected as the fault line, a fault is set for the fault line, the electromechanical-electromagnetic hybrid simulation model after the setting is simulated, and dynamic response data under the condition of whether the new construction device to be evaluated is obtained;

[0039] Step 4, comparing the dynamic response data under the condition of whether the new construction device to be evaluated is obtained, thereby detecting the power system stability improvement after the new construction device to be evaluated is put into operation.

[0040] Specifically, the embodiment can be applied to normal operation or maintenance:

[0041] Normal mode determination: select typical operation modes, winter large load wind power stop mode, winter small load wind power large mode, summer large load wind power stop mode, adjust the thermal power plant output according to the minimum operation mode of the thermal power plant during the heating period, adjust the Liaozhuanghe plant output to a reasonable range (3.5~6p.u.), and ensure power supply and demand balance.

[0042] Maintenance mode determination: select 500kV lines (Anhei #1 line), ring network single-circuit lines (Lanenjia line, Jia duo line, Nenduo line), and lines to the converter station (Heiduo line) as maintenance lines, adjust the reactive power compensation device, and adjust the power flow to a reasonable range (bus voltage 1~1.07p.u.).

[0043] The embodiment incorporates key line maintenance and other weak system operation modes into the standard analysis process, and the embodiment forcibly tests the effectiveness of the new construction device under the most severe working conditions. This makes the evaluation conclusion not only applicable to ideal states, but also reveals the true performance of the system under extreme pressure, thereby guiding the development of safer and more reliable operation control strategies (such as optimizing or disabling load shedding schemes), and significantly improving the forward-looking and risk prevention capabilities of power grid planning.

[0044] The dynamic response data includes the pre-fault steady-state voltage of the bus on both sides of the fault line, the pre-fault steady-state voltage of the bus on both sides of the maintenance line, the 500KV bus, the converter station bus, the transient overvoltage during the fault, the steady-state voltage drop during the fault, the voltage recovery speed after the fault is removed, and the steady-state voltage after the fault is removed.

[0045] Further limited, in step 4, the dynamic response data under the condition of whether the new construction device to be evaluated is compared, specifically:

[0046] Compare whether the transient overvoltage, steady-state voltage drop during a fault, voltage recovery speed after fault clearance, and the difference between the steady-state voltage after fault clearance and the steady-state voltage before fault clearance are reduced compared to the comparison between the newly constructed equipment to be evaluated and the newly constructed equipment without the newly constructed equipment to be evaluated. If so, it is determined that the newly constructed equipment has improved the voltage stability of the power system; otherwise, it is determined that the newly constructed equipment has not improved the voltage stability of the power system.

[0047] Further specifying, step 4 also includes: comparing whether the minimum load shedding capacity of the new equipment to be evaluated is reduced compared to the new equipment without evaluation; if so, it is determined that the new equipment improves the power supply reliability of the power system; if not, it is determined that the new equipment does not improve the power supply reliability of the power system.

[0048] Further specifying, step 4 also includes: comparing whether the DC power receiving capability of the newly built equipment to be evaluated has increased compared to the newly built equipment without evaluation; if so, it is determined that the newly built equipment has improved the DC power receiving capability of the power system; if not, it is determined that the newly built equipment has not improved the DC power receiving capability of the power system.

[0049] Further specifying, selecting a line from lines other than those under maintenance refers to selecting a line whose impact on the power grid meets the preset impact, a 500kV line, a single-circuit ring network line, or a regional transmission line.

[0050] Further specifying, the fault is set to a three-phase ground fault occurring at 2% of the line, lasting 160ms, and then the line is disconnected at 1% and 99% of the line, simulating the relay protection device disconnecting the faulty line.

[0051] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A method for detecting power system stability improvement based on electromechanical-electromagnetic hybrid simulation, characterized in that, The method includes the following: Step 1: Divide the area containing the newly built equipment to be evaluated from the power system model as the electromagnetic subnet model, and the remaining part as the electromechanical network model; Step 2: Based on the electromagnetic subnet model and the electromechanical network model, construct a hybrid electromechanical-electromagnetic simulation model; Step 3: In the electromagnetic subnet electromagnetic model of the electromechanical-electromagnetic hybrid simulation model, select a line other than the maintenance line as the fault line, set the fault for the fault line, and then simulate the electromechanical-electromagnetic hybrid simulation model to obtain dynamic response data with and without the new equipment to be evaluated. Step 4: Compare the dynamic response data with and without the new equipment to be evaluated to detect the improvement in power system stability after the new equipment to be evaluated is put into operation.

2. The method for detecting power system stability improvement based on electromechanical-electromagnetic hybrid simulation according to claim 1, characterized in that, In step 4, the dynamic response data will be compared with those without the newly constructed equipment to be evaluated, specifically as follows: Compare whether the transient overvoltage, steady-state voltage drop during a fault, voltage recovery speed after fault clearance, and the difference between the steady-state voltage after fault clearance and the steady-state voltage before fault clearance are reduced compared to the comparison between the newly constructed equipment to be evaluated and the newly constructed equipment without the newly constructed equipment to be evaluated. If so, it is determined that the newly constructed equipment has improved the voltage stability of the power system; otherwise, it is determined that the newly constructed equipment has not improved the voltage stability of the power system.

3. The method for detecting power system stability improvement based on electromechanical-electromagnetic hybrid simulation according to claim 1 or 2, characterized in that, Step 4 also includes: comparing whether the minimum load shedding capacity of the new equipment to be evaluated is reduced compared to the new equipment without evaluation. If so, it is determined that the new equipment improves the power supply reliability of the power system; if not, it is determined that the new equipment does not improve the power supply reliability of the power system.

4. The method for detecting power system stability improvement based on electromechanical-electromagnetic hybrid simulation according to claim 3, characterized in that, Step 4 also includes: comparing whether the DC power receiving capability of the newly built equipment to be evaluated has increased compared to the newly built equipment without evaluation. If so, it is determined that the newly built equipment has improved the DC power receiving capability of the power system; if not, it is determined that the newly built equipment has not improved the DC power receiving capability of the power system.

5. The method for detecting power system stability improvement based on electromechanical-electromagnetic hybrid simulation according to claim 1, characterized in that, Selecting a line from those not under maintenance refers to choosing a line whose impact on the power grid meets the preset impact criteria, a 500kV line, a single-circuit ring network line, or a regional transmission line.

6. The method for detecting power system stability improvement based on electromechanical-electromagnetic hybrid simulation according to claim 1, characterized in that, The fault setting involves a three-phase ground fault occurring at 2% of the line, lasting for 160ms, followed by disconnection of the line at 1% and 99% of the line, simulating the relay protection device disconnecting the faulty line.

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