CN-121983956-A - Method and system for calculating maximum active deficiency tolerance under voltage stability constraint

CN121983956ACN 121983956 ACN121983956 ACN 121983956ACN-121983956-A

Abstract

The invention discloses a method and a system for calculating maximum active deficiency tolerance under voltage stability constraint, and belongs to the technical field of safety and stability analysis and control of large power grids. The calculation method comprises the steps of determining a power balance model of a new energy high-duty ratio power system and a relation model of the new energy high-duty ratio power system after disturbance aiming at the new energy high-duty ratio power system, calculating reactive power provided by the new energy high-duty ratio power system after disturbance and reactive power consumed by the new energy high-duty ratio power system based on the power balance model and the parameter model, and calculating the maximum active deficiency tolerance of the new energy high-duty ratio power system under the voltage stability constraint based on a reactive power balance equation. The method can directly calculate the maximum active deficiency tolerance of the regional power grid through the model, reactive power and the like, is simple and convenient to calculate, is favorable for operation scheduling personnel to better master the stability characteristics of the power grid, and takes preventive control measures in time.

Inventors

WANG ANSI
ZHAO BING
WANG PANPAN
ZHANG YUNQI
WANG XULIANG
LIU XIAOSHI

Assignees

中国电力科学研究院有限公司
国家电网有限公司
国网宁夏电力有限公司

Dates

Publication Date: 20260505
Application Date: 20251229

Claims (16)

1. A method of calculating a maximum active deficit tolerance under voltage stability constraints, comprising: Aiming at a new energy high-duty ratio power system, determining a power balance model of the new energy high-duty ratio power system and a relation model of the new energy high-duty ratio power system after disturbance; Calculating reactive power provided and consumed by the new energy high-duty ratio power system after disturbance based on the power balance model and the parameter model; And calculating the maximum active deficiency tolerance of the new energy high-duty ratio power system under the voltage stability constraint based on the balance equation of the reactive power provided after the disturbance and the reactive power consumed.
2. The calculation method according to claim 1, wherein if the equivalent structure includes a first region and a second region after the new energy high-duty power system is equivalent, the power balance model of the new energy high-duty power system is determined by transmitting power from the second region to the first region, as follows: P L0 ＝P sup ＝P s +P w +P tie Q demand ＝Q sup Wherein, P L0 is the total load demand, P sup and Q sup are the total active power and reactive power supply in the first region, Q demand is the total reactive power demand in the first region, P s is the synchronous machine output of the first region, P w is the new energy output of the first region, and P tie is the link transmission power between the first region and the second region.
3. The computing method of claim 1, wherein the new energy high duty power system post-disturbance relationship model comprises: and a relation model between the system voltage and the active output after disturbance and a relation model between the reactive power demand and the critical voltage after disturbance.
4. A method of computing as claimed in claim 3, wherein the model of the relationship between system voltage and active force after perturbation is as follows: Wherein U eq is the system voltage in the first region, P s is the synchronous machine output of the first region, E eq and x eq are the first region equivalent synchronous machine potential and the system equivalent impedance, and delta eq is the first region equivalent machine power angle.
5. A method of calculating according to claim 3, wherein the post-disturbance system reactive demand versus threshold voltage model is as follows: Q demand (U cr )＝Q M (U cr )+Q z (U cr )+Q Loss (U cr ) Where Q demand (U cr ) is the reactive demand of the system when operating at the critical voltage, Q M (U cr ) is the reactive loss of the induction motor load when the voltage drops to the critical voltage after a disturbance, Q z (U cr ) is the reactive loss when operating near the critical voltage, Q Loss (U cr ) is the winding leakage reactance loss of the transformer.
6. The method according to claim 1, wherein the calculation formula for calculating the reactive power provided by the new energy high duty power system after disturbance is as follows: Q sup (U cr )＝Q smax +Q wmax Wherein, Q sup (U cr ) is the reactive power provided by the new energy high-duty ratio power system after disturbance, Q smax is the maximum reactive power output of the synchronous generator after disturbance, and Q wmax is the maximum reactive power output of the new energy unit after disturbance.
7. The method according to claim 1, wherein the calculation formula for calculating the maximum active deficit tolerance of the new energy high-duty power system under the voltage stability constraint is as follows: Wherein DeltaP cr is the maximum active power shortage tolerance of the new energy high-duty ratio power system under the voltage stability constraint, P L0 is the total load demand, U cr is the critical voltage, For the load power factor, P eq0 is the rated active power of the first region equivalent synchronous machine, eta w is the reactive power transmission efficiency of the new energy unit in the low-pass period, S w is the capacity of the new energy unit converter, P WLVRT is the active power output of the new energy unit in the low-voltage pass period, Q z0 is the initial consumption reactive power of the constant-impedance load, U eq0 is the rated voltage before failure, b is the static load index, X Mσ is the leakage reactance of the induction motor, and X eq is the equivalent impedance of the first region system.
8. A computing system for maximum active deficit tolerance under voltage stabilization constraints, comprising: The modeling unit is used for determining a power balance model of the new energy high-duty ratio power system and a relation model of the new energy high-duty ratio power system after disturbance aiming at the new energy high-duty ratio power system; The first calculation unit is used for calculating reactive power provided by the new energy high-duty ratio power system after disturbance and consumed reactive power based on the power balance model and the parameter model; and the second calculation unit is used for calculating the maximum active deficiency tolerance of the new energy high-duty ratio power system under the voltage stability constraint based on the balance equation of the reactive power provided after the disturbance and the reactive power consumed.
9. The computing system of claim 8, wherein if the equivalence structure includes a first region and a second region after the new energy high-duty power system is equated, the second region transmits power to the first region, a power balance model of the new energy high-duty power system is determined as follows: P L0 ＝P sup ＝P s +P w +P tie Q demand ＝Q sup Wherein, P L0 is the total load demand, P sup and Q sup are the total active power and reactive power supply in the first region, Q demand is the total reactive power demand in the first region, P s is the synchronous machine output of the first region, P w is the new energy output of the first region, and P tie is the link transmission power between the first region and the second region.
10. The computing system of claim 8, wherein the new energy high duty cycle power system post-disturbance relationship model comprises: and a relation model between the system voltage and the active output after disturbance and a relation model between the reactive power demand and the critical voltage after disturbance.
11. The computing system of claim 10, wherein the model of the relationship between post-disturbance system voltage and active force is as follows: Wherein U eq is the system voltage in the first region, P s is the synchronous machine output of the first region, E eq and x eq are the first region equivalent synchronous machine potential and the system equivalent impedance, and delta eq is the first region equivalent machine power angle.
12. The computing system of claim 10, wherein the post-disturbance system reactive demand versus threshold voltage model is as follows: Q demand (U cr )＝Q M (U cr )+Q z (U cr )+Q Loss (U cr ) Where Q demand (U cr ) is the reactive demand of the system when operating at the critical voltage, Q M (U cr ) is the reactive loss of the induction motor load when the voltage drops to the critical voltage after a disturbance, Q z (U cr ) is the reactive loss when operating near the critical voltage, Q Loss (U cr ) is the winding leakage reactance loss of the transformer.
13. The system of claim 8, wherein the calculation formula for calculating reactive power provided by the new energy high duty power system after disturbance is as follows: Q sup (U cr )＝Q smax +Q wmax Wherein, Q sup (U cr ) is the reactive power provided by the new energy high-duty ratio power system after disturbance, Q smax is the maximum reactive power output of the synchronous generator after disturbance, and Q wmax is the maximum reactive power output of the new energy unit after disturbance.
14. The system of claim 8, wherein the calculation formula for calculating the maximum active deficit tolerance of the new energy high duty power system under the voltage stability constraint is as follows: Wherein DeltaP cr is the maximum active power shortage tolerance of the new energy high-duty ratio power system under the voltage stability constraint, P L0 is the total load demand, U cr is the critical voltage, For the load power factor, P eq0 is the rated active power of the first region equivalent synchronous machine, eta w is the reactive power transmission efficiency of the new energy unit in the low-pass period, S w is the capacity of the new energy unit converter, P WLVRT is the active power output of the new energy unit in the low-voltage pass period, Q z0 is the initial consumption reactive power of the constant-impedance load, U eq0 is the rated voltage before failure, b is the static load index, X Mσ is the leakage reactance of the induction motor, and X eq is the equivalent impedance of the first region system. .
15. A computer device, comprising: One or more processors; A processor for executing one or more programs; The method of any of claims 1-7 is implemented when the one or more programs are executed by the one or more processors.
16. A computer readable storage medium, characterized in that a computer program is stored thereon, which computer program, when executed, implements the method according to any of claims 1-7.

Description

Method and system for calculating maximum active deficiency tolerance under voltage stability constraint Technical Field The invention relates to the technical field of safety and stability analysis and control of large power grids, in particular to a method and a system for calculating maximum active deficiency tolerance under voltage stability constraint. Background With the transformation of the energy structure in China into a deepwater area, the ratio of new energy (wind power and photovoltaic) in the electric power system continuously rises, and the installed capacity ratio of the new energy in a part of areas is broken through by 50%, so that a novel electric power system form of 'high new energy ratio' is formed. Meanwhile, the extra-high voltage direct current transmission technology is used as a core means of cross-region energy source configuration, the single-circuit direct current capacity of the extra-high voltage direct current transmission technology reaches tens of kilowatts, the scale of a direct current group formed by multiple circuits of direct currents is continuously enlarged, and the power supply structure and the operation characteristic of the system are further remodeled. The high-proportion new energy and large-scale direct current group effectively supports the landing of a double-carbon target, but the power electronization degree of the system is obviously improved, the occupation ratio of the traditional synchronous generator set is reduced year by year, the voltage stability characteristic of the system is fundamentally changed, and the novel safety risk challenges are faced. In new power systems, ac side short circuit faults remain a core trigger inducing a systematic risk. When the AC system has short-circuit fault, the voltage dip at the fault point can directly cause two key problems, namely, on one hand, the commutation process of a large-scale DC group is highly dependent on commutation voltage and short-circuit current provided by the AC system, the voltage dip easily causes simultaneous commutation failure of multiple DC circuits, the instant interruption of DC transmission power, and on the other hand, a new energy unit (especially wind power and photovoltaic) depends on grid connection of a power electronic converter, the low voltage ride-through capability of the new energy unit is limited by the capacity and control strategy of the converter, and serious voltage dip can trigger the off-grid protection of the new energy unit, so that a large amount of new energy output is suddenly cut off. The superposition of the two events can lead the system to have huge active power shortage in a short time. The scale of such active shortages often reaches millions or even tens of kilowatts, far exceeding the fault power disturbance level of conventional systems. Meanwhile, the total capacity of the current interconnection system is sufficient, the load level is higher, the frequency stability control technology is mature, the large-scale active lack generally does not cause frequency instability or obvious frequency deviation at first, so the voltage sensitivity becomes more prominent, and the voltage stability is closely related to the output, the load characteristic and the system supporting capability of a power supply mainly in that power electronic equipment such as a new energy unit, a direct current converter and the like are extremely sensitive to voltage abnormality. When the system is in the absence of active power, the voltage is gradually dropped through the chain reaction of current increase, reactive power loss surge and reactive notch expansion, and the voltage drop further triggers the low-voltage on-off network of more new energy units and the direct-current commutation failure recurrence, so that the vicious cycle of active power absence, voltage drop, power electronic equipment withdrawal and active power absence expansion is formed, and finally, systematic voltage instability and even breakdown are caused, and serious consequences such as large-area power failure are caused. In recent years, the reality of the risk is verified by a plurality of grid accidents, and the prevention and control urgency of the risk of coupling the active deficiency with the voltage stabilization is highlighted. At present, a great deal of research has been carried out on the voltage stability analysis of the new energy high-duty ratio system at home and abroad, and the research is mainly focused on the directions of voltage instability mechanism identification, low-voltage ride through strategy optimization, reactive compensation configuration and the like. The existing research focuses on reactive power and voltage dynamic characteristic research, and aims at the working condition of active power deficiency to tend to research the influence and control measures of frequency characteristics, in fact, the restraint of voltage stability on active power deficiency is more severe t