Yi Ding

A Framework for Incorporating Demand Response of Smart Buildings Into the Integrated Heat and Electricity Energy System

The electricity output of combined heat and power (CHP) units is constrained by their heat output corresponding to customers’ heat demand, which makes it difficult for the CHP units to frequently adjust their electricity output. Therefore, additional balancing power is required to integrate the variable wind power in the CHP-based heat and electricity integrated energy system (HE-IES). This paper expands the demand response (DR) concept to the HE-IES. A comprehensive DR strategy combining energy substitution and load shifting is first developed to exploit the demand flexibility of smart buildings. Besides electric balancing power, heat balancing power is also provided to relax the production constrains of CHP units. Moreover, a real-time DR exchange (DRX) market is developed where the building aggregators are stimulated to adjust buildings’ energy consumption behaviors and provide the required balancing power. Compared with the existing day-ahead DRX market, the real-time DRX market can balance the very short-term wind power fluctuation and reduce price spikes. Additionally, a novel optimum feasible region method is proposed to achieve the fast clearing of the DRX market to meet the higher requirement for clearing speed in the real-time market. Simulation results verify the advantages of the proposed technique.

Price elasticity matrix of demand in power system considering demand response programs

The increasing renewable energy power generations have brought more intermittency and volatility to the electric power system. Demand-side resources can improve the consumption of renewable energy by demand response (DR), which becomes one of the important means to improve the reliability of power system. In price-based DR, the sensitivity analysis of customers power demand to the changing electricity prices is pivotal for setting reasonable prices and forecasting loads of power system. This paper studies the price elasticity matrix of demand (PEMD). An improved PEMD model is proposed based on elasticity effect weight, which can unify the rigid loads and flexible loads. Moreover, the structure of PEMD, which is decided by price policies and load types, and the calculation method of PEMD are also proposed. Several cases are studied to prove the effectiveness of this method.

Reliability assessment of UHVDC transmission system based on bipole symmetry

This paper proposed a reliability assessment method of ultra-high voltage DC (UHVDC) transmission system. Considering the bipole symmetry of UHVDC transmission system, the state space model for evaluating reliability of UHVDC can be simplified for effectively reducing the problem dimension. Then, due to the standby effect of the alternating current filter and the recovery effect of the converter bridge, the Universal Generating Function (UGF) method is used to realize the state combination of the unipole multi-state system. Case studies of typical UHVDC transmission system are presented to illustrate the proposed method. Sensitivity analysis is also conducted to quantify dependency of reliability on parametric change.

Optimal day-ahead and intra-day scheduling of energy and operating reserve considering fluctuating wind power

High penetration of wind power increases the complexities in system planning and operation. How to determine the required amount of operating reserve becomes a major problem due to the uncertainty and fast fluctuation of wind generation. Most of existing schedule methods determine the amount of operating reserve in day-ahead optimal scheduling considering economic costs and reliability indexes. However, they are not completely accurate due to the day-ahead forecast error of wind power and loads. It is well known that the forecast error of wind power and loads decreases from long-term timescale to short-term timescale. Therefore, it is important to develop an optimal schedule of energy and operating reserve in both day-ahead and intra-day to minimize total system cost considering ever-changing forecasted wind power. The spinning reserve is solved by day-ahead schedule to deal with contingencies like outages of units and other instantaneous failures. It will not change in intra-day schedule. Regulating reserve is pre-scheduled in day-ahead schedule and later adjusted in intra-day schedule due to the reduction of forecast errors of loads and wind energy. Both of the reserves can be provided by generators and demand response. We illustrate our methods in a modified 4-bus 9-generator system. Analysis shows that the proposed methods can provide a useful reference for system operators to schedule day-ahead, intra-day plan of energy and operating reserve. The system fluctuation induced by accessing wind energy is restrained by progressively utilizing a series of optimal allocations of energy and operating reserve in thermal power plants to enhance the secure and economical system operation.