Power Quality Monitoring

Project description – supermarketThe problem:Despite very similar buildings and consumer structures, the consumption and loads insupermarket stores can be very different. The reason for this can be the variousmanufacturers of deep freezers, lighting and ventilation systems which often have verydifferent levels of energy efficiency but it can also be due to the various sites withdifferent weather conditions (snow, hours of sunlight etc), the number of customers eachday or the environmental awareness of the employees. Furthermore, non-linear consumersfrequently lead to serious problems with regard to power quality.Therefore, it makes sense to measure consumption levels and loads together with thegeneral power data in the stores, collect the data and benchmark the stores with eachother.The task:A supermarket chain wanted to measure the loads, consumption data and power qualityin the main feeders and several outputs in the respective stores and then collect the datain one main PC. With the help of concrete measurement data, stores with high consumptionlevels were intended to be identified in order to find reasons for the particularlyhigh consumption and peak loads. The supermarket chain then wanted to reducepeak loads using peak demand management and monitor the power quality in the individualoutputs with regard to harmonics, as produced by deep freezers for example. Inaddition, the consumption of gas and water was also to be measured and the data was tobe provided to the facility management. The communication media was an ISDNconnection.The solution:Stores:A UMG 507E was deployed in the main feeder which enabled direct access through anISDN router. On one hand, the device monitors power quality in the complete networkand on the other hand, allows peak demand management for six sheddable loads usingthe Emax function. The unit can be extended by up to 32 Emax channels using anexternal WAGO module. Additional superfluous consumptions can be avoided using atime switch program e.g. automatic switch-off for lighting when the store closes. Voltagebreaks and other events can be sent by e-mail with a document attachment upon request.The sub measurements are connected to the UMG 507E using an RS485 which alsofunctions as a gateway. Data from four outputs (freezers, ventilation, lighting and compressors)are collected using four UMG 96S´s with the clock and memory. Theconsumption of gas and water is measured using pulse meters and the pulse is passed onto the integral ProData ® .Headquarters:The data is compiled on a main data server. The measurement value memory in theinstruments is conveniently read-out using the PSW professional analysis software in theindividual stores. Due to the number of stores, the instruments are only read once permonth. The measurement data can easily be processed for the required time period comparisonin MS Excel sheets. These are integrated using MS Excel macros which read thedata produced by PSW professional into the database.216