Non-linear power consumption and decentralized power generation creates more and more disturbances into the grid. With this short blog we would like to introduce how easy it is to setup a measurement – but of course, less easy will be the problem solving. But there must be starting point somewhere.
Tag Archive for: Demand Side Power Quality
This paper discusses different approaches to investigate the interaction through harmonics, interharmonics, supraharmonics, and light flicker, between photovoltaic (PV) inverters and LED lamps in low-voltage installations. Single grid connected power generators and electronic loads like LED lamps can be easily characterized in terms of harmonics in a given range of frequency. This subject is relatively well understood, and specific standards for measuring and restricting emissions are already established to ensure a low probability of interference. However, when connected together, source and load exhibit behavior that requires further study and understanding. This work presents a discussion serving as a guide for future work on analysis of losses and other impacts of the disturbances regarding this specific load and source interaction. The following are taken into account: the nonlinearity of LED loads and PV converters; the technologies and methods used in control; and the changes in power flow caused by load and power production variations. Index Terms – electric power systems, power quality, harmonics, supraharmonics, solar power.
From PQTBlog
Published by:
- Tatiano Busatto, Fahim Abid, Anders Larsson and Math H. J. Bollen, Electric Power Engineering, Luleå University of Technology, Skellefteå 931 87, Sweden, @mail: tatiano.busatto@ltu.se
- Gaurav Singh, Department of Electrical and Computer Engineering, Clemson University, Clemson, South Carolina 29634, USA, @mail: gauravs@clemson.edu
Conference Paper: 16-19 Oct. 2016, Belo Horizonte, Brazil.
Published in 2016 17th International Conference on Harmonics and Quality of Power (ICHQP)
Introduction
With the constant development, the inclusion of new energy sources and consumption devices becoming increasingly complex, a broader understanding is required of the interaction between these elements and the electrical system. In this context, the use of distributed energy Read more
Accuracy of the measurement questioned.
Measuring instruments are usually classified according to standards and accuracy. Accuracy is an important indicator for being able to usefully build on a solid measurement result in the analysis and its resulting measures. However, it can be observed that although the measuring devices used correspond to a required accuracy class, the necessary sensors are often less in focus.
It can be seen that although class A measuring devices used in power quality applications correspond to a data sheet accuracy of 0.1% for U/I and 0.2S at the energy meter, upstream current transformers are often designed significantly worse (e.g. 0.5% or worse). And this is apart from the fact that not only accuracy plays a role in power quality measurements, but also the inevitable compatibility against harmonics – one of the modern and growing main players in power quality. Read more
Problem
Risks for electrical equipment in installations are often only noticed by listening carefully.
This is also the case here, although it is not uncommon in the metalworking industry. The cause of the extreme voltage distortions shown above in a broad frequency spectrum up to slightly above 20 kHz are powerful converters in the presses. A common disturbance pattern is disturbingly loud whistling tones in open circuit breakers, through which the largest proportion of the causing clock frequency currents must flow. Rightly Read more
Problem: Potential equalisation currents
Potential equalisation currents, often referred to as vagrant currents, are not only a problem in industrial plants. Currents can also have a disruptive effect on equipotential bonding in commercial and even residential buildings.
Cause: Leakage currents frequency inverter
The picture shows the cause of an annoying whistling in the speakers of a home stereo system. These are leakage currents of an inverter drive that must flow back to the transformer star point due to their characteristics. They always occur when a corresponding filter on the inverter is missing or defective. Common-mode voltage distortions of the phase-to-earth voltages then occur at the clock frequency at the inverter output. These clock frequency currents are then detectable at the equipotential bonding of the entire building and also at the disturbed audio system.
Solution
Retrofitting and EMC-compliant installation of an effective filter.
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Incorrect wiring of an inverter causes problems
Problem description
- Immediately after commissioning an inverter-driven CHP unit, several bus systems failed in the customer’s system. M-Bus, Profibus and Modbus modules were affected.
- As a result of the bus malfunctions, there were constant error messages and false alarms in the process control and thus also failures of the entire plant.
- Analyses of the system suppliers of the control equipment as well as complaints to the supplier of the CHP with subsequent inspection by the manufacturer did not lead to any results.
Approach
Certified power quality monitoring and fire protection enhancement
Preamble
The volume of digital data continues to increase rapidly and steadily. Not least caused by cryptocurrencies, such as Bitcoin (XBT), Ether (ETH), Litecoin (LTC), etc. or, for example, by the blockchain process, a quasi-type database that works on various networked servers. The increasing demand for data exchange also increases the need for data centres, which are planned, built and maintained on a large scale globally. However, data centres in the electrical energy context are subject to complex challenges that can influence (legally) secure 24/ operation.
The basic requirements
When planning the energy supply of a data centre, many demands must be taken into account:
- Secure location in terms of energy supply and environmental conditions
- High energy efficiency to minimise operating costs
- Maximum availability (Uptime Insitute Tier 1-4) through use of redundancies, e.g. UPS, generators
- High security (fire protection, access, defence against cyber attacks)
- System stability and reliability of the operating resources used
- Scalability
The problem description
Various studies show that power quality problems cost billions each year. Read more
Network quality monitoring in a bank data centre
Data centres are not only found in stand-alone form around the world, but are also found in many other sectors. These include banks, insurance companies, industrial enterprises, hospitals, airports, energy suppliers, public authorities, etc. It is not only the enormous energy demand that poses major challenges for data centre operators and energy suppliers. Additional factors that can lead to ad-hoc problems and serious damage are coming more and more into focus.
Investment in more security for 24/7 operation
As listed in this use case, HuiShang Bank Hefei / Anhui Province in China has chosen to invest further in Read more
Application example in the aviation industry
Basic
With the exception of a few special applications, power distribution systems worldwide operate at 50Hz or 60Hz. In the aviation and marine industries, where 400Hz networks are used to increase efficiency, this is different. This may be a challenge, as most of the measuring instruments available on the market are for applications in the 50 and 60 Hz range.
Misjudgement
It is often heard that the fundamental frequency is not important in the AC grid. Therefore, a measurement system used would be suitable for any frequency range. However, the non-compliant use of 50/60Hz Read more
Actual situation
In a large urban city, the technology for supplying fresh water is getting old. Although the pumping stations and the infrastructure are in good condition, the maintenance and repair costs are continuously and extremely increasing. Electrical monitoring of the entire system is only available to a limited extent, and if so, only partially. Read more