# Household Energy Management
## 2 Characteristics of Smart Appliances
In this way, distributed processing functionality would be obtained, resulting in a noticeable reduction in power in the NPS. The producer will also specify priority values (\(pr\)) for each \(WS\). An example of a 5-step scale of priorities was proposed, which corresponds to the following meanings:  
* For smart appliances with \(pr=1\) and \(pr=2\) there is always the possibility of power reduction, because limiting the power of these appliances or their lack of operation does not cause side effects for the functioning of the household. * For smart appliances with \(pr=3\) the power reduction occurs only if for smart appliances with \(pr=1\) and \(pr=2\) the power reduction did not bring the intended effects. * The values of \(pr=4\) and \(pr=5\) allow the smart appliances power to be reduced only in crisis situations for the stability of the NPS. For loads with \(pr=2\) and \(pr=3\), the user decides whether he agrees to reduce power. Figure 3 shows an example of a situation in which two smart appliances (\(A_{1}\) and \(A_{2}\)) with different priority values were started at different times, \(t_{0\_A1}\) and \(t_{0\_A2}\). Calling the EEM algorithm at time \(t_{i}\) will result in the need to select new \(P_{A\_SEL}\) settings for \(A_{1}\) and \(A_{2}\). The order of the smart appliances in which the power reduction to the \(P_{A\_SEL}\) level should take place will be determined by the \(pr\) values assigned to these appliances. If \(pr_{A1}>pr_{A2}\), then the power reduction will be performed first by the EEM algorithm for \(A_{2}\). The EEM algorithm will decide on the \(P_{A\_2\_sel}\) value, one of several possible levels, and then turn on \(A_{2}\) with the selected power value. Figure 3: Example of the impact of priorities on the operation of the EEM algorithm. Currently, there are a few appliances available on the market (e.g., washing machines, dryers), in which it is possible to set the start time (\(t_{s}\)) of such a device. The \(t_{s}\) time setting is done directly in the device or remotely, e.g., from a tablet or smartphone [30]. This type of functionality is planned in the EEM algorithm to reduce costs for consumed energy by shifting turning on smart appliances to off-peak periods. In cases where \(t_{s}=0\), the smart appliances are immediately activated by EEM. It has been proposed that the parameters for each type of smart appliance should be defined according to the entry  
\[(\mathbf{P_{A\_MIN}},\mathbf{P_{A\_NOM}},\mathbf{k},\mathbf{pr},t_{s}), \tag{1}\]  
where:  
* \(\mathbf{P_{A\_MIN}}\)--a vector containing the minimum power values specified for each \(WS\); if in the extreme case \(P_{A\_MIN}=0\), it means that the smart appliances can be turned off by EEM,
* \(\mathbf{P_{A\_NOM}}\)--a vector containing nominal power values specified for each \(WS\),
* \(\mathbf{K}\)--a vector containing the number of additional power reduction levels in each \(WS\),
* \(\mathbf{pr}\)--a vector containing priority values for each \(WS\),
* \(t_{s}\)--time by which the smart appliances activation can be shifted. The length of each vector appearing in (1) describing the parameters of a given smart appliance is equal to the number of defined \(WS\). It is assumed that the user may overwrite the priority value for each \(WS\). However, such action will require confirmation of the power reduction performed by the EEM algorithm, which may adversely affect the functions performed by the given smart appliance. For smart appliances in which the section is not highlighted, the vectors will be one-piece, and the priority value will then be set only by the user.