51results about How to "Relieve peak shaving pressure" patented technology

The invention discloses a method for accurately estimating wind power prediction error intervals. The method comprises the following steps: firstly, obtaining historical wind power data of a wind power plant; secondly, calculating wind power predication errors of all prediction points of the wind power plant, and establishing a wind power predication error distribution model; thirdly, establishing an error probability density function according to the distribution of the predication errors; fourthly, obtaining a confidence interval, meeting a certain confidence level, of the predication errors according to a given wind power predication value; and fifthly, calculating the shortest confidence interval through a Lagrange multiplier algorithm. On the basis of point predication, a probability density function of wind power prediction errors is obtained through interval prediction, and the confidence interval under a certain confidence level is calculated by a probability theory. In this way, the reliability of the interval to contain a wind power point predication value is determined, and the precision of wind power interval prediction is effectively improved.

The invention relates to a method for controlling distributed power resources of active power distribution networks. The method is characterized in that unified dispatching and partition controlling effects are realized by the method, and the method includes steps of (1), determining a power coordination control scheme for the power distribution networks; (2), determining power coordination control objectives of the power distribution networks; (3), judging whether a power coordination control target is a peak load shifting control objective or not; (4), implementing the peak load shifting control objective; (5), implementing a protocol load curve operation control objective. The control objectives include the protocol load curve operation control objective and the peak load shifting control objective. The method has the advantages that a resource coordination control mode for the active power distribution networks is provided by the method and conforms to principles of 'unified dispatching and hierarchical control' of the traditional power transmission-distribution networks, and the power coordination control scheme is provided for establishing a distributed power capacity management system and is suitable for regions, micro-grids and tie lines.

The invention discloses a nuclear power involvement grid peak shaving judging method based on grid peak shaving capacity balancing. The method is based on operation data of a system and the characteristic quantity of the system is extracted. The characteristic quantity comprises a unit involvement grid peak shaving sequence, different peak shaving means force outputting conditions, the adjustable capacity, the load level of the grid and the like. The peak shaving capacity conditions which have peak shaving priority over all peak shaving means of a nuclear power unit are calculated and whether the peak shaving capacity conditions meet the requirements of the grid or not is judged. The requirements for the mode of the nuclear power involvement grid and the peak shaving depth are determined. Finally, the nuclear power involvement grid peak shaving depth range is determined by combining with nuclear power self power adjusting constraints. By combining with actual requirements of the grid and according to the peak shaving priority, nuclear power is brought into grid peak shaving. Factors such as grid economy, safety, reliability and the like are considered and the peak shaving pressure of the grid is relieved.

The invention relates to an economic dispatching technology of a power system, in particular to a multi-source optimal dispatching method considering coordination of wind power, nuclear power and pumped storage. The method includes a step 1 of taking into account the cost of abandoning wind and the cost of peaking of nuclear power, and constructing a coordinated optimization model of wind core with multiple power sources; a step 2 of Linearizing the nuclear power peak shaving constraint by subdividing the nuclear power peak shaving depth, solve the scheduling model based on Cplex, and making the scheduling plan. By taking into account the cost of wind power and nuclear power peak load regulation, wind power and nuclear power are included in the coordinated dispatching, which can greatly alleviate the pressure of peak load regulation, reduce the frequent start-up and shutdown of conventional generating units, and improve the operation economy of the power system with wind power and nuclear power in the coastal area. By subdividing nuclear power peak shaving depth linearization nuclear power peak shaving constraint method, nuclear power peak shaving operation constraint linearizationis realized, so that the scheduling model can be solved efficiently based on commercial optimization solver Cplex, and an accurate optimal scheduling scheme can be obtained, which is helpful to reduce the system operation cost.

The invention discloses an ultra-low-load operation system and an operation method for coal-fired generating units. The system is composed of two coal-fired generating units which operate in a unifiedmode, and each coal-fired generating unit consists of a steam turbine, a steam system, a vacuum air exhaust system, a condensed water system and a water feeding system; the steam systems of the generating units are connected through a heat steam connecting tube; and the water feeding systems of the generating units are connected through a water feeding connecting tube. The ultra-low-load operation system concentrates steam outlet force when the two units operate under ultra-low load on a main boiler, and solves the problems that boiler consumption is unstable, a coal mill, a fan and a denitrification reactor are unstable and the like when current coal-fired generating unit operates under the ultra-low load, and greatly improves safety and reliability of boiler operation control.

The invention discloses a plant network coordination method for exciting the combined operation of a wind power plant and a pumped storage power station and a combined dispatching method thereof. Themethod comprises the steps of firstly, providing a plant-network coordination mechanism for exciting the combined operation of the wind power plant and the pumped storage power station from the requirements of stable operation of a power grid and income improvement of a power generator; on the basis, carrying out modeling analysis on the uncertainty of wind power output, fully considering the operation characteristics of the pumped storage power station, constructing a wind power-pumped storage power station coordinated operation mixed integer programming model with the maximum complex power generation income as the target, and then using an optimization solver for solving the model. By the adoption of the method, the combined dispatching of wind power and pumped storage can effectively restrain the output fluctuation of the wind power, the risk of wind curtailment of a power grid is greatly reduced, and meanwhile the power generation income of a wind power plant-pumped storage power station combined body is remarkably increased.

The invention relates to the technical field of power storage and supply, in particular to a user-side peak-shaving power storage and supply system and method. The user-side peak-shaving power storage and supply system is composed of a peak-shaving power supply regulator 1, a monitor 2, an electric control switch 3, a charger 4, an inerter 5, a storage battery pack 6, an input port 7, an output port 8 and a remote monitor 9. The user-side peak-shaving power storage and supply system can be applied in an off-grid manner, is economic and efficient, is convenient to popularize, can also be applied in a grid-connected manner to achieve a complete controlled effect and realize bidirectional monitoring and metering for power supply and power utilization and benign sharing, and has the advantages of being positive and effective as well as environment-friendly and energy-saving for peak shaving of a power grid, reducing occupancy to and wastes of social resources, having no adverse influences to the power grid, realizing grid-connected power supply under a controlled power grid condition, and improving the blackout start capacity of the power grid and the robustness of the power grid.

The invention relates to the technical field of wind power dissipation, in particular to a unit combination method considering deep peak load regulation of a thermal power unit under the condition ofgrid connection of wind power, in particular to a method for improving peak load regulation capacity of the thermal power unit under the condition of grid connection of wind power. Including: unit commitment algorithm; Objective function of unit commitment; Constraints of unit commitment; Solution of unit commitment; Operation Flow of Unit Commitment. Under the condition of large-scale wind powergrid connection, the invention considers that a certain reserve is reserved for the wind farm to balance the change of the wind power output. When the load is low, the conventional power plant unit has been adjusted to a lower output, if the wind farm output increases significantly at this time, the acceptance of wind power will be limited, resulting in wind power discarding limit. Genetic algorithm is used to find the global optimal solution, and the economy of deep peak shaving scheme is analyzed under the condition of large-scale wind power grid. Solve the problem of not abandoning the windabsorption, save the thermal power unit power generation cost, so that 'deep regulation absorption' is feasible.

The invention provides a power system source-load-storage coordinated rolling scheduling method based on flexibility margin, and relates to the field of power generation scheduling of power systems. The method comprises the following steps: firstly, determining an uncertain interval of wind power output and load, and establishing a flexible supply capacity model corresponding to each flexible resource; on the basis, respectively establishing a power system flexibility demand capacity model and a flexibility supply capacity model, and determining a flexibility margin index; then establishing asource load storage day-ahead coordination scheduling model and solving; and in each rolling period in the day, establishing and solving a source load storage intra-day rolling scheduling model of therolling period, and finally obtaining a scheduling result of each intra-day rolling period. Flexible resources such as a wind turbine generator, a thermal power generating unit, a gas-electric unit,a pumped storage unit and an interruptible load are taken into consideration, actual engineering can be effectively met through the scheduling plan formulated by the invention, and the operation economy and reliability of a power system are optimized.

The invention discloses a resident power consumer real-time off-peak transaction method based on an Internet platform. The method comprises the following steps: selecting a response target group of aregional power grid demand side; formulating a dynamic invitation mechanism according to the real-time peak clipping demand of the power grid, and sending the invitation mechanism to the response target group; and exciting the response target group according to the peak clipping feedback of the response target group. According to the method, a real-time invitation transaction mode is adopted to guide resident users to shift peaks, so that the load peak-valley difference is reduced, the peak regulation pressure of a power grid is relieved, and the network loss is reduced.

The invention belongs to the field of electric power system dispatching, and discloses a water-fire-electricity system trans-provincial peak-regulating load distribution method. According to the water-fire-electricity system trans-provincial peak-regulating load distribution method, the method is based on the characteristics of load changes of a plurality of provincial level power grids, a load sequencing strategy is brought in, and each power grid load sequencing position of time frames serves as heuristic information to conduct force output distribution. According to the technical scheme of the water-fire-electricity system trans-provincial peak-regulating load distribution method, the initial electricity receiving and force output process of each power grid is acquired through successive load shedding, output force of the time frames corresponding to all grids is accumulated, a time frame set going against the power station electric power balance limit is confirmed; as to any output force positive deviation time frame, a power grid with the maximum surplus load order position value is searched, the power output force of the grid at the time frame is further reduced, and meanwhile a negative deviation time frame with the maximum surplus load value is confirmed; the output force of the time frame is increased according to the same amplitude, and the force output process is repeated until all time frames satisfy the electric power balance limit. According to the water-fire-electricity system trans-provincial peak-regulating load distribution method, a target function does not need to built, the amount of optimizing calculation is substantially reduced, an optimizing result satisfying actual engineering requirements can be fast acquired, and the method is achievable, and has important theoretical and practical significance in regulating and controlling large power grid electricity resource distribution and relieving increasingly-serious power peak regulation pressure.

The invention provides a direct-current microgrid system and a control method. According to the invention, the DC microgrid system is connected with a power grid orderly via a bidirectional electric energy conversion module and a switch, and comprises a renewable power generation module, a direct-current bus, a hydrogen storage module, a power consumption module and a control module. In the direct-current microgrid system, power is distributed through the direct-current microgrid system, the hydrogen is produced, and the requirements for hydrogenation, charging (including hydrogen fuel cell vehicle charging and pure electric vehicle charging) and illumination are met; the wind power and photoelectricity are effectively consumed, the electric energy does not need to be converted multiple times in the alternating current and direct current forms, the energy utilization efficiency is improved, and the energy loss of the direct current microgrid is reduced. Moreover, the electric energy isfed back to the power grid, and the peak regulation pressure of the power grid is relieved.

The present invention discloses a method and a device for making a plan of power transmission and receiving between regions. The device comprises the steps of: determining a peak regulation demand factor [Alpha]I of the power grid of each region according to the peak regulation demand of the power grid of each region; constructing a target function as shown in the description of an optimization model of a plan of power transmission and receiving according to the peak regulation demand factor [Alpha]I of the power grid of each region; establishing constraint conditions of the target function; and establishing the optimization model of the plan of power transmission and receiving between the regions according to the target function and the constraint conditions; performing optimization calculation of the optimization model to obtain a plan of power transmission and receiving between the regions. The method and the device introduce the peak regulation demand factor to allow the optimization model to consider the actual peak modulation demand of the power grid of each region and consider the complementary features of the load and the power supply between the regions so as to effectively relieve the peak modulation pressure of the power grid of each region, improve the peak modulation capacity of the power grid of each region and the economic benefit of operation of the power grid and have high feasibility and reliability, and therefore, the method and the device for making a plan of power transmission and receiving between regions are suitable for engineering reality and the management system of large-region power grids in our country.

The invention discloses a peak regulation controller and method for a large-scale energy storage power station based on ANFIS short-term load forecast, and the controller comprises a peak regulation main station module and an energy storage substation module connected with the peak regulation main station module. The peak regulation main station module comprises a floating-point calculation processor, an FPGA processor, a CAN communication interface, a power module, a display module, an RAM storage unit, a scheduling network port, and a key. The floating-point calculation processor is connected with the FPGA processor, and the CAN communication interface and the key are connected with the floating-point calculation processor. The power module is connected with the floating-point calculation processor and the FPGA processor. The display module, the RAM storage unit and the scheduling network port are connected to the FPGA processor. The controller can estimate the comprehensive charge level of an energy storage power station in real time, achieves the prediction of a regional grid load, achieves the coordinative control of the charging and discharging power of a plurality of groups of energy storage batteries in the power station, gives full play to the quick and flexible power throughput capability of the large-scale energy storage power station, participates in the peak-load shifting of a power grid, and effectively alleviates the peak-load shifting pressure. Meanwhile, the controller optimizes the charge level of the energy storage batteries, avoids the overcharge and overdischarge faults, and prolongs the service life of the batteries.

The invention belongs to the technical field of power grids and particularly relates to a method for minimizing a peak-valley difference by coordinating an electric heat storage load with battery energy storage, and the power grids can minimize the peak-valley difference by coordinated operation of the electric heat storage load and the battery energy storage. The method includes the following steps: performing data acquisition; performing prediction calculation on a household load during a peak period; calculating influence of electricity price A on an added electric storage heat load at a valley moment; calculating charging and discharging coefficients of the battery energy storage; calculating charging and discharging time of a storage battery; and performing calculation on the method for minimizing the peak-valley difference according to the influence factors and period and valley moments. The method can alleviate the peak load regulating pressure of a unit, and can relieve outputof a heat power unit at the peak moment, so that the peak load regulating pressure of the heat power unit is reduced. A corresponding electricity price can be made from difference of electricity consumption in different periods, peak load shaving can be performed by combination of the storage battery, and the peak-valley difference is minimized.

The invention discloses a thermal power generating unit climbing pressure relieving method under high-proportion photovoltaic grid connection. The method comprises steps of (1) based on predicted photovoltaic power generation power and load power, performing calculation to obtain a net load duck curve caused by high-proportion photovoltaic grid connection; (2) building a light storage system structure model for high-proportion photovoltaic grid connection, and determining a high-proportion photovoltaic grid connection coordinated optimization operation method based on the light storage systemstructure model; (3) constructing a mathematical model for relieving the climbing pressure of a thermal power generating unit under high-proportion photovoltaic grid connection; (4) solving the constructed mathematical model for relieving the climbing pressure of the thermal power generating unit under high-proportion photovoltaic grid connection based on a linear programming simpleness method; and (5) based on the solving result, relieving the climbing pressure of the thermal power generating unit under high-proportion photovoltaic grid connection. The method is advantaged in that the photovoltaic absorption level is improved, comprehensive operation cost is reduced, peak-valley difference is reduced, the climbing pressure of the thermal power generating unit is relieved, and operation stability of the thermal power generating unit is guaranteed.

The invention relates to a peak regulation scheduling method for an energy storage power station in a power system, and belongs to the technical field of power system scheduling. According to the method, a power system peak regulation scheduling optimization model comprising an energy storage power station to improve the peak regulation capability of the system is constructed, and meanwhile, the voltage deviation of each node is considered in the model to meet the requirement of system safety. The model takes the minimum system peak regulation scheduling cost and the minimum time sequence average value of the sum of squares of normalized voltage deviations of all nodes as multiple targets, and the considered constraint conditions comprise system constraints, unit constraints and energy storage constraints. The genetic algorithm is employed for solving the optimization model. According to the method, the energy storage power station participates in system peak regulation to improve thesystem peak regulation capacity, and the thermal power generating unit peak regulation pressure is relieved; meanwhile, the system safety and the electric energy quality are guaranteed through dispatching, and a certain reference effect is achieved for the energy storage power station participating in peak regulation.

The invention discloses an extra-high-voltage direct current correction method considering sending-end and receiving-end power grids. The method comprises the following steps: establishing an extra-high-voltage direct current correction model objective function considering a new energy consumption space of the sending-end power grid and a peak regulation margin of the receiving-end power grid; establishing constraint conditions of the extra-high-voltage direct current correction model objective function; calculating and determining a corrected extra-high-voltage direct current tie line power curve according to the extra-high-voltage direct current correction model objective function and the constraint conditions; and adjusting the power of an extra-high-voltage direct current tie line according to the corrected extra-high-voltage direct current tie line power curve. The method considers reduction of wind curtailment and light curtailment rates of the sending end, and meanwhile, reducespeak shaving pressure of the receiving-end power grid and ensures stable operation of the receiving-end power grid.

The invention provides a power generation optimization scheduling method based on load area electricity prices. The method comprises steps of dividing a schedulable load curve into a base load, a waist load and a peak load so as to divide different areas into a large number of energy blocks and mark the energy blocks at different positions with different electricity prices; then filling the energyblocks with the power generated by different power plants with different electricity prices; and finally obtaining the optimal power generation optimization scheduling result. The method enables eachpower plant to fill the energy blocks corresponding to the load curve with the electricity price and power of load characteristics in combination with its own power generation characteristics, thereby mobilizing different types of power plants to use their peak load regulation advantages to earn more profits, to consciously participate in system peak load regulation, and to greatly relieve the system peak load regulation pressure.

The invention discloses a heat-moisture treatment device driven by an urban heat supply network, which belongs to the technical field of heat-moisture treatment devices. The heat-moisture treatment device comprises an absorption set, a dehumidification set and connecting pipes, wherein the high-temperature water supply of the urban heat supply network is used as the driving heat sources of the absorption set and the dehumidification set so as to realize the energy-level use and graded use of hot water of the heat supply network, the absorption set is used for realizing thermal load processing, and the dehumidification set is used for realizing moisture load processing; and the absorption set comprises a high voltage generator, a low voltage generator, a condenser, an absorber, an evaporator, a plurality of solution heat exchangers, a solution pump, connecting pipelines and accessories. The invention has the greatest advantages of improving the energy utilization and economy of a thermal power plant in summer, reducing the electrical load for refrigeration in summer, alleviating the pressure on peak load regulation so as to help to ensure the normal power demands of the residents in summer, realizing the graded use of thermal energies, and improving the annual utilization rate and comprehensive energy utilization rate of the heat supply network so as to facilitate energy conservation and emission reduction.

The invention discloses a virtual power plant peak regulation method based on incentive electricity price, and belongs to the technical field of economic operation and optimal dispatching of a power system. The method comprises the following steps: step 1, carrying out load prediction on a power grid dispatching control center before an operation day, and issuing load characteristics, peak regulation demands and weather prediction data of the next day; 2, enabling the virtual power plant control center to formulate excitation electricity prices in all time periods by using the data obtained in the step 1, and determining a scheduling plan; 3, determining the response capability of the load in each time period, and forming a day-ahead peak regulation plan by the virtual power plant; according to the output of the virtual power plant and the conventional unit, enabling the power grid dispatching control center to formulate a day-ahead peak regulation plan of the virtual power plant and the conventional unit; and 4, correcting the day-ahead peak regulation plan on the operation day to form an intra-day peak regulation plan. The maneuverability and flexibility of the demand side distributed resources participating in the power grid are fully improved, and the invention has good application value.

The invention discloses an energy storage peaking control method based on dual-time scale net load prediction. The method comprises the following steps: 1, based on a day-ahead net load prediction result, the SOC sequence of the energy storage system and the post-peaking tie line power are obtained through objective function optimization, and energy storage energy flow optimization is completed; 2, the post-peaking tie line power obtained in the first step is expanded to a tie power interval; and 3, based on the intraday rolling prediction net load power with the accuracy higher than the day-ahead prediction accuracy and the SOC sequence obtained in the first step, the actual charge / discharge power of the energy storage system is corrected in the tie line power interval in the second stepto complete energy storage peaking control. Compared with day-ahead net load prediction, ultra-short-term rolling prediction provides a more accurate reference for setting of the charge and dischargepower for energy storage, the fast energy storage and flexible throughput capabilities are fully utilized, the post-peaking tie line power is smoother, and the peaking pressure is alleviated.

The invention discloses an energy-saving control device for a coal-to-electricity user air source heat pump. The energy-saving control device comprises a communication module, a storage module, a calculation module, a microprocessor module, air source heat pump equipment and an interface module; a load aggregator transmits demand response information to the coal-to-electricity user through the communication module; the air source heat pump equipment is inserted into the interface module for communication; the storage module stores information collected in the communication module and a control strategy and related configuration parameters when the device works normally; the microprocessor module is used for controlling the air source heat pump equipment to operate based on the communication information; and based on the collected actual operation state of the air source heat pump equipment, coal-to-electricity user load reduction amount and energy-saving income are calculated.

The invention discloses a regional power grid electric vehicle peak regulation optimization scheduling method based on two stages, and relates to the field of regional intelligent power grids. According to the scheduling method, the method includes performing classification according to electric vehicle (EV) load operation characteristics, and building four EV load models of rigid, schedulable, flexible and intelligent battery replacement respectively; giving an EV peak regulation pricing strategy on the basis of a fuzzy analytic hierarchy process (FAHP) by considering various costs of EV participating in peak regulation; in the first stage, taking the minimum load peak-valley difference as a target, and performing decision making on EV peak regulation pricing under the target, so that the peak regulation capacity of a power system is reduced, and regional power grid load distribution is adjusted; and in the second stage, depending on the peak regulation pricing curve obtained in the first stage, arranging the EV load by taking the minimum charging cost of the EV user as a target. Compared with a mainstream scheduling strategy, the peak regulation pressure of a regional power grid can be more effectively relieved, the cost is reduced, the load peak-valley difference is reduced, and the wind power photovoltaic consumption level is improved.

The invention discloses a solid heat storage and energy storage coordinated scheduling and control method for improving wind power consumption, and belongs to the technical field of wind power consumption. The method comprises the steps of determining a solid heat storage and energy storage system optimization coordination control method; determining a solid heat storage and energy storage hybrid system double-layer optimization model by considering constraint conditions of a power system and a thermodynamic system according to wind curtailment characteristics; establishing a solid-state heat storage and energy storage system double-layer model objective function; establishing solid-state heat storage, battery energy storage and electric power and electric quantity balance constraint conditions according to the operation characteristics of the hybrid system; determining a fuzzy membership function of the objective functions of the double-layer model of the solid-state heat storage and energy storage system and the satisfaction degree corresponding to each objective function; solving two satisfaction values by using a fuzzy algorithm; and obtaining optimal configuration results of the capacity and efficiency of the solid-state heat storage device and the capacity and efficiency of the energy storage battery according to the average value. Electric heating, electric energy storage and heating decoupling are achieved, and the problem of clean energy consumption is efficiently solved through the solid-state heat storage device.

The invention discloses a pumped storage and wind-fire-nuclear deep peak shaving trading mechanism designing method. The method establishes an income model of each transaction entity on the basis of the cost-income method, points out that each transaction entity has the enthusiasm to participate in the bidding by analyzing the income of each transaction entity, and clarifies the feasibility of thetrading mechanism. Further, the bidding ability of each power source is analyzed, and the wind power bidding ability is the strongest, followed by the nuclear power unit, and finally the unit with low coal consumption rate and strong peak shaving ability in the thermal power unit. The trading mechanism can optimize allocation of power generation resources in the system. At the same time, the long-term implementation of the trading mechanism can make the system more economical. Therefore, the designing method effectively dredges the pumping loss of the pumped storage power station, can improvethe utilization rate of the pumped storage power station, and can promote long-term healthy development of the pumped storage power station; and the designing method can stimulate thermal power, windpower and nuclear power to actively participate in deep peak shaving to alleviate the current peaking situation.

The invention discloses an auxiliary service system based on participation of an alliance chain and load side resources and a compensation method. An equipment layer is used for providing the load side resources participating in auxiliary service and executing a scheduling instruction of a data layer; the data layer is used for providing real-time acquisition data of the intelligent fusion terminal, a scheduling instruction of the regulation and control system, electric quantity data of the energy management system and electricity price declaration data; the contract consensus layer is used for establishing trust between different main body nodes, automatically calculating auxiliary service market transaction compensation and apportioned expenses, distributing and calculating compensation expenses and providing guarantee for data and communication security; and the application layer is used for identity management, scheduling monitoring, transaction clearing and settlement, statement settlement, statistical analysis and information release. According to the invention, credible management of energy flows, information flows and capital flows among different subjects can be realized, the enthusiasm of load side resources to participate in auxiliary services is fully aroused, the peak regulation pressure of a power grid is effectively relieved, and the stable improvement of the new energy consumption level is promoted.

The invention discloses an ultra-low-load operation system and an operation method for coal-fired generating units. The system is composed of two coal-fired generating units which operate in a unifiedmode, and each coal-fired generating unit consists of a steam turbine, a steam system, a vacuum air exhaust system, a condensed water system and a water feeding system; the steam systems of the generating units are connected through a heat steam connecting tube; and the water feeding systems of the generating units are connected through a water feeding connecting tube. The ultra-low-load operation system concentrates steam outlet force when the two units operate under ultra-low load on a main boiler, and solves the problems that boiler consumption is unstable, a coal mill, a fan and a denitrification reactor are unstable and the like when current coal-fired generating unit operates under the ultra-low load, and greatly improves safety and reliability of boiler operation control.