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In terms of its size and the power to play a role there, the power system is an implied place of interference, and in general, its components respond to attacks of various properties.
As a result, all bad behaviors, even very local, can break the balance of the power system and cause the failure of the whole system.
Although the operator of the power system implements the means of action that can be faced, the abnormal combination of adverse events may lead to the complete or partial collapse of the power system.
After a generalized or location accident, the restoration of the power system is carried out by the operator of the national and regional control systems.
This is a complex and stressful action, taking into account technical constraints and economic risks.
Due to the features of the problems that arise during the repair process, analytical solutions cannot be considered because it has great limitations and multiple goals, sometimes opposing.
Therefore, the operator solution for the power system includes defining the recovery strategy, including a fixed program that applies to a given state, and general advice that makes it possible to end the recovery process.
Therefore, the problem of recovery is more than one
Target problem (
Provide load, reliability, recovery speed)
In highly combined substances, it is possible to have a large number of operations at each stage, and such a large number of states have been determined.
If certain operations are completely fixed, then the combination of satisfied states can only form part of the knowledge suitable for re-discussion.
Moreover, due to the special nature of such an event, this knowledge can only be expressed in a partial abstract.
Compared with traditional algorithm methods, artificial intelligence technology can deal with the combined nature of a large amount of information and problems related to power systems more easily.
The representation of global knowledge makes it possible to characterize solutions other than numerical values, which will allow selection in suggested solutions that meet a given requirement and limit combinations.
Knowledge representation model of expert system (ES)
Starting with the consistency of knowledge that has been implemented, various methods can resolve goals or information conflicts.
The crisis situation control situation depends on the operator's ability to analyze and solve problems under the constraint situation and their experience.
In this crisis situation, ES can be immune to emotional factors to help operators find solutions as soon as possible.
In this paper, we will propose the development of an ES prototype dedicated to restoring the west Algerian power system by using clips after a partial power outage, which is part of the entire Algerian power system.
Will show how to choose a heuristic method to answer the criteria for optimization (
Consistency and undervaluation)
Especially not in accordance with the Constitution.
The list of load voltages makes it possible to reduce the study space, so it is possible to combine the study.
Recovery: Power supply recovery problems and strategies under the operating conditions of power system [1]
Described by five operating conditions, which are included in the diagram1. [
Figure 1 slightly]
In the set of control system operations, two algebraic sets representing equations and inequality constraints are defined.
The constraints of equality mainly refer to the balance between the total amount generated and the power consumed, although the unequal limits assess the obligation to comply with certain variable limits of the power system, these limitations can cause the system to lose integrity.
This may be a problem with the set points associated with the production unit, or it may be a limitation of the voltage and current of the equipment on the power system network.
These limitations, when they are respected, are noted in figure 1. 1.
Chart of E and I on constraints of equality and inequality, and chart [bar. E]and [bar. I]
Constraints in the opposite case.
Stable operation of power system-
It is stated most of the time.
serious failure of one or several of its elements may cause it to crash in whole or in part.
This kind of collapse can be gradual or sudden, so preventive control measures and switching equipment cannot guarantee its integrity, nor is it a limitation of exploitation, given the structure of the power system, that is, the feasibility of restrictions on equality and inequality.
Therefore, if the failure occurring on the power system affects the whole or part of the power system, it is called a generalized fault. Therefore, in the case of insufficient voltage, the application of a production plan or an automatic recovery plan has been shown to be unsuitable or may still worsen the situation. [2]
The recovery of the power system is a complex and stressful operation that can take a few minutes to a few hours and sometimes a few days if the situation is very bad.
After evaluating the network status and available means of the power system after the failure, each control system is ready to rebuild the network.
The national control system is responsible for 220 kV of the entire interconnected and power grid system, and the regional control system is located locally (220 kV and 60 kV).
The recovery of the power system network mainly includes the recovery of power generation, transmission and distribution systems, which is finally considered to be the need to simplify the problem to a load with a constant voltage.
For power generation and transport energy systems, recovery is usually carried out in the following stages [3]
* Restart the generator or generator set that does not have an island;
* Sync of island areas in order to benefit from the advantages of connectivity;
* Energize buses and lines; * Load recovery.
Starting from the state of complete power failure, the goal is to start with the recovery procedures for determining several target states and means to achieve them, especially through conversion or control actions of electricity transportation, establish a fixed or evolutionary plan (or plans)of restoration.
They are usually theoretical or specific strategies for each power system network.
In addition to the connection of electrical components, the desired target state must be stable-
Stateor alarm status operation (see Fig. 1. )
Recovery strategy, although special for each network and for the same network, for the same network, from one region to another, releases almost the same hypothesis [3]
: * With the start of the recovery program, it is assumed that the default value at the origin of the fault has been eliminated.
This assumption means that the recovery is applied to a power system network with no voltage and that the initial default value is not important.
* Division of isolated areas of action (
power production unit can be regarded as a sub-unit. network)
It is based on production data, geographical distribution, black start-up capability, 'hot' restart capability of other units, and possible paths to start from the first unit's excitation second.
* According to the huge capacity of the hydraulic unit to absorb MVAR, a related structure can only be input once by a generator, gradually applying an excitation, making it possible to avoid the transient caused by the switching action.
* One of the accepted priorities is to supply power to the auxiliary equipment of the power plant, either to carry out the 'hot' start of the power plant unit as soon as possible, or to help the nuclear thermal power plant.
* Load recovery is carried out in small increments (20 MW to50 MW)
In order to avoid excessive instantaneous frequency deviation.
* In each area, in order to achieve the interconnect of the generator at the most rapid speed, it is allowed to increase the short circuit
So that the local power system network has stronger robustness.
According to these common various recovery policy assumptions, we can distinguish the corresponding various programs for each recovery policy at a specific period of the recovery process.
We can distinguish between two periods of recovery. 4]
: The first cycle: It corresponds to the identification of the initial available power supply.
Each power supply will become a separate power supply and will make itself a sub-power supply. network.
In other words, each power supply, usually a power generation unit, has an island effect on itself.
Phase 2: will start at the end of Phase 1.
It involves the construction of the power system network framework, or
Load, or load slightly, it will be done in sync with most power generation units.
Power generation devices with traditional thermal combustion devices must be successfully started, while power generation devices with gas turbines must be successfully started.
The main goal of this stage is to realize the network configuration of the required power system and realize the connectivity of the island area.
To achieve this specifically, for each isolated island area, we would like to make it in physical form: * there are additional lines under voltage, I. e.
Inject energy into the lines that have not yet become it;
* Restore load;
* When they can connect the power generation plan.
The whole process must be carried out by avoiding all operations involving the security of the power system network, resulting in a new crash.
Therefore, the main goal of starting a business is: 1.
For power system operators, the composition of a healthy power system network, regardless of whether it is overloaded or not; 2.
For consumers, quickly re-feed all loads as soon as possible.
Expert system is developed with the development of artificial intelligence research. )
I was in my twenties and Sixties.
Functionally, they can be defined as software designed to help or replace people in areas that are considered human expertise [5]
* The structure is not enough to constitute an accurate, complete and direct transfer in the computer working method;
* Easy to modify or supplement (
Based on accumulated experience).
We can recognize three from there. 3)
Common Goal of ES: Target 1: easily capture known unitshow, i. e.
: Promote the most direct expression rules compared to the form of the expert.
Goal 2: develop the entire knowledge unithow, i. e. :1.
combination of rules and/or chain groups that will be used to infer knowledge.
Often, describe how new knowledge is derived.
Goal 3: easily support revision of the entire knowledge unithow, i. e.
: Facilitate the addition and release of rules.
ES is a technology developed to achieve these three goals.
In order to meet the previous 3 goals, the following 'tools' have been developed: * language to express the knowledge provided by experts to meet goal 1; * a KNOWLEDGE-BASE (KB)
Collect specific or general knowledge of the areas directly provided by experts or accumulated by the system itself.
This KB is isolated and organized to meet goal 3;
* reasoning engine (IE)
Or dedutive machines, a general program that uses KB knowledge as data (
So may not change).
IE aims to meet goal 2. 1. ;
* ES ensures a complementary function of dialogue and interpretation of its own behavior, I . E. e.
Demonstrate how to solve (OBJECTIVE 2. 2)
Be led and ensure acquisition and revision of the Knowledge Unithow (
Goals 1 and 3).
The features of the problems encountered in the power system network have led to the emergence of artificial intelligence technology in this field.
If these problems can be solved by numerical techniques, a large part of the problem is characterized [6], [7]
* Amount of information to be processed;
* Complexity of the network structure of the power system;
* The combined nature of the set of solutions;
* Conflict of goals: several goals to be achieved are sometimes opposite.
The knowledge representation model provided by ES get can effectively present a set of situations and resolve conflicts of knowledge or goals.
This principle is divided into particles of knowledge by knowledge related to complex phenomena, making it possible to establish operational rules for useful information, or rules for analyzing situations.
Represents the possibility of global information related to the final presentation of reasoning, thus providing a certain degree of knowledge modularity, allowing representation of solutions other than numerical values, in addition to limiting combination information.
CLIPS is the initials acronym word for C Language Integrated System products, and it is privileged to write ES prototypes.
CLIPS is an interpreter (Shell)
Make it possible to develop ES.
It was developed by the software technology department of NASA/lyphib.
Johnson Space Center knows that its prototype was developed in 1985 and has not stopped continuous improvement [11].
The representation formalism of knowledge in fragments is the rule of production.
CLIPS are completely modular and then organize the knowledge in KB through the definition of listspatterns, each list can belong to a different module.
In addition, it has the function of consisting of two programming paradigms, that is, representing program knowledge by definition of simple and universal functions, and objects-
For representation.
The knowledge control of byIE is realized, using forward-
Link based on RETE algorithm.
CLIPSthus actually answers all aspects of the ES allocation mentioned in the previous paragraph.
Therefore, each program written with fragments becomes ES.
According to the chart of the figure. 2.
The West Algerian interconnected power system network operating at 220 kV includes two energy production power plants, MHP (
Traditional heat, and TIA (
Hot gas pipeline)
, 9 transmission buses of OUJ and OUS and 2 interconnect buses. [
Figure 2:
Recovery Strategy adopted in the first phase (
Identification of available power supply)
, Consisting of state diagrams representing the power system network topology associated at each available power supply.
In this way, we can not only individually identify the power system network target associated with each power supply, but also identify the action direction corresponding to each state in the second phase of recovery.
The directed arc is associated with the action in the state diagram and determines that there is no-
The load voltage between the two buses, as well as the closing sequence of circuit breakers associated with the line, ensures this action.
The existing power supply includes two power plants MHP and TIA, in addition, connecting to Morocco through the connected bus OUJ and through the connected bus with the Centre center connected power system network OUS.
In order to simplify the need, we believe that the available power supply, especially the level of the power generation unit, will respond appropriately, so that the voltage on the bus connected to the power supply can be considered within the allowable range.
In the first phase of recovery, the identification process of the available power supply is based on the following production rule Corpus: R1: the recovery process is initiated if the power system network is out of power (
Activation in recovery phase)
R2: identify the available power supply if the recovery phase is active. 3: If the power supply (s)available(s)is (are)
Determine and then determine the target generator set (s)(or buses)(
There are generally no successful power plants isolated)
R4: if the available power supply is determined, start powering up if the target busis is determinedload phase (
Activate no-load phase)
During the second recovery period, that is, the recovery period when there is no vitality at the time of recovery, reasoning is based on the following production rules: if there is no vitality
The load stage is active, and if the available power supply is determined, if the target bus is determined, the recovery bus is determined
Connect the power supply to the load of the target busR6: if at least one power generation unit plant is running successfully on an isolated island, then he will be given priority to power off
If the bus between the power bus and the target bus is recognized, a recovery path is formed.
R8: if the recovery path is constituted, then determine the best path from the power bus to the target bus. The third set of rules to supplement the two rules, in order to avoid excessive frequency offset and achieve the robustness of the power system, especially for load recovery: R9: if there is no power on
Load processing starts from the interconnect bus and avoids restoring the load if there is no power plant unit (
Control frequency is not available)
R10: if there is no incentive
The load process starts at the power generation unit plant and then considers restoring the load on this action (
Possibility of frequency control)
R11: If more than one power plant unit successfully realizes its island, then through the synchronous action between these power plants, we assume that MHP's power plant has not successfully realized the island after the generalized power outage, therefore, voltage and power are needed to power the auxiliary equipment.
This voltagecan is provided starting with the other three power supplies previously identified, namely OUJ, OUS and TIP.
The directional state diagram related to the SIA interconnected power system network represents the recovery process starting from OUJ's interconnected bus, and therefore, the length (in km)
Of the lines connecting the two buses, related to the Arc cost is :[
Figure 3 slightly]
At the same time as the power bus, the bus OUJ represents the status of the graph indicating the availability of this power supply.
The arc that OUJ points to TLE initially represents no-
Only one action is used to turn off the circuit breaker associated with the line connecting the two bus OUJ and TLE, which is located on the side of the OUJ bus.
Therefore, each directional arc represents only one single action.
In order to achieve the target node represented by the bus associated with the power generation unit plant MHP, we must develop the directional research diagram of Figure 13.
It is easy to prove that the combination explosion makes it very expensive to explore this map through systematic research techniques, which we will not risk to do ourselves.
In order to avoid this problem of system Graph Research, a very simple heuristic algorithm is proposed.
It is based on the reasoning that 'for all power buses, if there is a power bus and a goalkeeper bus, then there is a path to connect them, including their bus '.
Therefore, it is necessary to determine this path and fully motivate no-
load power system network represented by a directed graph, the priority is assigned to each node associated with the power bus.
The assignment of priority will be done by propagation, and for all power buses connected between the power bus and the target power bus, the priority is close.
The assignment of priority makes it possible to identify without any scheduling, except for all else, only the power bus involved in the energy conversion process.
For example, under CLIPS, the following rules represent modifications that the power bus receives from the state with priority 1 after it is determined to be available power. (
Defrule determines-Start-
The bus 'identifies the start-up bus and sets its priority to 1 and its discharge status '(InitialSource(ID_BUS ? BUS))=> (assert (Start (ID_BUS ? BUS)(Priority 1)(StatusEMISSION))))
This rule asserts the fact that the electric bus is in the receiving power mode before powering on.
In addition, it is known that all buses are in acceptance mode before the recovery procedure is started, and once power is on, each bus will be in power mode launch.
Then use the algorithm *[8],[9],[10]
We can find the best path to reach the MHP bus starting from the OUJ bus by ordering the bus included in the best path
Load voltage, as well as lines that ensure these actions.
In fact, by the criteria based on tolerance and consistency, we can define two functions, g and h, respectively, about the cost of the arc associated with the length line
Load and ensure that each bus is on the best path.
The sum of the two functions g and h determines the function f that represents the total estimated length of the path to the target.
The promise of each bus identified by the function h, once its priority becomes 1, and receives-end no-
The load bus voltage of the line part between the power bus and the target bus.
By developing the research path according to the directional state diagram of the graph
3. the best path is obtained using function f.
The following rules of production are written under the formalism of clips [11],[12]
, Translation of reasoning based on the first and second phases of the recovery rule corpus.
At the beginning of the recovery process, the developed SE prototype presents a menu from which the power available can be identified.
With this power supply, we can quickly identify the target bus.
After that, no one
The load voltage corresponding to the optimal path is proposed.
Once the priority bus is powered on, the process corresponding to the second phase of the second phase will continue until there is no-
Load, or avoid frequency offset by increasing the load.
The case study here is an example of the session (Fig. 4. )
Indicate the bus to be powered on and the line used for this task.
Let's assume that none of the power generation unit plants operate successfully after a power outage.
Therefore, the available power supply will be the power supply of the interconnected power system network with Morocco and the center.
After determining the connected available power supply with Morocco through BUS15, BUS1 was identified as the target or target bus to be reached.
Therefore, the target network to be reached at this stage corresponds to the list no.
Consists of load voltage.
These scientists include motivated bus candidates, each with a priority of 1, confirming that they are not in oneload voltage.
So the following list is listed: * Liste1: BUS15 BUS4 BUS3 BUS1 * Liste2: BUS15 BUS7 BUS3 BUS1 * Liste3: BUS15
Load voltage from the power bus to the target.
By comparison
Load voltage, we identify the least serious voltage, the commitment of each bus related to the response list.
In order to avoid the occurrence of over-voltage in this process, we use voltage sensitivity [
Partial derivativeUi/[
Partial derivativePi(
I: Load Bus and U, P: voltage MW load on this bus)
On each power bus that determines the load margin, it can be solved if needed. [
Figure 4 slightly]
According to the results of the delegation in the table below, it seems that Liste1 is the most promising;
Therefore, the bus associated with this list will be considered as affecting acceptable heuristic values.
Therefore, buses related to BUS4 and BUS3 are more promising than buses related to BUS5 and bus7.
After that, SE determined no-
The load voltage, which includes the buses of OUJ, TLE, ZAH and MHP, and the lines that can ensure this action, namely, L14, 9-9, and l1.
The results are almost consistent with the results of the operator's wait.
Multiple power supplies can work at the same time, and multiple actions of the closed line can be carried out at the same time. these actions can determine the best path, and avoid conflicts that motivate two paths to the same target bus at the same time, this will lead to a new breakdown of the voltage.
When I get to the target bus, I. e.
BUS1, in order to quickly return one or more units available, the auxiliary equipment of these units will be given priority.
Once the devices are available and ready to restore the voltage, they should be synchronized with the network to avoid new crashes.
It is necessary to avoid at this level that the power does not take the opposite approach as long as the OUJ is in the launch state, because the MHP is against the OUJ.
Bus 1 will then emit power, so if this bus is not up yet, or another bus, it can charge the power generation unit plant bus first.
The process will then continue until it is fully restored.
Conclusion in this paper, after the introduction of the generalized blackoutis, an ES prototype dedicated to the restoration of the power system network in Siah.
The recovery process is modeled through a series of production rules, which makes it possible to identify the actions to be taken during the two phases of recovery.
The use of heuristicextremely can simply reduce the space research by the one-time optimal path vitality bus beltload voltage.
The use of interpreter CLIPS allows representation of knowledge to implement production rules.
The results obtained largely correspond to the results that power system operators wait. Bibliography[1]Lester H.
Working under pressure and strain, IEEE Spectrum, pp. 48-53, March 1978[2]P-H.
Darnault,
Power system recovery: Methods and implementation strategies, IEEE Power Engineering Press, New York, 2000 [1 [4]U. G.
Knight,
Henry Farney, expert at
Chapman Hall, London, MCArthur,
Hua Song, Alan John, Raj Aggarwal, application of computational intelligence in power systems, Science Press and kluwer Academic Press, Beijing, 1996 [1 [8]Stuart J.
Russell and Peter nowig Modern Approach, Prentice- EnglewoodCliffs Hall, New Jersey, 1995 [9]George F. William . Luger Stubblefield Structure and strategy for complex problem solving>, Third Edition, Addison Wesley Longman, 1998[10]Steven L. Tanimoto Introduction to lips by Computer Science Press. , Swiignton, 1987 [11]Joseph C. Gary D. jalatano Expert System: Principles and programming, 4 th edition, Course Technology, 2004 [12] Ibrahim Hilal, Mr. Hatem Fathalla. Mr. S. Mansour SolimanAl- Debieky, 'power system recovery using expert system technology', IEEE Power system transaction, 2004, pp 747-752L. School of Electrical Engineering and electronic technology. University of Science and Technology, B. P. 1505 Oran EL- M'aouer of Alia Email: zerna1 @ yahoo
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