Test objective name

KIT.TC2 FlexOffice/SmartFab Electrical Peak Shaving

Author / organization

Zhichao Wu, Alexander Engelmann / KIT

Short description

This test case is used to investigate sizing battery capacity for peak shaving.

Present use / development status

Test objective

optimization

Description incl. justification

The goal of this test case is to optimize the capacity size of stationary storage batteries for shaving the electrical peak demand from the grid caused by controllable and uncontrollable loads attached. The load considered within the system mainly includes the machines in the SmartFab and the electrical consumers in the FlexOffice system configuration. The peak shaving is constrained by the running production machines and the comfortable level of the office temperature. The room temperature in the office should be kept at a comfortable level at the same time. An electrical heat pump is switched on to keep the room warm when necessary. The battery is charged with the excess energy generated from photovoltaics connected in the system.
The peak energy used from the external grid is supposed to be reduced by using the energy storage. However, both the regulatory ability and economics cost of the battery increase with the battery capacity size. The test objective is to find the optimum between the peak shaving capability and the cost of installing and using the battery.

System configuration

FlexOffice/SmartFab (see deliverable D2.3, Appendix F)

Use case

System Under Test

The FlexOffice/SmartFab system can be divided into a thermal
domain and an electrical domain. This test only deals with the
electrical part of the system, see Figure F.2.

Object Under Investigation

External electric grid
• peak load power
• power and energy imported and exported

Renewable generation
• Photovoltaics power generation
SmartFab
• Load of the machines

FlexOffice
• temperature inside the office
• electric load of heat pump

Battery
• battery capacity
• state of charge of the battery
• terminal current and voltage of the battery.

Function Under Investigation

Electrical peak shaving for the system under test as shown in Figure F.2.

Objective Function / Target Metrics

The objective function is to minimize the cost generated by the electrical peaks consumed from the grid, the total electrical grid energy used and the cost of the battery installation.
The object function can be written as:

Where ????? is the KPI that represents the maximum of the electric power required from the grid, which is related to power tariff tier. ????? is the electric load from the grid. Thus, the second item in the equation represents the total amount of energy imported from the grid. ????? is the battery capacity size. ?,?,? are weighting coefficients that transfer the calculated value to economic cost. The weighting coefficients can be functions by their own, indicating e.g. binary decisions. This is e.g. the case for the coefficient ? as the tariff changes if the peak power exceeds different thresholds values. Further details can be found in deliverable D

Acceptable test result

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