Model of interruptible load contract for minimum compensation cost

As an effective measure of demand response programs, interruptible load management has been widely used in electricity markets. This paper addresses the problem of what impacts of interruptible load (IL) contracts will have on the equilibrium outcomes of electricity wholesale markets. First, a market demand model is developed to take considerations of IL contracts. Next, a linear supply function equilibrium model is presented for wholesale markets with IL contracts. The introduction of IL contracts leads to a non-smooth equilibrium problem. To solve this equilibrium problem, a novel solution method is proposed. Finally, numerical examples are presented to verify the effectiveness of the method, in which the uncertainty in market demand is considered to further reflect IL contracts' flexibility. It is shown that with IL contracts, market price and its fluctuation can be lowered. This effect is more obvious when the uncertainty in market demand is relatively large. Furthermore, to achieve the target of lowering market price and its fluctuation, the interruption threshold prices in the IL contracts should be determined carefully.

To ensure the safe and stable operation of the power system in the power market environment, a transaction model of power reserve ancillary services oriented to interruptible loads is constructed. By analyzing the benefits of interruptible users and power grid enterprises, a transaction model of interruptible load is established based on it. After obtaining the value of the minimum cost of power system to purchase interruptible load, the capacity cost, opportunity cost and standby use cost of power reserve are calculated respectively. The objective function of auxiliary power reserve service transaction model with interruptible load is established and the constraint conditions are set, and then the transaction result of auxiliary power reserve service is obtained by solving the objective function of the model. The experimental results show that the model can effectively calculate the power interruption compensation price of user interruptible load, and obtain the interruptible load transaction results according to the rapid capacity quotation, power quotation, etc. At the same time, the model has the lowest cost of reserve capacity and reserve use cost in a certain period of time, and the application effect is good.

There are two compensation methods for interruptible loads (ILs), namely low price compensation before supply unavailability and high price compensation after supply unavailability. Low price compensation is independent of power supply unavailability, while the high compensation is performed only after actual power supply unavailability. However, the IL with low price (ILL) and the IL with high price compensation (ILH) have only been studied separately till now. Based on risk management, this paper analyzes the different economic properties of the two compensation methods and concludes that their coordination is beneficial to restrain market power and reduce the cost of reserve capacity. The authors propose the coordination models and optimization algorithms by taking the sum of the deterministic reduction of revenue resulting from ILL and the risk of compensating ILH as the objective function. Simulation results are presented to validate the effectiveness of the proposed method.

This paper presents a novel adaptive control strategy for integrating direct load control (DLC) with interruptible load management (ILM) to provide instantaneous reserves for ancillary services in deregulated power systems. Fuzzy dynamic programming is used to satisfy customers' requirements and yields a near optimal pre-scheduling of the DLC. Then, the energy payback associated with the DLC is further eliminated by the adaptive control strategy, which exploits interruptible loads to modify the DLC schedule in real-time. Through the developed adaptive control strategy, the influences of the load uncertainties and forecasting errors on the pre-scheduling of the DLC can also be excluded. The proposed algorithm was practically tested on the Taiwan power (Taipower) 38-unit system with 20 air-conditioner loads and 15 interruptible loads. The outcomes reveal that an exact amount of instantaneous reserves can be successfully acquired, and the results are robust against dynamic disturbances of the power system.

With the increasing penetration of renewable energy sources such as wind and solar power, higher requirements of flexible supply ability for power systems are put forward. In this context, an optimal dispatching method considering two types of demand response is proposed to improve power system flexibility. On the demand side, both the time-of-use (TOU) price and interruptible load are used to guide consumers to actively optimize the load curve, so as to relieve the pressure of the flexible supply of conventional units on the supply side. The demand response model consisting of TOU price and interruptible load is built. Then, taking the minimum cost as the objective function, the optimization model for power system dispatching is solved. Finally, the modified IEEE 30 bus system is taken as a case study. The results show that the consideration of two-type demand response in the optimal dispatching can improve the flexibility while ensuring economy, which verifies the effectiveness of the proposed method.

In electric power systems, the generated power should be equal with the demand and power of network is mainly controlled through generation system. In such operation, the demand is satisfied through changing the generated power and afterward, the safe operation of power system is reached. But during recent years, a new concept has been developed in electric power systems namely demand side management (DSM). DSM is the modification of consumer demand for energy through various methods such as financial incentives and education. Usually, the goal of demand side management is to encourage the consumer to use less energy during peak hours, or to move the time of energy use to off-peak times such as nighttime and weekends. One of the important models of DSM is interruptible loads. Interruptible loads are the right for an electricity utility to interrupt supply to a customer, typically during a system emergency, to relieve short term network constraints up to a couple of hours. Interruptible loads can be deployed in one of two ways. The network operator gives notice of an interruptible load event to the customer, then relies on the customer to reduce their electricity usage; or unilaterally interrupts supply to the customer. In this paper, the effect of interruptible loads on the power system reliability is investigated. A multi machine power system is considered as cases study. Simulation results show the great effects of interruptible loads on the power system reliability.

Interruptible load as one of the important measures of demand response could provides the Safe and stable operation of power system with new schedulable recourse. According to the characteristic of the load forecasting accuracy in inverse proportion to the time span, this paper proposed that Interruptible load dispatch can be divided into the day level, the hour level and 15 min level in time dimension, and realizes the coordinative optimization of Interruptible load dispatch on different time scale. In this mode of coordinative optimal dispatch of interruptible load on multi time scale, the deviations left over by the preceding level are corrected by the next level based on the idea of "multi-level coordination, level by level refining"; and that could improve the reliability and practicality of Interruptible load dispatch. In the end, the example analysis will verify the scientific and Rational of the mode.

In demand-side-management, the interruptible load management (ILM) plays an important role in constructing smart grid. One important issue is concentrate on how to determine the incentive payment for the ILM. The integration of consumers' willingness to curtail load in the ILM is helpful to the optimum allocation of the limited electricity resource. In order to design such kind of mechanisms, the consumers' type parameters are introduced to reflect the consumers' willingness to load interruption. In the meantime, the pay-as-you-go method and the pay-in-advance method are presented to the incentive payment. The results show that consumers with relatively large willingness to curtail load get more payments. The self disclosure of consumers' willingness is another merit of these methods. Simulation results certify the validity of the proposed methods on ILM.

Coordinated optimization of source–storage–load in distribution network based on edge computation

Introduce the viewpoint of interruptible load into N-1 static security analysis of transmission capacity of transmission section; broaden the conditions of traditional N-1 analysis through using the interrupt load management in receiving areas. A detailed mathematical model of the power flow constraints of transmission section considering the interruptible load is established and the solving methods based on sensitivity analysis is also given, and the relationship between the increments of limit tranimission power of section and the interruptible load quantities is obtained on this basis. The IEEE39 nodes numerical example in BPA running environment shows that the application of interruptible load to improve limit tranimission power of section can improve the operation economy while guaranteeing the security of the power system.

In this paper, an economic scheduling of distributed generating units and drydock pumps in a shipyard is proposed. The objective function is to minimize the total electricity bill payment of a shipyard while considering its own generation to meet the demand. The volatile electricity market price, contracted capacity constraint, and interruptible loads (ILs) are all considered during the optimization. A significant saving can be achieved by the proposed optimization model.

Interruptible load management plays an important role in maintaining the reliability and security of power systems and reducing price spike of power markets, thus has been widely used in power systems. Interruptible loads dispatch problem with multi-period and multi-interruptible-load is usually a multi-objective, combinatorial optimization problem, and its solution method needs to be carefully investigated. Application of intelligent optimization algorithms to the multi-period interruptible load dispatch problem is discussed in this paper. Multi objectives, such as minimizing the interruption payments and interruption frequency, can be included in the proposed interruptible load dispatch model. The characteristics of different interruptible loads are also considered. Numerical simulations using discrete binary particle swarm optimization (BPSO) and the genetic algorithm (GA) show that the BPSO can obtain better solutions than that of the GA. Thus the BPSO presents better potentials in solving the interruptible load dispatch problem.

With the reform of the electricity market, considering demand response is an important way to improve the efficiency of microgrids. Aiming at the problem of power load scheduling, a demand-side response method considering interruptible load is proposed. First, the power consumption type of different users in the microgrid is analyzed. Second, the microgrid optimal dispatch model with interruptible load is established, and then the minimum operating cost of the microgrid and the maximum peak-cutting capacity in a specific period are obtained. Finally, a numerical example shows that the proposed interruptible load optimization scheduling method is beneficial to peak shifting and valley filling and to improve the economics of the microgrid.

Since electric vehicles (EVs) can operate in two modes, charging and regeneration, the idle EVs can support the system as a reserve resource through vehicle-to-grid (V2G) technology. Suppose, an ideal aggregator who has a great number of EVs joins the grid, and its idle EVs can supply aggregator itself partial power demand. The grid makes a contract for the interruptible loads (ILs) with the aggregator, they agree on the time and capacity that the grid can reduce the aggregator's power supply, meanwhile the aggregator could manage its idle EVs to supply its demand and get the compensation from the grid. Here the grid charge the working and idle EVs during off-peak. The wind speed profile follows a Weibull distribution. Based on 24-hour load forecast curve, an optimal model, whose objective is to minimize the total cost including generating cost, reserve cost, emission cost, loss of load cost and penalty cost for not using the available wind power capacity, is proposed. This model is applied to IEEE 30-bus system. The real load fluctuations, the wind power output and the fault outage of generators are simulated hourly. Then the optimal allocation of generators and minimum total cost are obtained by particle swarm optimization (PSO). Finally, based on Monte Carlo simulation, previous steps are repeated for 1000 times to achieve the final cost and its relationship curves with both the IL capacity and compensational price. (5 pages)

The millisecond-level source-grid-load precise control system detects power grid faults in real time, integrates various types of power supplies, pumped storage generators, energy storage power stations and interruptible loads into the control range, and realizes coordinated control of all resource objects in 100 milliseconds according to the operation mode and fault type of power grid. The system can not only solve various steady state problems of power system, but also meet the requirement of rapid measures for transient stability problems. When the fault occurs, the scheme of source-grid-load coordination control considers the regulation and control ability of some power supplies in order to reduce the shed load amounts, and the control system can just accurately trip some interruptible loads in industrial enterprise users, while important industrial loads remain, which have signed economic compensation contracts with power companies in advance. This paper describes the system architecture, functional design, key technology and engineering application.