WEB-BASED CUSTOMER INTERRUPTION MONITORING USING DMS SYSTEM DATABASE

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1 WEB-BASED CUSTOMER INTERRUPTION MONITORING USING DMS SYSTEM DATABASE K. Kivikko, S. Antila, A. Mäkinen and P. Järventausta Tampere University of Technology, Institute of Power Engineering Abstract This paper presents a web application for customer-specific interruption data viewing that is developed in a research project at Tampere University of Technology (TUT), Finland. The application is integrated with commercial DMS system of ABB Oy and it uses the same database as DMS system. Also the content of interruption database and the construction of interruption sector are described in this paper. 1. INTRODUCTION In modern information society requirements and expectations associated with continuity of power supply have become increasingly important. Electricity is not anymore a luxury article like few decades ago, but it has become a necessity and a part of our everyday life. Even short interruptions and voltage sags can be harmful when the amount of computers, programmable logics etc. in industry and as well in households have increased rapidly. According to Finnish Electricity Market Act, the supply of electricity is faulty if the quality of electricity or the manner of supply does not correspond to what can be considered agreed upon. Unless otherwise agreed, the supply of electricity is faulty if the supply has continuously or repeatedly interrupted and these interruptions cannot be considered minor when taking into account their reason and circumstances. The standard EN gives the main characteristics of the supply voltage at the customer s supply terminals under normal operating conditions with regard to frequency, magnitude, waveform and symmetry of the three phase voltages. Interruption statistics are recorded both for distribution network companies own needs and for Energy Market Authority, the market regulator. In the future customers may also get compensation for interruptions longer than 12 hours on the ground of addition that will be made to Electricity Market Act. In deregulated electricity market distribution companies are still in monopolistic situation in their area. In Finland Electricity Market Act has created a need to measure the efficiency of distribution companies and the same kind of need can be found in many other countries, too. When measuring the efficiency, the market regulator in Finland takes at present into account power quality in the form of interruption time. The market regulator uses Data Envelopment Analysis (DEA) to measure the efficiency of the distribution companies and the total interruption time is in the DEA model as an input [6]. Using interruption time for regulatory purposes settles new needs for the reliability of outage statistics because interruption time means money for distribution network companies and whole society. Data system development has an important role in development of outage statistics. Although in some distribution companies outage statistics are still handled with pencil and paper, the development of distribution automation is changing outage statistics to more automated direction. Nowadays, in most Finnish distribution companies interruption statistics are collected by data systems, e.g. Distribution Management System (DMS) [2]. Many functions that include in interruption statistics are carried out automatically and automatic functions can be supplemented with manual functions. This data is saved in relational databases and in the future it can be presented to customers, for example, by using Internet. Many people are finding that there are many things they would like to do in the Internet that are still not possible today. For example, customers already find the menus of local restaurants in the Internet, but they would also like to know if a particular restaurant has seating available at 7 pm tonight. The same thing goes with interruption data, too. Customers can find planned interruptions from distribution companies web site, but finding customer-specific interruption data or making notice of fault is still rare. This kind of service could be very useful for certain type of customers. This paper proposes a web application for customer interruption monitoring. The application presents in the Internet existing outage data measured and saved by the SCADA and DMS systems. Also new technologies, which make the development of web and mobile applications possible, are presented. Microsoft s new Visual Studio.NET programming tool and C# programming language, which are part

2 of Microsoft s.net architecture, were used in implementation of the web application. Applications to present power quality data in the Internet are being developed worldwide, too. Reference [3] describes a low-cost smart web sensor, which is designed and implemented to acquire, process and transmit data over network and to construct dynamic HTML pages. Reference [4] presents a web-based multi-channel power quality monitoring system, which consists of PQ meters, data transmission and displaying in the Internet. Reference [5] depicts a concept of database management system to store power quality data and a web-based user interface of the system. Departing from papers mentioned above this paper presents an Internet application that is integrated with DMS and is using data gathered by other existing data systems. 2. INTEREST GROUP S NEEDS IN OUTAGE STATISTICS Different parties in electricity market need different kind of interruption data. Interruption data can be divided to detailed fault statistics and summaries of interruption statistics. Different interest groups in electricity market include customers, distribution companies, Energy Market Authority and Finnish Electricity Association and whether they need detailed or summarised interruption data depends on the party under consideration (see Figure 1). Customer Detailed fault statistics Distribution company Energy Market Authority Summaries of interruption statistics Finnish Electricity Association Figure 1: Different interest groups and their needs in interruption statistics. Customers are interested in not only summarised interruption data but also detailed fault statistics, which tell at what time and for how long has electricity distribution interrupted. Summarised data could be, for example, average interruption time and frequency in customers distribution company compared to other companies in the same area. On the other hand, separate customer groups may have different needs. Households are interested mostly in interruptions while, for example, industrial customers and distributed generation producers need more specific power quality data including voltage levels, dips and harmonics. Distribution companies need both summarised and detailed data, too. Interruption statistics can help distribution companies to focus network investments to those lines that have biggest fault frequencies or have caused biggest interruption costs. Interruption statistics have to support network planning so distribution companies have enough incentives to collect them reliably. Summarised data indicates how amount of reclosures, interruptions and interruption time is developing in the long run. With this data they can examine how network investments are affecting to continuity of supply. This can help the distribution companies to focus their small investment resources to the right areas in the network. The Energy Market Authority uses customers total interruption time to depict power quality in distribution companies efficiency measurement. Efficiency influences to companies maximum allowed return on capital, so interruption time means money for distribution companies. The Energy Market Authority needs reliable summaries of interruption statistics. Presently the market regulator calculates the total interruption time of the distribution company from distribution substationbased interruption times by dividing it with the number of distribution substations and multiplying with the total number of customers. This settles the distribution companies to unequal situation when the number of customers in each distribution substation is not constant and networks contain both cable and overhead lines. In the future also the number of interruptions and the number of reclosures may be a part of the regulation model in Finland. In that case the power quality input in DEA-model will comprise of multiple different factors, which all have a certain weighting in the formulation of the power quality input. For different parties the information content of summarised data is different. The authorities are interested about data that concerns the whole company, a certain company may need data from a particular area in the network and a customer wants data that concerns him/her. In common for all of them is that in every parties interests is to decrease the duration and amount of interruptions. For customers even short interruption can cause inconvenience and damage. For distribution companies there are many ways to decrease the duration and amount of interruption, but they all cost a great deal of money. On the other hand, companies benefit when their efficiency develops, because efficiency have influence on their maximum allowed return on capital. Energy Market Authority is interested in keeping distribution network in good shape and decreasing interruptions for national economic point of view.

3 3. CONTENT OF OUTAGE DATABASE Let s take a look at the logic how the interruption data is gathered to the DMS database and how the number and durations of interruptions can be searched for a certain customer. In Figure 2 is an example network with which the construction of the interruption sector can be illustrated. breaker B1 opened disconnector ds2 B closed disconnector Figure 2: Example network to illustrate the construction of the interruption sector. Let s assume that the connection time to disconnect the faulted part of the network is ½ hours and the repairing time (including the connection time) is 3 hours. If the fault occurs in the point 1 (in Figure 2) the lower breaker (B1) is opened. Therefore the network between breaker B1 and disconnector A leaves without supply. Now the supply can be restored within connection time to distribution substations ds3, ds4, ds5 and ds6 by opening disconnector B and closing disconnector A. Only the distribution substations ds1 and ds2 leave without supply for the whole repairing time. In this case, two interruption sectors are constructed to DMS database. The first one has an interruption time of ½ hours and the second one 3 hours (see Table 1). Table 1: Interruption sectors in the database. When we want to find out a certain customers interruption time we need the information in Table 1. To all interruption sectors (i.e. Number column in Table 1) is linked those distribution substations that belong to that interruption sector. Each distribution substation can belong to zero or more interruption sectors depending on how many interruptions there has been in the time interval concerned. Every customer is linked to certain distribution substation, respectively. With the distribution substation number that is found from A 1. distribution substation 1 ds3 ds4 ds6 ds5 Distribution Number Borders Started Ended Duration Substations 1 K1-B :00: :00:00 03:00: B-A :00: :30:00 00:30:00 4 customers information the interruption sectors to which the customer belongs can be determined. The total interruption time, for example, for the customer can be calculated as the sum of the durations of these interruption sectors. So the operation times of the breakers and disconnectors are saved to the DMS database, the network that leaves without supply is linked to customers, and that way the calculation of the interruption times can be made automatically by the DMS or other systems. In the future also reclosures can be linked to distribution substations and to customers similarly. Already at present planned interruptions can be saved to the DMS database. There are also some problems that can be attached to these kinds of data systems. In very large fault cases (e.g. major storms etc.) that affect large areas in the distribution network the interruption times may not be registered correctly in all cases. Probably the operation times of breakers are registered correctly, but the connections that are made manually may leave without updating in the database. Also the faults that occur in the low voltage network are not necessarily saved in the database and if they are, the starting time is not saved automatically, because low voltage network is protected with fuses, not with relays and breakers like the medium voltage network. The starting time of the fault in the low voltage network is probably got when an angry customer calls to the operation centre. Of course, one have to remember that the same problems apply no matter in which way the interruption statistics are kept; manually or automatic, with pencil and paper or with data systems. 4. SYSTEM ARCHITECTURE Distribution Management System (DMS) is the centre of integration putting together the real-time process information, network data and intelligent applications for normal state and fault management. The overall aim of the DMS is the minimisation of the operational costs (e.g. power losses, interruption costs) subject to the technical constraints (e.g. voltage level, thermal limits, the operation of protection). The DMS presents the real-time electrical state of the distribution network on the geographical user-interface. It can inform the operator of various abnormalities (e.g. faults, voltage drops, overloadings). DMS also offers a way to incorporate the power quality monitoring with the network data. The pilot system in Koillis-Satakunnan Sähkö Oy consists of database server containing Network and DMS databases, web server containing the

4 application proposed in this paper and the client i.e. web browser that is using this application (see Figure 3). SCADA DMS AM/FM/GIS DMS Database Network Database Web server Web application Figure 3: System architecture of the application presented in this paper. The interruption data is gathered by the SCADA and DMS systems and it is stored to DMS database. The interruption data consists of times when breakers have operated and this data can be supplemented with operations of remote and manual controlled disconnectors. The application is integrated in the real working environment that consists of commercial products of ABB Oy. A web server was added to the existing environment to present the dynamic aspx-pages in the Internet. SQL Server and Access are used as database providers. Network database is stored to SQL Server and DMS system uses Access database. Some tables are linked to DMS database from Network database. The web application uses DMS database as the source of interruption data. 5. WHY WEB-BASED APPLICATIONS? Internet technologies have become commonly used in past few years and that s no wonder because web applications have many advantages compared to ordinary applications. These are, for example, fewer application updates and on demand access. Web applications can be platform independent, portable, reused and accessed at much reduced cost. Webbased applications provide an easy, effective and low investment means of accessing data. Users do not need to purchase any expensive hardware or software to access the application throughout the world. Web technologies make it possible to use same graphical user interface (GUI) everywhere and access the application locally within the local area network (LAN), or remotely through the Extranet and Internet without any additional development or maintenance cost. When developing web-based applications, data security and performance of the application and web server must be taken into consideration by different way. For example, the performance of the application is limited by the speed of data communication connection the user is using. Concentration on core businesses is at present a trend among Finnish distribution companies and same kind of development can be found in other countries, too. Companies are outsourcing their functions and only the most important business (i.e. controlling the network assets) is left to the distribution company. For example, network planning and construction and maintenance are more often given to another company providing this kind of services. One example of future trends could be outsourcing power quality measuring and reporting. In this example the advantages of web applications are undeniable when a distribution company is buying the power quality monitoring services from an application service provider (ASP) and power quality data is collected to ASP-company s database server. The data is accessed through the Internet and power quality reports can be made with the web application in the user interface of a web browser. The distribution company benefits from easy-to-use power quality monitoring applications, which do not spend the company s human resources like ordinary applications with all the maintenance and updating tasks do. On the other hand, the ASP-company benefits from fewer application and database updates when all the applications and databases are located in the same place. 6. WEB-BASED INTERRUPTION VIEWING APPLICATION The web application for customer interruption viewing presents in the Internet customer-specific interruption data and also reports made by the DMS system. These reports tell about the state of the distribution network at present or as well in a certain fault case. Distribution companies could offer this kind of application for customers as a new service. It would not have to be a charged service; it could as well be a free value added service for the customers of the distribution company. In the future reclosures and interruptions that are caused by a fault in lowvoltage network can be presented with this application, too. A wider concept for power quality monitoring is presented in reference [1]. The user interface of the application can be seen in figures 4 and 5. The application shows in the front page without logging in some information about the faults that are not repaired yet. This information includes the starting time of the fault, substation, section of the network and, for example, the type of the fault (i.e. 2-phase or 3-phase short circuit, earth fault). From the front page customers can move on to a separate browser window to look at the reports made by DMS system and operation centre personnel. These reports are listed in a table where each report has its own link (see Figure 4).

5 But, the interruptions in the low voltage network cause only about 5 % of the total interruption time. Microsoft s new Visual Studio.NET programming tool and C# programming language, which are part of Microsoft s.net architecture, were used in implementation of the web application. In choosing the programming tool and language the needs to develop portable solutions in the future were taken into consideration..net environment is very attractive in that point of view. Figure 4: The user interface of the web application and a report telling about the state of the network. With a customer specification number and password authorised customers can move on to examine their customer-specific interruptions. All interruptions that have occurred in pre-defined time interval are listed in a table where the starting time, ending time and duration for each interruption and the total interruption time are shown. By clicking a button in this table customers can move on to examine more detailed data for a certain interruption. This detailed interruption data includes also the substation and section of the network as well as the cause of the interruption and the weather conditions at the time the fault occurred (see Figure 5). Figure 5: Interruption data for a certain customer and the detailed interruption data for a certain fault. Showing all the interruptions to the customers in the accuracy of a second can lead to increased number of complaints if the customers do not agree with the distribution company with respect to interruption times. This could be avoided, for example, by showing the customers only the total interruption time in each month. One should also remember that the interruptions that occur in the low voltage network do not necessarily include to these numbers. Data security is one important issue when developing web applications and portable solutions. If these applications were commercialised data security and also performance aspects should be taken into consideration in a different way than they have been considered in these pilot implementations. At present the web server is protected with a password and as well is the data. Certain users can access only that data that concerns them. In future digest authentication and SSL connection shall be used to protect the data better. Also the web server should be kept perfectly up to date to avoid unauthorized usage of the resources. 7. CONCLUSIONS In this paper were presented new data systems that distribution companies can use in interruption statistics and informing their customers about interruptions. In our research one goal was to develop a web application, which uses existing interruption data gathered by other systems and can be integrated with existing commercial data systems. One big challenge in our research has been to test this application and also other applications developed in same projects in their real working environment in Koillis-Satakunnan Sähkö Oy. The real working environment usually brings out new problems that were not considered in the research environment and that is why these kinds of applications should always be tested in an environment they will actually be used in the future. A new motivation for distribution companies to keep their interruption statistics up to date and reliable could be, for example, giving annual reports to the customers about their interruptions. One possibility for implementation is this kind of web application, which gives a flexible and easy-to-use means for accessing the interruption data. The development and commercialising of these applications is about to start by a company founded by the researchers.

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