CN105119267B - A kind of power grid static voltage stability horizontal analysis method - Google Patents

Abstract

The invention relates to a method for analyzing the static voltage stability level of a power grid. First, determine the data of the horizontal year mode, form a steady-state calculation data file, and perform power flow calculation; then, based on the ground-state data with better convergence, form an expected accident set and formulate faults; secondly, perform static voltage stability calculation and analysis; thirdly, At the power limit point, the weak node of grid voltage stability is determined through modal analysis; finally, the static voltage stability level of the grid is improved by applying reactive power compensation measures at the weak node of the grid. The invention can increase the consideration of the transmission section of the regional power grid, extend the consideration range of static voltage stability, and analyze the voltage collapse more thoroughly; at the same time, based on the online data of the power grid, the database technology is used to quickly update the steady-state calculation data file and improve work efficiency .

Description

A Method for Analyzing Static Voltage Stability Level of Power Grid

technical field

The invention relates to the field of power system operation and control, in particular to a method for analyzing the static voltage stability level of a power grid.

Background technique

Power system voltage stability assessment is an important part in the calculation and analysis of power grid security and stability. The purpose of voltage stability calculation and analysis is to verify the static, transient and long-term voltage stability of the power grid, and to study and determine the reactive power compensation equipment configuration scheme, reactive power and voltage control strategy, low-voltage load shedding scheme, etc. of the power grid to ensure the safety of voltage stability stabilization measures.

Up to now, the theoretical system of the voltage stability problem has not been perfected, and the related research mainly focuses on the static stability. Introduction to commonly used static voltage stability analysis methods: First, evaluate the voltage stability level of the system by calculating various voltage stability safety indicators (load node power margin, regional power margin, and whole network power margin, and static voltage stability reserve coefficient); Secondly, identify areas with relatively weak voltage stability through modal analysis or sensitivity analysis; finally, improve the static voltage stability level of the power grid by installing reactive power compensation devices in areas with relatively weak voltage stability or strengthening regional grid construction. See Chinese Invention Patent (Application No. 201010599850.X) for details.

In recent years, with the emergence and wide application of the phase angle measurement unit (PMU), the evaluation method of the local voltage stability level using local measurement data has gradually received attention and application. See Chinese Invention Patent (Application No. 200910263112.5) for details.

The existing static voltage stability analysis methods only consider the size of the load node/area power margin index, and have not considered the transmission power limit index of the transmission section. In reality, the power transmission section is the main channel connecting the regional power grid with the external power grid/power supply, and its transmission power will have a certain impact on the voltage stability level of the sending section/receiving end grid. In terms of information system construction, the existing technology focuses on quasi-real-time power grid conditions for operation monitoring of static voltage applications. Considering that the development of voltage collapse is relatively slow, static voltage stabilization should be more applied to grid arrangement, planning grid security level assessment and other aspects.

Contents of the invention

In view of this, the object of the present invention is to propose a method for analyzing the static voltage stability level of the power grid, which increases the consideration of the transmission section of the regional power grid and extends the consideration range of the static voltage stability.

The present invention is realized by adopting the following scheme: a method for analyzing the static voltage stability level of a power grid, which specifically includes the following steps:

Step S1: Determine horizontal year data;

Step S2: forming a steady-state calculation data file;

Step S3: Perform basic power flow analysis and calculation according to the steady-state calculation data file formed in step S2. If the calculation results converge, the power flow distribution is reasonable and the voltage does not exceed the limit, then enter step S4, otherwise return to step S1;

Step S4: forming an expected accident set;

Step S5: static voltage stability analysis;

Step S6: weak node identification;

Step S7: Formulate improvement measures.

Further, the horizontal annual mode in the step S1 includes the annual maximum load mode, the annual minimum load mode and various maintenance modes of the power grid. Preferably, it is considered that under the maximum load mode of the general urban power grid, the load reactive power demand is relatively large, and the terminal voltage is relatively low; while under the minimum load mode, the grid has surplus reactive power and the voltage is relatively high. Therefore, the above two modes of operation are generally considered emphatically.

Further, the step S2 is specifically: using database technology to establish a comparison table between the power grid CIM model and the BPA model, and then based on the power grid E file, quickly update the data of the BPA model, generate a BPA power flow data file, and then obtain a stable State computing data files.

Further, the expected accident set described in step S4 includes grid normal mode and grid fault mode, and the grid fault mode includes DC unipolar blocking, DC bipolar blocking, external contact line N-1, double circuit N on the same tower -2, line N-1 in the area, line N-2 in the area, main transformer N-1 in the area.

Further, the step S5 specifically includes the following steps:

Step S51: designing computing scenarios;

Step S52: Determine the result index of the static voltage stability analysis;

Step S53: Calculate the index in step S52, and judge whether each margin index exceeds the standard, if it exceeds the standard, go to step S6, otherwise, return to step S1.

In particular, the content that needs to be considered in the scenario includes: (1) specify the scope of the regional power grid to be calculated, the connection lines of the regional and external power grids, and determine the scope of the regional power grid; (2) set the load and generator output within the scope of the regional power grid (3) Set the voltage range standard.

Further, the result indicators of the static voltage stability analysis include load node power margins, regional/network-wide power margins, static voltage stability reserve coefficients, and section transmission power limits.

Further, the step S6 specifically includes: based on the result of static voltage stability calculation in step S5, conduct modal analysis at the stability limit point to determine voltage instability regions and typical characteristics of loss of stability in the system, and then realize weak node identification.

Further, the step S6 specifically includes: based on the result of static voltage stability calculation in step S5, conduct modal analysis at any point on the P-V curve to determine voltage instability regions and typical characteristics of loss of stability in the system, and then realize weak node identification.

Furthermore, for a power transmission scheme, if the system cannot meet the requirements of the voltage stability margin, it is necessary to formulate improvement measures at weak nodes. Measures in the step S7 include preventive control, such as adjusting the on-load transformer tap, generator operating voltage adjustment, shunt capacitor reactance switching, etc.; emergency control, such as load shedding, etc.; and planning suggestions, such as strengthening the grid structure, increasing Local units connected to the grid, etc.

Compared with the prior art, the present invention (1) applies the steady-state calculation data file processing technology adopted in the power grid real-time monitoring system to offline analysis and calculation. Based on this technology, existing system data (SCADA system, load forecasting system, power generation planning system, and maintenance planning system) to quickly generate data files for voltage stability calculations, providing convenience for grid arrangement and planning grid safety level assessment, eliminating the need for manual data file preparation, and greatly improving work efficiency; (2) In the grid voltage stability evaluation process, in addition to calculating the load node power margin, regional power margin, whole network power margin and static voltage stability reserve coefficient indicators, the section transmission power limit index is also considered, which increases the power transmission of the regional grid. The consideration of cross-section extends the scope of consideration of static voltage stability.

Description of drawings

Fig. 1 is a flow chart of the method of the present invention.

Fig. 2 is a schematic diagram of forming a steady-state calculation data file in an embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, this embodiment provides a method for analyzing the static voltage stability level of the power grid, which specifically includes the following steps:

Step S1: Determine horizontal year data;

Step S2: forming a steady-state calculation data file;

Step S3: Perform basic power flow analysis and calculation according to the steady-state calculation data file formed in step S2. If the calculation results converge, the power flow distribution is reasonable and the voltage does not exceed the limit, then enter step S4, otherwise return to step S1;

Step S4: forming an expected accident set;

Step S5: static voltage stability analysis;

Step S6: weak node identification;

Step S7: Formulate improvement measures.

In this embodiment, the horizontal annual modes in the step S1 include the annual maximum load mode, the annual minimum load mode and various maintenance modes of the power grid. Preferably, it is considered that under the maximum load mode of the general urban power grid, the load reactive power demand is relatively large, and the terminal voltage is relatively low; while under the minimum load mode, the grid has surplus reactive power and the voltage is relatively high. Therefore, the above two modes of operation are generally considered emphatically.

In this embodiment, the step S2 is specifically: using database technology to establish a comparison table between the CIM model of the power grid and the BPA model, and then based on the E file of the power grid, the data of the BPA model is quickly updated to generate a BPA power flow data file, Then the steady-state calculation data file is obtained.

In this embodiment, the expected accident set described in step S4 includes grid normal mode and grid fault mode, and the grid fault mode includes DC unipolar blocking, DC bipolar blocking, external contact line N-1, same-tower Double circuit N-2, line N-1 in the area, line N-2 in the area, main transformer N-1 in the area.

In this embodiment, the step S5 specifically includes the following steps:

Step S51: designing computing scenarios;

Step S52: Determine the result index of the static voltage stability analysis;

Step S53: Calculate the index in step S52, and judge whether each margin index exceeds the standard, if it exceeds the standard, go to step S6, otherwise, return to step S1.

In particular, in this embodiment, the content that needs to be considered in the scenario includes: (1) clarify the scope of the regional power grid to be calculated, the tie lines of the power grid inside and outside the district, and determine the scope of the regional power grid; (2) set the scope of the regional power grid Internal load and generating set output growth mode; (3) Set the voltage range standard.

In this embodiment, the result indicators of the static voltage stability analysis include load node power margins, regional/entire network power margins, static voltage stability reserve coefficients, and section transmission power limits.

In this embodiment, the step S6 specifically includes: based on the result of static voltage stability calculation in step S5, conduct modal analysis at the stability limit point to determine the voltage instability region and the typical characteristics of loss of stability in the system, and then realize the weak Node identification.

In this embodiment, the step S6 is specifically: based on the result of static voltage stability calculation in step S5, perform modal analysis at any point on the P-V curve to determine the voltage instability region and the typical characteristics of loss of stability in the system, and then realize the weak Node identification.

In this embodiment, for a power transmission scheme, if the system cannot meet the voltage stability margin requirement, it is necessary to formulate improvement measures at weak nodes. Measures in the step S7 include preventive control, such as adjusting the on-load transformer tap, generator operating voltage adjustment, shunt capacitor reactance switching, etc.; emergency control, such as load shedding, etc.; and planning suggestions, such as strengthening the grid structure, increasing Local units connected to the grid, etc.

In particular, this implementation also provides the following specific implementation process:

As shown in Figure 2, the typical daily E files and CIM models of the power grid in the historical period are exported from the SCADA system for the analysis of the static voltage stability of the typical daily power grid; In addition to the daily data files, it is also necessary to export the corresponding result data files during the planning period from the load forecasting system, power generation planning system, and maintenance planning system.

Establish an offline database oriented to the BPA data model, and establish a corresponding table with the BPA model. The table includes: partition, ACBUS, AC LINE, LINE HG, TRAN, DC BUS, DC LINE, serial compensation, etc.; some corresponding relationships are listed below.

BPA data name Database field naming B* AC Bus_Card Key OWNER AC Bus_Owner name AC Bus_Name KV AC Bus_KV ZONE AC Bus_Zone LOAD P(MW) AC Bus_Load P LOAD Q(MVar) AC Bus_Load Q PMAX(MW) AC Bus_Pmax PGEN (MW) AC Bus_PGen

Use the offline database to generate steady-state data files in various modes of the power grid, and then perform power flow calculations.

Based on the steady-state data files, all possible faults are set, and then the more serious faults are screened out for subsequent calculations. Screening principle: Analyze all user-set faults to find out those faults with the smallest voltage stability margin. The voltage stability margin of each fault refers to the difference between the power transmission level P ₀ of the initial operating point before the fault and the power transmission level P _n of the operating point where the last power flow solution exists after the fault (P _n - P ₀ ).

Static stability analysis mainly has two application methods: inter-regional one-dimensional power transmission, intra-regional load increase and output increase. For the regional power grid, the load and generator output growth methods are designed respectively, and then the normal mode and fault mode (fault The type comes from the result of fault screening) to carry out the static voltage stability calculation of the power grid.

Taking a regional power grid as an example, the calculation results are as follows.

(1) The reactive power margin of load nodes is shown in the table below.

serial number Substation name 110kV side (Mvar) 1 A substation -309 2 B substation -214 3 C substation -144 4 D substation -226 5 E substation -284

(2) The indicators of regional/network-wide power margin and static voltage stability reserve coefficient are shown in the table below.

Before failure Station A main transformer N-1 Station A main transformer N-2 initial voltage 0.98 0.9457 0.9747 Ultimate voltage 0.61 0.6295 0.8291 reserve factor 38% 33% / normal load 1152 1152 1152 limit power 2075 1635 399 power margin 80% 42% -65%

(3) The section transmission power limit is shown in the table below.

Before failure Section A N-1 A Section N-2 initial voltage 0.99 0.98 0.96 restore power 4061 4058 4056 Ultimate voltage 0.91 0.89 0.90 limit power 6314 6092 5323 margin factor 55% 50% 31%

For the region/whole network and sections, respectively, conduct modal analysis at their limit power points, and determine the weak points of static voltage stability of the power grid according to the size of the participating factors. The calculation results are shown in the table below. Weak points generally select nodes with relatively large participation factors.

serial number node name Participation factor 1 A substation 10kV busbar 1.000 2 A substation 110kV busbar 0.966 3 B substation 10kV busbar 0.737 4 B substation 110kV busbar 0.727 5 C substation 10kV busbar 0.560

For power grids whose margin indicators do not meet the standard requirements, the improvement measures are formulated until the margin indicators meet the requirements. For example, for power receiving capacity, generally through adjusting generator and SVC voltage control, input of capacitors and reactors, ULTC tap adjustment, load shedding, etc.; section power transmission capacity, generally through increasing transmission line construction, etc.

In particular, the BPA software of China Electric Power Research Institute is used for calculation and analysis in the implementation process.

In summary, the present invention first utilizes the database technology to establish a comparison table between the grid CIM model and the BPA model, and then based on the grid E file, quickly updates the BPA model data to generate the BPA power flow data file and obtain the steady-state calculation data file . This method can use the existing system data (SCADA system, load forecasting system, power generation planning system, and maintenance planning system) to quickly generate data files for voltage stability calculations, and provide convenience for power grid arrangement and planning. Manual compilation of data files is eliminated, which greatly improves work efficiency. Secondly, the core of the voltage collapse problem is that the system cannot meet the reactive power demand. The influencing factor may be the excessive use of parallel capacitor compensation, but it may also be caused by the transmission power of the transmission section exceeding the transmission limit. The present invention proposes that on the basis of the existing methods, the consideration of the transmission power limit of the power transmission section is added. In addition to the power receiving capacity of the power supply area of the power grid, the power transmission capacity of the power transmission channel of the power grid is considered at the same time, and the voltage collapse analysis is more thorough. Finally, in terms of application effects, the present invention is more in line with the voltage collapse mechanism, and the evaluation results are closer to reality; in terms of source data processing, the existing automation system is fully utilized to quickly generate steady-state data files in various ways, eliminating the need for artificial Prepare data files to improve work efficiency.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (1)

1. A kind of 1. power grid static voltage stability horizontal analysis method, it is characterised in that comprise the following steps：

   Step S1：Determine forcasted years mode data；

   Step S2：Form stable state and calculate data file；

   Step S3：The stable state formed according to step S2 calculates data files, carries out basic tidal current analysis calculating, if result of calculation is received Hold back, trend is reasonably distributed and voltage is not out-of-limit, then enter step S4, otherwise return to step S1；

   Step S4：Form contingency set；

   Step S5：Static voltage stability analysis；

   Step S6：Weak node identifies；

   Step S7：Formulate measure for improvement；

   Wherein, the step S5 specifically includes following steps：

   Step S51：Design calculates scene；

   Step S52：Determine the result index of static voltage stability analysis；

   Step S53：Index in calculation procedure S52, and judge whether each margin index is exceeded, and S6 is entered step if exceeded, Otherwise, return to step S1；

   Wherein, it is abundant to include load bus power margin, region/the whole network power for the result index of the static voltage stability analysis Degree, static voltage stability reserve factor and section transmission power limit；

   Wherein, the step S6 is specially：Based on step S5 static voltage stabilities calculate as a result, at stability limit point carry out Model analysis, determines spread of voltage region in system and loses stable characteristic feature, so realize weak node identification '

   Wherein, forcasted years mode described in the step S1 includes annual peak load mode, year minimum load mode and power grid Each maintenance mode；

   Wherein, the step S2 is specially：Using database technology, the contrast relationship of power grid CIM model and BPA models is established Table, is then based on power grid E files, and the data of BPA models are quickly updated, and generates BPA flow data files, and then obtain Stable state calculates data file；

   Wherein, the contingency set described in the step S4 includes power grid normal mode and electric network fault mode, the power grid event Barrier mode includes the locking of direct current monopole, DC bipolar block, contact with foreign countries circuit N-1, common-tower double-return N-2, circuit N- in region 1st, circuit N-2 in region, main transformer N-1 in region；

   Wherein, the step S6 is specially：Based on step S5 static voltage stabilities calculate as a result, on P-V curves any point Model analysis is carried out, spread of voltage region in system is determined and loses stable characteristic feature, and then realize weak node Identification；

   Wherein, measure includes prevention and control, emergent control and planning proposal in the step S7.