Power Quality Monitoring: Analyse and Improve your Energy Performance Presented by: David Bradley B.Eng (Hons), MBA, C.Eng, MIET
Energy Management & Power Quality Key Drivers PART L The energy efficiency requirements of the Building Regulations are set out in Part L2 for England ISO 50001:2011 The standard specifies the requirements for establishing, implementing, maintaining and improving an energy management system ESOS Energy Savings Opportunity Scheme, ESOS is a mandatory energy assessment scheme for organisations in the UK that meet the qualification criteria EPC Energy Performance Certificates DECC Department of Energy & Climate Change (DECC) BREEAM is the world's leading sustainability assessment method LEED Leadership in Energy and Environmental Design is one of the most popular green building certification programs used worldwide EE 2012/27/UE Directive: EU reaches its 20% energy efficiency target
Energy Management & Power Monitoring What is behind am&t? Automatic Monitoring and Targeting A Tool to Identify Waste and help cut Costs and Carbon Emissions Automatically Provides Information to people who can take decisions and actions 3 Key Components: Meters and Monitoring Devices Communication and Data Capture Software
am&t purpose in an ISO50001 process Reports & Dashboards Energy policy Plan Metering Plan Act Review Management Energy planning Implementat ion Do Measure, Monitoring, Analysis, Following Up Check Check Implementation Data Collection
Overall measurement chain accuracy
Transformer/Main Incomer panel Network management & optimisation Alarms Load curves Predictive power MSB Control the quality of the energy delivered (EN50160) Detection of voltage dips, interuptions & swells Current unbalance Individual harmonic distorsion DB Sub D/B Q800
Main distribution panels Power management & Energy metering Load curves Load shedding Breaker status monitoring Sub-metering History of average values MSB / MDB DB SUBDB DIGIWARE
Sub-distribution panels Power management & Energy metering U,I, P, Q, S, PF Cost allocation Energy consumption breakdown Total harmonic distortion per load MSB / MDB DB DB DIGIWARE & MID
Retrofit metering A lot of installations are on existing switchboards or PDUs Space is often tight The solution is to use Split core CTs up to 600A Rogowski coils from 600A to 6000A C:\Users\DGB\Desktop\DIRIS Digiware client installation GB.mov
Meter communication protocols Protocol PULSE MODBUS PROFIBUS M-BUS SNMP Applications Non-critical process Non-critical process, Monitoring Speed N/A High latency (1 sec) Quantity of Data Physical support One parameter Pair Mbus Critical process, automation Low latency (1 ms) Meters & remote index reading Slow Resilient Large amount Limited amount Limited amount RS485 Ethernet Radio GSM RS485 Sub-D9 EN-13757-2 Cost Low Low High Mid High Alarms, equipment status Fast + real time alarms Large amount Ethernet Availability Widely available Widely available Few meters Few electrical meters Specialist meters
Example architecture Unlimited number of metering points Vertelis Energy Management Server Building Management System Simultaneous BMS and EMS connection Users on network can view data CAT5 Ethernet Different meters for: 1. Billing tenants 2. Power quality Gateway / Datalogger Gateway / Datalogger Gateway / Datalogger Gateway / Datalogger Meter Meter Meter Meter RS485 Modbus Meter Meter RS485 Modbus 20 / 32 devices per gateway
Gateways A gateway converts one physical communication support to another e.g.: RS485 twisted pair to CAT5 Ethernet Radio wireless to CAT5 Ethernet It also allows multiple high level systems to access data from meters simultaneously Some provide an onboard webserver to view instant readings (U, V, I, F, PF) from the meters attached to them They can also act as data loggers
Metering layout (flats) CAT5 Ethernet Flat 5a Flat 5b Flat 5c Countis E44 or Diris A14 Floor 5 RS485 Modbus Floor 4 RS485 Modbus Floor 3 Gateway/Datalogger RS485 Modbus ELECTRICAL RISER
Metering layout (switchboard or non-billing) Voltage Current (main incomer) Current (outgoing) Current (outgoing) Current (outgoing) Current (outgoing) Current (outgoing) CAT5 Ethernet I45 Gateway Datalogger I33 RS485 Modbus To EMS/BMS Digibus (CAT5 Ethernet cable)
Water meters Most common issues Water meters are in remote locations e.g. down a manhole or far from a connection point to the network The data output from the water meter is already taken by the utility for their own billing purposes Communication protocols Pulse (1 pulse = 1m3): Only data is consumption. Mbus: more data is available on instant flow rates
Gas meters Gas meters have the same remote location and utility connection issues as water meters They also generally have pulse or Mbus outputs The element of risk is much higher IGEM/GM/7 gives guidelines for connecting to a gas meter Requires use of ATEX components and electrical isolator (e.g. Chatterbox e) Locate non approved components outside
EMS vs BMS - (BEMS) System BMS EMS Host PLC Server, virtual server, cloud Strengths Real time data Load management Alarms Rugged Large amounts of data Data storage Hardware upgrades Dashboards Customisable graphics Billing Carbon reporting
Energy Networks Association G5/4-1 2005 Energy Networks Association Document G5/4-1 2005, details the maximum levels of harmonic distortion that electricity consumers are permitted to export onto the distribution network. The document forms part of the supply agreement between Electricity Company and consumer. Enforcement of the limits can include a refusal to supply until it can be demonstrated that harmonic levels have been adequately addressed, which remains the responsibility of the consumer.
Waveform Distortion Fundamental Pure Sinewave PLUS 3 rd Harmonic EQUALS Distorted Waveform 3rd Harmonic is third order of Fundamental Frequency i.e. 150 Hz (3x50Hz) 5th Harmonic is fifth order of Fundamental Frequency i.e. 250 Hz (5x50Hz)
Potential Sources of Harmonics Switch mode power supplies Arc-furnaces / arc-welders Frequency converters LED lighting Induction Motors
G5/4: Stage 1 Maximum Permissible Harmonic Current Emissions in Amperes RMS for Aggregate Loads and Equipment Rated >16A per phase. PCC<=5% THD(I) Harmonic Emission Harmonic Emission Harmonic Emission Harmonic Emission order h current I h order h current I h order h current I h order h current I h 2 28.9 15 1.4 28 1.0 41 1.8 3 48.1 16 1.8 29 3.1 42 0.3 4 9.0 17 13.6 30 0.5 43 1.6 5 28.9 18 0.8 31 2.8 44 0.7 6 3.0 19 9.1 32 0.9 45 0.3 7 41.2 20 1.4 33 0.4 46 0.6 8 7.2 21 0.7 34 0.8 47 1.4 9 9.6 22 1.3 35 2.3 48 0.3 10 5.8 23 7.5 36 0.4 49 1.3 11 39.4 24 0.6 37 2.1 50 0.6 12 1.2 25 4.0 38 0.8 13 27.8 26 1.1 39 0.4 14 2.1 27 0.5 40 0.7 The G5/4 covers both even and odd harmonics so it's important to ensure installed meters can measure both (not all meters can measure even harmonics!)
Effects of harmonics : Skin Effect
Effects of Harmonic Currents Neutral Highly unbalanced systems or systems with high triplen harmonics can have a neutral current > phase currents This can also cause higher than normal voltage drops between neutral and GND at the 230V outlets MCCBs Devices fitted with an electronic trip unit respond to the peak current. If this is raised by harmonic currents the circuit breaker may trip prematurely Bus bars & panels Risk of neutral bus bars and lugs being overloaded (triplen harmonics) Can become mechanically resonant and emit a hum at the harmonic frequencies
Effects of Harmonic Currents cont. Torque pulsation in motors Overheating and dielectric failure of capacitors Lighting ballast failures / Electronic lighting failure PC monitor stroboscopic affect / failure
Crest Factor Example The two waveforms both have an rms current of 5 A, but the crest factors are very different. The sinusoidal current waveform has a crest factor of 1.414: crest factor = peak current / rms current = 7.07 A / 5 A = 1.414 The non-sinusoidal current waveform, on the other hand, has a peak value of 21.21 A. The crest factor for this waveform is then: crest factor = peak current / rms current = 21.21 A / 5 A = 4.24 In the examples shown above, both loads draw the same amount of true power (assuming that the input voltage is the same for both). This means that a power source selected to feed the loads at 230VAC would need to provide the 1,150VA that both loads require. A power source with a power output rating of 1,150VA may not, however, be able to provide the required peak currents that the non-sinusoidal load demands.
How do we measure Harmonics? Example harmonic report from power quality meter covering both odd and even harmonics
Harmonics filter and impact on Power Factor Rectifier LC Filter DC/DC output Stage Typical input stage on a switch mode power supply. The LC filter will improve the THDI seen by the source, improve the Power Factor and provide a Leading Load
Backup Systems with UPS and Genset kw Charge capacitive Charge inductive Cos φ 0,8 Cos φ 0,9 100% kw Cos φ 0,9 Cos φ 0,8 1 Cos φ 0,7 0,75 Cos φ 0,6 0,5 100% kva 0,25 1 0,8 0,6 0,4 0,2 0,2 0,4 0,6 0,8 1
Backup Genset Gensets are not able to supply loads with large Leading Power Factors (Capacitive Loads) 29
Importance of PF and UPS/Genset operation Genset Capacitive reactive power available: 500kVA 115kVAR max Incompatibility between load and operation on backup Genset Load Demand = 155kVAR Option to account for PF and Genset Backup: 320kW cos ϕ = 0,9 Leading Oversize the Genset Install Power Factor Correction (PFC)
Voltage Imbalance - EN50160 Un-balanced networks can result in major issues with induction motors, variable speed drives and affect efficiences. Temperature rise due to unbalanced voltages De-rating curve for motors
Electrical event types Name Definition Cause Effect Image Sag V < 90% Vrms t > 10ms Typical: V < 50% Vrms t < 500ms Inrush current Network faults (short circuit and insulation) IT equipment off Lights switch off Motors slow -> inrush when restart Swell V > 110% Vrms t > 10ms Elec network switching Capacitor banks Protection tripping on network Premature wear Dielectric degrading over time Interruption V < 1% Vrms t > 10ms High current inrush Fault leading to tripping Equipment goes off Transient t < 20ms Lightning strike Network or capacitor switching Destruction of electronic equip. Differential tripping Flicker 93% < V < 99.9% Vrms Long term Fluctuating power demand Arc furnaces, motors User discomfort Lighting unstable Equip. malfunction
Capturing electrical events Power quality software Diris Q800 power quality meter Voltage Amplitude EN 50160 Capture events > 10ms Meter uses a sliding window upon event detection all the data is stored in memory Data retrieved and viewed in software Can be exported to excel
Power Quality Meter Real Time Reporting
Power Quality Meter features Harmonics
Graphic Waveforms Voltage
Event Recording Recording : Events
LV Schematic Select the Correct Meter Power Quality Meter on the main incomer and Multi-function meters / Digiware on the outgoers
Socomec s am&t ECA Tax Savings From design specification to commissioning Provide: Recommended electrical sub-meters with current sensors Recommended data loggers / gateways Recommended software Architecture guides Commissioning and certification of the installation
Recommended parts list
Recommended architecture
Manufacturer approval