CN108832620B - Method and system for evaluating effect of emergency control strategy based on deviation area - Google Patents

Abstract

The present invention provides a method and system for evaluating the effect of an emergency control strategy based on the deviation area. The method includes: when the power system fails, call the fault emergency control strategy table according to the fault scene information, determine the online matching emergency control strategy, simulate, etc. Value power angle trajectory P _fz (δ _fz ) and expected remaining deceleration area S _xn ; calculate the actual equivalent power angle δ _sj and transient deviation area according to the actual generator power angle and speed deviation at each moment after the power system fault occurs S _pc (δ _dj ); Determine the effect of the emergency control strategy according to the value of S _pc (δ _dj ) and compare the absolute value of S _pc (δ _dj ) with the size of S _xn ; determine the operating status of the power system, and according to the emergency control strategy The effect and system operating status determine whether to end the evaluation. The present invention can evaluate the prevention and control effect of the emergency control strategy of the electric power system in real time, find out the fault scene where the strategy is invalid as early as possible, and provide valuable decision-making time for adopting additional control or active disconnection.

Description

A method and system for evaluating the effectiveness of emergency control strategies based on deviation area

Technical Field

The present invention relates to the field of power control, and more particularly, to a method and system for evaluating the effect of an emergency control strategy based on a deviation area.

Background Art

In recent years, with the continuous expansion of the scale of power systems and the access of a large number of new equipment, the characteristics of power grids have become more complex, and their safe and stable operation faces more severe challenges. Since power grid failures are difficult to avoid, efficient and reliable power system emergency control is an important guarantee for the safe and stable operation of the power grid. However, the long-term operation practice of power systems has shown that no matter how perfect the emergency control strategy is, it is always possible that the implemented emergency control strategy will not achieve the expected effect due to the superposition of some unforeseen accidental factors.

If the prevention and control effects of emergency control strategies can be evaluated in real time and failure scenarios where strategies are ineffective can be discovered as early as possible, valuable decision-making time can be provided for taking additional controls or proactively decoupling.

Emergency control schemes for power systems can be divided into three categories: "offline decision-making, real-time matching", "online decision-making, real-time matching" and "real-time decision-making, real-time matching". Offline decision-making generally refers to the formulation of decision tables by conducting a large number of simulations of anticipated accidents in the day before or earlier; online decision-making refers to the generation of decision tables in the ultra-short term, such as rolling generation of strategy tables every 15 minutes; real-time decision-making directly calculates the control strategy based on the actual situation of the system without generating a decision table. At present, offline decision-making, as the most mature control method, still occupies a dominant position in practical applications. Online decision-making methods have been applied in some power grids, while real-time decision-making remains in the research stage. Therefore, the present invention mainly evaluates the prevention and control effects of offline decision-making methods and online decision-making methods.

In the process of formulating and implementing existing offline and online emergency control strategies, two types of deviations are easily introduced in the decision-making and matching stages: one is model deviation. Whether relying on experience to formulate strategy tables offline or to generate strategy tables online, they all rely on power grid simulation models, and there are generally deviations between simulation models and actual systems. The other is scenario deviation, because "real-time matching" is achieved by comparing the measured values of voltage, current, power, etc. with the simulation results. Therefore, there may be deviations between the matched expected fault scenarios and the actual fault scenarios.

The existence of model deviation and scenario deviation causes the simulation trajectory under the expected fault scenario to not coincide with the actual multi-machine disturbed trajectory, that is, there is a trajectory deviation. When the trajectory deviation is large, it may cause the emergency control strategy to fail to achieve the expected effect, causing the pre-established control strategy to be invalid in the actual scenario. Therefore, how to timely and effectively evaluate the effectiveness of the emergency control strategy of the power system has become an urgent problem to be solved in the field of power control.

Summary of the invention

In order to solve the technical problem that in the process of formulating and implementing the existing offline and online emergency control strategies in the background technology, the trajectory deviation between the simulated trajectory under the expected fault scenario and the actual multi-machine disturbed trajectory caused by the existence of model deviation and scenario deviation leads to the emergency control strategy failing to achieve the expected effect, the present invention provides a method for evaluating the effect of the emergency control strategy based on the deviation area, the method comprising:

Step 1: When a fault occurs in the power system, the fault emergency control strategy table is called according to the fault scenario information to determine the online matching emergency control strategy, the simulation equivalent power angle trajectory P _fz (δ _eq ) and the expected remaining deceleration area S _xn , wherein the simulation equivalent power angle trajectory P _fz (δ _eq ) is a single-machine infinite system power angle curve formed by the power angle trajectory of the generator of the multi-machine system through the complementary group inertia center-relative motion transformation, δ _eq is the simulation equivalent power angle under the expected fault, and the expected remaining deceleration area S _xn is the area enclosed by the virtual electromagnetic power trajectory and the virtual mechanical power trajectory obtained after constructing the virtual mechanical power trajectory and the virtual electromagnetic power trajectory according to the simulation equivalent power angle trajectory P _fz (δ _eq ) obtained under the expected fault scenario, the virtual mechanical power trajectory is a curve formed by horizontal extension of the equivalent mechanical power at point E, and the virtual electromagnetic power trajectory is a curve formed by the equivalent electromagnetic power at point E through sine prediction, and the point E is the farthest point in the first swing process;

Step 2: The actual generator power angle and speed deviation data measured during the operation of the power system are transformed by the center of inertia-relative motion of the complementary group to obtain the actual equivalent power angle trajectory P _sj (δ _sj ); the actual equivalent electromagnetic power P e-sj (δ _sj ) is determined according to the actual equivalent power angle trajectory P _sj (δ _sj ) and the actual equivalent power angle δ _sj corresponding to the actual generator power angle measured at each moment after the fault occurs; and the simulation equivalent electromagnetic power P _{e-fz (} δ _eq ＝δ sj ) corresponding to the simulation equivalent power angle δ _eq equal to the actual equivalent power angle δ _sj is determined according to the simulation equivalent power angle trajectory P _fz (δ _eq ) and the actual equivalent power angle δ _sj corresponding to the actual generator power angle measured at each moment after the fault occurs; and the actual equivalent power angle is calculated from δ ₀ to δ _sj by the simulation equivalent electromagnetic power P _e-fz (δ _eq ＝δ _sj ) and the actual equivalent electromagnetic power P _e-sj (δ _sj ) The transient deviation area S _pc (δ _sj ) at time _sj , where the actual equivalent power angle at the time of fault occurrence is δ ₀ ;

Step 3: Determine the effect of the emergency control strategy according to the positive or negative value of the transient deviation area S _pc (δ _sj ) when the fault occurs and compare the absolute value of S _pc (δ _sj ) with the expected remaining deceleration area S _xn , wherein the effect includes whether the strategy is effective or not;

Step 4: Determine the operating status of the power system and determine whether to end the evaluation based on the effectiveness of the emergency control strategy and the system operating status.

Further, determining the operating state of the power system and determining whether to terminate the evaluation according to the effect of the emergency control strategy and the operating state of the system include:

When the output evaluation result is that the strategy is effective, the power system has not reached a steady state; or when the output evaluation result is that the strategy is invalid, the power system is in a non-out-of-step state, then return to step 2;

When the emergency control strategy is effective and the power system operation state reaches a steady state, or when the emergency control strategy is invalid and the power system operation state is out of step, that is, the out-of-step decoupling device is activated, the evaluation ends.

Furthermore, before calling the fault emergency control strategy table according to the fault scenario information, it also includes calculating the simulated equivalent power angle trajectory P _fz (δ _eq ) and the expected remaining deceleration area S _xn when the emergency control strategy is adopted under the expected fault scenario, so as to form a fault emergency control strategy table, wherein the simulated equivalent power angle trajectory P _fz (δ _eq ) is the power angle trajectory of the generator of the multi-machine system formed by the complementary group inertia center-relative motion transformation to form a single-machine infinite system power angle curve, and δ _eq is the simulated equivalent power angle under the expected fault.

Furthermore, the simulation equivalent power angle trajectory P _fz (δ _eq ) and the expected remaining deceleration area S _xn are both obtained offline or online in a rolling manner, and are synchronously performed and stored during the generation of the fault emergency control strategy table.

Further, the simulation equivalent power angle trajectory P _fz (δ _eq ) and the actual equivalent power angle trajectory P _sj (δ _sj ) are equivalent by using complementary group inertia center-relative motion transformation, and the method includes:

For a power system with n generators, the extended equal area method is used to group the n generators, where the units with disturbed operation belong to group K and the remaining units belong to group W. Then, the system of n generators is simplified and equivalent to a single-machine infinite system by using the complementary group inertia center-relative motion transformation, and its motion equation is:

Where, _Meq , _ωeq and _δeq are the equivalent inertia, equivalent speed deviation and equivalent power angle of a single machine infinite system, respectively; _Pm,eq and _Pe,eq are the equivalent mechanical power and electromagnetic power, respectively;

Assume that _Mi , _ωi and _δi are the moment of inertia, speed deviation and power angle of the i-th generator, respectively, and _Pmi and _Pei are the mechanical power and electromagnetic power of the i-th generator, respectively. The method for obtaining the parameters in the formula is:

P _m,eq =(M _W P _mK -M _K P _mW )/M _T ;P _e,eq =(M _W P _eK -M _K P _eW )/M _T ;

Wherein, subscripts W and K represent W and K generator groups respectively, and subscript T represents all generator sets.

Further, the transient deviation area S pc (δ sj ) when the actual equivalent power angle swings from δ ₀ to δ _sj is calculated by the simulation equivalent electromagnetic power P _e-fz (δ _eq =δ _sj ) and the actual equivalent electromagnetic power _{P e-sj} (δ _{sj )} as follows:

Furthermore, the effect of the emergency control strategy is determined based on the positive or negative value of the transient deviation area S _pc (δ _sj ) at the current moment and the absolute value of S _pc (δ _sj ) compared with the expected remaining deceleration area S _xn .

When S _pc (δ _sj ) ≥ 0, the output evaluation result is that the strategy is effective;

When S _pc (δ _sj )<0 and |S _pc |>>S _xn , the output evaluation result is that the strategy is invalid;

When P _pc (δ _sj )<0 and |S _pc |<S _xn , the output evaluation result is that the strategy is effective.

Furthermore, the power system reaching a steady state means that the power angle difference fluctuation between the generators in the power system is maintained within a preset range.

According to another aspect of the present invention, the present invention provides a system for evaluating the effect of an emergency control strategy based on a deviation area, the system comprising:

A matching unit, which is used to call the fault emergency control strategy table according to the fault scenario information when a fault occurs in the power system, determine the online matching emergency control strategy, the simulation equivalent power angle trajectory P _fz (δ _eq ) and the expected remaining deceleration area S _xn , wherein the simulation equivalent power angle trajectory P _fz (δ _eq ) is a single-machine infinite system power angle curve formed by the power angle trajectory of the generator of the multi-machine system through the complementary group inertia center-relative motion transformation, δ _eq is the simulation equivalent power angle under the expected fault, and the expected remaining deceleration area S _xn is the area enclosed by the virtual electromagnetic power trajectory and the virtual mechanical power trajectory obtained after constructing the virtual mechanical power trajectory and the virtual electromagnetic power trajectory according to the simulation equivalent power angle trajectory P _fz (δ _eq ) obtained under the expected fault scenario, the virtual mechanical power trajectory is a curve formed by horizontal extension of the equivalent mechanical power at point E, and the virtual electromagnetic power trajectory is a curve formed by the equivalent electromagnetic power at point E through sine prediction, and the point E is the farthest point in the first swing process;

A deviation area determination unit, which is used to obtain an actual equivalent power angle trajectory P _sj (δ _sj ) after subjecting the actual generator power angle and speed deviation data measured during the operation of the power system to a complementary group inertia center-relative motion transformation, determine the actual equivalent electromagnetic power P e-sj (δ _sj ) according to the actual equivalent power angle trajectory P _sj (δ _sj ) and the actual equivalent power angle δ _sj corresponding to the actual generator power angle measured at each moment after the fault occurs, and determine the simulated equivalent electromagnetic power P _{e- fz} (δ _eq ＝δ sj ) corresponding to the time when the simulated equivalent power angle δ _eq is equal to the actual equivalent power angle δ _sj according to the simulated equivalent power angle trajectory P _fz (δ _eq ) and the actual equivalent power angle δ _sj corresponding to the actual generator power angle measured at each moment after the _fault occurs, and calculate the actual equivalent power angle from δ sj by using the simulated equivalent electromagnetic power P _e-fz (δ _eq ＝δ _sj ) and the actual equivalent electromagnetic power P _e-sj (δ _sj ) The transient deviation area S _pc (δ _sj ) when the fault occurs from ₀ to δ _sj , where the actual equivalent power angle at the time of the fault is δ ₀ ;

a control effect determination unit, which is used to determine the effect of the emergency control strategy according to the positive or negative value of the transient deviation area δ _pc (δ _sj ) at the current moment and the comparison between the absolute value of S _pc (δ _sj ) and the expected remaining deceleration area S _xn , wherein the effect includes a strategy being effective and a strategy being invalid;

The operating state determination unit is used to determine the operating state of the power system and determine whether to end the evaluation according to the effect of the emergency control strategy and the system operating state.

Further, the operating state determination unit determines the operating state of the power system, and determines whether to end the evaluation according to the effect of the emergency control strategy and the system operating state, including:

When the emergency control strategy is effective and the power system operation state is not in a steady state, or when the emergency control strategy is ineffective and the power system operation state is not out of step, returning to the deviation area determination unit;

When the emergency control strategy is effective and the power system operating state reaches a steady state, or when the emergency control strategy is invalid and the power system operating state is out of step, that is, the out-of-step decoupling device is activated, the evaluation ends.

Furthermore, the system also includes a control strategy establishing unit, which is used to calculate the simulated equivalent power angle trajectory P _fz (δ _eq ) and the expected remaining deceleration area S _xn when the emergency control strategy is adopted under the expected fault scenario, and form a fault emergency control strategy table, wherein the simulated equivalent power angle trajectory P _fz (δ _eq ) is the power angle trajectory of the generator of the multi-machine system formed by the complementary group inertia center-relative motion transformation to form a single-machine infinite system power angle curve, and δ _eq is the simulated equivalent power angle under the expected fault.

Furthermore, the simulated equivalent power angle trajectory _Pfz ( _δeq ) and the expected remaining deceleration area _Sxn generated in the control strategy establishment unit are obtained offline or online in a rolling manner, and are performed and stored synchronously during the generation of the fault emergency control strategy table.

Furthermore, the simulation equivalent power angle trajectory P _fz (δ _eq ) and the actual equivalent power angle trajectory P _sj (δ _sj ) of the control strategy establishment unit are equivalent by using the complementary group inertia center-relative motion transformation, which includes:

For a power system with n generators, the extended equal area method is used to group the n generators, where the units with disturbed operation belong to group K and the remaining units belong to group W. Then, the system of n generators is simplified and equivalent to a single-machine infinite system by using the complementary group inertia center-relative motion transformation, and its motion equation is:

Where, _Meq , _ωeq and _δeq are the equivalent inertia, equivalent speed deviation and equivalent power angle of a single machine infinite system, respectively; _Pm,eq and _Pe,eq are the equivalent mechanical power and electromagnetic power, respectively;

Assume that _Mi , _ωi and _δi are the moment of inertia, speed deviation and power angle of the i-th generator, respectively, and _Pmi and _Pei are the mechanical power and electromagnetic power of the i-th generator, respectively. The method for obtaining the parameters in the formula is:

P _m,eq =(M _W P _mK -M _K P _mW )/M _T ;P _e,eq =(M _W P _eK -M _K P _eW )/M _T ;

Wherein, subscripts W and K represent W and K generator groups respectively, and subscript T represents all generator sets.

Further, the deviation area determination unit calculates the transient deviation area S pc (δ sj ) when the actual equivalent power angle swings from _{δ 0} to δ _sj by using the simulated equivalent electromagnetic power P _e-fz (δ _eq =δ _sj ) and the actual equivalent electromagnetic power P _{e-sj (} δ _sj ) as follows:

Further, the control effect determination unit determines the effect of the emergency control strategy according to the positive or negative value of the transient deviation area S _pc (δ _sj ) at the current moment and the absolute value of S _pc (δ _sj ) compared with the expected remaining deceleration area S _xn , including:

When S _pc (δ _sj ) ≥ 0, the output evaluation result is that the strategy is effective;

When S _pc (δ _sj )<0 and |S _pc |>>S _xn , the output evaluation result is that the strategy is invalid;

When S _pc (δ _sj )<0 and |S _pc |<S _xn , the output evaluation result is that the strategy is effective.

Furthermore, the operation state determination unit determines that the power system reaches a steady state when the power angle difference fluctuation between the generators in the power system is maintained within a preset range.

The method and system for evaluating the effect of an emergency control strategy based on a transient deviation area provided by the present invention respectively transform the power angle trajectory of a multi-machine system under an expected fault scenario and the measured power angle trajectory provided by a wide-area measurement system through a complementary group inertia center-relative motion transformation to form an equivalent single-machine infinite system power angle trajectory, and then integrate the trajectory deviation to obtain a transient deviation area. According to the positive and negative values of the transient deviation area and the relationship between the absolute value of the transient deviation area and the expected remaining deceleration area, the control effect of the emergency control strategy is evaluated in real time. The calculation process of the transient deviation area is relatively simple, and the required information types are few, and only the measured power angle trajectory data is required. In addition, the evaluation speed is fast, and the control measure failure and fault scenarios can be quickly identified ahead of the fast decoupling device, thereby making up for the deficiency of the current offline and online control strategies that it is difficult to exhaust fault scenarios to a certain extent, and providing valuable decision-making time for quickly identifying fault scenarios where the control strategy is invalid and for taking additional control or active decoupling.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

1 is a flow chart of a method for evaluating the effect of an emergency control strategy based on a deviation area according to a preferred embodiment of the present invention;

2 is a simulation equivalent power angle trajectory diagram of evaluating the effect of the emergency control strategy based on the deviation area according to a preferred embodiment of the present invention;

3 is a schematic diagram showing a comparison between a simulation equivalent power angle trajectory diagram and an actual equivalent power angle trajectory diagram for evaluating the effect of an emergency control strategy based on a deviation area according to a preferred embodiment of the present invention;

4 is a structural diagram of a system for evaluating the effect of an emergency control strategy based on a deviation area according to a preferred embodiment of the present invention;

5 is a grid structure diagram of a standard example of a method for evaluating the effect of an emergency control strategy based on a deviation area according to another preferred embodiment of the present invention;

FIG6 is a transient deviation area trajectory diagram of another preferred embodiment of the present invention;

FIG. 7 is a generator power angle curve diagram of another preferred embodiment of the present invention.

DETAILED DESCRIPTION

Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units/elements are marked with the same reference numerals.

Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

Embodiment 1

Fig. 1 is a flow chart of a method for evaluating the effect of an emergency control strategy based on a deviation area according to a preferred embodiment of the present invention. As shown in Fig. 1 , the method 100 for evaluating the effect of an emergency control strategy based on a deviation area according to the present invention starts from step 101 .

In step 101, the simulation equivalent power angle trajectory P _fz (δ _eq ) and the expected remaining deceleration area S _xn when the emergency control strategy is adopted under the expected fault scenario are calculated to form a fault emergency control strategy table, wherein the simulation equivalent power angle trajectory P _fz (δ _eq ) is the power angle trajectory of the generator of the multi-machine system formed by the complementary group inertia center-relative motion transformation to form a single-machine infinite system power angle curve, and δ _eq is the simulation equivalent power angle under the expected fault.

Preferably, the simulation equivalent power angle trajectory P _fz (δ _eq ) and the expected remaining deceleration area S _xn are both obtained offline or online rolling, and are synchronously performed and stored during the generation process of the fault emergency control strategy table.

In step 102, when a fault occurs in the power system, the fault emergency control strategy table is called according to the fault scenario information to determine the online matching emergency control strategy, the simulated equivalent power angle trajectory P _fz (δ _eq ) and the expected remaining deceleration area S _xn , wherein the simulated equivalent power angle trajectory P _fz (δ _eq ) is a single-machine infinite system power angle curve formed by the power angle trajectory of the generator of the multi-machine system through the complementary group inertia center-relative motion transformation, δ _eq is the simulated equivalent power angle under the expected fault, and the expected remaining deceleration area S _xn is the area enclosed by the virtual electromagnetic power trajectory and the virtual mechanical power trajectory obtained after constructing the virtual mechanical power trajectory and the virtual electromagnetic power trajectory according to the simulated equivalent power angle trajectory P _fz (δ _eq ) obtained under the expected fault scenario, the virtual mechanical power trajectory is a curve formed by horizontal extension of the equivalent mechanical power at point E, and the virtual electromagnetic power trajectory is a curve formed by the equivalent electromagnetic power at point E through sinusoidal prediction, and the point E is the farthest point in the first swing process.

FIG2 is a diagram of the simulated equivalent power angle trajectory of a preferred embodiment of the present invention. As shown in FIG2, _PB is the simulated equivalent power angle trajectory, the point E is the farthest point in the first swing process, and the expected remaining deceleration area _Sxn is the area enclosed by the virtual electromagnetic power trajectory and the virtual mechanical power trajectory obtained after constructing the virtual mechanical power trajectory and the virtual electromagnetic power trajectory according to the simulated equivalent power angle trajectory _PB , wherein the virtual mechanical power trajectory is a curve formed by horizontal extension of the equivalent mechanical power at point E, and the virtual electromagnetic power trajectory is the equivalent electromagnetic power, that is, the curve formed by the simulated equivalent power angle trajectory _PB at point E through sine prediction. When the curve _PB swings back after reaching the farthest point E, it means that the emergency control strategy under the expected fault scenario can effectively prevent the system from becoming unstable after implementation.

In step 103, the actual generator power angle and speed deviation data measured during the operation of the power system are transformed by the center of inertia-relative motion of the complementary group to obtain the actual equivalent power angle trajectory P _sj (δ _sj ), and the actual equivalent power angle δ _sj corresponding to the actual generator power _angle measured at each moment after the fault occurs is determined. The simulated equivalent electromagnetic power P _{e-fz (δ eq ＝δ sj ) corresponding to the simulated equivalent power angle δ eq equals the actual equivalent power angle δ sj is determined according to the simulated equivalent power angle trajectory P fz (δ eq ) and the actual equivalent} power angle δ _sj corresponding to the actual generator power angle measured at each moment after the fault occurs. The actual _equivalent power angle is calculated from δ ₀ to δ sj by using the simulated equivalent electromagnetic power P _e-fz (δ _eq ＝δ _sj ) and the actual equivalent electromagnetic power P _{e-sj (δ sj )} . The transient deviation area S _pc (δ _sj ) at time _sj , where the actual equivalent power angle at the time of fault occurrence is δ ₀ .

Preferably, the simulation equivalent power angle trajectory P _fz (δ _eq ) and the actual equivalent power angle trajectory P _sj (δ _sj ) are equivalent by using complementary group inertia center-relative motion transformation, and the method comprises:

For a power system with n generators, the extended equal area method is used to group the n generators, where the units with disturbed operation belong to group K and the remaining units belong to group W. Then, the system of n generators is simplified and equivalent to a single-machine infinite system by using the complementary group inertia center-relative motion transformation, and its motion equation is:

Where, _Meq , _ωeq and _δeq are the equivalent inertia, equivalent speed deviation and equivalent power angle of a single machine infinite system, respectively; _Pm,eq and _Pe,eq are the equivalent mechanical power and electromagnetic power, respectively;

Assume that _Mi , _ωi and _δi are the moment of inertia, speed deviation and power angle of the i-th generator, respectively, and _Pmi and _Pei are the mechanical power and electromagnetic power of the i-th generator, respectively. The method for obtaining the parameters in the formula is:

P _m,eq =(M _W P _mK -M _K P _mW )/M _T ;P _e,eq =(M _W P _eK -M _K P _eW )/M _T ;

Wherein, subscripts W and K represent W and K groups respectively, and subscript T represents all generating units.

Preferably, the calculation formula for calculating the transient deviation area S pc (δ _sj ) when the actual equivalent power angle swings from δ ₀ to δ _sj by using the simulated equivalent electromagnetic power Pe _-fz (δ _eq =δ _sj ) and the actual equivalent electromagnetic power _{Pe -sj} (δ _sj ) is:

In step 104, the effect of the emergency control strategy is determined according to the sign of the transient deviation area S _pc (δ _sj ) when the fault occurs and by comparing the absolute value of S _pc (δ _sj ) with the expected remaining deceleration area S _xn , wherein the effect includes effective strategy and ineffective strategy.

Preferably, determining the effect of the emergency control strategy according to the positive or negative value of the transient deviation area S _pc (δ _sj ) at the current moment and the absolute value of S _pc (δ _sj ) compared with the expected remaining deceleration area S _xn includes:

When S _pc (δ _sj ) ≥ 0, the output evaluation result is that the strategy is effective;

When S _pc (δ _sj )<0 and |S _pc |>>S _xn , the output evaluation result is that the strategy is invalid;

When S _pc (δ _sj )<0 and |S _pc |<S _xn , the output evaluation result is that the strategy is effective.

FIG3 is a schematic diagram of the comparison between the simulation equivalent power angle trajectory diagram and the actual equivalent power angle trajectory diagram for evaluating the effect of the emergency control strategy based on the deviation area according to the preferred embodiment of the present invention. In the actual operation process, affected by the operating conditions, model deviation, etc., there may be a deviation between the actual equivalent power angle trajectory and the simulation equivalent power angle trajectory. As shown in FIG3, curve _PB is the simulation equivalent power angle trajectory, and curves _PA and _PC are the actual equivalent power angle trajectories under two possible scenarios. It can be seen from FIG3 that if the actual equivalent power angle trajectory runs on _PA , then the actual remaining deceleration area increases relative to the simulation equivalent power angle trajectory _PB . If the actual equivalent power angle trajectory runs on _PC , then the actual remaining deceleration area decreases relative to the simulation equivalent power angle trajectory _PB . In extreme cases, when the actual remaining deceleration area is less than 0, the actual equivalent power angle trajectory will cross the dynamic saddle point (DSP), and the system will become unstable. At this time, it can be considered that the emergency control measures have failed and cannot prevent the system from becoming unstable. Therefore, the basic principle of evaluation of this method is:

If S _pc (δ _sj ) ≥ 0, it means that the actual remaining deceleration area of the system is larger than the expected value, and the actual operation state is better than the simulation expected result. Therefore, it is believed that the emergency control strategy in this scenario can achieve the expected control effect, that is, the strategy is effective.

If S _pc (δ _sj )<0, it means that the actual remaining deceleration area of the system is less than the expected value, and the actual operating state is worse than the simulation expected result. At this time, whether the system is unstable depends on the degree of deterioration, that is:

If S _pc (δ _sj )<0 and |S _pc |<S _xn during operation, it means that during the power angle swing process, although the accumulation effect of trajectory deviation deteriorates the transient stability of the system, the degree of deterioration is relatively light and is not enough to offset the expected remaining deceleration area S _xn , so the emergency control strategy is still effective.

If V _pc (δ _sj )<0 and |S _pc |>>S _xn during operation, it means that the accumulation effect of trajectory deviation has seriously deteriorated the transient stability of the system, and the degree of deterioration has offset the expected remaining deceleration area S _xn , so the emergency control strategy will fail.

In step 105, the operating state of the power system is determined, and whether to continue the evaluation is determined according to the effect of the emergency control strategy and the operating state of the power system, that is:

When the emergency control strategy is effective and the power system operating state is not in steady state, or when the emergency control strategy is invalid and the power system operating state is not out of step, the final operating state of the system cannot be determined, so the evaluation continues and jumps to step 103.

When the emergency control strategy is effective and the power system operation state reaches a steady state, or when the emergency control strategy is invalid and the power system operation state is out of step, that is, the out-of-step decoupling device is activated, the evaluation ends.

Preferably, the power system reaching a steady state means that the power angle difference fluctuation between the generators in the power system is maintained within a preset range. Generally, the preset range is -5° to 5°.

Fig. 4 is a structural diagram of a system for evaluating the effect of an emergency control strategy based on a deviation area according to a preferred embodiment of the present invention. As shown in Fig. 4, a system 400 for evaluating the effect of an emergency control strategy based on a deviation area according to a preferred embodiment of the present invention comprises:

The control strategy establishing unit 401 is used to calculate the simulated equivalent power angle trajectory P _fz (δ _eq ) and the expected remaining deceleration area S _xn when the emergency control strategy is adopted under the expected fault scenario, and form a fault emergency control strategy table, wherein the simulated equivalent power angle trajectory P _fz (δ _eq ) is the power angle trajectory of the generator of the multi-machine system formed by the complementary group inertia center-relative motion transformation to form a single-machine infinite system power angle curve, and δ _eq is the simulated equivalent power angle under the expected fault.

Preferably, the simulation equivalent power angle trajectory P _fz (δ _eq ) and the expected remaining deceleration area S _xn generated in the control strategy establishment unit 301 are obtained offline or online in a rolling manner, and are performed and stored synchronously during the generation of the fault emergency control strategy table.

The matching unit 302 is used to call the fault emergency control strategy table according to the fault scenario information when a fault occurs in the power system, and determine the online matching emergency control strategy, the simulation equivalent power angle trajectory _Pfz ( _δeq ), the expected transient kinetic energy _Vfz trajectory and the expected remaining deceleration area _Sxn , wherein the simulation equivalent power angle trajectory _Pfz ( _δeq ) is the power angle trajectory of the generator of the multi-machine system formed by the complementary group inertia center-relative motion transformation to form a single-machine infinite system power angle curve, _δeq is the simulation equivalent power angle under the expected fault, and the expected remaining deceleration area _Sxn is the temporary stability margin under the expected fault.

Preferably, the simulation equivalent power angle trajectory P _fz (δ _eq ) and the actual equivalent power angle trajectory P _sj (δ _sj ) of the control strategy establishment unit 301 are equivalent by using the complementary group inertia center-relative motion transformation, which includes:

For a power system with n generators, the extended equal area method is used to group the n generators, where the units with disturbed operation belong to group K and the remaining units belong to group W. Then, the system of n generators is simplified and equivalent to a single-machine infinite system by using the complementary group inertia center-relative motion transformation, and its motion equation is:

Where, _Meq , _ωeq and _δeq are the equivalent inertia, equivalent speed deviation and equivalent power angle of a single machine infinite system, respectively; _Pm,eq and _Pe,eq are the equivalent mechanical power and electromagnetic power, respectively;

Assume that _Mi , _ωi and _δi are the moment of inertia, speed deviation and power angle of the i-th generator, respectively, and _Pmi and _Pei are the mechanical power and electromagnetic power of the i-th generator, respectively. The method for obtaining the parameters in the formula is:

P _m,eq =(M _W P _mK -M _K P _mW )/M _T ;P _e,eq =(M _W P _eK -M _K P _eW )/M _T ;

Wherein, subscripts W and K represent W and K generator groups respectively, and subscript T represents all generator sets.

The deviation area determination unit 303 is used to obtain an actual equivalent power angle trajectory S _sj (δ _sj ) after the complementary group inertia center-relative motion transformation of the actual generator power angle and speed deviation data measured during the operation of the power system, determine the actual equivalent electromagnetic power P e-sj (δ _sj ) according to the actual equivalent power angle trajectory P _sj (δ _sj ) and the actual equivalent power angle δ _sj corresponding to the actual generator power angle measured at each moment after the fault occurs, and determine the simulated equivalent electromagnetic power P _{e-fz (} δ _{eq ＝} δ sj ) corresponding to the time when the simulated equivalent power angle δ _eq is equal to the actual equivalent power angle δ _sj according to the simulated equivalent power angle trajectory P _fz (δ _eq ) and the actual equivalent power angle δ _sj corresponding to the actual generator power angle measured at each moment after the fault occurs, and calculate the actual equivalent power angle from δ sj by using the simulated equivalent electromagnetic power _{P e-fz} (δ _eq ＝δ _sj ) and the actual equivalent electromagnetic power P _e-sj (δ _sj ). The transient deviation area S _pc (δ _sj ) when the fault angle swings from ₀ to δ _sj , where the actual equivalent power angle at the time of fault occurrence is δ ₀ .

Preferably, the deviation area determination unit calculates the transient deviation area S pc (δ sj ) when the actual equivalent power angle swings from _{δ 0} to δ _sj by using the simulated equivalent electromagnetic power P _e-fz (δ _eq =δ _sj ) and the actual equivalent electromagnetic power P _{e-Spc (} δ _sj ) as follows:

The control effect determination unit 304 is used to determine the effect of the emergency control strategy according to the positive or negative value of the transient deviation area S _pc (δ _sj ) at the current moment and by comparing the absolute value of S _pc (δ _sj ) with the expected remaining deceleration area S _xn , wherein the effect includes a valid strategy and an invalid strategy.

Preferably, the control effect determination unit determines the effect of the emergency control strategy according to the positive or negative value of the transient deviation area S _pc (δ _sj ) at the current moment and the absolute value of S _pc (δ _sj ) compared with the expected remaining deceleration area S _xn , including:

When S _pc (δ _sj ) ≥ 0, the output evaluation result is that the strategy is effective;

When S _pc (δ _sj )<0 and |S _pc |>>S _xn , the output evaluation result is that the strategy is invalid;

When S _pc (δ _sj )<0 and |S _pc |<S _xn , the output evaluation result is that the strategy is effective.

The operating state determination unit 305 is used to determine the operating state of the power system and determine whether to end the evaluation according to the effect of the emergency control strategy and the system operating state.

Preferably, the operating state determination unit determines the operating state of the power system, and determines whether to end the evaluation according to the effect of the emergency control strategy and the system operating state, including:

When the emergency control strategy is effective and the power system operation state is not in a steady state, or when the emergency control strategy is ineffective and the power system operation state is not out of step, returning to the deviation area determination unit;

When the emergency control strategy is effective and the power system operating state reaches a steady state, or when the emergency control strategy is invalid and the power system operating state is out of step, that is, the out-of-step decoupling device is activated, the evaluation ends.

Preferably, the operation state determination unit determines that the power system reaches a steady state when the power angle difference fluctuation between the generators in the power system is maintained within a preset range. Generally, the preset range is -5° to 5°.

Embodiment 2

FIG5 is a grid structure diagram of a standard example of a method for evaluating the effect of an emergency control strategy based on a deviation area according to another preferred embodiment of the present invention. As shown in FIG5 , this preferred embodiment adopts the IEEE39 node system standard example. Assume that the expected fault scenario is: a permanent three-phase short circuit fault occurs in line 16-17, and the fault is cleared by cutting off the line at 0.4s. The emergency control strategy formulated for this fault scenario is: cutting off the active power of generator G_33 by 400MW at 30 cycles.

Assuming that the actual duration of the fault is 23 cycles, the evaluation process of the prevention and control effect of the above emergency control strategy by the method of the present invention is as follows:

In step 1, the power angle trajectory of the multi-machine system under the expected fault scenario is transformed offline into an equivalent simulation power angle trajectory through the center-relative motion transformation of the complementary group inertia, a virtual trajectory is constructed, and the expected remaining deceleration area S _xn = 0.0024 pu is calculated.

In step 2, it is determined whether the system fails. If a failure occurs, the emergency control strategy, the equivalent simulation power angle trajectory P _fz (δ _eq ) and the expected remaining deceleration area S _xn are matched online according to the fault scenario information. It is assumed that the matched fault scenario is the above-mentioned expected fault scenario.

In step 3 _, the actual generator power angle and speed deviation data provided by the measurement system are transformed into the center of inertia-relative motion of the complementary group to obtain the actual equivalent power angle trajectory P _sj (δ _sj ), and the actual equivalent power angle δ _sj corresponding to the actual generator power angle measured at each moment after the fault occurs is determined. The simulated equivalent electromagnetic power P _e-fz (δ eq ＝δ _sj ) corresponding to the simulated equivalent power angle δ _eq equals the actual equivalent power angle δ _sj is determined according to the simulated equivalent power angle trajectory P _fz (δ _{eq )} and the actual equivalent power angle δ _sj corresponding to the actual generator power angle measured at each moment after the fault occurs. The actual equivalent power angle is calculated from δ ₀ to δ _sj by using the simulated equivalent electromagnetic power P _{e-fz ( δ eq} ＝δ _sj ) and the actual equivalent electromagnetic power P _e-sj (δ _sj ). The transient deviation area S _pc (δ _sj ) at the time _sj , where the actual equivalent power angle at the time of the fault is δ ₀ , and the calculation formula of the transient deviation area S _pc (δ _sj ) is:

In step 4, when S _pc (δ _sj ) ≥ 0, the evaluation result is output as the strategy is effective;

When S _pc (δ _dj )<0 and |S _pc |>>S _xn , the output evaluation result is that the strategy is invalid;

When S _pc (δ _dj )<0 and |S _pc |<S _xn , the output evaluation result is that the strategy is effective.

In step 5, when the output evaluation result is that the strategy is effective, the power system has not reached a steady state; or when the output evaluation result is that the strategy is invalid, the power system is in a non-out-of-step state, and the process returns to step 3.

In step 6, when the output evaluation result indicates that the strategy is effective, the power system reaches a steady state, or when the output evaluation result indicates that the strategy is invalid, the power system is in an out-of-step state, and the evaluation ends.

Figure 6 is a transient deviation area trajectory diagram of another preferred embodiment of the present invention. Repeating the above steps 3 to 6 to obtain a transient deviation area trajectory as shown in Figure 6, it can be seen that the emergency control strategy is judged to be invalid at 0.46s.

Figure 7 is a generator power angle curve diagram of another preferred embodiment of the present invention. As shown in Figure 7, the actual generator power angle trajectory is fully displayed, and it can be seen that the relative power angle between generators exceeds 180 degrees and continues to increase, indicating that the power system eventually suffers from power angle instability, and the evaluation result is correct.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/said/the [means, components, etc.]" are to be openly interpreted as at least one instance of the means, components, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed, unless explicitly stated otherwise.

Claims (16)

1. A method for evaluating the effect of an emergency control strategy based on a deviation area, characterized in that the method comprises: Step 1: When a fault occurs in the power system, the fault emergency control strategy table is called according to the fault scenario information to determine the online matching emergency control strategy, the simulation equivalent power angle trajectory P _fz (δ _eq ) and the expected remaining deceleration area S _xn , wherein the simulation equivalent power angle trajectory P _fz (δ _eq ) is a single-machine infinite system power angle curve formed by the power angle trajectory of the generator of the multi-machine system through the complementary group inertia center-relative motion transformation, δ _eq is the simulation equivalent power angle under the expected fault, and the expected remaining deceleration area S _xn is the area enclosed by the virtual electromagnetic power trajectory and the virtual mechanical power trajectory obtained after constructing the virtual mechanical power trajectory and the virtual electromagnetic power trajectory according to the simulation equivalent power angle trajectory P _fz (δ _eq ) obtained under the expected fault scenario, the virtual mechanical power trajectory is a curve formed by horizontal extension of the equivalent mechanical power at point E, and the virtual electromagnetic power trajectory is a curve formed by the equivalent electromagnetic power at point E through sine prediction, and the point E is the farthest point in the first swing process; Step 2: The actual generator power angle and speed deviation data measured during the operation of the power system are transformed by the center of inertia-relative motion transformation of the complementary group to obtain the actual equivalent power angle trajectory P _sj (δ _sj ); the actual equivalent electromagnetic power P e-sj (δ _sj ) is determined according to the actual equivalent power angle trajectory P _sj (δ _sj ) and the actual equivalent power angle δ _sj corresponding to the actual generator power angle measured at each moment after the fault occurs; and the simulated equivalent electromagnetic power P _e-fz (δ _eq ＝δ sj ) corresponding to the actual equivalent power angle δ _eq equal to the actual equivalent power angle δ _sj is determined according to the simulated equivalent power angle trajectory P _fz (δ eq ) and the actual equivalent power angle δ sj corresponding to the actual generator power angle measured at each moment after the fault occurs; and the simulated equivalent electromagnetic power P _e-fz (δ _eq ＝δ _sj ) corresponding to the actual equivalent power angle δ _sj is calculated by the simulated equivalent electromagnetic power P _e-fz (δ _eq ＝δ _sj ) and the actual equivalent electromagnetic power P _e-sj (δ _sj ) calculates the transient deviation area S _pc (δ _sj ) when the actual equivalent power angle swings from δ0 to δsj, where the actual equivalent power angle at the time of the fault occurrence is δ ₀ ; Step 3: Determine the effect of the emergency control strategy according to the positive or negative value of the transient deviation area S _pc (δ _sj ) when the fault occurs and compare the absolute value of S _pc (δ _sj ) with the expected remaining deceleration area S _xn , wherein the effect includes whether the strategy is effective or not; Step 4: Determine the operating status of the power system and determine whether to end the evaluation based on the effectiveness of the emergency control strategy and the system operating status. 2. The method according to claim 1 is characterized in that determining the operating state of the power system and determining whether to end the evaluation according to the effect of the emergency control strategy and the operating state of the system comprises: When the output evaluation result is that the strategy is effective, the power system has not reached a steady state; or when the output evaluation result is that the strategy is invalid, the power system is in a non-out-of-step state, then return to step 2; When the emergency control strategy is effective and the power system operation state reaches a steady state, or when the emergency control strategy is invalid and the power system operation state is out of step, that is, the out-of-step decoupling device is activated, the evaluation ends. 3. The method according to claim 1 or 2 is characterized in that before calling the fault emergency control strategy table according to the fault scenario information, it also includes calculating the simulation equivalent power angle trajectory _Pfz ( _δeq ) and the expected remaining deceleration area _Sxn when the emergency control strategy is adopted under the expected fault scenario to form a fault emergency control strategy table, wherein the simulation equivalent power angle trajectory _Pfz ( _δeq ) is the power angle trajectory of the generator of the multi-machine system formed by the complementary group inertia center-relative motion transformation to form a single-machine infinite system power angle curve, and _δeq is the simulation equivalent power angle under the expected fault. 4. The method according to claim 3 is characterized in that the simulation equivalent power angle trajectory _Pfz ( _δeq ) and the expected remaining deceleration area _Sxn are both obtained offline or online rolling, and are synchronously performed and stored during the generation process of the fault emergency control strategy table. 5. The method according to claim 3, characterized in that the simulation equivalent power angle trajectory P _fz (δ _eq ) and the actual equivalent power angle trajectory P _sj (δ _sj ) are equivalent by using complementary group inertia center-relative motion transformation, and the method comprises: For a power system with n generators, the extended equal area method is used to group the n generators, where the units with disturbed operation belong to group K and the remaining units belong to group W. Then, the system of n generators is simplified and equivalent to a single-machine infinite system by using the complementary group inertia center-relative motion transformation, and its motion equation is:

Where, _Meq , _ωeq and _δeq are the equivalent inertia, equivalent speed deviation and equivalent power angle of a single machine infinite system, respectively; _Pm,eq and _Pe,eq are the equivalent mechanical power and electromagnetic power, respectively; Assume that _Mi , _ωi and _δi are the moment of inertia, speed deviation and power angle of the i-th generator, respectively, and _Pmi and _Pei are the mechanical power and electromagnetic power of the i-th generator, respectively. The method for obtaining the parameters in the formula is:

P _m,eq =(M _W P _mK -M _K P _mW )/M _T ;P _e,eq =(M _W P _eK -M _K P _eW )/M _T ;

Wherein, subscripts W and K represent W and K generator groups respectively, and subscript T represents all generator sets. 6. The method according to claim 5, characterized in that the calculation formula for calculating the transient deviation area S pc (δ _sj ) when the actual equivalent power angle swings from δ ₀ to δ _sj by using the simulated equivalent electromagnetic power Pe _-fz ( _{δ eq} =δ _sj ) and the actual equivalent electromagnetic power _{Pe -sj} (δ _sj ) is:

7. The method according to claim 6, characterized in that determining the effect of the emergency control strategy according to the positive or negative value of the transient deviation area S _pc (δ _sj ) at the current moment and the absolute value of S _pc (δ _sj ) compared with the expected remaining deceleration area S _xn comprises: When S _pc (δ _sj ) ≥ 0, the output evaluation result is that the strategy is effective; When S _pc (δ _sj )<0 and |S _pc |>>S _xn , the output evaluation result is that the strategy is invalid; When S _pc (δ _sj )<0 and |S _pc |<S _xn , the output evaluation result is that the strategy is effective. 8. The method according to claim 1 is characterized in that the power system reaching a steady state means that the power angle difference fluctuation between the generators in the power system is maintained within a preset range. 9. A system for evaluating the effect of an emergency control strategy based on a deviation area, characterized in that the system comprises: A matching unit, which is used to call the fault emergency control strategy table according to the fault scenario information when a fault occurs in the power system, determine the online matching emergency control strategy, the simulation equivalent power angle trajectory _Pdz ( _δeq ) and the expected remaining deceleration area _Sxn , wherein the simulation equivalent power angle trajectory _Pfz ( _δeq ) is a single-machine infinite system power angle curve formed by the power angle trajectory of the generator of the multi-machine system through the complementary group inertia center-relative motion transformation, _δeq is the simulation equivalent power angle under the expected fault, and the expected remaining deceleration area _Sxn is the area enclosed by the virtual electromagnetic power trajectory and the virtual mechanical power trajectory obtained after constructing the virtual mechanical power trajectory and the virtual electromagnetic power trajectory according to the simulation equivalent power angle trajectory _Pfz ( _δeq ) obtained under the expected fault scenario, the virtual mechanical power trajectory is a curve formed by horizontal extension of the equivalent mechanical power at point E, and the virtual electromagnetic power trajectory is a curve formed by the equivalent electromagnetic power at point E through sine prediction, and the point E is the farthest point in the first swing process; A deviation area determination unit, which is used to obtain an actual equivalent power angle trajectory P _sj (δ _sj ) after transforming the actual generator power angle and speed deviation data measured during the operation of the power system through the complementary group inertia center-relative motion transformation, determine the actual equivalent electromagnetic power P e-sj (δ _sj ) according to the actual equivalent power angle trajectory S _sj (δ _sj ) and the actual equivalent power angle δ _sj corresponding to the actual generator power angle measured at each moment after the fault occurs, and determine the simulated equivalent electromagnetic power P _{e- fz} (δ _eq ＝δ sj ) corresponding to the time when the simulated equivalent power angle δ _eq is equal to the actual equivalent power angle δ _sj according to the simulated equivalent power angle trajectory P _fz (δ _eq ) and the actual equivalent power angle δ _sj corresponding to the actual generator power angle measured at each moment after the _fault occurs, and calculate the actual equivalent power angle from δ sj by using the simulated equivalent electromagnetic power P _e-fz (δ _eq ＝δ _sj ) and the actual equivalent electromagnetic power P _e-sj (δ _sj ) The transient deviation area S _pc (δ _sj ) when the fault occurs from ₀ to δ _sj , where the actual equivalent power angle at the time of the fault is δ ₀ ; a control effect determination unit, which is used to determine the effect of the emergency control strategy according to the positive or negative value of the transient deviation area S _pc (δ _sj ) at the current moment and the comparison between the absolute value of S _pc (δ _sj ) and the expected remaining deceleration area S _xn , wherein the effect includes the strategy being effective and the strategy being invalid; The operating state determination unit is used to determine the operating state of the power system and determine whether to end the evaluation according to the effect of the emergency control strategy and the system operating state. 10. The system according to claim 9, characterized in that the operating state determination unit determines the operating state of the power system, and determines whether to end the evaluation according to the effect of the emergency control strategy and the system operating state, comprising: When the emergency control strategy is effective and the power system operation state is not in a steady state, or when the emergency control strategy is ineffective and the power system operation state is not out of step, returning to the deviation area determination unit; When the emergency control strategy is effective and the power system operating state reaches a steady state, or when the emergency control strategy is invalid and the power system operating state is out of step, that is, the out-of-step decoupling device is activated, the evaluation ends. 11. The system according to claim 9 or 10 is characterized in that the system also includes a control strategy establishment unit, which is used to calculate the simulated equivalent power angle trajectory _Pfz ( _δeq ) and the expected remaining deceleration area _Sxn when the emergency control strategy is adopted under the expected fault scenario, and form a fault emergency control strategy table, wherein the simulated equivalent power angle trajectory _Pfz ( _δeq ) is the power angle trajectory of the generator of the multi-machine system formed by the complementary group inertia center-relative motion transformation to form a single-machine infinite system power angle curve, and _δeq is the simulated equivalent power angle under the expected fault. 12. The system according to claim 11 is characterized in that the simulation equivalent power angle trajectory _Pfz ( _δeq ) and the expected remaining deceleration area _Sxn generated in the control strategy establishment unit are obtained offline or online rolling, and are synchronously performed and stored in the process of generating the fault emergency control strategy table. 13. The system according to claim 12, characterized in that the simulation equivalent power angle trajectory P _fz (δ _eq ) and the actual equivalent power angle trajectory P _sj (δ _sj ) of the control strategy establishment unit are equivalent by using the complementary group inertia center-relative motion transformation, which comprises: For a power system with n generators, the extended equal area method is used to group the n generators, where the units with disturbed operation belong to group K and the remaining units belong to group W. Then, the system of n generators is simplified and equivalent to a single-machine infinite system by using the complementary group inertia center-relative motion transformation, and its motion equation is:

Where, _Meq , _ωeq and _δeq are the equivalent inertia, equivalent speed deviation and equivalent power angle of a single machine infinite system, respectively; _Pm,eq and _Pe,eq are the equivalent mechanical power and electromagnetic power, respectively; Assume that _Mi , _ωi and _δi are the moment of inertia, speed deviation and power angle of the i-th generator, respectively, and _Pmi and _Pei are the mechanical power and electromagnetic power of the i-th generator, respectively. The method for obtaining the parameters in the formula is:

P _m,eq =(M _W P _mK -M _K P _mW )/M _T ;P _e,eq =(M _W P _eK -M _K P _eW )/M _T ;

Wherein, subscripts W and K represent W and K generator groups respectively, and subscript T represents all generator sets. 14. The system according to claim 13, characterized in that the deviation area determination unit calculates the transient deviation area S pc (δ _sj ) when the actual equivalent power angle swings from δ ₀ to δ _sj by using the simulated equivalent electromagnetic power Pe _-fz (δ _eq =δ _sj ) and the actual equivalent electromagnetic power Pe _{-sj (} δ _sj ) as follows:

15. The system according to claim 14, characterized in that the control effect determination unit determines the effect of the emergency control strategy according to the positive or negative value of the transient deviation area S _pc (δ _sj ) at the current moment and the absolute value of S _pc (δ _sj ) compared with the expected remaining deceleration area S _xn, including: When S _pc (δ _sj ) ≥ 0, the output evaluation result is that the strategy is effective; When S _pc (δ _sj )<0 and |S _pc |>>S _xn , the output evaluation result is that the strategy is invalid; When S _pc (δ _sj )<0 and |S _pc |<S _xn , the output evaluation result is that the strategy is effective. 16. The system according to claim 11, characterized in that the operation status determination unit determines that the power system reaches a steady state means that the power angle difference fluctuation between the generators in the power system remains within a preset range.

Images