确定带电动汽车充电器的公寓楼的最大需求

March 2024V 1.1 Interested in how to determine maximum demandfor an EV charger installation in an apartmentcomplex? Here’s what you need to know. Disclaimer: The Electric Vehicle Council (EVC) is not your local electrical regulator.Therefore, this guidance should be considered in combination with input from yourrelevant electrical regulator or licensed electrical inspector. It is not to be interpreted aslegal guidance. If in doubt, please contact the relevant electrical regulator in your regionfor clarification. What is the maximum demand? Maximum demand is the expected peak load in an electrical system. It is determinedat the time of design or modification to the electrical installation, in order to informthe required capacity of upstream electrical equipment, in accordance with section2.2.2 of AS/NZS 3000:2018 (Australian/ New Zealand Wiring Rules). If an incorrect determination of maximum demand is obtained, there will be negativeconsequences. The installation will be more expensive than necessary if the maximumdemand is overestimated. The circuit breakers will trip, or fuses will blow, if themaximum demand is underestimated. Getting it right is important. The standard presents four methods to determine maximum demand as part of theinstallation. The methods most relevant to installing EV chargers in apartment complexes are (a)calculation and (b) assessment, backed up by (d) limitation. Method (a) calculation, isrelevant to domestic installations and is covered in thatguideline, it is good forapplications where use of EV chargers at full capacity at anytime is required.Method(c) measurement, can be used for any installation once complete and functioning asintended. Headroom The dynamic limit of an electrical installation’s connection capacity is the differencebetween the fixed supply connection capacity defined by the incoming circuit breaker,and the balance of building use of each phase that varies over time and is not‘orchestrated’ or controlled. It is this headroom or spare capacity that we can target forEV charging. Consider excludingIn the graph below of a building’s daily energy use, the two blue lines represent thedynamic limit at two points in time. The shaded area represents a period to considerexcluding EV charging, as there is low headroom. Method (b):Assessment There are many ways to carry out an assessment of an electrical installation.One wayis to draw up a table of all loads present, including their nameplate rating, normalcondition current draw, power factor and when the loads will be drawing, to add upthe overall draw at any one time.For large installations with many loads, this wouldbe time consuming. AS/NZS 3000:2018 clause 2.2.2 states that “The maximum demand may be assessedwhere - (i) the electrical equipment operates under conditions of fluctuating orintermittent loading, or a definite duty cycle;“.Applying control to electricalequipment in your installation, such as a load management system, can ensure adefinite duty cycle. The underpinning assumption is that the implementation of a suitable loadmanagement system in the context of an apartment complex can ensure that EVcharging is actively prevented from contributing to building-level maximumdemand. In this guideline, we treat a 'suitable load management system' as comprising of twoaspects: 'primary load management', which is the part of the system that operates all thetime, and which defines theuser experience, and'back-up load management', which only comes into play if the primary system failsto perform correctly,but which guarantees that the EV load will not compromisethe rest of the building electrical supply. Primary Load Management There are many architectures one could use to make sure EV infrastructure stays underdesired load limits, this is not an exhaustive list of approaches in use today, and this isan evolving space - more approaches to load management will emerge over time. Timeclocks - Usings timeclocks or timer relays to bring in contactors that feed certain circuits atcertain times is an effective and cheap but crude method of control.While generallyreliable, if timers are reprogrammed at a future date, run times could undesirablyoverlap, creating higher than expected loads.Using the approach in the context of anapartment complex will support regular top-up charging, but will generally not supportfull recharging of individual vehicles overnight. PLC - Some EVSE coordination systems comprise of a communication gateway connectedvia a building automation network, such as Modbus, to a control system such as aProgrammable Logic Controller.The EVSE are connected via ethernet on the OCPP(open charge point protocol).This architecture can use communication to the EVSE toramp charging up and down rather than switching chargers on and off. Building management system - A building management system(BMS) is connected to the internet and could - inaddition to providing local smart control - take input from