Due to the increasing changes in the electrical grids, load flow information is becoming more and more important to create transparency in the smart grid. For distribution grid operators, this is particularly important in combination with power quality data. For many distribution grid operators, corresponding information on grid level 7 (low voltage) is either not available at all or only insufficient. Without a proper smart grid solution, this would be equivalent to “flying blind”.

Since many consumers are increasingly also producers, i.e. so-called prosumers, new technical as well as commercial solutions are increasingly in demand. Intelligent metering systems (smart meters) are of no help here, as they are only suitable for grid management to a limited extent due to data protection regulations and insufficient performance, among other things.

For transparency in the smart grid, read a possible solution here in this blog.

The challenge

One of the great challenges is that the formerly centralised electrical energy world has developed into a highly dynamic as well as very complex decentralised system. In this process, it must be possible to systemically process new but relevant information in a targeted handling of data.

Effects of a smart grid on measurement technology

Basically, the common measurement data of voltage, current and frequency as well as their derived quantities are still required. However, and here comes the possible challenge for the smart grid application: The measurement data will be combined with new customer needs and put into relation (e.g. scalability, real-time, connection to existing control systems, integration into new platform solutions, connectivity, distinct technical consulting needs, cyber security, additional costs, etc.). Thus, the conventional IEC groupings of electrical measuring devices will possibly change and overlap even more in order to enable transparency in the smart grid.

In addition, it certainly makes sense to continue to use analogue indicators (electromechanical) redundantly for essential functions. These can withstand any failure and/or attack of a data communication. This is also clear from the matrix shown below.

Distribution system operators are contractually obliged to provide energy to their customers in the agreed quantity and quality. In order for them to be able to verify compliance with these services, “transparency in the cable” must first be established. With the information about the current load flows, these become controllable at grid level (6) 7 and thus also enable efficient utilisation of the grid quality limits. The aim here is to be able to avoid expensive grid expansion and the associated high costs.
This also promotes the issue of general resource conservation (e.g. dispensing with additional quantities of copper).

To increase transparency in the Smart Grid, we propose a certified power quality measurement and power analysis up to 32 channels in the sub-distribution. The signal processing is implemented on the measuring device of the LINAX® PQ5000CL series. There, the respective current measured values of the so-called Current Link modules are processed. Thanks to the Current Link technology, the individual Current Link modules and their sensors (Rogowski) are networked in a scalable manner by means of a signal loop via coaxial cables. This reduces the installation effort to an absolute minimum and ensures professional cable routing.

In addition, this measuring system for determining the power quality and load flows is extremely cost-efficient and metrologically certified on top. Thus, the scalable measuring instrument virtually combines the areas of transducers according to IEC 60688, power metering and monitoring according to IEC 61557-12 as well as power quality instruments according to IEC 62586-1.

LINAX®PQ5000CL

• Metrologically certified PQI according to IEC61000-4-30 Ed. 3 class A as basic device
• A scalable system for the areas of certified power quality as well as for load and efficiency management for up to 10 channels (32 conductors)
• An optional basic current measurement (e.g. directly after the transformer) with a high accuracy due to current transformer sensors
• 3P or 3PN by means of Current Link per feeder (max. 32 currents)
• One measurement campaign synchronised in time for multiple feeders in contrast to traditional measurement per feeder
• Direct conformity reporting and event display through PQEasy reporting via web browser (e.g. according to
  EN50160)
• Fault recording of voltage events, optionally with time-synchronised currents of the individual channels (IEC61000-4-30 Ed. 3)
• Time-synchronised load management for U/I/P/Q/cosφ
• Current measurement per Current Link channel up to 1’000A and overcurrents up to 20’000A
• Network tariff meter P & Q (purchase & delivery)
• Upgrade for control task in the smart grid (e.g. power quality grid utilisation)
• System management by means of a user-friendly multi-device tool for easy commissioning and efficient maintenance
• Large distribution systems (feeders) are continuously monitored with only one metrologically certified measuring system
• Low space requirement & low wiring effort based on the scalable current sensors
• Due to the non-invasive Rogowski measuring technique, it is not necessary to shut down the system for installation of the measuring system.
  (Attention: observe occupational health & safety)
• Very high robustness due to proven coaxial principle (advantages see page 9)
• Current values are time-synchronous to voltage (IEC61000-4-30)
• Open, but cyber secure communication system enables high connection flexibility to parallel as well as higher-level systems
• Very fast roll-out with robust measurement technology