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Document date: 10. 1. 2022
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Smart Charging Solutions
Charging station
Etrel INCH charging station supports many functionalities that can help with overload prevention, frequency regulation, power management of one charger or power management of a cluster of chargers.
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Each scope consists of several smart charging features, and new ones are being added routinely with normal charging station updates.
Additional measurements
The charging station can operate on its own, however, it can be beneficial to use additional data at the location where possible. For example, data of household consumption and data of possible production of energy at the location, can be measured and transmitted to the charging device where the data is evaluated, analysed and used in algorithms. One possibility for this is the collection of data with the use of Etrel Load Guard. Additional measurements enable better operation of smart charging.
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Figure 2: Etrel Load Guard
Back Office (Software Solutions)
Additional option is the use of charging monitoring system, for example Etrel Ocean, which enables additional smart charging features and better operation of existent. With monitoring system, the overview and control of larger number of charging stations becomes simple. The major benefits, that are supported with the use of Etrel Ocean are:
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Cluster management
Demand response activation
Load area power management
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Figure 3: Etrel Ocean
Smart Charging Solutions at the Location
Overload Prevention
Main functionality of the overload prevention algorithm is to decrease the EV charging load to prevent the overload of grid connection point. This function has the highest priority among all the power management algorithms. The EV charging load shall be controlled so that the total load (household load + charging load) of grid connection point is below the rated current of the main fuse.
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Detection and visualisation of surplus energy returned to the grid (Production from renewable energy sources).
Frequency Regulation
Frequency regulation can prevent grid breakdowns. Frequency depends on the balance of production and consumption in the electricity grid. When the consumption is bigger than production the frequency falls below nominal value. In the event when the production is bigger than the consumption frequency can raise above the nominal value of frequency.
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In the case when the frequency is lowered because the consumption is too high, the charging station can simply decrease the charging power (currents). Regulation of the charging current is made on basis of the frequency limit settings. If the system frequency is lower than nominal value, the charging current will also be lowered. Nominal value of frequency in the power system can be different, usually defined as 50 Hz or 60 Hz.
Start when frequency under [Hz] | Delay start (when persistently under) [s] | Decrease output current to [A] | Delay end (when persistently above) [s] |
50.0 | 10 | 32 | 4 |
49.0 | 8 | 25 | 8 |
48.0 | 6 | 15 | 10 |
47.0 | 4 | 6 | 20 |
46.0 | 2 | 0 | 40 |
Table is showing an example of defined stages of frequency regulation and setting of one stage in charging station’s web interface is shown at the figure below.
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It is possible that the under-frequency regulation can be subsidised and represents an income to the charging station’s owner.
Charging Process Optimization
Economic/Price Optimization of Charging
When different energy tariffs are set, the charging station can optimize the charging process to ensure that the price of charging will be the lowest possible. Based on the set parameters, the charging algorithm calculates the optimal charging schedule plan.
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Evaluation of on-site production (e.g., photovoltaics).
Operation Optimization
In some cases, the easiness of the charging process can be supported with the use of machine learning and pattern recognition to evaluate the user habits and offer the charging schedule plan, optimized to specific user (by evaluation of the historic data of charging).
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Machine learning and pattern recognition using built-in AI to predict and optimise each charging session.
Collection of user's departure time to refine automatically suggested charging profile.
Support for Modbus protocol for integration with external smart building systems.
Power Management
Basic power management is performed on individual charging station and consist of several settings and is supported by other functionalities. It can also be performed on the level of back end for load areas, sub load areas, or individual charging stations.
Cluster Management
The goal of this functionality is to distribute the power available for charging among several chargers in the cluster when multiple EVs are charging. Cluster management on level of charging station is using one charging station designated as master of the cluster.
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Algorithm must also prevent grid connection point overload if the full charging power of all charging station in cluster would cause overload.
Operation
One of the charging stations is assigned role of a cluster master. Cluster master serves as a main communication channel between all the charge points in the cluster and is responsible for power management algorithms. This allows cluster to do the power management even if the communication with the back office is lost as all the calculations are done within the cluster.
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For this recalculation the algorithm considers a “fairness factor”. A high factor means, that all EVs are considered on an equal basis: the share of EV’s set point current in the sum of set point currents of all EVs in the cluster corresponds to the share of EV’s required current in the sum of required currents of all EVs in the cluster.
Additional Options
If the cluster is part of a household, multi-dwelling house or if additional loads are connected to the same connection point Load guard unit should be added to the installation. Load guard can measure values of all the loads in the installation and with this data charging station can manage the charging power.
Additional options for cluster management are supported on the level of back-office, with the use of Etrel Ocean monitoring system.
Smart Charging Solutions On Level of Back Office (Software solutions)
Software solutions represents power management solutions that are done by the back-office software. Etrel Ocean monitoring system can be used. All charging stations that use OCPP 1.6 protocol can be managed by the software.
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Main software power management solutions:
Cluster management
Demand response activation
Load area power management
Power Management
Basic power management is performed on individual charging station and consist of several settings and is supported by other functionalities. It can also be performed on the level of back end for load areas, sub load areas, or individual charging stations. Limitation in using only software solution is the communication. If the communication between the charger, other charging stations of the cluster and back office fails, new schedules and power management can't be communicated to the charging stations.
Best case scenario is using combination of both options which represents a safe failback to the cluster management on level of charging stations in case of communication loss.
Cluster Management
Solution for power management of clusters using software (monitoring system) is very similar to the solution of cluster management enabled on the level of the charger. The main difference is that cluster master is not used, as back office software works as a cluster master and delegates the schedules and charging power values to each charging station that is part of the cluster.
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Larger cluster (up to 300 electric vehicles) is possible with use of INCH Brain (IPC) and connection to Etrel Ocean management software.
Demand Response Activation
In some cases, the demand response functionality is needed. Distribution system operator can set the rules, that can be implemented in Etrel Ocean to enable the control of charging stations operation:
Remote power manipulation by DSO.
Remote power manipulation by energy supplier.
Load Area Power Management
Load area power management allows operator to group charging station and clusters into load areas. Software allows operator to manage the power of each load area separately. This gives operator ability to manage power only in the area where problems occur.
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In the first option Etrel Ocean gathers all the data from each charging stations separately and aggregates them with the data from charging station from the same load area. This data is then exchanged with the smart grid system which controls the grid (other power plants and consumers).
In the second option, the data from each charging station (grid connection point) is sent to the smart grid system and it is that system responsibility to aggregate data to load areas and sub load areas and to manage power consumption of all load areas.
List of Smart Charging Features
Economic/Price Optimization of Charging
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