CN116760032A - Design method for integral event triggering switching load frequency controller - Google Patents

Abstract

The invention discloses a design method for an integral event triggering switching load frequency controller, which relates to the technical field of power control and comprises the following steps: constructing an IETM model; obtaining a switching controller rule considering network spoofing attack according to the LFC system state space model and the IETM model; obtaining an LFC system switching control model capable of switching between an interval delay system and a distributed delay system according to the LFC system state space model and a switching controller rule considering network spoofing attack; and establishing a time-lag related Lyapunov functional with an integral term, obtaining an H-infinity asymptotic stability criterion of an LFC system switching control model according to the time-lag related Lyapunov functional, and designing an integral event triggering switching load frequency controller based on the IETM model based on the H-infinity asymptotic stability criterion. The integral event triggering switching load frequency controller designed by the invention has the advantages of reducing network resource occupation and having good control effect even under the network attack condition.

Description

An integral event triggered switching load frequency controller design method

Technical field

The present invention relates to the technical field of power control, and specifically to a design method for an integral event-triggered switching load frequency controller.

Background technique

The stable operation of the power system is one of the prerequisites for modern industrial production. Over the years, many advances have been made in power system stability research. The load frequency control system (LFC) maintains the stability of the power system frequency by balancing loads and power generation. At the same time, ultra-high voltage technology increases the distance between the LFC power system control center and the power station. Therefore, open communication network technology and equipment are needed to transmit monitoring signals between the control center and the generator. Therefore, the LFC system is a typical network control system, and issues of network security and transmission efficiency also need to be emphasized.

The widespread application of open communication networks and equipment in LFC power systems has brought inevitable challenges to safe operation, such as packet loss, network delay and network attacks.

Because the power system is equipped with communication equipment and an open communication network, its control and measurement signals are obtained through sampling. When small fluctuations occur in the system, traditional time-triggered control may cause unnecessary network bandwidth usage. In the communication network of the LFC system, a longer transmission gap can reduce the amount of information sent and save communication capacity. An effective way to utilize less communication bandwidth and reduce communication network workload is event triggering mechanism (ETM). By setting the trigger parameters to track the dynamic changes of the state error, "Adaptive event-triggering $H_\infty$load frequency control for network-based powersystems" developed an improved adaptive ETM suitable for LFC systems, whose event trigger threshold can is dynamically adjusted to save limited network resources. "An event-triggered approach for load frequency control with supplementary ADP" proposes a new ETM with adaptive dynamic scheduling for LFC power systems. In addition, "Event-triggered$H_\infty$ load frequency control for multi-area nonlinear power systems based on non-fragile proportional integral control strategy" proposes a dynamic event triggering mechanism for multi-area power systems that can Reduce the number of transmitted packets. But these ETM conditions are built based on the current sampling status value and the last trigger status. However, when constructing trigger conditions, using the system state integral value over a period of time will further reduce network bandwidth usage.

The LFC system is equipped with communication equipment and an open communication network. In LFC, control and measurement signals are obtained through sampling. If the transmission mechanism of control and measurement signals adopts traditional time-triggered control, it may cause unnecessary occupation of network bandwidth. It is known that longer signaling gaps can reduce the amount of information sent and save communication capacity. An effective way to utilize less communication bandwidth and reduce communication network workload is event triggering mechanism (ETM).

The traditional ETM (Nomarl ETM, NETM) is:

(1)

in, Refers to the sampling period,/> is the time when the sensor transmits a signal for the i-th time in the power communication system, and Represents the moment when the sensor transmits the signal for the i+1th time in the power communication system,

.

refers to/> Added on a time basis/> At the moment of sampling period, W is the positive definite matrix to be designed, and the constant trigger parameter satisfies/> . /> is defined as/> , which refers to the current sampling status/> ,/> and recent/> Sent status/> , error between. After the trigger condition (1) is met, // will be sent/> , at this time/> is the latest transmission time. /> Represents a non-zero natural number.

The currently common integral event triggering mechanism (IETM) is based on the traditional ETM, replacing the value of the current sampling state with the integral value of the sampling state within a period of time to further reduce the transmission of unnecessary signals in the communication network. Reduce the occupation of communication network resources.

The traditional integral event triggering mechanism (IETM) converts the current sampling state in equation (1) Replace with a period of time/> Integral of internal sampled state values, such as/> , forming the integral ETM (IETM) as follows:

In the current research literature, the integral event triggering mechanism is often used in multi-agent systems (multi-agent systems), fuzzy network systems (T-SFuzzy Networked Systems) and stochastic LTIsystems (stochastic LTIsystems). See the literature "Distributed integral- basedevent-triggered scheme for cooperative output regulation of switched multi-agent systems", "A distributeddelay method for event-triggered control of T-S fuzzy networked systems with transmission delay", "Integral-based event triggering controller design for stochastic LTI systems via convexoptimisation". On the one hand, the triggering conditions of the integral event triggering mechanism used in the above three documents can be more stringent and compact to further reduce signal transmission and thereby reduce network resource occupation. On the other hand, the integral event triggering mechanism (IETM) has not yet been applied in the power system. The LFC system of the power system relies on the power communication network to collect the power system signals, trigger the transmission to the control center to generate control commands for frequency adjustment, and the common The improvement points of ETM applied in LFC systems often lie in improving the trigger parameters to dynamically adjusted values, or using several past sampling state values to replace the current sampling state value, without considering that the state integral value over a period of time includes More status information values, so applying IETM in the LFC system is an innovation. The purpose of this patent is how to apply superior and more compact IETM conditions to the LFC system to further reduce signal transmission, save network resources and maintain good control effects.

Contents of the invention

The present invention provides a design method for an integral event-triggered switching load frequency controller, which can achieve the above objectives.

The technical solutions adopted by the present invention are as follows:

A design method for an integral event-triggered switching load frequency controller, including the following steps:

S1. Build IETM model:

in, Represents the moment when the sensor transmits the signal for the i+1th time in the power communication system,/> Indicates the number of sampling intervals,/> Represents the sampling interval,/> Refers to the fixed waiting time in IETM used in power communication systems, its value is greater than 0,/> It is based on the integral information and dynamic trigger parameters of the power system status/> owned, Based on error/> Get if/> , then it meets the power status signal transmission conditions, otherwise it does not meet;

S2. Based on the LFC system state space model and the IETM model constructed in step S1, obtain the switching controller rules that consider network spoofing attacks;

S3. Based on the LFC system state space model and the switching controller rules that consider network spoofing attacks, obtain an LFC system switching control model that can switch between the interval delay system and the distributed delay system;

S4. Establish a delay-related Lyapunov functional with an integral term. According to the delay-related Lyapunov functional, the H∞ asymptotic stability criterion of the LFC system switching control model is obtained. Based on the H∞ asymptotic stability criterion of the LFC system switching control model, Based on the near-stability criterion, based on the IETM model obtained in step S1, an integral event-triggered switching load frequency controller is designed.

Specifically, in step S1,

Among them, the error , refers to/> Integral of power system state sampled values within a time period/> and the last transmitted power system status/> error between;

,

,/> ,/> Respectively represent the adjustment coefficients of dynamic trigger parameters.

Specifically, the LFC system state space model is:

in, ,/> ,/> ,/> ,/> Represents the coefficient matrix of the k-th region, state variable/> and output status variables/> Expressed as:

Among them, col {} is the expression form of column vector, Represents the regional control error of the kth region, defined as ,/> Represents the exchange power deviation between the k-th area and other areas,/> Refers to the error coefficient of the k-th area,/> Represents the frequency deviation of the k-th region,/> Represents the output power deviation of the i-th generator in the k-th area,/> Represents the position deviation of the i-th generator valve in the k-th area,/> Represents the fan output power deviation in the k-th area,/> Indicates the integral value of ACE in the kth area;/> is the disturbance variable of the k-th region,/> Refers to the load change amount of the k-th area,/> Indicates the synchronization coefficient of the tie line between the k-th area and the j-th area,/> Refers to the wind speed change in the k-th area, K _k refers to the control gain matrix of the k-th area,/> ,/> represent the proportional and integral control coefficients of the PI controller in the k-th area respectively, is a nonlinear function.

Specifically, in step S2, the switching controller rules considering network spoofing attacks are:

in, For the network delay from the IETM model to the control center,/> It is a PI controller/> Trigger status received moment, PI controller/> for:

,

Represents the random occurrence state of network spoofing attacks, following Bernoulli distribution, /> Indicates that no spoofing attack has occurred in the power communication network,/> It means that the power communication network is suffering from spoofing attacks and hackers have intercepted the transmission signals/> , and replace it with a spoof signal/> ,/> The variance and expected value of are expressed as and/> and/> , pass the condition

Limit the spoofing signals suffered by the power network in the k-th area , of which/> Represents a known constant matrix.

Specifically, in step S3, the LFC system switching control model is:

in, .

Specifically, in step S4, the H∞ asymptotic stability criterion is obtained by derivation and expectation of the delay-related Lyapunov functional, as well as Shur's complement theorem and mathematical transformation.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The IETM model in the present invention alternates between continuous IETM and periodic sampling, and the sensors in the LFC system Waiting within the time period does not need to track the status of the power system at this time; after that, the sensor continues to monitor the entire/> status of the power system and verify/> Whether it is met, once the triggering conditions of IETM are met, the new power system status value/> Will be triggered to transmit, minimum trigger interval due to fixed waiting time /> The setting avoids the Zeno phenomenon;

function in its domain/> is monotonically increasing, and its value range is/> . This trigger threshold It will be dynamically adjusted as the error changes. When/> When it is large, it means that the system has changed greatly. At this time,/> Becoming smaller, trigger conditions become easier to satisfy, and more system states are triggered and transmitted. When/> When lowered, the system becomes more stable. Dynamic trigger parameters/> becomes larger, the system state is not easily transmitted. with constant trigger parameters/> Compared to dynamic trigger parameters/> The settings can effectively save network bandwidth resources and improve transmission efficiency.

(2) The IETM model in the present invention makes full use of the integral information and errors of the power system state within a period of time. , which is better than the ETM currently used in the LFC system.

(3) Dynamic trigger parameters in the IETM model of the present invention It is more compact and flexible than the ETM currently used in LFC systems, and the trigger conditions are more difficult to meet, further reducing signal transmission.

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, embodiments of the present invention are given below and described in detail with reference to the accompanying drawings.

Description of the drawings

In order to explain the technical solutions of the embodiments of the present invention more clearly, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and therefore do not It should be regarded as a limitation of the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1 is a flow chart of the design method of the integral event triggered switching load frequency controller according to the present invention;

Figure 2 shows expectations =0.3, variance/> =0.46/> ;

Figure 3 shows the state response under the traditional ETM model;

Figure 4 shows the state response under the traditional IETM model;

Figure 5 shows the state response under the IETM model proposed by the present invention;

Figure 6 shows the control command u(t) under the traditional ETM model;

Figure 7 shows the control command u(t) under the traditional IETM model;

Figure 8 shows the IETM model proposed by the present invention. ;

Figure 9 shows the control command u(t) under the IETM model proposed by the present invention;

Figure 10 shows the trigger gap under the traditional ETM model;

Figure 11 shows the trigger gap under the traditional IETM model;

Figure 12 shows the trigger gap under the IETM model proposed by the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, rather than all embodiments.

Please refer to Figure 1. The present invention discloses a design method for an integral event-triggered switching load frequency controller, specifically as follows:

1. Build IETM model

This invention further improves the existing integral event triggering mechanism (IETM) and obtains an improved IETM model:

(2)

in, Represents the moment when the sensor transmits the signal for the i+1th time in the power communication system,/> Indicates the number of sampling intervals,/> Represents the sampling interval,/> Refers to the fixed waiting time in IETM used in power communication systems, its value is greater than 0,/> It is based on the integral information and dynamic trigger parameters of the power system status/> owned, Based on error/> Get if/> , then it meets the power status signal transmission conditions, otherwise it does not meet;

Among them, the error , refers to/> Integral of power system state sampled values within a time period/> and the last transmitted power system status/> error between;

,

,/> ,/> Respectively represent the adjustment coefficients of dynamic trigger parameters. The advantages of setting dynamic trigger parameters in this way are explained as follows:

function in its domain/> is monotonically increasing, and its value range is/> . This trigger threshold It will be dynamically adjusted as the error changes. When/> When it is large, it means that the system has changed greatly. At this time,/> Becoming smaller, trigger conditions become easier to satisfy, and more system states are triggered and transmitted. When/> When lowered, the system becomes more stable. Dynamic trigger parameters/> becomes larger, the system state is not easily transmitted. Dynamic trigger parameters compared to constants/> The settings can effectively save network bandwidth resources and improve transmission efficiency.

The IETM model in the present invention makes full use of the integral information and errors of the system state in the past period of time. , which is better than the ETM model in the architecture of traditional power switching load frequency control system. When/> and When , the proposed IETM degenerates into NETM (Equation (1)). Furthermore, it can be derived from Jensen’s inequality

.

It can be seen that the IETM invented in this patent has more stringent trigger conditions than the traditional integral event triggering mechanism (IETM), so it can further reduce signal transmission in the power communication network and save network resources.

At the same time, the dynamic trigger parameters in the IETM model in the present invention Compared with the ETM model in the traditional power switching load frequency control system architecture, it is more compact and flexible, and the triggering conditions are more difficult to meet, further reducing signal transmission.

2. Based on the LFC system state space model and the constructed IETM model, the switching controller rules that consider network spoofing attacks are obtained.

In interconnected power systems, Represents the regional control error of the k-th region, defined as/> , of which/> Represents the exchange power deviation between the k-th area and other areas,/> Refers to the error coefficient of the k-th area,/> represents the frequency deviation of the k-th region. At the same time, considering the integration of wind energy and interconnected power systems, // , Wind power power deviation in the kth area/> ,/> As the state variable of the k-th region, the state variable in the k-th region and output status variables/> The options are as follows:

in, Represents the output power deviation of the i-th generator in the k-th area,/> Represents the position deviation of the i-th generator valve in the k-th area,/> represents the integral value of ACE in the kth region; let As the disturbance variable of the kth wind power area, where,/> Refers to the load change amount of the k-th area,/> Indicates the synchronization coefficient of the tie line between the kth area and the jth area, and the PI controller of the kth area/> The definition is as follows:

Its control signal is based on the output state variable Obtained, its coefficient matrix, which is the control matrix, is expressed as/> ,/> Represent the proportional and integral control coefficients of the PI controller in the k-th area respectively;

Introducing nonlinear functions , then the LFC system state space model of the kth wind power grid-connected area is constructed as:

(3)

in ,/> ,/> ,/> ,/> Represents the coefficient matrix of the k-th region;

At the same time, combined with the IETM model (equation (2)), it is assumed that the network delay from the IETM trigger to the control center is , the trigger status received by the controller is given by/> ,/> Express, therefore, we get:

Under the conditions of the IETM model (equation (2)), the switching controller rules of the k-th region LFC system are constructed as follows:

(4)

About the above switching controller rules The explanation is as follows:

As mentioned above, It represents that the controller receives the trigger status/> moment, when/> when, that is, when the controller receives the trigger status/> After the moment, wait/> seconds, the control command of the controller at this time is , order/> , then the control command of the controller can also be expressed as/> . After the waiting time, until the next trigger state/> Before the time of transmission, that is/> , during this process, the sensor will continuously monitor the status of the system, forming/> Integral of internal sampled state values,/> , monitor whether the triggering conditions of the IETM model are met at any time. If they are met, the sensor will transmit at the new transmission moment/> Transmit new trigger value , that is, in/> time ago, the control command of the controller still remains at/> , due to/> The definition of /> During continuous monitoring/> , can also be expressed as/> , of which/> .

Under the above switching controller rules of the LFC system (Equation (4)), consider the existence of network attacks in the power network, taking spoofing attacks as an example:

Assume that the dynamic output signal of the k-th region (can also be expressed as/> ) has been captured by a hacker, and the hacker randomly releases spoofing signals/> (can also be expressed as/> ), taking into account randomly occurring spoofing attacks,/> The controller rules in are rewritten as switching controller rules that take network spoofing attacks into account:

(5)

The random occurrence state of the spoofing attack is given by Description, which follows the Bernoulli distribution, /> Indicates that no spoofing attack has occurred in the power communication network,/> It means that the power communication network is suffering from spoofing attacks and hackers have intercepted the transmission signals/> , and replace it with a spoof signal/> ,/> The variance and expected value of are expressed as and/> and/> , limiting the spoofing signals suffered by the power network in the k-th area through the following conditions/> :

in represents a known constant matrix, and/> is the system matrix defined previously.

3. According to the LFC system state space model (Equation (3)) and the switching controller rule that considers network spoofing attacks (Equation (5)), the LFC system switching that can switch between the interval delay system and the distributed delay system is obtained Control model:

in, .

Due to the setting of the waiting time in the proposed IETM model, the two signal transmission times in the LFC system are divided into two time periods, one is from the signal transmission time to the waiting time, and the other is from the waiting time to the next signal. Transmission time, the signal received by the control center in the two time periods can be expressed in two forms (i.e. Equation (4)). After considering the spoofing attack, the control signal is expressed as Equation (5), and the control signal is expressed as Eq. (5) shows the switching form, then the LFC system that receives this switching control signal can be established as an expression of two time periods, that is, a switching system model (the two expressions are expressed in the form of an interval delay system respectively and distributed delay systems).

More specifically, the waiting time in the trigger mechanism of the IETM model (equation (2)) The setting allows the controller signal to be expressed as the switching control law shown in Equation (4). Further considering the network attacks existing in the power communication network, the controller switching control law (Equation (4)) is rewritten as the control law (Equation (4) 5)), combined with the LFC system state space model (Equation (3)) of the kth wind power grid-connected area, the LFC system switching control model (Equation (6)) can be obtained. It can be seen that in/> In time period, the model of the LFC system can be expressed as an input delay system considering spoofing attacks. Waiting period/> After that, in/> During the time period, the sensor will continuously monitor the status of the system. Once the trigger condition is met, that is, the IETM model (Equation (2)) is satisfied, a new power system state value will be sent. At this time, the model of the LFC system can be established as a distributed delay system considering spoofing attacks.

4. Establish a delay-related Lyapunov functional with an integral term. According to the delay-related Lyapunov functional, the H∞ asymptotic stability criterion of the LFC system switching control model is obtained. Based on the H∞ asymptotic stability criterion of the LFC system switching control model, Based on the near-stability criterion, based on the IETM model of the present invention obtained previously, an integral event-triggered switching load frequency controller is designed, specifically as follows:

The H∞ asymptotic stability criterion of the LFC system switching control model (Equation (6)) is obtained through some time-delay-related Lyapunov functionals (LKF) with integral terms. In addition, the proposed design method of the integral event triggered switching load frequency controller is completed on the basis of the LFC system state space model (equation (3)) obtained in the present invention. The stability principle and integral event triggered switching load frequency controller design method are completed on the basis of ensuring the following H∞ performance objectives:

1) When =0, the LFC system switching control model is asymptotically stable, that is, in the equilibrium state field, there is/> and/> A continuous first derivative with respect to x exists if/> Positive determination and/> Negative definite, the system is asymptotically stable in equilibrium.

2) Under zero initial conditions, for any non-zero , for a given disturbance suppression level , if any/> Established, the LFC system switching control model satisfies H∞ performance.

First construct the Lyapunov function as:

(7)

By deriving the derivation and expectation of equation (7), and through Shur's complement theorem and mathematical conversion, it is deduced that the disturbance suppression level is satisfied The asymptotic stability condition of , under zero initial conditions, can finally be obtained:

(8)

In the formula, is the disturbance suppression level, when/> , there is a scalar/> , making the following equation hold:

(9)

Therefore, when It is proved that the closed-loop system equation generated under zero initial conditions, that is, the LFC system switching control model (Equation (6)), has H∞ suppression performance: for/> =0. From the LFC system switching control model, it is further concluded that the LFC system switching control model is asymptotically stable in a safety sense.

Due to the control matrix of each area is an unknown matrix, so it meets the disturbance suppression level/> The asymptotic stability condition of contains coupled nonlinear terms, which cannot be solved directly using the LMI tool in matlab. Therefore, the nonlinear terms are redefined as unknown quantities. Through mathematical transformation, the disturbance suppression level will be satisfied/> The asymptotic stability conditions are converted into linear matrix inequalities, and the control matrix of each area is solved through the LMI tool in matlab, that is, the integral event-triggered switching load frequency controller is obtained.

Next, the effectiveness of the IETM model obtained by the present invention on the LFC system under deception attacks is verified through a power system case.

For comparison and verification, three event triggering schemes (traditional ETM model (formula (1)), traditional IETM model and the IETM model proposed by the present invention) were selected for simulation.

The parameters of the wind power generation system are shown in Table 1. Set relevant parameters to

,

=1.08,/> =0.03,/> =0.06,

,

,

,

,

.

Table 1: Parameters of wind power generation system

0.015 0.1 5 0.08 0.40 0.215 1.5 0.20

Spoofing attacks are assumed to follow Bernoulli distribution. =0, there is no spoofing attack,/> =1, there is a spoofing attack in the communication network. Figure 2 depicts/> , expectations/> =0.3, variance/> =0.46.

When three event triggering schemes (traditional ETM model (formula (1)), traditional IETM model and the IETM model proposed by the present invention) are used under the attack conditions shown in Figure 2. The gain of the integral event-triggered switching load frequency controller designed in this invention can be obtained through the LMI tool in matlab, as shown in Table 2.

Table 2: Controller gains under three event triggering schemes

Traditional ETM model Traditional IETM model The IETM model proposed by this invention K=[-0.0382 -0.0014] K=[1.7095 -0.0411] K=[-0.0733 0.031]

When these three event triggering schemes shown in Table 2 are used in combination with the obtained controller, the state responses of the power system are shown in Figures 3, 4 and 5 respectively.

In Figure 3, Figure 4 and Figure 5, the state response trends of the power system are almost the same. It can be seen that no matter which event triggering scheme is used for the asymptotically stable operation of the power system, its state stability can be ensured by the integrated event triggered switching load frequency controller designed by the present invention obtained from the LMI tool in matlab.

In addition, considering spoofing attacks, when adopting the traditional ETM model, the control input command

It can be realized, and its control command curve is shown in Figure 6.

When using the traditional IETM model, control input commands

,

Its control command u(t) curve is shown in Figure 7.

When using the IETM model proposed by this invention, due to the waiting time The setting of the control input command satisfies the switching controller rule (equation (5)) that takes into account network spoofing attacks. During the waiting time, the input control command is expressed as

.

time delay The curve is shown in Figure 8. After the waiting time has passed, the input control command is displayed as

.

When using the IETM model proposed by the present invention, the input control command is described, as shown in Figure 9.

At the same time, Figure 10, Figure 11 and Figure 12 describe the triggering moments under three ETMs. It is obvious that within the same observation period, the number of triggers under the traditional ETM model is the highest. When using an integral event trigger generator, the trigger frequency is greatly reduced. Compared with the traditional IETM model, the IETM model proposed by the present invention has fewer trigger times, and its effect of saving network bandwidth is more obvious. The reason is that the triggering conditions of the IETM model proposed in the present invention are more difficult to satisfy than the triggering conditions of the traditional IETM model. Furthermore, the trends in Figures 6 and 7, Figure 9 can be better explained in Figures 10, 11 and 12. It can be seen that in the traditional ETM model, triggers are the most frequent. Therefore, its control signal is updated most frequently and fluctuates most violently. As the system state stabilizes, the control signal approaches zero. The IETM model proposed by the present invention can effectively reduce the trigger transmission of signals. Compared with the traditional IETM model and the traditional IETM model, the control signal fluctuation of the IETM model proposed by the present invention is reduced. Therefore, it can be seen from Figures 10-12 that the IETM model proposed by the present invention can effectively reduce signal transmission in the communication network, and further save communication resources on the premise that the system is asymptotically stable.

In order to further verify the superiority of the IETM model proposed in this invention. Set the sampling period h=0.03s and the observation period T=8s. Then Table 3 shows the total number of triggers for the event triggering scheme shown in Table 2. The waiting time of the IETM model proposed by the present invention is set to Tw=0.03. As can be seen from Table 3, when using the traditional ETM model, the number of triggers is the highest. When using the IETM model proposed by the present invention, the number of triggers can be better reduced and network bandwidth resources can be saved. In addition, it can be seen from Table 3 that by increasing the integration period in the IETM model proposed by the present invention, to further reduce the total number of triggers.

Table 3: Total number of triggers under different event triggering mechanisms

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (6)

1. An integral event triggering switching load frequency controller design method is characterized by comprising the following steps:

s1, constructing an IETM model:

wherein ,indicating the moment of the (i+1) th transmission signal of the sensor in the power communication system,/for the sensor>The number of sampling intervals is indicated,representing the sampling interval, +.> Refers to a fixed latency in IETM employed in an electrical communication system, having a value greater than 0,/or->Is based on the integral information of the power system state and the dynamic triggering parameter +.>Obtained (I)>Based on error->Obtained if->The power state signal transmission condition is met, otherwise, the power state signal transmission condition is not met;

s2, obtaining a switching controller rule considering network spoofing attack according to the LFC system state space model and the IETM model constructed in the step S1;

s3, obtaining an LFC system switching control model capable of switching between the interval delay system and the distributed delay system according to the LFC system state space model and a switching controller rule considering network spoofing attack;

s4, establishing a time-lag related Lyapunov functional with an integral term, obtaining an H-infinity asymptotic stability criterion of an LFC system switching control model according to the time-lag related Lyapunov functional, and designing an integral event triggering switching load frequency controller based on the H-infinity asymptotic stability criterion of the LFC system switching control model and the IETM model obtained in the step S1.

2. The method for designing an integrated event-triggered switching load frequency controller as claimed in claim 1, wherein, in step S1,

wherein the error isRefers to->Integration of power system status sample values over a period of time +.>And the last transmitted power system state +.>The error between the two is W is a positive definite matrix to be designed;

，

，/>，/>respectively represent the adjustment coefficients of the dynamic trigger parameters.

3. The integration event triggered switching load frequency controller design method of claim 2, wherein the LFC system state space model is:

wherein ,、/>、/>、/>、/>coefficient matrix representing the kth region, state variable +.>And output state variable +.>The expression is as follows:

wherein ,col{ } is an expression of a column vector,the zone control error representing the kth zone is defined as，/>Indicating the switching power deviation of the kth region and the other regions,/->Error coefficient of the kth region, +.>Represents the frequency deviation of the kth region, +.>Represents the output power deviation of the ith generator in the kth region,/->Indicating the valve position deviation of the ith generator in the kth zone,/->Represents the output power deviation of the fan in the kth zone, < + >>An integral value representing the kth region ACE; />Is the disturbance variable of the kth region, +.>Refers to the variation of wind speed in the kth zone, < >>Refers to the amount of load change in the kth region,representing the link synchronisation coefficient between the kth region and the jth region, K _k Control gain matrix, which refers to the kth region,/for the control gain matrix>，/> The proportional and integral control coefficients of the PI controller of the kth region are represented respectively,as a nonlinear function.

4. The method for designing an integrated event triggered switching load frequency controller according to claim 3, wherein in step S2, the switching controller rule considering the spoofing attack is:

wherein ,network delay for IETM model to control center, < >>Is PI controller->Receiving trigger status->PI controller +.>The method comprises the following steps:

，

representing the random occurrence of network spoofing attacks, following Bernoulli distribution, < >>Indicating that no spoofing attack has occurred in the power communication network,/->Indicating that the power communication network is being subjected to spoofing attacks, the hacker has intercepted the transmission signal +.>And replace it with a fraud signal +.>，/>The variance and expected value are expressed as a sum and />By conditions of

Limiting fraud suffered by a kth regional power network, wherein />Representing a known constant matrix.

5. The method for designing an integrated event triggered switching load frequency controller according to claim 4, wherein in step S3, the LFC system switching control model is:

wherein ,。

6. the method for designing an integral event triggered switching load frequency controller according to claim 5, wherein in step S4, H-infinity asymptotic stability criteria are obtained by performing derivative and expectation on a delay-related lyapunov functional, and by performing chur' S complement theorem and mathematical transformation.