Decentralized Demand Management Based on Alternating Direction Method of Multipliers Algorithm for Industrial Park with CHP Units and Thermal Storage

This paper proposes a decentralized demand management approach to reduce the energy bill of industrial park and improve its economic gains.A demand management model for industrial park considering the integrated demand response of combined heat and power(CHP)units and thermal storage is firstly proposed.Specifically,by increasing the electricity outputs of CHP units during peak-load periods,not only the peak demand charge but also the energy charge can be reduced.The thermal storage can efficiently utilize the waste heat provided by CHP units and further increase the flexibility of CHP units.The heat dissipation of thermal storage,thermal delay effect,and heat losses of heat pipelines are considered for ensuring reliable solutions to the industrial park.The proposed model is formulated as a multi-period alternating current(AC)optimal power flow problem via the second-order conic programming formulation.The alternating direction method of multipliers(ADMM)algorithm is used to compute the proposed demand management model in a distributed manner,which can protect private data of all participants while achieving solutions with high quality.Numerical case studies validate the effectiveness of the proposed demand management approach in reducing peak demand charge,and the performance of the ADMM-based decentralized computation algorithm in deriving the same optimal results of demand management as the centralized approach is also validated.

Dispatch Model for Integrated Heat and Power Systems Considering Internal Composition of CHP Plants

An integrated heat and power system(IHPS)is a promising approach for alleviating wind curtailment problems.In an IHPS,the combined heat and power(CHP)plant is the key component,which supplies both heat and electric loads,and couples the thermal system and power system.However,existing research commonly ignores or simplifies the internal composition of CHP plants,which could lead to some unavoidable errors.This paper focuses on the internal composition of CHP plants,and models the physical processes in different components and flexible resources in the CHP plant.Furthermore,a joint dispatch problem of an IHPS with the above CHP plant models is formulated,and an iterative algorithm is developed to handle the nonlinearity in this problem.Case studies are performed based on a real CHP plant in Northern China,and the results indicate that the synergistic effect of different energy resources in the CHP plant is realized by the joint dispatch model,which promotes wind power accommodation and reduces fossil fuel consumption.

Accommodation of Curtailed Wind Power by Electric Boilers Equipped in Different Locations of Heat-supply Network for Power System with CHPs

Electric boilers (EBs) provide an alternative method to deal with the accommodation of curtailed wind power. To pursue the minimum coal consumption in the system, a dispatching model integrating combined-heat-and-power (CHP) plants and EBs in different locations is developed, and the penalty of wind power curtailment and cost of EB employment are also incorporated in the model. The transmission loss and transportation lag of heat-supply network as well as the elasticity of heat load are considered in this paper. A kind of constrained programming with stochastic and fuzzy parameters is applied to deal with the uncertainties. A case in East Inner Mongolia in China demonstrates that the EBs are able to absorb curtailed wind power and supply the heat. The results indicate that the utility of EBs in the primary or secondary heat-supply network to accommodate curtailed wind power is mainly related to the efficiency of heat transmission and the elasticity of heat load.

Environmental impacts concerning flexible power generation in a biogas production

Combined heat-and-power units(CHPUs)of biogas plants can be operated at partial load or in intervals to respond to market conditions or interventions by the grid operators.In this study,we present calculations for the specific greenhouse gas(GHG)emissions of electricity from biogas driven CHPUs in dependence of engine load.Following the methodology of life cycle assessment and using measured data from five real-world biogas plants in Bavaria,we investigated the following scenarios for the operation of the CHPU:(1)full load,(2)80%load response and(3)60%load response.Our system boundary included the whole biogas production chain,starting from the production/supply of the input materials and ending at the supply of electricity(functional unit:1 kWh of electrical energy fed into the grid).As electrical efficiency and engine load are positively correlated,partial-load operation results in higher specific GHG emissions of electricity from biogas.The impact of decreasing efficiency of the CHPU under partial load on overall specific GHG emissions turned out to be higher than the influence of methane slip from the engine.Furthermore,the increase of further efficiencies such as higher yields,efficient use of synthetic and organic fertilizers,as well as minimization of fuel consumption and the use of regenerative fuels also lead to further decrease of GHG emissions.