**6. Implementation and Testing of the Paraconsistent Expert System - PESPAL2v**

The paraconsistent expert system PESPAL2v was implemented to carry out analysis of the types of disconnection through information received by codes of the SCADA system and add this information to the restoring plan of the electric power system of an area being stud‐ ied belonging to the AES-Eletropaulo Company which is an electric power concessionary company of Brazil.

The prototype was implemented on JAVA platform and tests with real values, which were extracted from the electric power lines of an area considered as a pilot and were stored in a history database, were carried out.

**Figure 14.** Initial data modeling diagram of the SCADA system.

feeding, secondary an primary windings of the transformers.

performed by the special modules of capture and modeling.

After the data modeling of the SCADA system database 1 stores information about, besides those which identify the substation, breakers and other equipment and their measurements of amplitude of tensions and currents. The detections are so that in a time interval(Δt) PESPAL2v is provided with measurements of intensities of currents in each load of the substa‐ tion and the measurements of amplitude of tension on the buses in each stage of the load

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Database 1 provides data for risk analysis that are the intensity of current of loads on the three buses (IA, IB, IC) and the amplitudes of tension of the bus on the three phases (VR, VS, VT). These values receive a paraconsistent logical treatment by PESLPA2v such that the contra‐ diction effects are decreased or totally excluded. Such contradictions are due to measure‐ ment mistakes inherent to the SCADA system. This treatment of the primary signals is

After the data modeling of the SCADA system database 2 stores information about, besides those which identify the substation, breakers (and other equipment), and types of classifica‐ tion of the alarms occurred in the events. The detections are so that in a time interval (Δt) PESPAL2v is provided with the types of alarms that occurred in the installed component in the substation including the action of the relay keys (RC) with the types which classify the acti‐

*Database 1 – Quantity values*

*Database 2 – Alarms*

vated alarm: CR1, CR2 or Crbus.

The project was in its first version developed so that the prototype PESPAL2v performs offline, however, with the information and data from events which represent real situations oc‐ curred in the area under study in the years 2007 and 2008. The pilot area, where the PESPAL2v was tested with respect to its action analysis of overload risk and suggestions for the restor‐ ing, is composed by three OSs (operating substation), twelve TDSs (transformation and dis‐ tribution station), twelve STCs (station of transformation to the consumer), three CBEs (capacitor bank station) and several aerial and underground lines.

The decision-making process of the SEPPAL2v was designed through the acquisition of knowl‐ edge from the operators responsible for the electric operation in this area. When a contin‐ gency occurs, SEPPAL2v receives the evidence degrees of overload risk through its paraconsistent logical model, performs a diagnosis and activates a flowchart with later available resources in performing the emergency maneuvers in the AES-Eletropaulo electric network considered as pilot.

#### **6.1. Modeling and preparation of primary signals**

Initially a large amount of data of the SCADA system related to that period was modeled to prepare the signals which are input to the prototype PES PAL2v. The data stored in the SCA‐ DA system were modeled by creating two databases: the database of quantity values which will be called Database 1 and the database of alarms which will be called Database 2, as shown in Figure 14.

Electric Power System Operation Decision Support by Expert System Built with Paraconsistent Annotated Logic http://dx.doi.org/10.5772/51379 53

**Figure 14.** Initial data modeling diagram of the SCADA system.

#### *Database 1 – Quantity values*

the evidence degrees of overload risks obtained by the paraconsistent analysis on several

The reconnecting maps were done based on operational norms and restrictions of each sub‐ station and sequences of optimized restoring were established taking into consideration the

**6. Implementation and Testing of the Paraconsistent Expert System -**

The paraconsistent expert system PESPAL2v was implemented to carry out analysis of the types of disconnection through information received by codes of the SCADA system and add this information to the restoring plan of the electric power system of an area being stud‐ ied belonging to the AES-Eletropaulo Company which is an electric power concessionary

The prototype was implemented on JAVA platform and tests with real values, which were extracted from the electric power lines of an area considered as a pilot and were stored in a

The project was in its first version developed so that the prototype PESPAL2v performs offline, however, with the information and data from events which represent real situations oc‐ curred in the area under study in the years 2007 and 2008. The pilot area, where the PESPAL2v was tested with respect to its action analysis of overload risk and suggestions for the restor‐ ing, is composed by three OSs (operating substation), twelve TDSs (transformation and dis‐ tribution station), twelve STCs (station of transformation to the consumer), three CBEs

The decision-making process of the SEPPAL2v was designed through the acquisition of knowl‐ edge from the operators responsible for the electric operation in this area. When a contin‐ gency occurs, SEPPAL2v receives the evidence degrees of overload risk through its paraconsistent logical model, performs a diagnosis and activates a flowchart with later available resources in performing the emergency maneuvers in the AES-Eletropaulo electric

Initially a large amount of data of the SCADA system related to that period was modeled to prepare the signals which are input to the prototype PES PAL2v. The data stored in the SCA‐ DA system were modeled by creating two databases: the database of quantity values which will be called Database 1 and the database of alarms which will be called Database 2, as

values of risk degrees of overload before and after the contingency.

(capacitor bank station) and several aerial and underground lines.

points of the electric power system.

52 Advances in Expert Systems

**PESPAL2v**

company of Brazil.

history database, were carried out.

network considered as pilot.

shown in Figure 14.

**6.1. Modeling and preparation of primary signals**

After the data modeling of the SCADA system database 1 stores information about, besides those which identify the substation, breakers and other equipment and their measurements of amplitude of tensions and currents. The detections are so that in a time interval(Δt) PESPAL2v is provided with measurements of intensities of currents in each load of the substa‐ tion and the measurements of amplitude of tension on the buses in each stage of the load feeding, secondary an primary windings of the transformers.

Database 1 provides data for risk analysis that are the intensity of current of loads on the three buses (IA, IB, IC) and the amplitudes of tension of the bus on the three phases (VR, VS, VT). These values receive a paraconsistent logical treatment by PESLPA2v such that the contra‐ diction effects are decreased or totally excluded. Such contradictions are due to measure‐ ment mistakes inherent to the SCADA system. This treatment of the primary signals is performed by the special modules of capture and modeling.

#### *Database 2 – Alarms*

After the data modeling of the SCADA system database 2 stores information about, besides those which identify the substation, breakers (and other equipment), and types of classifica‐ tion of the alarms occurred in the events. The detections are so that in a time interval (Δt) PESPAL2v is provided with the types of alarms that occurred in the installed component in the substation including the action of the relay keys (RC) with the types which classify the acti‐ vated alarm: CR1, CR2 or Crbus.

Database 2 provides data for two purposes:

*a) Data for detecting the topology -* The data stored in the Database 2 represent the state (on or off) of the breakers and splitting keys. The signal of these states provides an overview of the topology of the substation which is transfered as evidence to the paraconsistent models of the breakers. The evidence degrees resulting from this analysis will influence the process of restoring suggestion generated by PESPAL2v.

Based on the flowchart the steps for the restoring are following according to the diagnosis made based on the analysis which encompasses the classification of the alarm type, the val‐ ues in engineering units of the measurements of currents and tensions, the risk evidence de‐

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PES PAL2v has working screens where one can check the efficiency of the installed paraconsis‐

Figure 16 below shows the values exposed on the screen of a typical substation (called "*Dia‐ dema*") used in the pilot system. On the screen one can see the evidence degrees of overload

All the procedures for the analysis were carried out by the algorithms which were based on the PAL2v whose signal treatment considers normalized values, that is, values in the closed interval [0,1] of real numbers. In order to obtain previewing values in units of engineering, recovering the approximate values of current intensity and voltage, it is necessary to per‐

The application of the Paraconsistent Expert System - PESPAL2v in this version can work in two modes according to the user: "Analysis" mode and "Training" mode. These two modes

a) When the "Analysis" mode is selected, the Paraconsistent Expert System - PESPAL2v per‐ forms the analysis of overload risks, outputs the values of the risk degrees, current intensi‐ ty and the breakers which are off. Next, the system interacts with the user and suggests

tent algorithms and the monitoring on each essential point of the substation.

risks on all measurement points of the operating system being analyzed.

**Figure 16.** Working screen: significant values obtained from the Substation *Diadema*.

form a denormalization process of the obtained values.

**6.3. Tests and description of the application PESPAL2v**

*6.2.1. Denormalization Process*

are described in what follows.

grees obtained by the paraconsistent analysis carried out.

**6.2. Verification of values on working screens**

*b) Data for detecting the occurrence type -* The data stored in the Database 2 provide the alarm type and corresponding classification of the disruptions through several codes which are in‐ serted on the restoring map of operating substation. The classification of the types of occur‐ rences, together with the risk analysis signal PESPAL2v the activation of the flowchart corresponding to the restoring map of the area affected by the contingency.

Figure 15 shows the signal flow where Database 1 and 2 are related with the modules of risk analysis, previewing and diagnosis.

**Figure 15.** Signal flow between Database 1 and 2 and modules of paraconsistent analysis.

The decision-making module receives three types of signals: the values of intensities of the currents of the load (I) directly from Database 1; the values of the evidence degrees (µER) from the paraconsistent analysis of overload risk; and signals from Database 2 related to the alarm types of occurrences. The analysis of these three signals results a diagnosis which acti‐ vates a flowchart of restoring plan and the interaction with the user to find the best way to carry out the system restoring.

Based on the flowchart the steps for the restoring are following according to the diagnosis made based on the analysis which encompasses the classification of the alarm type, the val‐ ues in engineering units of the measurements of currents and tensions, the risk evidence de‐ grees obtained by the paraconsistent analysis carried out.

#### **6.2. Verification of values on working screens**

Database 2 provides data for two purposes:

54 Advances in Expert Systems

restoring suggestion generated by PESPAL2v.

analysis, previewing and diagnosis.

carry out the system restoring.

*a) Data for detecting the topology -* The data stored in the Database 2 represent the state (on or off) of the breakers and splitting keys. The signal of these states provides an overview of the topology of the substation which is transfered as evidence to the paraconsistent models of the breakers. The evidence degrees resulting from this analysis will influence the process of

*b) Data for detecting the occurrence type -* The data stored in the Database 2 provide the alarm type and corresponding classification of the disruptions through several codes which are in‐ serted on the restoring map of operating substation. The classification of the types of occur‐ rences, together with the risk analysis signal PESPAL2v the activation of the flowchart

Figure 15 shows the signal flow where Database 1 and 2 are related with the modules of risk

corresponding to the restoring map of the area affected by the contingency.

**Figure 15.** Signal flow between Database 1 and 2 and modules of paraconsistent analysis.

The decision-making module receives three types of signals: the values of intensities of the currents of the load (I) directly from Database 1; the values of the evidence degrees (µER) from the paraconsistent analysis of overload risk; and signals from Database 2 related to the alarm types of occurrences. The analysis of these three signals results a diagnosis which acti‐ vates a flowchart of restoring plan and the interaction with the user to find the best way to

PES PAL2v has working screens where one can check the efficiency of the installed paraconsis‐ tent algorithms and the monitoring on each essential point of the substation.

Figure 16 below shows the values exposed on the screen of a typical substation (called "*Dia‐ dema*") used in the pilot system. On the screen one can see the evidence degrees of overload risks on all measurement points of the operating system being analyzed.


**Figure 16.** Working screen: significant values obtained from the Substation *Diadema*.

#### *6.2.1. Denormalization Process*

All the procedures for the analysis were carried out by the algorithms which were based on the PAL2v whose signal treatment considers normalized values, that is, values in the closed interval [0,1] of real numbers. In order to obtain previewing values in units of engineering, recovering the approximate values of current intensity and voltage, it is necessary to per‐ form a denormalization process of the obtained values.

### **6.3. Tests and description of the application PESPAL2v**

The application of the Paraconsistent Expert System - PESPAL2v in this version can work in two modes according to the user: "Analysis" mode and "Training" mode. These two modes are described in what follows.

a) When the "Analysis" mode is selected, the Paraconsistent Expert System - PESPAL2v per‐ forms the analysis of overload risks, outputs the values of the risk degrees, current intensi‐ ty and the breakers which are off. Next, the system interacts with the user and suggests optimized procedures for reconnecting. The suggestions are done in an interactive way through descriptions, visualization of the flowchart of the reconnecting maps and other re‐ striction graphs.

**7. Conclusion**

ing.

tem.

In this work it was shown that the paraconsistent logics has a great capability of application in technological processes with the aim to solve complex problems. The Paraconsistent Ex‐ pert System - PESPAL2v was designed with an analyzing block of contingency which is capa‐ ble of computing the risk degrees of outage by overloading of the electric power system. Moreover, given such occurrence, it is also capable of analyzing the conditions and of offer‐

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Currently the expert system built with the PAL2v is being used to assist operation and train‐ ing of operators at the operational substations of the electric power system of the AES-Ele‐ tropaulo – electric utility in Brazil. In the practice the paraconsistent expert system PESPAL2v has shown to be an efficient tool, with which the user understands and accepts the reason‐ ing methods used in the problem solving, since paraconsistent logics are more intuitive and has algorithms with simple structure. Generally speaking, it reached the following goals:

**a.** Assist the operator in the selection of the main control actions at the time of the restor‐

**b.** Outline and implement restoring plans based on the operational state of the electric sys‐

In operation, the PESPAL2v has shown to be computational software where the modulation parameters are easy to adjust and the analyzing block of contingencies is adapted to provide resulting information in a satisfactory way. It was tested under several conditions using real

The sub-transmission system which was tested was composed of 12 substations where it was possible to modify and test several topological configurations. Under all tested condi‐ tions, PESPAL2v showed good results and responded well to various situations in comparison

The prototype application build in this first phase leave the necessary conditions fulfilled, so that the analysis process can be automatically started for the online implementation, topic which is for future projects. In this case, the alarms activated due to failures at the substa‐ tions whose data were stored in the database, will start the application so that the analysis phases of the process are started in real-time. Under these conditions PESPAL2v will with no

ing a list of sequences of optimized restoring for the operation.

**c.** Show the restoring state in its optimized form.

values which were stored into a database for 12 months.

to previous situations which were also stored into database.

doubt a very useful tool to the operation of the electric power system.

**d.** Promote the operators' training.

**e.** Optimize the restoring process.

Together to the above three main features, we can add three more:

**f.** Detect "islands" – areas that due to disconnection remained isolated.

b) When the mode "Training" is selected, the Paraconsistent Expert System - PESPAL2v will simulate the failure and step by step will present details about the procedures of the recon‐ necting flowchart. In order to begin the process the user has to inform the application the name of the substation he or she wants to simulate.

When this information is input, the application shows on the reserved space at the left of the screen the unifilar representation of the selected substation. The next step is the user's action which selects the breakers which will be simulated as "off" in order to configurate a type of failure occurrence.

When the simulation process is started the application, based on the breakers selected as "off" by the user, detects the type of alarm (CRs) which represents the disconnections and performs a search on the substation's database for the date that such failure occurred.

When the date of the occurrence is detected the application activates the networks of para‐ consistent analysis obtaining the evidence degrees of overload risk and other specific infor‐ mation together with the first suggestions from the flowchart of the reconnecting map.

The interactive process is similar to the one presented in the "Analysis" mode: the sugges‐ tions and actions already determined by the flowchart will be step by step presented until the end of the optimized reconnecting. Doing so, the training is totally performed from real data of failure occurrences represented by values stored in the database.

Figure 17 shows a screen of an operating substation in its unifilar diagram with all available values obtained by the paraconsistent analysis. A menu, where restoring sequences of the electric power system after a contingency, is shown to the user.

**Figure 17.** Analysis screen – Unifilar diagram and menu with information generated by PESPAL2v.
