Modeling And Simulation Research On Direct Load Control For The Energy Internet

With the gradual depletion of fossil fuels, the contradiction between energy crisis and environmental issues become more and more acute, and accompanied by wind power, solar and other clean energy installed capacity increased year by year, clean electricity energy must be the dominant of the future energy mix, and gradually replace fossil energy. It is a extremely difficult task for the power grid cope with the grid connect accommodation of large-scale wind power as the representative of clean electricity energy, because of wind power’s inherent randomness and uncertainty, the energy internet concept is proposed by energy industry, under the framework of energy internet, clean energy grid connect, energy storage, and the problem of energy deployment and transportation can be effectively addressed.This paper is based on the background of the wind power accommodation in distribution network, and regards direct load control technology belongs to incentive based demand response as the cutting point, and has systematic studied on direct load control strategy considering the thermal comfort level of consumers and payback load effect, direct load control model and simulation technology for clean energy accommodation, and the virtual energy storage potential of air conditioning load direct load control is excavated deeply under the background of energy internet. The main content of this dissertation is as follows:(1) Users are the main body participating in direct load control project, and payback load effect will direct impact on the effect of the implementation of direct load control. The paper studies the control strategy of central air conditioning load considering the thermal comfort level of consumers and payback load effect under the background of the energy internet. The influencing factors of the consumer thermal comfort level of central air conditioning load and payback load effect are analyzed. Theory of enthalpy is used to decouple the effective temperature into two variables latent heat and sensible heat which is stands for the thermal comfort level of consumers. The variables are fuzzed by fuzzy control theory, and then the DLC strategy of fuzzy thermal comfort level control algorithm based on least enthalpy estimation is proposed. The thermal comfort level of consumers and payback load effect curtailment are affected by different turn-off duration. At last, the simulation result shows the proposed method can effectively reduce the payback load, maintain the thermal comfort level 80% above, and 25%-35% energy saving effect is reached.(2) For coping with the task of the clean energy grid connect accommodation in distribution network, the paper studied the direct load control technology and proposed a novel load power control method by changing the set point temperature in the thermodynamic controllable loads. The thermodynamics controllable loads transmission dynamic model is established based on a set of two coupled partial differential equations, and then it is approximated to the control oriented finite-dimensional state space model using the finite difference method. The power tracking sliding mode variable structure control (SMVSC) strategy is proposed which can deal with the uncertainties of variable power generation, and its convergence is verified by Lyapunov stability theory. Taking a small distribution network, as an example,1000 cooling air conditioning loads are simulated and power tracking error analysis shows that wind power can effectively track the wind power accommodation target, and the set point temperature control analysis results show that the proposed method is accepted by more than 90% users. The method paved the path for the demand-side response load in clean energy Accommodation applications.(3) For excavating deeply the virtual energy storage potential of air conditioning load direct load control, the paper studied the virtual storage features and energy storage capacity of aggregate air condition loads (ACLs) of demand side reflected from wind power accommodation under the background of the energy internet. The virtual energy storage features of changed set temperature aggregate ACLs was verified by Monte carlo simulation, The aggregate ACLs state space model was established on the base of two coupled partial differential equations, and the power of wind power-energy storage-aggregate ACLs union system used as the sliding surface of power tracking sliding mode variable structure control strategy was proposed which can realize the smoothing output of union system power. At last, the aggregate ACLs accommodation of real wind power plant was simulated by changing the set temperature, the result shows that the proposed method can accommodate the wind power filtered by a low time constant, and the set temperature changed within 1℃, the virtual energy storage capacity can reach more than 90MWh. The method paves the path for the energy reasonable allocation in energy internet and reducing of energy storage allocation.(4) For realizing clean energy accommodation by coordinating control of electric vehicles in distribution network, the paper studied the model and control method of aggregate plug-in electric vehicles charging loads (Evs) direct load control for the uncertainly clean energy accommodation. This paper assumes that the dispatch department can direct control the charging power by broadcasting a universal control signal in real time to complete the wind power accommodation. First, the aggregate plug-in electric vehicles charging loads model based on a partial differential equation is established by using the transport-based load method. Then, the model is simulated through the real resident travel data, the effectiveness is verified by Monte Carlo simulation. This paper developed the sliding mode variable structure control strategy to track the wind power output by using the difference between supply and demand in real time. Last, the performance of the control strategy is verified through the real wind power output curve, and also paved the path in clean energy accommodation applications.