CN116760032A - Design method for integral event triggering switching load frequency controller - Google Patents
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- H—ELECTRICITY
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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
Technical Field
The invention relates to the technical field of power control, in particular to a design method of an integral event triggering switching load frequency controller.
Background
Stable operation of the power system is one of the preconditions for modern industrial production. Many developments have been made over the years in power system stability studies. The load frequency control system (load frequency control system, LFC) maintains the stability of the power system frequency by balancing the load and the generated power. Meanwhile, the ultra-high voltage technology increases the distance between the control center of the LFC power system and the power station. Thus, open communication network technology and equipment is required to transmit monitoring signals between the control center and the generator, so the LFC system is a typical network control system, and there is also a need to emphasize the problems of network security and transmission efficiency.
The wide application of open communication networks and devices in LFC power systems presents unavoidable challenges for secure operation, such as packet loss, network delay, and network attacks.
Because the power system is equipped with communication devices and an open communication network, its control and measurement signals are obtained by sampling. Conventional time-triggered control may result in unnecessary network bandwidth occupation when small fluctuations occur in the system. In the communication network of the LFC system, a longer transmission gap can reduce the amount of information transmitted and save communication capacity. One effective way to utilize less communication bandwidth and reduce communication network workload is an Event Triggered Mechanism (ETM). By setting the trigger parameters to track dynamic changes in state errors, "Adaptive event-trigger $h_ _ index $ load frequency control for network-based powersystems" a modified Adaptive ETM for LFC systems has been developed whose event trigger thresholds can be 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_info $ load frequency control for multi-area nonlinear power systems based on non-fragile proportional integral control strategy" proposes a dynamic Event triggering mechanism for a multi-zone power system that can reduce the number of transmission packets. But these ETM conditions are all constructed based on the current sample state value and the last trigger state. However, when constructing the trigger condition, using the system state integration value over a period of time will further reduce network bandwidth occupation.
The LFC system is equipped with a communication device and an open communication network, in which control and measurement signals are obtained by sampling. The transmission mechanism of the control and measurement signals may lead to unnecessary network bandwidth occupation if conventional time triggered control is employed. It is well known that longer signaling gaps can reduce the amount of information transmitted and save communication capacity. One effective way to utilize less communication bandwidth and reduce communication network workload is Event Triggered Mechanism (ETM).
The conventional ETM (nomal ETM, NETM) is:
（1）
wherein ,refer to the sampling period +.>For the moment of the ith transmission signal of the sensor in the power communication systemIndicating the instant at which the sensor transmits the signal the i +1 th time in the power communication system,
。
refer to +.>On the basis of time add->With a sampling period ofW is the positive definite matrix to be designed and the constant triggering parameter satisfies +.>。/>Is defined as +.>Which refers to the current sampling state +.>，/>And recently->Status of transmission->，Errors between them. After the trigger condition (1) is satisfied, +.>At this time->Is the latest transmission time. />Representing a non-zero natural number.
The current common Integral Event Triggering Mechanism (IETM) is to replace the value of the current sampling state with the integral value of the sampling state in a period of time on the basis of the traditional ETM, so as to further reduce the transmission of unnecessary signals in the communication network and reduce the occupation of communication network resources.
The conventional Integral Event Trigger Mechanism (IETM) will be the current sampling state in equation (1)Replaced by +.>Integration of the intra-sampled state values, e.g. +.>The Integral ETM (IETM) is formed as follows:
in the current research literature, integrated event triggering mechanisms are commonly applied in multi-agent systems (multi-agent systems), fuzzy network systems (T-SFuzzy Networked Systems) and random systems (stochastic LTI systems), see documents "Distributed Integral-baseinvent-triggered scheme for cooperative output regulation of switched multi-agent systems", "A distributed delay method for event-triggered control of T-S fuzzy networked systems withtransmission delay", "integrate-based event triggering controller design for stochastic LTI systems via convexoptimisation", respectively. On the one hand, the integral event triggering mechanism adopted by the three documents can be more severe and compact in triggering condition, so that the transmission of signals is further reduced, and the effect of reducing the occupation of network resources is achieved. On the other hand, an Integral Event Triggering Mechanism (IETM) is not applied to an electric power system, an LFC system of the electric power system relies on an electric power communication network to collect electric power system signals, a control command is triggered to be transmitted to a control center to generate for adjusting the frequency, and a common improvement point of an ETM applied to the LFC system is often to improve a triggering parameter into a dynamic adjustment value or replace a current sampling state value with a past several sampling state values, and a state integral value of a period of time is not considered to contain more state information values, so that the application of the IETM in the LFC system is an innovation. How to apply the more superior and more compact IETM conditions in the LFC system to further reduce the signal transmission, save the network resources and maintain good control effect becomes the object of the present patent.
Disclosure of Invention
The present invention provides a design method for an integral event triggering switching load frequency controller, which can achieve the above-mentioned purpose.
The technical scheme adopted by the invention is as follows:
a design method of an integral event triggering switching load frequency controller comprises 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>Representing the number of sampling intervals, +.>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 +.>The obtained product is used for the treatment of the skin,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.
Specifically, 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 +.>Errors between;
，
，/>，/>respectively represent the adjustment coefficients of the dynamic trigger parameters.
Specifically, 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 load variation of the kth zone, < + >>Represents the link synchronization coefficient between the kth region and the jth region, +.>Refers to the variation of the wind speed in the kth 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.
Specifically, in step S2, the handover controller rule considering the spoofing attack is:
wherein ,network delay for IETM model to control center, < >>Is PI controller->Receiving the trigger statePI 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 sum +.> and />By conditions of
Limiting fraud suffered by a kth regional power network, wherein />Representing a known constant matrix.
Specifically, in step S3, the LFC system switching control model is:
wherein ,。
specifically, in step S4, the H-infinity asymptotic stability criterion is obtained by deriving and expecting the delay-related lyapunov functional, and by chur' S complement theory and mathematical transformation.
Compared with the prior art, the invention has the beneficial effects that:
(1) The IETM model in the invention alternates between continuous IETM and periodic sampling, and the sensors in the LFC system are inWaiting in a time period, and not needing to track the state of the power system at the moment; after this, the sensor continuously monitors the whole +.>And verifies +.>If it is, a new power system status value +.>Will be triggered to transmit, the minimum trigger interval is due to a fixed waiting time +>Is arranged to avoid the phenomenon of gano;
function ofIn its domain->Monotonically increasing in a range of values +.>. This trigger thresholdWill dynamically adjust as the error changes. When->Larger means that the system is changed more. At this time, a->Becomes smaller, the trigger condition becomes easier to satisfy, and more system states are triggered and transmitted. When->When lowered, the system becomes more stable. Dynamic trigger parameter->And the system state is not easy to transmit because of the enlargement. And constant trigger parameter->In contrast, dynamic triggering parameter->The setting of the system can effectively save network bandwidth resources and improve transmission efficiency.
(2) The IETM model in the invention fully utilizes the integral information and the error of the state of the power system in a period of timeIs better than the ETM applied in the LFC system at present.
(3) Dynamic trigger parameters in IETM model in the present inventionCompared with the ETM applied in the present LFC system, the ETM is more compact and flexible, the triggering condition is more difficult to meet, and the transmission of signals is further reduced.
In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a design method of an integral event triggered switching load frequency controller according to the present invention;
FIG. 2 is a view of what is desired=0.3, variance->=0.46>；
FIG. 3 is a state response under a conventional ETM model;
FIG. 4 is a state response under a conventional IETM model;
FIG. 5 is a state response under the IETM model according to the invention;
FIG. 6 is a control command u (t) under a conventional ETM model;
FIG. 7 is a control command u (t) under a conventional IETM model;
FIG. 8 shows the IETM model according to the invention；
FIG. 9 is a control command u (t) in the IETM model according to the invention;
FIG. 10 is a trigger gap under a conventional ETM model;
FIG. 11 is a trigger gap under a conventional IETM model;
fig. 12 shows the trigger gap in the IETM model according to the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention.
Referring to fig. 1, the invention discloses a design method of an integral event triggering switching load frequency controller, which specifically comprises the following steps:
1. construction of IETM model
The invention further improves on the basis of the existing Integral Event Triggering Mechanism (IETM), and obtains an improved IETM model:
（2）
wherein ,indicating the moment of the (i+1) th transmission signal of the sensor in the power communication system,/for the sensor>Representing the number of sampling intervals, +.>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 +.>The obtained product is used for the treatment of the skin,based on error->Obtained if->The power state signal transmission condition is met, otherwise, the power state signal transmission condition is not met;
wherein the error isRefers to->Integration of power system status sample values over a period of time +.>And the last transmitted power system state +.>Errors between;
，
，/>，/>respectively represent the adjustment coefficients of the dynamic trigger parameters. The advantage of setting the dynamic trigger parameters in this way is explained as follows:
function ofIn its domain->Monotonically increasing in a range of values +.>. This trigger thresholdWill dynamically adjust as the error changes. When->Larger means that the system is changed more. At this time, a->Becomes smaller, the trigger condition becomes easier to satisfy, and more system states are triggered and transmitted. When->When lowered, the system becomes more stable. Dynamic trigger parameter->And the system state is not easy to transmit because of the enlargement. Dynamic triggering parameter compared to constant>The setting of the system can effectively save network bandwidth resources and improve transmission efficiency.
The IETM model in the invention fully utilizes integral information and errors of the system state in the past period of timeAnd the method is better than the ETM model in the framework of the traditional power switching load frequency control system. When->Andwhen the proposed IETM degenerates to NETM (formula (1)). In addition, it can be derived from the Jensen inequality
。
Compared with the traditional Integral Event Triggering Mechanism (IETM), the IETM disclosed by the patent has more severe triggering conditions, so that the transmission of signals in the power communication network can be further reduced, and network resources are saved.
At the same time in the IETM model in the inventionDynamic trigger parameters of (a)Compared with an ETM model in the framework of a traditional power switching load frequency control system, the ETM model is more compact and flexible, trigger conditions are more difficult to meet, and signal transmission is further reduced.
2. And obtaining a switching controller rule considering network spoofing attack according to the LFC system state space model and the constructed IETM model.
In an interconnected electrical power system,the zone control error representing the kth zone is defined as +.>, wherein />Indicating the switching power deviation of the kth region and the other regions,/->Error coefficient of the kth region, +.>Representing the frequency deviation of the kth region, at the same time, regarding the integration of wind energy with the interconnected power system, will +.>Wind power deviation +.>、/>As state variables in the kth region, state variables in the kth regionAnd output state variable +.>Is selected as follows:
wherein ,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,/->An integral value representing the kth region ACE; order theAs disturbance variable of the kth wind power section, wherein +.>Refers to the load variation of the kth zone, < + >>Represents the link synchronization coefficient between the kth region and the jth region, PI controller of the kth region +.>The definition is as follows:
the control signal being based on an output state variableThe coefficient matrix, i.e. the control matrix, is thus expressed as +.>，/> Proportional and integral control coefficients of the PI controller respectively representing the kth region;
introducing non-linear functionsThe LFC system state space model of the kth wind power grid-connected area is constructed as follows:
（3）
wherein 、/>、/>、/>、/>A coefficient matrix representing a kth region;
in combination with the IETM model (equation (2)), it is assumed that the network delay of the IETM trigger to the control center isThe trigger state received by the controller is composed of +.>，/>Representing, therefore, that:
under the IETM model (formula (2)), the switching controller rule of the kth zone LFC system is constructed as follows:
（4）
rules regarding the above handover controllerThe explanation of (2) is as follows:
as described above, the liquid crystal display device,representing that the controller receives the trigger status +.>When->When the controller receives the trigger state +.>After the moment of (2), wait->Second, at this time, the control command of the controller isLet->The control command of the controller can also be expressed as +.>. After waiting for a period of time until the next triggering state +.>Before the moment of transmission, i.e.)>In the process, the sensor continuously monitors the state of the system to form +.>Integration of the internal sampled state value, +.>Monitoring whether the triggering condition of the IETM model is met at any time, and if the triggering condition is met, enabling the sensor to be at a new transmission moment +.>Transmitting new trigger valuesI.e. at +.>Before the moment, the control command of the controller remains +.>Due to->Definition of->During continuous monitoring->Can also be expressed as +.>, wherein />。
Under the above handover controller rule of LFC system (equation (4)), consider that there is a network attack in the power network, taking spoofing attack as an example:
assuming a dynamic output signal for the kth region(also denoted as->) Has been captured by a hacker and the hacker randomly releases the fraud signal +.>(also denoted as->) Considering that a spoofing attack occurs randomly, +.>The controller rules in (a) are rewritten as handover controller rules that take into account spoofing attacks:
（5）
the random occurrence state of the spoofing attack is defined byDescription, which follows 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 sum +.> and />Limiting the fraud suffered by the power network of the kth zone by the following conditions +.>：
wherein Represents a known constant matrix, and +.>Is a previously defined system matrix.
3. Obtaining an LFC system switching control model capable of switching between an interval delay system and a distributed delay system according to an LFC system state space model (formula (3)) and a switching controller rule (formula (5)) considering network spoofing attack:
wherein ,。
due to the setting of the waiting time in the proposed IETM model, the signal transmission time of the front and back two times in the LFC system is divided into two time periods, one period is the signal transmission time to the waiting time, the other period is the signal transmission time of the next time after the waiting time, the signals received by the control center in the two time periods can be expressed in two forms (namely, the formula (4)), after the spoofing attack is considered, the control signal is expressed in the formula (5), the control signal is expressed in the switching form shown in the formula (5), and then the LFC system which receives the switching control signal can be established as the expression modes of the two time periods, namely, the switching system model (the two expression modes are respectively expressed in the form of an interval delay system and the form of a distributed delay system).
More specifically, the IETM model (2) triggers a mechanism for waiting for a timeThe setting of (2) enables the controller signal to be expressed as a switching control law shown in the formula (4), the network attack existing in the power communication network is further considered, the controller switching control law (formula (4)) is rewritten as a control law (formula (5)), and the LFC system state space model (formula (3)) of the kth wind power grid-connected area is combined, so that the LFC system switching control model (formula (6)) can be obtained, and the situation that in the following is seen can be seen>During a time period, the model of the LFC system may be expressed as an input delay system that accounts for spoofing attacks. Waiting period->After that, in->During the time period, the sensor will continuously monitor the state of the system. Once the trigger condition is met, i.e. the IETM model is met (equation (2)), a new power system state value will be sent, at which point the LFC system model may be built as a distributed delay system that takes into account spoofing attacks.
4. 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 prior art, wherein the method comprises the following steps of:
the H-infinity asymptotic stability criterion for the LFC system switching control model (equation (6)) is obtained by some time-lag dependent Lyapunov functional (LKF) with integral terms. In addition, the design method of the integral event triggering switching load frequency controller is completed on the basis of the LFC system state space model (formula (3)) obtained by the invention. The design method of the stabilizing principle and the integral event triggering switching load frequency controller is completed on the basis of guaranteeing the following H-infinity performance targets:
1) When (when)When=0, the LFC system switching control model is progressively stable, i.e. in the equilibrium regime there is +.> and />The continuous first derivative of x is present if +.>Just fix and->Negative, the system is asymptotically stable at equilibrium.
2) For any non-zero under zero initial conditionsFor a given disturbance rejection levelIf there is->And (3) if the LFC system switching control model is established, the H-infinity performance is met.
First, construct the lyapunov function as:
（7）
deriving by deriving and expecting equation (7), by chur's complement theory and mathematical transformationTo meet the disturbance rejection levelUnder zero initial conditions, the final gain is obtained:
（8）
in the formula ,for disturbance inhibition level, when->There is a scalar +.>So that the following equation holds:
（9）
thus, whenThe closed loop system formula generated under zero initial conditions, i.e., LFC system switching control model (formula (6)), is proved to have H-infinity suppression performance: for->=0, further deriving from the LFC system switching control model that the LFC system switching control model is progressively stable in a safe sense.
Due to the control matrix of each zoneIs an unknown matrix, thus satisfying the disturbance suppression level +.>Contains coupled nonlinear terms that cannot be solved directly using the LMI tool in matlab, thus will be nonlinearThe sexual term is redefined as an unknown, and by mathematical transformation, the disturbance rejection level +.>The progressive stabilizing condition of (2) is converted into a linear matrix inequality, and a control matrix of each area is solved through an LMI tool in matlab, so that the integral event triggering switching load frequency controller is obtained.
The IETM model obtained by the invention is used for verifying the effectiveness of the LFC system under the spoofing attack through the power system case.
For comparison and verification, three event triggering schemes (conventional ETM model (equation (1)), conventional IETM model and proposed IETM model of the present invention) were selected for simulation.
The parameters of the wind power generation system are shown in table 1. Setting the relevant parameters as
，
=1.08，/>=0.03，/>=0.06，
，
，
，
，
。
Table 1: parameters of a wind power generation system
| 0.015 | |
| 0.1 | |
| 5 | |
| 0.08 | |
| 0.40 | |
| 0.215 | |
| 1.5 | |
| 0.20 |
Assume that the spoofing attack follows a bernoulli distribution.No spoofing attack exists when =0, +.>When=1, there is a spoofing attack in the communication network. FIG. 2 depicts->Hope->=0.3, variance->=0.46。
When three event triggering schemes (conventional ETM model (formula (1)), conventional IETM model and proposed IETM model of the present invention) are used under the attack condition shown in fig. 2. The gain of the designed integral event triggered switching load frequency controller of the present invention can be obtained by LMI tool in matlab as shown in table 2.
Table 2: controller gain under three event-triggered schemes
| Traditional ETM model | Traditional IETM model | The invention provides an IETM model |
| K=[-0.0382 -0.0014] | K=[1.7095 -0.0411] | K=[-0.0733 0.031] |
When the 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 fig. 3, 4 and 5, respectively.
In fig. 3, 4 and 5, the state response trend of the power system is almost the same. It can be seen that the state stability of the asymptotically stable operation of the power system can be ensured by the integral event-triggered switching load frequency controller designed by the present invention obtained from the LMI tool in matlab, whichever event-triggered scheme is adopted.
In addition, when the conventional ETM model is adopted, the input command is controlled in consideration of spoofing attack
It can be realized that the control command curve is shown in fig. 6.
When employing the conventional IETM model, control input commands
,
The control command u (t) curve is shown in fig. 7.
When using the IETM model proposed by the present invention, due to latencyThe control input command satisfies the handover controller rule considering the spoofing attack (equation (5)). During the waiting time, the input control command is expressed as
。
Time delayThe curve is shown in fig. 8. After the waiting time has elapsed, the input control command is displayed as
。
When the IETM model proposed by the present invention is employed, the input control command is described as shown in fig. 9.
Meanwhile, fig. 10, 11 and 12 describe trigger timings under three ETMs. It is apparent that the number of triggers under the conventional ETM model is the largest in the same observation period. When the generator is triggered using an integration event, the trigger frequency is greatly reduced. Compared with the traditional IETM model, the IETM model provided by the invention has fewer triggering times, and the effect of saving network bandwidth is more obvious. The reason for this is that the triggering condition of the IETM model proposed by the present invention is more difficult to satisfy than that of the conventional IETM model. Further, the trends in fig. 6 and 7, 9 can be better explained in fig. 10, 11 and 12. It can be seen that in the conventional ETM model, the triggering is most frequent. Therefore, its control signal is updated most frequently and fluctuates most severely. As the system state stabilizes, the control signal goes to zero. The IETM model provided by the invention can effectively reduce the triggering transmission of signals. Compared with the traditional IETM model and the traditional IETM model, the control signal fluctuation of the IETM model is reduced. Therefore, as can be seen from fig. 10-12, the IETM model provided by the present invention can effectively reduce signal transmission in the communication network, and further save communication resources on the premise of asymptotically stabilizing the system.
To further verify the superiority of the IETM model proposed by the present invention. The sampling period h=0.03 s and the observation period t=8s are set. Table 3 shows the total trigger times for the event trigger scheme shown in table 2. The latency of the IETM model proposed by the present invention is set to tw=0.03. As can be seen from table 3, the number of triggers is the greatest when the ETM model is conventional. When the IETM model provided by the invention is used, the triggering times can be reduced better, and the network bandwidth resources can be saved. It can also be seen from Table 3 that by increasing the integration period in the IETM model proposed by the present inventionTo further reduce the total trigger count.
Table 3: total trigger times under different event trigger mechanisms
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should 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.
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| CN113488993A (en) * | 2021-06-24 | 2021-10-08 | 西安理工大学 | Event-triggered sliding mode load frequency control method for multi-region interconnected power system |
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| CN113488993A (en) * | 2021-06-24 | 2021-10-08 | 西安理工大学 | Event-triggered sliding mode load frequency control method for multi-region interconnected power system |
| CN113555873A (en) * | 2021-07-29 | 2021-10-26 | 山西大学 | Load frequency control method of multi-region interconnected power system under denial of service attack |
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