The Assessment Method Of Building Energy Flexibility And Its Utility In Residential Buildings

With the improvement of renewable energy utilization and the development of smart grid,it is more feasible to enhance the flexibility of supply side and demand side to meet the real-time generation,transmission,distribution,power consumption and dispatch of power grid.Facts have proved that fully tapping the energy flexibility potential of building users can effectively achieve the goals of reducing energy costs,transferring peak power consumption,increasing the proportion of renewable energy in the field,and enhancing the stability of power network.From the perspective of interaction between users and smart grid,this paper constructs the definition of energy flexibility potential of building users.It divides the participants into three categories:flexible load,distributed energy system and energy storage system,and determines the research scope of building users as a whole energy;and the size of energy flexibility potential,as a unique and original characteristic of building users,has the characteristics of time,bidirectional interaction and adjustable characteristics of capacity or energy consumption.Based on the principles of comprehensiveness,comprehensiveness and applicability,this paper establishes a set of evaluation parameters for regulating potential(increasing or decreasing bi-directional regulation range),response time and relative regulation potential of building capacity or energy use;and based on the set of parameters,it puts forward the logic of building energy flexible database.According to the flexible characteristics,users are sorted to form a hierarchical scheduling method for different types of users to participate in flexible demand response.Considering the environmental geological conditions,design parameters of building body,parameters of energy equipment and usage of building and its equipment,the evaluation parameters are calculated by combining theoretical model with dynamic simulation,which ensures the scientificity and operability of the results.Taking the typical residential user units and groups in hot summer and cold winter areas as an example,it analyses the flexible adjustment potential characteristics of such users when they participate in dispatching by adjusting the operating temperature of air conditioning,closing air conditioning,reducing lighting power,changing the working time of washing machines and configuring renewable energy system.When the air-conditioning temperature is increased to provide downward flexibility potential,its value and outdoor temperature show a piecewise regression relationship;the response ability of the strategy is weak between 0 and 5 o'clock every night;and the ability is strong between 17 and 23 o'clock at night.The flexible adjustment ability of downward air-conditioning temperature supply load upward has nothing to do with operation date and start time;the comprehensive ability between 5 and 6 o'clock is stronger,and the flexible adjustment ability decreases with the extension of response time;the larger the temperature adjustment range,the greater the flexible adjustment ability.In addition,the thermal performance of the building envelope has little effect on the flexible adjustment potential of the strategy,and the service level of the building has a greater impact on the evaluation parameters.In the intermittent energy consumption mode,which takes into account the human energy use behavior and comfort requirements,the flexible adjustment potential of users has obvious disadvantages in terms of time,bidirectional interaction and adjustable load.It should be noted that the rebound effect of load by using the strategy should be fully considered to avoid new energy use peak time.The flexibility potential of air conditioning start-stop strategy is related to the outdoor temperature;when the outdoor temperature is maintained between 24 and 28 degrees Celsius,the response time is the longest and the load can be reduced the largest;when the outdoor temperature is too low or too high,the flexibility adjustment potential is zero.The strategy of reducing lighting power is better at 18 to 23 o'clock at night.When using the transferable load of intelligent appliances such as washing machines to respond to flexible demand,it will cause the reduction of load in the original working period and the increase of load in the period after energy transfer.We can use different strategies to overlay or offset the changing load.The solar photovoltaic panel will change the interaction mode between users and power grid:when the configuration of photovoltaic panel is small,its power generation can't fully cover the user's electricity load demand.During the daytime,it will weaken the user's electricity purchases,thereby reducing the demand for downward regulation of the power grid;at night it will not have an impact.When the configuration of photovoltaic panels is large and residual power is connected to the grid,the user will have the flexible adjustment ability of purchasing power from the grid and connecting residual power to the grid.Residential user groups can provide considerable flexible adjustment potential value by using the above combination strategy.Among them,the contribution of air conditioning load is the highest,followed by washing machine,and the load reduction provided by reducing lighting power is the smallest.Moreover,the user's energy consumption mode and willingness to respond will greatly affect the effect of the user group in responding to the flexible demand of power grid.