Power Quality Analyzer Isolates Problem

Power Quality Analyzer Isolates Problem

hinking that it was being overcharged for electricity consumption, a transport company that runs a train service in one of the largest cities in the world complained about abusive charges from its distribution company. Believing that it had done nothing wrong, the distribution company servicing the transport company requested a harmonic analysis be performed at the point where the customer?s load connected.

According to the transport company, its meters read an almost perfect power factor. However, upon closer examination by the distribution company, it was discovered that the power factor was not as perfect as the company claimed. It was actually 0.67. To determine the cause of the discrepancy, a CPM Leading-Edge Technology Inc. (CPM) power quality analyzer was left on site for a week to monitor the load behavior and see if any other relevant information was captured.

After a week-long survey, the data obtained provided some interesting information. The maximum voltage total harmonic distortion (THD) dropped dramatically between 1 and 6 A.M., when the train system was not in operation. However, when the train was in operation, the maximum voltage THD was extremely high at 36 percent. A closer look at the current spectrum revealed that the 5th harmonic was the major contributor to the distortion. The presence of the 5th harmonic was not surprising considering that the load was a six-pulse rectifier. Nevertheless, the 5th harmonic?s high level (about 80 percent in some cases) was not normal.

After further investigation, it was discovered that, because the distribution company was charging it for a lower than accepted power factor, the transport company had introduced power factor correction capacitors to the system. However, the question of why the meters were measuring unity power factor still remained. Additional probing uncovered the fact that the meters were bandwidth limited and had been filtering the rich harmonic content generated by the six-pulse rectifier. By trying to correct the lower power factor, the transport company had actually made the power factor worse.

After transferring the transport company to an alternate bus, the utility again measured the original bus. The measurements showed that voltage THD values dropped to 2 percent, proving that the low power factor was clearly a customer-generated problem.

To minimize the surcharges and the damage done to the distribution transformer, CPM recommended that the transport company disconnect the power factor correction capacitors while a harmonic filter was designed.

CPM Leading-Edge Technology Inc.

?Inquire R.S. 140

Data Warehouse Creates Centralized Solution

New Brunswick Power (NB Power) is the principal supplier of electrical energy to 334,000 customers in the Canadian province of New Brunswick. In 1995/96, NB Power?s gross revenue increased from $942 million to $1.018 billion. Steady growth like this, coupled with the regulatory changes taking place in the electric utility industry, were the two primary reasons that the company had to rethink many of its business processes, planning ahead for future growth and keeping up with the competition. This business process re-engineering started with the creation of a data warehouse in order to facilitate access to its corporate data for corporate end users, an important part of the process. Access to this critical information enables the company?s users to make better business decisions.

NB Power has moved more than 20 million corporate records, ranging from the accounts receivable/payable department records to its complete vehicle information, from traditional legacy systems and newly developed client/server applications, to a full scale data warehouse. The data warehouse is also being populated with external data such as the automated call distribution data, supplied by the local telephone company, to help manage the corporation?s regional call centers. By the year 2000, NB Power plans to have all corporate data?relating to its entire business process?stored in the data warehouse. In 1993, NB Power had purchased Cognos? data query and analysis tools, PowerPlay and Impromptu, to help access data. This access proved key to accessing the data stored in the newly implemented data warehouse.

As the first step in its evaluation of front end tools for its data warehouse, NB Power went to industry analysts seeking their guidance. ONB Power chose PowerPlay and Impromptu because of the ease-of-use, its superb reputation in the industry and price,O said Matt Rickard, NB Power systems development manager. Impromptu, an interactive database query, access and report writing tool, gives users the ability to quickly locate the data they need for reports and better decision making. PowerPlay, the client, enables users to track trends in their business by Odrilling downO on their corporate data. While IS maintains security and access parameters for both Impromptu and PowerPlay users, IS involvement is not necessary for users to locate and bring corporate data to their desktops.

OPrior to implementing the data warehouse, we had all of our corporate information stored on mainframe-based legacy systems, making it very difficult to write reports and get information out of the applications?it could take three days to a month for analysts to get the report they needed,O said Rickard.

According to Rickard, training for Impromptu and PowerPlay consisted of a one-day introductory course on a general database as well as on-site training with NB Power?s own data model. Users also attended an advanced Impromptu training course so they could master the Impromptu?s filtering capability that allows them to specify and separate the data they want to view. This gentle learning curve probably accounts for the rapid deployment of the application across the company. Currently, there are approximately 240 Impromptu users and twenty PowerPlay users.

NB Power has servers in the head office, five customer service regions and four generating regions running Impromptu. PowerPlay is installed on the end-users? desktops. The data warehouse and catalogs are stored on the central server, which makes administration of the application very easy. All hardware is from Compaq, and Windows NT is the operating system with Windows 95 and Windows for Workgroups as the client. Users in field offices are connected to the head office data warehouse server through a wide area network.

The main emphasis to date has been using Impromptu to reduce the large backlog of operational reports. With the operational side now under control, NB Power has begun concentrating on management information. Each of the corporate business units is in the process of identifying key performance indicators. Utilizing the information contained in the data warehouse, PowerPlay will be used by middle and senior management, as a tool to assist them in the management of the business units by displaying trends for each of the key performance indicators. As this process is further developed, the use of PowerPlay will increase.

OThe project has been a great success. We are beginning to see an associated cost savings in addition to the overall increase in productivity,O said Rickard. OOur next steps are to create Impromptu reports that can be made available on our corporate Intranet.O

Cognos?Inquire R.S. 141

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