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GB/T 40581-2021: Calculation specification for power system security and stability
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Basic data | Standard ID | GB/T 40581-2021 (GB/T40581-2021) | | Description (Translated English) | Calculation specification for power system security and stability | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | F21 | | Word Count Estimation | 38,366 | | Issuing agency(ies) | State Administration for Market Regulation, China National Standardization Administration | GB/T 40581-2021: Calculation specification for power system security and stability---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Calculation specification for power system security and stability
ICS 29.020
CCSF21
National Standards of People's Republic of China
Power System Security and Stability Calculation Specification
Released on 2021-10-11
2022-05-01 implementation
State Administration for Market Regulation
Issued by the National Standardization Management Committee
Table of contents
Foreword Ⅲ
Introduction Ⅳ
1 Scope 1
2 Normative references 1
3 Terms and definitions 1
4 Overall requirements and tasks of safe and stable computing 5
5 Basic conditions for safe and stable calculation 6
6 Methods and criteria for safe and stable calculation 12
7 Security and stability calculation analysis and measures to improve stability 27
8 Management of safe and stable calculation analysis 29
References 32
Power System Security and Stability Calculation Specification
1 Scope
This document specifies the requirements, basic conditions, methods and criteria for power system safety and stability calculations, measures to improve stability, and safety
Stable calculation and analysis management.
This document is applicable to the planning, design, construction, production and operation, scientific testing, and safety of equipment manufacturing of 220kV and above power systems
Stable calculation and analysis work. The safety and stability calculation work of the power system below 220kV can be implemented by reference.
2 Normative references
The content of the following documents constitutes an indispensable clause of this document through normative references in the text. Among them, dated quotations
Only the version corresponding to the date is applicable to this document; for undated reference documents, the latest version (including all amendments) is applicable to
This document.
GB/T 15544.1 Three-phase AC system short-circuit current calculation Part 1.Current calculation
GB/T 26399 Technical Guidelines for Power System Security and Stability Control
GB/T 31464 Grid Operation Guidelines
GB 38755-2019 Safety and Stability Guidelines for Power Systems
3 Terms and definitions
The following terms and definitions defined in GB 38755-2019 apply to this document.
3.1
Powersystemsecurity
The ability of the power system to withstand disturbances (such as sudden loss of power system components, or short-circuit faults, etc.) during operation.
Note. It is characterized by two characteristics.
a) The power system can withstand the transient process caused by the disturbance and transition to an acceptable operating condition;
b) Under the new operating conditions, various constraints are met.
[Source. GB 38755-2019, 2.1, with modification]
3.2
Power system stability
The ability of the power system to maintain stable operation after being disturbed.
Note. The stability of the power system is divided into three categories. power angle stability, voltage stability and frequency stability. The specific classification is shown in Figure 1.
4 Overall requirements and tasks of safe and stable computing
4.1 General requirements for safe and stable calculations
The safety and stability calculation of the power system should be based on the specific conditions and requirements of the system, and the reactive voltage, short-circuit current, static safety, and static
State stability, transient power angle stability, dynamic power angle stability, voltage stability, frequency stability, long-term dynamic process, subsynchronous/supersynchronous oscillation and subsynchronous
Step resonance and short-circuit ratio are calculated and analyzed, and the basic stability characteristics of the system are studied, the safety and stability level of the power grid is checked, and the power grid is optimized
Plan the plan, put forward the control strategy to ensure the safe and stable operation of the system and the measures to improve the stability of the system.
4.2 The task of safe and stable computing
4.2.1 Reactive voltage analysis
Reactive power and voltage analysis mainly analyzes reactive power balance and voltage control strategies to realize the layered and zoned in-situ reactive power balance to ensure that the
The bus voltage of each voltage level can be controlled at a reasonable level after failure and under special mode, and it has flexible voltage adjustment methods. For the Union
It is necessary to carry out calculation and analysis of voltage fluctuations for weak power grid tie lines, weak sections in the network, etc.
4.2.2 Short-circuit current safety check
The short-circuit current safety check is used for the short-circuit current in the power system when a short-circuit occurs in the power system under the specified startup mode or network topology.
Calculate and analyze the attenuation of the AC component and DC component to check whether the short-circuit current level of each bus in the system meets the relevant circuit breaker opening.
The requirements of breaking capacity, research measures to limit the level of short-circuit current. The forms of short-circuit faults should include three-phase short-circuit faults and single-phase ground faults.
The short circuit should be checked according to the metallic short circuit.
4.2.3 Power system static safety analysis
The static safety analysis of the power system refers to the application of the N-1 principle to disconnect the lines, transformers and other components one by one without faults, and check whether other components are
Therefore, overload and voltage over-limit are used to test whether the structural strength and operation mode of the power grid meet the requirements of safe operation.
4.2.4 Static stability calculation analysis
4.2.4.1 Power system static stability calculation analysis includes static power angle stability and static voltage stability calculation analysis. According to the corresponding criteria, use
In order to determine the stability of the power system and the transmission power limit of the transmission section (line), check the stability reserve under a given mode.
4.2.4.2 For large power supply transmission lines, cross-regional or inter-provincial interconnection lines, weak sections in the network, etc., static stability calculation and analysis should be performed.
4.2.5 Calculation and analysis of transient power angle stability
The transient power angle stability calculation analysis is used to verify the stability of the system under the specified operating mode and fault form, and to protect the relay.
The corresponding requirements are put forward for protection and automatic devices and various measures.
4.2.6 Calculation and analysis of dynamic power angle stability
4.2.6.1 Dynamic power angle stability can be divided into small disturbance dynamic power angle stability and large disturbance dynamic power angle stability. Small disturbance dynamic power angle stability analysis
Because the disturbance is small enough, the system can be described by a linearized state equation. In the large disturbance dynamic power angle stability analysis, the disturbance is so large that the system is not suitable for application.
Linear equation to describe.
4.2.6.2 The dynamic power angle stability calculation analysis is used to perform the dynamic power angle stability of the system under the specified operation mode and disturbance state.
Check to determine whether there is a negatively damped or weakly damped oscillation mode in the system, and control the power flow of the sensitive section in the system and improve the damping of the system
Features, grid-connected unit excitation and its additional control system, configuration and parameter optimization of the speed control system, and various safety and stability measures are proposed
The corresponding requirements.
4.2.7 Calculation and analysis of voltage stability
Voltage stability calculation analysis is used to verify the voltage stability of the system under the specified operating mode and fault form, and to verify the system voltage stability.
Voltage stability control strategy, low voltage load shedding plan, reactive power compensation configuration and various safety and stability measures put forward corresponding requirements.
4.2.8 Frequency stability calculation analysis
Frequency stability calculation analysis is used when the whole system (or the part after de-arrangement) has frequency oscillation or is disturbed by large active power.
When the system frequency fluctuates widely, the frequency stability of the system is calculated and analyzed, and the frequency stability control countermeasures of the system are included.
Including governor parameter optimization, low-frequency load shedding plan, low-frequency splitting plan, high-frequency cut-off plan, overspeed protection control strategy, DC modulation
And various security and stability measures put forward corresponding requirements.
4.2.9 Calculation and analysis of long-term dynamic process
4.2.9.1 In the long-term dynamic process simulation calculation, the system is described by nonlinear equations, and numerical integration suitable for rigid dynamic systems should be used.
Algorithm, generally an implicit integration algorithm with automatic variable step length; should be included in the slow motion of the power system that is not considered in the general transient stability calculation
State component characteristics. The time range for long-term dynamic process calculation can range from tens of seconds to tens of minutes or even hours.
4.2.9.2 The calculation and analysis of the long-term dynamic process are used to calibrate the long-term dynamic process of the system under the specified operation mode and disturbance pattern.
And research, study the control strategies to ensure the safety and stability of the power grid, and propose corresponding measures for relay protection and automatic devices as well as various safety and stability measures
Require.
4.2.10 Calculation and Analysis of Subsynchronous/Supersynchronous Oscillation and Subsynchronous Resonance
Subsynchronous oscillation/subsynchronous resonance calculation is used to stabilize the subsynchronous oscillation/subsynchronous resonance of the power system under different operating modes
Calculate and analyze the performance, and countermeasures for suppression of subsynchronous oscillation/subsynchronous resonance, including operation mode adjustment schemes, subsynchronous oscillation/subsynchronization
The resonance damping control scheme and the torsional vibration protection measures of the unit shaft system put forward corresponding requirements.
New energy sub-synchronous/super-synchronous oscillation calculation is used to compare the sub-synchronization of power systems with new energy under different control methods and operation modes.
Calculate and analyze the stability of step/super-synchronous oscillation, and countermeasures against sub-synchronous/super-synchronous oscillation, including adjustments to the access system and operation mode
The plan, new energy system control strategy adjustment, and sub-synchronous/super-synchronous oscillation damping control plan put forward corresponding requirements.
4.2.11 Calculation and analysis of short-circuit ratio
The calculation and analysis of the short-circuit ratio are used to measure the strength of the AC system connected to the DC or new energy field stations.
5 Basic conditions for safe and stable calculation
5.1 Calculation conditions and basic data
5.1.1 The basic conditions that should be determined before the calculation and analysis of the safety and stability of the power system include the wiring and operation mode of the power system, and the various elements of the power system.
Models and parameters of components and their control systems, load models and parameters, fault types and fault removal time, reclosing action time, relay protection
And the model and operating time of the safety automatic device.
5.1.2 Through modeling research and actual measurement work, various components, control devices and loads suitable for the safety and stability calculation of the power system shall be established.
Detailed models and parameters. Reasonable models and parameters should be used in calculation analysis to ensure the accuracy of simulation calculation. For completed parameters
For the components and control devices that have been measured and passed the audit, the measured models and parameters shall be adopted; for those that have been put into production but have not yet completed the actual measurement of the parameters or have not yet
The components and control devices put into production should adopt the factory model and parameters provided by the manufacturer and approved by the competent authority or its entrusted agency.
Or refer to the same type of equipment that has been tested, and select models and parameters approved by the competent authority or its entrusted agency.
5.1.3 In the calculation and analysis of system design, production operation and experimental research, the accuracy and consistency of the adopted models and parameters shall be ensured.
In the calculation and analysis at the planning and design stage, for parts other than the existing system, a typical model approved by the competent authority or its commissioned agency can be used.
Type and parameters.
5.2 System wiring and operation mode
5.2.1 Selection principle
According to the purpose of calculation and analysis, the system wiring and operation mode should be set for the unfavorable conditions that may actually occur in the operation of the system. answer
Select the possible unfavorable conditions for the safety and stability of the system from the following three operating modes, and perform calculation and analysis.
a) Normal methods. including planned maintenance methods and large hydropower, thermal power, and maximum
Or possible operation modes such as minimum load, minimum start-up and pumped storage operating conditions, and maximum or minimum new energy power generation;
b) Post-failure mode. The short-term steady-state operation mode that occurs after the power system failure is eliminated and before the normal operation mode is restored;
c) Special methods. including holiday operation methods, main lines, transformers or other important components of the system, equipment unplanned maintenance and equipment
More serious methods such as the start-up of the equipment and the withdrawal of the main safety and stability control devices of the power grid.
5.2.2 Operation mode arrangement
5.2.2.1 According to the studied operation mode, consider the power plant's startup and shutdown plan, load curve, DC transmission plan, network structure, power transmission and reception
According to actual conditions such as plans and equipment maintenance plans, the basic power flow data calculated by the system is determined as the initial boundary of power flow and stability calculations.
5.2.2.2 The start-up method should be adjusted according to the actual load needs, and the power flow calculation method should be arranged in consideration of the actual possible unfavorable conditions.
5.2.2.3 The active power and reactive power of the load should conform to reality. It is necessary to strengthen the analysis of the actual load, and reflect the
Unfavorable situations that can occur. The power factor of the load should be verified according to the actual situation. For some special types of loads (such as rectifier loads)
Special attention should be paid.
5.2.2.4 Active rotating reserve and reactive power reserve shall meet the requirements of GB 38755-2019.It should be a certain ratio not greater than the actual load
(2%~5% is usually selected according to the size of the grid)
Sure. On the basis of meeting the spinning reserve capacity, fewer start-up units should be started, especially no idle-running units. In order to consider the most serious situation, send
When the power transmission capacity of the sending-end system is concerned, the sending-end system may not consider spinning reserve; when studying the loss of large power supply of the receiving-end system, the actual situation of the sending-end system should be taken into consideration.
Possible spinning reserve.
5.2.2.5 Plant electricity should be handled according to load and cannot be directly deducted from power generation output. The plant power load of thermal power and nuclear power units is based on actual conditions
Sure.
5.3 Simplification and equivalence of power system
5.3.1 According to the purpose and requirements of the calculation and analysis, the external power grid or the low-voltage network of the researched power grid can be reasonably simplified when necessary.
5.3.2 Principles of simplification of power system network wiring.
a) The power flow distribution and voltage level of each main line and transmission section before and after the network simplification are basically unchanged;
b) In principle, the research network reserves the network wiring with voltages of 220kV and above (reserved voltages of 110kV and below with transmission function)
Network); the load should be hung on the medium-voltage side or low-voltage side of the transformer with the lowest voltage level; in principle, the low-voltage electromagnetic loop network line
Reserve;
c) The power supply in the simplified low-voltage network can, in principle, be offset by the local load, and has a greater impact on the short-circuit current and stability characteristics of the system.
Large power sources can be reserved as needed.
5.3.3 According to the purpose of the research, the external system of the researched system can be appropriately equivalent. The tidal current distribution and distribution of the tie line should be kept
The voltage level remains unchanged, and the stability characteristics and stability level of the studied system remain basically unchanged.
5.3.4 Dynamic equivalence is closely related to the physical problems of power system stability calculation and analysis. In the calculation and analysis of the safety and stability of the power system,
According to the research problem, the dynamic equivalence principle of different equivalence methods is as follows.
a) Equivalent methods suitable for short-circuit current, subsynchronous/supersynchronous oscillation and subsynchronous resonance analysis of large-scale power systems, requirements
The research system has close short-circuit currents before and after the equivalence;
b) Equivalent method for transient power angle stability and large disturbance dynamic power angle stability analysis of large-scale power systems, requiring research
Under the same large disturbance, the system has close rotor rocking curves before and after the equivalent;
c) The equivalent method for small-disturbance dynamic power angle stability analysis of large-scale power systems requires the research system to be before and after the equivalent value.
The main oscillation modes and modal distributions studied are basically the same;
d) Equivalence method suitable for online dynamic safety analysis of large-scale power systems, requiring the study of the main dynamics of the system before and after equivalence
The state characteristics are basically the same.
5.4 Fault type, location, reclosing and fault removal time
5.4.1 Fault location and fault type
5.4.1.1 The location of the failure should be selected to be unfavorable to the stability of the system. The line fault should be selected at the outlet of the substation on both sides of the line, and the transformer is faulty
It should be selected at the high-voltage side or the medium-voltage side outlet, and the generator transformer set outlet failure should be selected at the high-voltage side outlet of the step-up transformer; 3/2 circuit breaker switch failure
The fault should be set as the middle switch refused to move.
5.4.1.2 The type of failure should be selected according to the requirements of GB 38755-2019, combined with the specific needs of the calculation.
In the specific calculation, pay attention to the following issues.
a) For single-circuit line failures of double-circuit lines, multi-circuit lines, and ring network lines with the same voltage level, three-phase faults should be used as a stability check
The main type of failure. According to the provisions of GB 38755-2019, for special lines such as power AC transmission lines, three-phase
When short-circuit faults require stable control measures, the single-phase permanent fault and the three-phase fault-free disconnection of the line should be checked. line
When single-phase permanent faults or three-phase fault-free disconnection cause system stability and damage, it is advisable to adjust the grid operation mode to ensure the system.
The system is stable, and it is not advisable to adopt stability control measures such as machine cut and load cut.
b) A single-phase grounding fault occurs when the different names of the parallel double-circuit lines on the same pole are the same, and the coincidence is unsuccessful.
Parallel double-circuit lines are disconnected without failure at the same time, and after necessary stability control measures such as machine cut and load cut are taken, the system should be able to maintain stability
(Each system can determine whether to adopt a higher standard according to their own characteristics and reliability requirements, as if a three-phase failure occurs in a parallel double-circuit line.
Disconnect at the same time for verification). When the total number of poles and towers erected on the same pole for the outgoing and incoming lines of a power plant or substation does not exceed 20 bases,
And when the length of the line erected on the same pole does not exceed 10% of the total length of the line, the above fault can be classified as the third level of safety and stability
standard.
5.4.2 Fault removal time
The fault removal time is the time from the initiation of the fault to the interruption of the arc of the circuit breaker, which mainly includes the protection action time, the intermediate relay time and the open circuit
The full breaking time of the device, etc., should be selected according to the following data.
a) 220kV line.
---Near the fault point side. 0.12s;
--- Far fault point side. 0.12s.
b) 330kV line.
---Near the fault point side. 0.1s;
--- Far fault point side. 0.1s.
c) 500kV line.
---Near the fault point side. 0.09s;
--- Far fault point side. 0.1s.
d) 750kV line.
---Near the fault point side. 0.09s;
--- Far fault point side. 0.1s.
e) 1000kV line.
---Near the fault point side. 0.09s;
--- Far fault point side. 0.1s.
The fault removal time of the busbar and transformer of each voltage level should be selected according to the near-end fault removal time of the line of the same voltage level.
In the special mode, the protection action time should be selected according to the actual setting value.
5.4.3 Reclosing time
The reclosing time is the time from the removal of the fault to the re-closing of the main breaker of the circuit breaker, which mainly includes the reclosing setting time and the circuit breaker
The inherent closing time. It should be determined based on factors such as system conditions and the need for system stability.
5.4.4 Types of DC faults
For the DC transmission system, according to the requirements of GB 38755-2019, the
Stability check for faults or disturbance types such as drop, restart, commutation failure, etc..
a) For the following faults or disturbances, the system should be kept stable without taking stability control measures.
1) Single converter blocking in DC system;
2) Single-pole blocking of DC system;
3) Short-circuit failure of DC unipolar line.
For the DC unipolar failure of the power supply, if necessary, measures such as cutting the machine or quickly reducing the power output can be adopted.
b) When the following faults or disturbances will cause the safety and stability of the system to be destroyed, in order to maintain the safety and stability of the system, the machine can be cut, the load can be cut, and the DC
Stable control measures such as emergency power control or pumping-off of pumped storage power stations.
1) Two or more converters in the DC system are blocked (not including two converters with the same pole);
2) DC system bipolar blocking;
3) Short-circuit failure of DC bipolar line.
c) The DC commutation failure caused by the AC fault in the near area of the receiving end should correspond to the three-level safety and stability standard according to the triggered AC fault type.
allow. DC failure or abnormality causes continuous DC commutation failure or rapid DC power drop, and the impact exceeds the system's ability to withstand
During operation, stable control measures such as switching off the machine and blocking the DC can be taken.
d) In the actual operation of the power grid, in order to reduce the impact of the fault and speed up the recovery of the system, the DC single converter is blocked, the DC single pole is blocked and other faults
Reasonable measures can be taken to improve the safety level of operating power grids.
5.4.5 Types of new energy failures
For new energy stations, in accordance with the requirements of GB 38755-2019, any new energy station should be disconnected from the network, new energy large-scale disconnection, etc.
Stability check for obstacles or disturbance types.
a) If any new energy plant is disconnected from the grid, the system should be stable without taking stability control measures;
b) When new energy sources are disconnected from the grid on a large scale and cause stability damage, unified measures should be set in accordance with the third-level security and stability standards.
5.5 System component models and parameters
5.5.1 Synchronous motor
5.5.1.1 Adopt the time-domain simulation method based on numerical integration for power system transient power angle stability calculation, dynamic power angle stability calculation and
In the calculation and analysis of transient voltage stability, the synchronous generator should adopt a detailed model that takes into account the sub-transient potential (E"q, E"d) changes of the damping winding.
The salient pole generator (turbine generator) should adopt the 5th or 6th order transient electric potential change model, and the salient pole generator (hydrogenerator) should adopt the
For the 5-order transient electric potential change model, the synchronous tuning camera should be handled as a generator without mechanical power input.
5.5.1.2 When the synchronous generator adopts the sub-transient potential change model that takes into account the damping winding, the damping factor in the generator rotor motion equation
D (standard unit torque/standard unit speed deviation) should be smaller (recommended 0≤D≤0.05); when the synchronous generator adopts a model that does not include the damping winding,
The damping factor D should be used to reflect the role of the damping winding (for example, for a turbo-generator, take D≈1.0~2.0; for a hydro-generator, take D
≈0.5~1.0).
5.5.1.3 The parameters of the synchronous generator should adopt the measured parameters or the factory parameters provided by the manufacturer. In the planning and design stage, there is no
For planning units with specific parameters, typical models and parameters of units of the same type that have been put into production can be used.
5.5.2 Synchronous motor control system
5.5.2.1 Excitation system and its additional control system
When calculating the stability of the power system, the excitation system of the generator set and its additional control system (such as power system stabilizer
PSS).
The model of the excitation system and its additional control system should be based on the adjustment characteristics of the actual device, and the appropriate standard simulation model should be selected, and its parameters
The measured parameters or the measured parameters of the same type of system should be used. For a special excitation system, a custom model can be used according to its situation.
5.5.2.2 Prime mover and its regulating system
Use time-domain simulation methods for power system stability calculation analysis, or use eigenvalue analysis methods for power system small disturbances
When calculating and analyzing the stability of the state power angle, the prime mover and its regulating system of the unit should be taken into account. The parameters of the prime mover and its regulation system should adopt actual
Measured parameters or factory parameters provided by the manufacturer. In the planning and design stage, for the planned units that do not have specific parameters, the ones that have been put into production can be used.
Typical models and parameters of the same type of units.
5.5.3 Load
5.5.3.1 The load model includes a comprehensive static model (comprehensive index model) and a comprehensive dynamic model (motor model and comprehensive index model).
In the power system planning, design, and operation phases, the load model should adopt a comprehensive dynamic model (motor model and comprehensive index model).
5.5.3.2 Each power grid shall determine the composition and parameters of the load model according to the specific conditions of the power grid.
5.5.3.3 The comprehensive load characteristic parameters on the system bus can be based on the characteristic parameters of the typical load and the composition, capacity and capacity of the actual load equipment.
It can be determined by factors such as utilization rate, and it can also be determined based on actual measurement and identification, and it can be verified by means of system test or accident recording.
5.5.3.4 The comprehensive static model reflects the law of load active and reactive power changes with voltage and frequency, usually formula (1) ~ formula (6) can be used.
Show. The coefficients A, B, and C are used to represent the constant impedance (Z), constant current (I), and constant power (P) of the load.
The proportion is called ZIP model.
P=P0(ApU2 BpU1 CpU0)(1 LdpΔf) (1)
Q=Q0(AqU2 BqU1 CqU0)(1 LdqΔf) (2)
Ap Bp Cp=1.0 (3)
Aq Bq Cq=1.0 (4)
Ldp=
dP
df f=f0
(5)
Ldq=
dQ
df f=f0
(6)
Where.
P --- the active power of the load, in megawatts (MW);
P0 --- The active power of the load at rated voltage, in megawatts (MW);
Ap --- the proportion of the constant impedance (Z) part of the load active power in the node load active power, %;
U --- the ratio of the load voltage to its rated voltage;
Bp --- The proportion of the constant current (I) part of the load active power in the node load active power, %;
Cp --- The proportion of the constant power (P) part of the load active power in the node load active power, %;
Ldp --- the active frequency factor of the load, the value range is 0~3.0, generally 1.2~1.8;
Δf ---frequency deviation, standard unit value;
Q --- The reactive power of the load, in megavars (Mvar);
Q0 --- The reactive power of the load at rated voltage, in megavars (Mvar);
Aq --- the proportion of the constant impedance (Z) part of the reactive power of the load in the reactive power of the node load, %;
Bq --- The proportion of the constant current (I) part of the reactive power of the load in the reactive power of the node load, %;
Cq --- The proportion of the constant power (P) part of the reactive power of the load in the reactive power of the node load, %;
Ldq --- the reactive frequency factor of the load, the value range is -2.0~0, generally -2.0;
f0 --- rated frequency, 50Hz.
5.5.3.5 The comprehensive dynamic load model shall adopt the equivalent induction motor and static load model. Equivalent motor model should adopt third-order electromechanical
The transient motor model and the static model should adopt the ZIP model.
5.5.3.6 The auxiliary power load shall include the motor load.
5.5.3.7 When the frequency domain analysis method based on the calculation of eigenvalues is used to calculate the small disturbance dynamic power angle stability of the power system, the load model
Constant impedance model can be used, static load model or dynamic load model can also be used. When the constant impedance model is used, the damping effect of the load
It can be approximately considered in the damping factor D of the generator rotor motion equation of this system. The specific value is determined by the damping in the load model.
The size used is discretionary.
5.5.4 Lines, high-voltage reactors, series compensation devices and transformers
5.5.4.1 In the steady-state and electromechanical transient calculations of the power system, the transmission lines and transformers should be calculated according to the π-type equivalent circuit.
The parameters of the high-voltage reactor and series compensation device shall be measured parameters. When calculating asymmetric faults, the measured line zero sequence should be used
Parameters, the zero sequence parameters of the transformer should be able to reflect the connection mode of the transformer winding; for example, the neutral point of the transformer and high-voltage reactor is grounded through a small reactance,
The sequence parameters should include a small neutral point reactance.
5.5.4.2 For newly-built lines, high-voltage reactors, series compensation devices and transformers in the planning and design, the parameters can take typical values.
5.5.5 DC transmission
5.5.5.1 In the power system stability calculation, the DC transmission can adopt a quasi-steady-state model and simulate it according to the actual situation of the DC control system; flexible
A suitable mathematical model can be used for direct current transmission.
5.5.5.2 The DC transmission model used for stability calculation shall be based on the manufacturer's detailed model, joint debugging test, system debugging, fault recording and other data.
And the parameters are checked, so that the transient characteristics of the HVDC transmission model are basically consistent with the actual characteristics of the project.
5.5.5.3 If the DC modulation function is used for DC transmission, the DC modulation should be taken into account in the stability calculation, and the control of the actual DC modulation function should be adopted.
System rules and parameters.
5.5.5.4 The DC restart and commutation failure should be taken into account in the stability calculation, and the actual control laws and parameters should be used.
5.5.5.5 The electromagnetic transient model of the DC transmission and its control and protection system shall be used in the calculation of subsynchronous/supersynchronous oscillation.
5.5.5.6 Carry out large-scale power grid security and stability analysis, and if necessary, carry out electromagnetic transient-electromechanical transient hybrid simulation.
5.5.5.7 The parameters of DC transmission should adopt the measured parameters or the factory parameters provided by the manufacturer. In the planning and design stage,
For DC transmission with physical parameters, typical models and parameters of the same type of DC that have been put into production can be used.
5.5.6 Wind power and photovoltaic power generation
5.5.6.1 In the relevant analysis work, the mathematical model suitable for the wind turbine should be adopted according to the calculation purpose, and the parameters of the model should be determined by the wind farm.
Provide measured parameters. For wind turbines that do not yet have specific parameters, typical models and parameters of similar turbines can be used temporarily, wind turbine models
And the parameters need to be re-checked after confirming.
5.5.6.2 In the simulation calculation, a detailed or equivalent model can be used for a single wind farm according to the calculation purpose, and the equivalent model of the wind farm should be able to
Reflect the dynamic characteristics of wind farms.
5.5.6.3 The photovoltaic power generation system is mainly composed of photovoltaic arrays and inverters. When conducting simulation modeling research, the main points of the system should be
The components construct a mathematical model separately, combine various models according to the actual connection method, and according to the calculation purpose and the scale of the photovoltaic array,
A detailed or equivalent model is used to form a simulation model of the photovoltaic power generation system. The photovoltaic equivalent model should be able to better reflect the dynamics of photovoltaic power plants
characteristic.
5.5.6.4 If there are static reactive power compensators (SVC) and other dynamic reactive power compensation equipment in wind farms and photovoltaic power plants, they should be detailed
Modeling.
5.5.6.5 In the calculation and analysis of power grid security and stability, wind farms and photovoltaic power stations should be modeled at the station level of new energy;
When calculating, model the distributed wind power, photovoltaic and other new energy units connected to the low-voltage distribution network.
5.6 Models and parameters of stability control measures
5.6.1 When stability control devices are installed in the power system or system stability control measures need to be studied, it should be taken into account in the power system stability calculation
The role of stability control measures.
5.6.2 Should be based on interlock cutting machine, fast pressing force (quick closing), interlocking load cutting, high frequency cutting machine, low frequency automatic load reduction, low pressure automatic load reduction
The actual operating time of devices such as load, power plant out-of-step splitting, grid accident splitting (including fast splitting, low-voltage splitting, etc.), as well as power electronic equipment
Set the control law, and carry out the simulation calculation of power system stability control measures.
5.6.3 In the planning stage, the typical action time can be selected with reference to the actual action level of the relay protection and stability control device.
6 Methods and criteria for safe and stable calculation
6.1 Power flow calculation
6.1.1 Initial power flow calculation
Pay attention to the initial power flow calculation in the operating mode.
a) Reactive power balance and compensation should be in accordance with the requirements of GB 38755-2019, and the reactive power compensation should be basically layered and zoned to avoid reactive power.
The power flows between the voltage levels and transmits reactive power over long distances. The receiving end system should also have sufficient dynamic reactive power reserve capacity
quantity. When the above requirements cannot be met in actual operation, the calculation shall be carried out according to the actual situation that may be unfavorable to the stability of the system.
When the generator (tuning camera) is required to absorb reactive power during the low period of the system, the manufacturer’s regulations or actual test results should be used to
And the degree of phase advance that can be achieved in actual operation determines the upper limit of the reactive power absorbed by the unit.
b) The reactive power output of the unit should take into account the actual maximum and minimum capacity constraints, and the reactive power upper and lower limits should be set according to the actual PQ curve of the unit
When the reactive power reaches the limit, it should be automatically converted to PQ node.
c) The large-capacity FM unit in the system should be selected as the balancing machine. The active and reactive power of the balancing machine should not exceed the normal range.
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