The system of priority distribution of the allocated limited electrical capacity of the household

. The structure of household electricity consumption is dependent on many factors, such as time, climate, territorial, historical, social, age, gender, and political factors. Operation of the power grid of households is possible within the allocated power limit and is limited by the devices installed for automatic disconnection of the power supply network. A 6-level hierarchical, with alternating precedence, system of electric power distribution for households is proposed. The highest (first) level is urgent needs and without which in the modern world it is impossible to exist. The second refers to devices to ensure the physiological and social needs of a person, the third is large household appliances. The fourth and fifth levels of the pyramid of household electricity consumption are related to heat supply systems and the concept of thermal inertia of buildings. The sixth is the devices of the lowest priority, supplied with energy according to the residual principle. An example is charging an electric car. The proposed method of distribution of electrical power allows to ensure comfortable living in the household while limiting the total power of the allocated electrical energy.


Introduction
The structure of household energy consumption depends on many factors, such as time, climate, territory, history, social, age, gender, and politics. Total energy consumption is further influenced by the number of household members, their employment and social life, habits, and lifestyles. Schlemminger et al. provided a dataset of household electricity load profiles measured in 38 private homes in Northern Germany, giving measurements of electrical household load for three phases of voltage, current, active, total and reactive power at 10-second resolution [1]. Makonin et al. provided measurements of one household in Canada from 2012 to 2014 with one minute resolution [2]. Kelly et al. published a household level dataset measured in five UK households at 16 kHz temporal resolution [3]. Electrical load profile datasets of 74 German households at one-second resolution are publicly available [4]. Measurements of 370 households in Portugal from 2011 to 2014 at 15-minute resolution have been made available [5]. Hebrail provided measurements of electricity consumption of one household in France from 2006 to 2010 with one minute resolution [6]. The intensity of electric energy consumption of a household during the day has a fluctuating character with a pronounced increase in the average values from 18 to 23 hours of the time of the day [7 -16].
Although there is a large amount of data, they are not linked to the full composition of electrical equipment by its purpose, from the point of view of the presence of electric heating devices and water heating and have a varying resolution. Nevertheless, these data make it possible to judge the overall nature of electric energy consumption by a household.
If we take the EU data as an example, the average cost shares for heating are 64.6%, hot water preparation 13.9%, cooking 6.22%, lighting 1.48%, household electrical appliances 13.4% (incl. large 39%, small 61%), air conditioning 0.39% [17]. The above data make it possible to determine the average yearly consumption of energy in the EU by one household, which equals 15. Autonomous heating and hot water supply of facilities by means of electric energy with its direct transformation into thermal energy is not encouraged by normative design documents in countries with cold climates of winter time of the year. This is caused by the low energy efficiency of the initial utilization of electrical energy. It is considered that the electric heating of homes, has a higher carbon footprint than when heating with the use of hydrocarbon heat generators. Electric energy efficiency of gas turbine power plants is 30-35% [18,19], and the stated efficiency of gas condensing boilers is 85-95% in respect to the highest calorific value according to the type of heating units used [20,21,22,23,24].
Power-to-heat technologies, frequently shortened to PtH or P2H, apply to equipment in which electrical energy generates heat, to be used in stand-alone heating systems in households. A heat pump can extract energy from a medium (air or water) and convert it into heat energy at a factor greater than one. Integration of P2H technologies with thermal storage and hybrid power generation systems give even higher energy efficiency [25,26,27]. The coefficient of conversion of electrical to thermal energy depends on the ambient temperature during the heating season. For some areas of Germany the average seasonal coefficient of conversion of electric energy to heat was 2.15, for Canada the range of variation of heat pump efficiency was from 1.5 to 4.5, but the whole period of the year was considered [28]. For Moscow, the COP was determined for the period October-April 2018-2019 using air and ground-source heat pumps [29]. COP changes for ground-source heat pumps were in the 2.6-3.o range during the heating season, air-ground combination heat pumps COP 2.7-3.5 . However, most standard residential air-source heat pumps have a very low COP at temperatures below minus 5 C, ranging from 1.1-1.4, which does not allow for higher energy efficiency compared to ramp generation with hydrocarbon-fuel boilers. For households with autonomous heating systems using heat pumps and an average atmospheric temperature during the heated period of the year +5 ... +10 degrees C, the systems with electric heat energy generation are energy efficient. At lower average temperatures of the atmosphere from +5 to -3 degrees C effective and comfortable use of heat pumps with electric additional block of electric heating of the coolant and only at average temperatures of the heating period less than -3 degrees C it is economically expedient to use heating boilers on hydrocarbon fuel. In the Russian Federation the use of heat pumps for households is currently not widespread. This is due to the low cost of hydrocarbon fuel (gas), the use of high-temperature devices for space heating (radiators), the low temperature of the atmosphere during the heating period, the high cost of heat pumps. For households with a heated area of up to 100 square meters the use for heating systems with boilers on hydrocarbon fuel have higher economic costs.
The reasons are: 1.
Energy efficiency of heat supply with the use of heat pumps is above the options of systems with boilers on hydrocarbon fuel with COP more than 2.5 (typical for the territories of southern Russia). 2.
The selection of parameters of heating boilers on hydrocarbon fuel is conducted on the basis of statistical data of atmospheric temperature for the area of location of the object at the coldest temperature values for 50 years. This results in the operation of boilers in the heating period of time with a permanent excess capacity, and especially at temperatures above 0 C.
3. Energy efficiency of hydrocarbon-fuel boilers when using them at low thermal loads is considerably lower than when operating at nominal loads. Operation of heat generators goes into the mode of periodic on-off, which leads to a reduction of efficiency indicators below 50% [30]. 4. Generation of heat energy on hydrocarbon energy sources demands combustion products disposal and fuel supply systems, and also complex service support. When estimating the whole life cycle of heating systems of a household, the total proportion of the cost of these components is as much as 10%.
Operation of the power grid of households is allowed within the allotted power limit and is restricted by the devices automatically disconnecting the supplying power grid that are installed. This limit is 15 kW in the Russian Federation for apartments in high-rise buildings, and 45 kW in individual houses with a three-phase network. Household electricity consumption is hierarchical, based on the provision of social and physiological needs of the person and the technical characteristics of the premises. The foundations of the hierarchical view of the household electric power distribution are outlined in the author's work [19], where a four-level pyramid of energy distribution with alternating transition criteria of the lower layers, connected with heat supply, is proposed. In this work, however, there is no explicit definition of the second upper level, which permits a delay in the time of realization of the demand and fails to take into account some significant loads related to the charging of electric cars, the number of which in recent years is growing at a high rate.

Purpose of work
To establish a complete hierarchical structure of the distribution of electric power assigned to the household. Define the purpose of each layer and assess the quantitative values of load levels. Evaluate the conditions and criteria for changing the levels of the power distribution hierarchy according to physiological and social needs.
Household electric energy consumption has a hierarchical nature which is based on providing social and physiological needs of a person and technical characteristics of premises, household appliances, and heating system. In order to make the hierarchical distribution of the allotted power for the household more accurate than in [19], the structure of the levels of distribution of electric energy in the form of a pyramid with six levels, presented in Figure 1, is suggested. The top level is the urgent needs and the necessities without which it is impossible to exist in today's world. These are: lighting, safety and security, the need to exchange information. This level of needs that cannot be delayed, they must be realized without delay. The hourly level of consumption of electric power of this level, on average for a household doesn't surpass 2.5 kWh, and the daily consumption is 10 kWh. Energy consumption at this level has been reducing in the last years due to the application of energy-saving bulbs in place of incandescent bulbs. The second top level of the pyramid relates to appliances for human physiological and social needs. These are appliances of small appliances-devices for performing various tasks of cooking or heating food and drinks, as well as for taking care of clothes and maintaining cleanliness in the household. A distinctive characteristic of these appliances is that they have low power, are applied in the presence of the user and have a short duration of operation. Besides, not more than two or three such devices are used in a household at the same time, and the total power of per hour consumption does not surpass 3 kWh. The total time of use of appliances of this level during the day does not surpass 4 hours. The third level of the electricity consumption pyramid is large household appliances. These are appliances which are used for long-term everyday household tasks: cooking and storage of food, laundry and other works. The basic differences of the equipment of this consumption level are that they are large in size and weight, they are stationary and their work is permanent or long-term, but allows temporary interruption of work, which does not lead to the loss of comfort or quality of work as intended. This includes refrigerators, freezers, stoves, washing machines, dishwashers and dryers. In case of necessity, the equipment of this level of electric power distribution permits a temporary stoppage of up to several tens of minutes. The household's maximum amount of energy consumption of this level can be 15 kWh, with a daily consumption of up to 70 kW. The fourth and fifth levels of the household energy consumption pyramid are connected with heating systems and the concept of thermal inertia of buildings. Maintaining the necessary temperature regime in the room is the most important human need, but the walls of the room have a large mass and the change of temperature inside the room occurs slowly. If the heating is switched off for some time, measured in tens of minutes, the temperature inside the room will not change. Heating can be classified as a low priority load. Preparation of hot water and heating in autonomous heating systems are produced by one heat generator, and HWS has priority. Accordingly, the fourth level of the energy consumption pyramid is HWS. The fifth -heating. The equipment of heat supply systems of the fourth and fifth levels when using electric heat power generation allows intermediate accumulation of thermal energy and the use of heat pumps. The accumulation of thermal energy for HWS and water heating can be provided by heat accumulators with a Keeping the temperature in the room belongs to the primary physiological needs and at a particular level of temperature in the room there is a change in the structure of the value system. In case the room is cold, a person is prepared not to use, for instance, the washing machine, but to use energy for heating. Correspondingly, there is a situation with the change of priorities of energy use and the structure of electrical load management can be characterized as multi-level, hierarchical, with variable priorities. In Figure 1, the arrows show the possible changes in priorities. Electricity consumption in a household must not exceed the allocated limits. The simultaneous use of all electric appliances in the case of an autonomous heating system with an electric boiler may exceed the allocated limit, in which case all appliances will be disconnected. To exclude the situation of disconnection of the electric power supply to the household it is necessary to determine the individual priorities, set numerical values (conditions for changing the priorities) of the disconnection of some loads. Electric stoves and microwave ovens are used for cooking. Electric stoves include several burners and an oven. The total energy consumption of food preparation for a household is usually 7kWh. However, ovens can and a number of burners can be turned off temporarily without loss of comfort. Only 1 or 2 low-powered burners should be considered appliances of permanent applicability. The rest of the kitchen heating appliances, as well as other equipment of large appliances can be temporarily turned off. To avoid disconnection of the electric network when the total power limit is exceeded, it is necessary to prioritize the energy consumption. It is possible to disconnect power to some electric appliances if they do not affect the realization of human needs or have a large thermal inertia.
The overall electrical energy consumption is the sum of the energy consumption of all electrical appliances turned on at the same time. The limit (15 kW) will almost always be surpassed, if the HWS heating, electric stove more than two burners and any electrical appliance or lighting is switched on. Comfortable living in the household in the absence of priority redistribution of electric power is excluded.
The character of the schedule of total consumption of electricity in the home is erratic. Reducing the weight share of energy costs for hot water preparation in this case is due to the use of an indirect heating boiler of 150 liters and an electric boiler with an algorithm for smooth operation at nominal capacity.
On the basis of situational graphs of consumption of electric energy, availability of priority of preparation of hot water before heating, inherent in the algorithms of operation of electric boilers, reserve volume of heated water in the boiler of indirect heating, intervals between using hot water by residents of an apartment or an individual house, we can state that the limit of 15 kW per hour for allocated electric power of the household with heated area up to 80 meters is enough.
The sixth level priority line for charging electric cars and other equipment designed to consume residual energy is formed by the inclusion of an additional priority relay in the circuit of energy consumption after the input circuit breaker. Comfortable consumption of electrical energy is provided by the installation of the priority relay of the power line of the electric boiler [31]. All appliances consumption refers to the priority level, the boiler is connected through a relay with the lowest priority. The algorithm of the electric boiler operates in the priority of HWS in relation to the heating mode. The priority relay is an electromechanical device, whose reliability depends on the number of actuations. To avoid permanent operation of the priority relay. Time relay must be added to the load circuit [32]. The set duration of the period of operation of the time relay is determined by the nature of fluctuations in the consumption of electrical energy in the room. It is advisable to consider loads of intermittent power greater than 1 kW. This can be a cooking stove, an iron, a kettle, a washing machine. The interval of checking the simultaneous use of these devices according to their operating schedules should not be less than five minutes. This is what should be accepted as the minimum interval of operation of the time relay of the priority control system of the power supply system of the household.

Conclusion
1. The structure of household energy consumption is influenced by many factors, including temporal, climatic, territorial, historical, social, age, gender, and political factors. The overall energy use is also influenced by the number and gender of family members, their employment and social life, habits, and lifestyles. 2. Energy consumption is of a multi-level hierarchical nature with alternating prioritization.
When a household is allocated a limit on its electrical energy consumption, simply adding up the capacity of the electrical appliances in use will result in multiple power outages. 3. Using the principles of priority switching off groups of electrical appliances allows you to eliminate the disconnection of limited power supply to the household while living as comfortably as possible. 4. The allocation of household electrical energy can be characterized by a hierarchical principle with six levels of priorities with alternating physiological thresholds for the use of heating appliances. 5. Individual houses and apartments of high-rise buildings with heated area up to 80 meters can use electric boilers effectively as heat generators for autonomous heat supply systems. As equipment for HWS preparation it is rational to apply indirect heating boilers of 150 liters with control by a three-way valve with priority on hot water. 6. The dedicated limit of 15 kilowatts per hour is enough to comfortably use any existing electrical appliances, and autonomous heating system for premises up to 80 square meters in the central part of the Russian Federation and up to 100 square meters in its southern and eastern regions or apartments in high-rise apartment buildings. 7. If heat pumps and heat accumulators are used for heating systems, the limit of 15 kWh is sufficient for the convenient usage of standard electric appliances in households up to 150 square meters, which are located in the central and southern parts of the Russian Federation.