Frequency coordination power control method and system for multi-source isolated grid smelting

Abstract

The present application belongs to the technical field of supervisory control and data acquisition system of power grid, and particularly relates to a frequency coordination power control method and system for multi-source isolated network smelting, which comprises the following steps: determining a smelting load adjustable power interval according to a smelting stage allowed active power interval and a power unit allowed active power interval, determining a frequency support active power demand of a frequency regulation event when an isolated network bus frequency exceeds an allowed deviation, forming a smelting load transient regulation amount by a power unit and outputting an active power regulation instruction to multiple controllable power sources; continuously obtaining a multi-source actual response increment according to actual controllable power source actual response amounts of each controllable power source, and updating the smelting load transient regulation amount accordingly, so that the smelting load active power gradually recovers in the process of forming the actual output of the multiple controllable power sources, thereby reducing the possibility of active power imbalance in the power transfer process.

Description

Technical Field

[0001] This invention relates to the technical field of power grid monitoring, control, and data acquisition systems. More specifically, this invention relates to a frequency-coordinated power control method and system for multi-source isolated grid smelting. Background Technology

[0002] Submerged arc furnaces are continuous high-power smelting loads. During the smelting process, the load resistance, arc state, and operating power change with each smelting stage. In a low-frequency flexible submerged arc furnace power supply system, the output voltage and current on the load side can be adjusted by power electronic power units, and the active power on the load side can be adjusted using voltage source control or current source control methods. Simultaneously, the electrode control system adjusts the arc length and the electrical state within the furnace by changing the electrode positions. Therefore, smelting loads with power units possess both a relatively fast power electronic adjustment path and a relatively slow electrode mechanical adjustment path.

[0003] When a smelting facility is powered by an isolated grid consisting of multiple power sources, the frequency of the isolated grid bus is related to the real-time balance between the active power generated and the active power of the load. The capacity, current operating point, remaining regulation capacity and active power response process of different power sources may be different. After the smelting load power changes or the output capacity of some power sources changes, the controllable power sources and adjustable loads within the isolated grid need to re-establish the active power balance.

[0004] Chinese patent document CN102842904B discloses a microgrid coordinated frequency control method based on power deficit prediction and allocation. When a power deficit occurs in the microgrid, it predicts the total active power deficit based on frequency changes and allocates power control quantities to energy storage, distributed power sources, and loads. Chinese patent document CN103299511B discloses a technical solution integrating the control of self-provided power generation facilities with the control of smelting facilities. It determines load control parameters based on generator operating characteristics and generator control parameters based on load operating characteristics. International PCT application WO2017143955A1 discloses an electric furnace power control method. It generates an electric furnace power deviation based on the grid operating frequency and drives the electrodes to rise and fall according to the electric furnace power deviation to change the electric furnace power.

[0005] The aforementioned technologies can achieve power distribution among multiple power sources and loads, joint control between power generation facilities and smelting facilities, or change the power of electric furnaces based on the islanded grid frequency. However, when a smelting load with power units is connected to a multi-source islanded grid, after a controllable power source receives an active power adjustment command, its actual active power still needs to undergo its own active power response process to form the target change. If the smelting load withdraws its transient adjustment on the load side only based on the issuance of the active power adjustment command or the temporary restoration of the islanded grid bus frequency, the active power of the smelting load may be re-increased before the actual active power of the controllable power source has formed a corresponding change, causing a mismatch between the power change of the controllable power source and the power recovery time of the smelting load. Therefore, it is necessary to solve the problem of continuous power handover between the actual output formation process of multiple controllable power sources and the rapid power adjustment process of the smelting load. Summary of the Invention

[0006] To address the technical problem of the difficulty in continuously matching the actual output formation process of multiple controllable power sources with the rapid power adjustment process of smelting loads, this invention provides solutions in the following aspects.

[0007] In a first aspect, the present invention provides a frequency-coordinated power control method for multi-source isolated grid smelting, comprising: acquiring the isolated grid bus frequency, rated isolated grid frequency, allowable deviation of isolated grid frequency, reference active power of smelting load, allowable active power range of smelting stage, allowable active power range of power unit, and actual active power of each controllable power source; determining the adjustable power range of smelting load based on the allowable active power range of smelting stage and the allowable active power range of power unit; when the isolated grid bus frequency first exceeds the allowable deviation of isolated grid frequency corresponding to the rated isolated grid frequency, determining the corresponding control time as the start time of the frequency modulation event, and determining the frequency-supported active power demand of the frequency modulation event based on the isolated grid bus frequency at the start time of the frequency modulation event; determining the target active power adjustment amount of each controllable power source based on the frequency-supported active power demand of the frequency modulation event, such that the algebraic sum of each target active power adjustment amount is in the same direction as the frequency-supported active power demand of the frequency modulation event and the absolute value does not exceed the frequency-supported active power demand of the frequency modulation event. The system calculates the absolute value of the power demand and outputs an active power adjustment command. Based on the frequency-supported active power demand of the frequency-modulated event, it determines the transient adjustment amount of the smelting load within the adjustable power range of the smelting load. The power unit changes the active power of the smelting load according to the transient adjustment amount of the smelting load. During the execution of the active power adjustment command, the system continuously acquires the actual active power of the controllable power source. The actual active power of the controllable power source at the start of the frequency-modulated event is used as the starting active power of the frequency-modulated event. The system determines the actual response amount of the controllable power source formed along the adjustment direction corresponding to the active power adjustment command, and the absolute value of the response amount does not exceed the absolute value of the target active power adjustment amount. The system summarizes the actual response amounts of the controllable power source to form a multi-source actual response increment. Based on the difference between the frequency-supported active power demand of the frequency-modulated event and the multi-source actual response increment, the system determines the remaining frequency-supported active power demand. Based on the remaining frequency-supported active power demand, the system updates the transient adjustment amount of the smelting load, so that the active power of the smelting load recovers to the reference active power of the smelting load.

[0008] Preferably, the current smelting stage is obtained, and the smelting load reference active power and the allowable active power range of the smelting stage corresponding to the current smelting stage are obtained from the smelting process control program; the common range of the allowable active power range of the smelting stage and the allowable active power range of the power unit is used as the adjustable power range of the smelting load; when there is no common range or the smelting load reference active power is not within the adjustable power range of the smelting load, the transient adjustment of the smelting load is determined to be zero.

[0009] Preferably, a frequency adjustment coefficient is configured to determine the frequency support active power requirement of the frequency modulation event based on the degree to which the island bus frequency exceeds the allowable deviation of the island frequency at the start of the frequency modulation event and the frequency adjustment coefficient, and to keep the frequency support active power requirement of the frequency modulation event unchanged before the end of the frequency modulation event.

[0010] Preferably, the adjustable power boundary of each controllable power source is obtained, and the adjustable capacity for increasing or decreasing power of the controllable power source is determined based on the adjustment direction of the active power demand supported by the frequency modulation event and the initial active power of the frequency modulation event. When the active power demand supported by the frequency modulation event is positive, if the sum of the adjustable capacities for increasing power of all controllable power sources is zero, then the adjustment amount of all the target active power is set to zero; otherwise, the active power demand supported by the frequency modulation event is allocated according to the proportion of the adjustable capacity for increasing power of each controllable power source to the sum of the adjustable capacities for increasing power of all controllable power sources. The upper limit of the target active power adjustment amount is set as the corresponding adjustable capacity of the controllable power supply. When the active power demand supported by the frequency modulation event is negative, if the sum of the adjustable capacities of all controllable power supplies is zero, then the target active power adjustment amount is set to zero. Otherwise, the absolute value of the active power demand supported by the frequency modulation event is allocated according to the proportion of the adjustable capacity of each controllable power supply to the sum of the adjustable capacities of all controllable power supplies. The upper limit of the absolute value of the target active power adjustment amount is set as the corresponding adjustable capacity of the controllable power supply, and the target active power adjustment amount is set to negative.

[0011] Preferably, when the target active power adjustment is positive, the change in the actual active power of the controllable power source relative to the active power at the start of the frequency modulation event along the direction of increasing active power, and whose absolute value does not exceed the absolute value of the target active power adjustment, is determined as the actual response of the controllable power source; when the target active power adjustment is negative, the change in the actual active power of the controllable power source relative to the active power at the start of the frequency modulation event along the direction of decreasing active power, and whose absolute value does not exceed the absolute value of the target active power adjustment, is determined as the actual response of the controllable power source.

[0012] Preferably, the adjustable power range of the smelting load includes a lower limit and an upper limit of the adjustable power of the smelting load. The adjustable capacity for load reduction and adjustment capacity for load increase are determined based on the reference active power of the smelting load and the adjustable power range of the smelting load. The active power control command for the smelting load is determined based on the difference between the reference active power of the smelting load and the transient adjustment amount of the smelting load, and a power handover allowable error is configured. When the absolute value of the remaining frequency-supported active power demand does not exceed the power handover allowable error, and the islanded bus... When the absolute value of the deviation between the frequency and the rated island frequency does not exceed the allowable deviation of the island frequency, the transient adjustment of the smelting load is set to zero; when the active power demand supported by the remaining frequency is positive and greater than the adjustable capacity of the smelting load reduction, the active power control command of the smelting load is set to the lower limit of the adjustable power of the smelting load; when the active power demand supported by the remaining frequency is negative and its absolute value is greater than the adjustable capacity of the smelting load expansion, the active power control command of the smelting load is set to the upper limit of the adjustable power of the smelting load.

[0013] Preferably, the current smelting stage is obtained; the transient adjustment of the smelting load is executed by the power electronic power conversion of the power unit, and is not generated by the electrode position change driven by the electrode control system; after the frequency modulation event ends, the electrode control system adjusts the electrode position according to the smelting control logic corresponding to the current smelting stage.

[0014] In a second aspect, the present invention provides a frequency-coordinated power control system for multi-source islanded smelting, comprising a controller, a frequency acquisition interface, a power acquisition interface, multiple controllable power supplies, and a power unit connected to the smelting load; the frequency acquisition interface and the power acquisition interface are respectively connected to the controller signal, providing the controller with the islanded bus frequency and the actual active power of the controllable power supplies; the controller acquires the rated islanded frequency and the allowable deviation of the islanded frequency, determines the adjustable power range of the smelting load, and determines the start time of the frequency modulation event when the deviation of the islanded bus frequency relative to the rated islanded frequency first exceeds the allowable deviation of the islanded frequency; the frequency modulation event is determined based on the islanded bus frequency at the start time of the frequency modulation event. The frequency supports the active power demand; based on the frequency-supported active power demand of the frequency-modulated event, the transient adjustment amount of the smelting load is determined within the adjustable power range of the smelting load, and active power adjustment commands are output to multiple controllable power sources, causing the power units to change the active power of the smelting load according to the transient adjustment amount of the smelting load; based on the change of the actual active power of each controllable power source relative to the start time of the frequency-modulated event along the direction of the active power adjustment command, the actual response amount of the controllable power source is determined and summarized into the multi-source actual response increment, and the remaining frequency supports the active power demand is determined by the difference between the frequency-supported active power demand of the frequency-modulated event and the multi-source actual response increment, and the transient adjustment amount of the smelting load is updated.

[0015] Preferably, it further includes an electrode control system; the controller is also used to obtain the current smelting stage, the electrode control system is connected to the electrode actuator of the smelting load; during the period when the power unit performs power electronic power conversion according to the transient adjustment amount of the smelting load, the electrode control system maintains the smelting control logic corresponding to the current smelting stage, and after the frequency modulation event ends, the electrode control system adjusts the electrode position according to the smelting control logic corresponding to the current smelting stage.

[0016] Preferably, the controller is further configured to determine the target active power adjustment amount of each controllable power source, and to determine the actual active power change of each controllable power source formed along the adjustment direction corresponding to the active power adjustment command and whose absolute value does not exceed the absolute value of the target active power adjustment amount as the actual response amount of the controllable power source.

[0017] The beneficial effects of this invention are as follows:

[0018] The power unit provides transient frequency support for the smelting load side during the period before the actual output of multiple controllable power sources reaches the target change. The actual active power change of each controllable power source that has reached the target and is consistent with the active power adjustment command serves as the basis for power handover. This allows the transient adjustment of the smelting load to gradually decrease with the incremental response of multiple sources, thereby ensuring that the degree of active power recovery of the smelting load corresponds to the degree of actual output of multiple controllable power sources. This reduces the possibility of prematurely withdrawing the transient adjustment of the load side based solely on the issuance of commands or instantaneous frequency recovery, which could lead to a recurrence of active power imbalance. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the frequency-coordinated power control method for multi-source isolated grid smelting in this invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In this embodiment, the multi-source isolated grid includes at least two controllable power sources and an isolated grid bus powered by multiple controllable power sources. The smelting load is connected to the isolated grid bus through a power unit. The power unit performs power electronic power conversion on the active power of the smelting load. The electrode control system adjusts the electrode position according to the smelting process control requirements.

[0022] The islanded bus frequency refers to the AC bus frequency formed by the combined action of multiple controllable power sources and the loads within the islanded network; the smelting power supply frequency refers to the frequency corresponding to the low-frequency AC power output by the power unit to the smelting load; the islanded bus frequency and the smelting power supply frequency are different technical quantities. In this embodiment, the islanded bus frequency is used to establish a frequency-coordinated power control relationship, and the smelting power supply frequency continues to be determined according to the low-frequency power supply requirements of the smelting process.

[0023] To unify the direction of active power regulation, a positive direction is defined as increasing the net active power of the isolated grid, and a negative direction as decreasing the net active power of the isolated grid. According to this directional convention, a positive target active power regulation value indicates an increase in the active power of the controllable power source, and a negative target active power regulation value indicates a decrease in the active power of the controllable power source. Similarly, a positive transient regulation value for the smelting load indicates a decrease in the active power of the smelting load, and a negative transient regulation value indicates an increase in the active power of the smelting load. Thus, both the increase in controllable power supply and the decrease in smelting load provide positive net active power support for the isolated grid.

[0024] Before control operation, the smelting process control program saves the benchmark active power of the smelting load and the allowable active power range of the smelting stage corresponding to different smelting stages; the controller obtains the allowable active power range of the power unit from the power unit, and obtains the actual active power of the controllable power supply and the adjustable power boundary of the controllable power supply from each controllable power supply.

[0025] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0026] See Figure 1 This is a flowchart of the frequency coordinated power control method for multi-source isolated grid smelting provided in the embodiments of the present invention, such as... Figure 1 As shown, the method may include:

[0027] S1. Obtain the isolated bus frequency, current smelting stage, and actual active power of the controllable power supply.

[0028] The controller acquires the isolated bus frequency, rated isolated frequency, current smelting stage, smelting load reference active power, allowable active power range for the smelting stage, allowable active power range for power units, and actual active power of each controllable power source according to the control cycle.

[0029] use Indicates the control cycle number; using Indicates the controllable power supply serial number. ,in Indicates the total number of controllable power supplies and Then the first The frequency of the isolated bus in each control cycle is expressed as: The rated island frequency is expressed as ;No. The first control cycle The actual active power of a controllable power source is expressed as follows: ;No. The adjustable power boundary of a controllable power source is determined by the current lower limit of permissible active power. and the current maximum allowed active power Composition; the benchmark active power of the smelting load is expressed as Its technical meaning is the normal active power setting when the current frequency regulation event is not executed in the current smelting stage.

[0030] S2. Determine the adjustable power range of the smelting load based on the allowable active power range of the smelting stage and the allowable active power range of the power unit.

[0031] The lower and upper limits of the allowable active power range during the smelting stage are respectively expressed as: and The lower and upper limits of the allowable active power range of the power unit are expressed as follows: and Therefore, the adjustable power range of the smelting load is taken as the common range of the two active power ranges:

[0032]

[0033]

[0034] In the formula, This is the lower limit of the adjustable power for smelting load. The upper limit of adjustable power for smelting load. This is the lower limit of the permissible active power during the smelting stage. This is the lower limit of the allowable active power of the power unit. This refers to the upper limit of the permitted active power during the smelting stage. This represents the upper limit of the active power allowed for the power unit. `max` indicates taking the larger of the two inputs, and `min` indicates taking the smaller of the two inputs.

[0035] A common range is formed by using a higher lower limit and a lower upper limit, so that when the smelting load participates in frequency support, it does not exceed the range of active power that can be accepted in the current smelting stage, nor does it exceed the range of active power that the power unit can currently execute.

[0036] when and When the smelting load is within the adjustable power range, the smelting load is allowed to participate in the current frequency regulation event through the power unit; otherwise, the transient adjustment of the smelting load is set to zero, and the current smelting process control is maintained.

[0037] Calculate the adjustable capacity for smelting load reduction and smelting load increase:

[0038]

[0039]

[0040] In the formula, Adjustable capacity for reducing smelting load. Adjustable capacity to increase smelting load. The active power is the reference value for the smelting load. This is the lower limit of the adjustable power for smelting load. The upper limit of adjustable power for smelting load. The reference active power for the smelting load. The adjustable capacity for smelting load reduction represents the maximum support that can be achieved by reducing the active power of the smelting load in the positive direction frequency support, while the adjustable capacity for smelting load increase represents the maximum power that can be absorbed by increasing the active power of the smelting load in the negative direction frequency support.

[0041] S3. Determine the active power demand supported by the frequency modulation event based on the frequency of the isolated network bus, and form the target active power adjustment amount.

[0042] First, calculate the islanded network frequency deviation. The islanded network frequency deviation is determined by subtracting the current islanded network bus frequency from the rated islanded network frequency. Therefore, the islanded network frequency deviation is positive when the islanded network bus frequency is lower than the rated islanded network frequency, and negative when the islanded network bus frequency is higher than the rated islanded network frequency.

[0043]

[0044] In the formula, For the first The frequency deviation of the isolated network in each control cycle For the rated island frequency, For the first The frequency of the isolated bus in each control cycle.

[0045] Configure the allowable deviation of the isolated network frequency and frequency adjustment coefficient In each control cycle, the active power demand is supported by the cyclic frequency based on the islanded grid frequency deviation.

[0046]

[0047] In the formula, For the first The frequency of each control cycle supports the active power demand. For the first The frequency deviation of the isolated network in each control cycle For the allowable frequency deviation of the island network, This is the frequency adjustment coefficient. A positive value for the periodic frequency supporting active power demand indicates that the net active power of the islanded grid needs to be increased, while a negative value indicates that the net active power of the islanded grid needs to be decreased.

[0048] The allowable frequency deviation of the isolated network creates a frequency dead zone, preventing normal frequency fluctuations within the allowable deviation from initiating power handover; the frequency regulation coefficient maps the frequency deviation exceeding the allowable deviation to active power demand, ensuring that the direction of active power demand is consistent with the agreed-upon direction of unified power support.

[0049] The permissible deviation of the isolated grid frequency is determined based on the permissible frequency range for isolated grid operation and the rated isolated grid frequency. Specifically, it is the smaller of the difference between the rated isolated grid frequency and the lower limit of the permissible frequency for isolated grid operation, and the difference between the upper limit of the permissible frequency for isolated grid operation and the rated isolated grid frequency. The frequency adjustment coefficient is determined based on the expected maximum isolated grid frequency deviation and the active power adjustment capability available for frequency support. Specifically, it is the ratio of the active power adjustment capability available for frequency support to the effective frequency deviation range, where the effective frequency deviation range is the difference between the expected maximum isolated grid frequency deviation and the permissible deviation of the isolated grid frequency. The permissible error for power handover is determined based on the active power measurement resolution and the control command resolution. Specifically, it is the sum of the active power measurement resolution and the control command resolution as the permissible error for power handover.

[0050] When the active power demand supported by the periodic frequency is not zero for the first time, the corresponding control period will be determined as the start time of the frequency regulation event for the current frequency regulation event. And record the starting active power of each controllable power source during frequency modulation events:

[0051]

[0052] In the formula, This is the controllable power supply serial number. For the first The frequency modulation event of a controllable power supply starts with active power. For the first The actual active power of a controllable power source at the start of a frequency modulation event.

[0053] The period frequency at the start of the frequency modulation event supports the active power demand. The frequency of the frequency modulation event identified as the current frequency modulation event supports the active power demand. Before the current frequency regulation event ends, the active power demand supported by the frequency regulation event remains unchanged. The islanded bus frequency is used for exiting the current frequency regulation event and for re-entering the frequency regulation event in the opposite direction. This fixed reference ensures that the pullback of the transient adjustment of the smelting load is driven only by the actual active power response formed by multiple controllable power sources, and is not prematurely withdrawn due to a temporary rise in the islanded bus frequency. The active power demand supported by the periodic frequency is formed with the control cycle, while the active power demand supported by the frequency regulation event frequency is only taken from the active power demand supported by the periodic frequency at the start of the frequency regulation event and remains unchanged within the current frequency regulation event; the two have different time ranges.

[0054] when At that time, the first The adjustable power boost capacity of a controllable power supply is:

[0055]

[0056] In the formula, This is the controllable power supply serial number. For the first A controllable power supply with adjustable power and capacity. For the first The current allowable active power limit of a controllable power source. For the first The frequency modulation event of a controllable power supply starts with active power.

[0057] when At that time, the first The adjustable capacity of the controllable power supply is:

[0058]

[0059] In the formula, This is the controllable power supply serial number. For the first A controllable power supply with adjustable capacity and reduced power output. For the first The frequency modulation event of a controllable power supply starts with active power. For the first The current allowable lower limit of active power of a controllable power source.

[0060] When the frequency-supported active power demand of a frequency-modulated event is positive and the sum of the adjustable capacities for increased power output of all controllable power sources is zero, the total target active power adjustment is set to zero, and proportional division is not performed. Similarly, when the frequency-supported active power demand of a frequency-modulated event is negative and the sum of the adjustable capacities for decreased power output of all controllable power sources is zero, the total target active power adjustment is also set to zero. When adjustable capacities for increased power output exist, the active power demand for positive-direction frequency-modulated events is allocated according to the proportion of the adjustable capacities for increased power output of controllable power sources to the sum of the adjustable capacities for increased power output of all controllable power sources. When adjustable capacities for decreased power output exist, the active power demand for negative-direction frequency-modulated events is allocated according to the proportion of the adjustable capacities for decreased power output of controllable power sources to the sum of the adjustable capacities for decreased power output of all controllable power sources.

[0061] when and At that time, the target active power regulation of the controllable power supply is:

[0062]

[0063] In the formula, This refers to the controllable power source number corresponding to the current target active power adjustment. To find the controllable power supply number in the summation, For the first The target active power regulation of a controllable power supply. For the first A controllable power supply with adjustable power and capacity. To support the active power requirements of frequency modulation events. This represents the total number of controllable power sources.

[0064] when and At that time, the target active power regulation of the controllable power supply is:

[0065]

[0066] In the formula, This is the controllable power supply serial number. For the first The target active power regulation of a controllable power supply. For the first The adjustable capacity of the controllable power supply's boost power. This relationship ensures that when the positive demand exceeds the boost power capacity of all controllable power supplies, the target active power adjustment of each controllable power supply remains at its corresponding adjustable capacity.

[0067] when and At that time, the target active power regulation of the controllable power supply is:

[0068]

[0069] In the formula, This refers to the controllable power source number corresponding to the current target active power adjustment. To find the controllable power supply number in the summation, For the first The target active power regulation of a controllable power supply. For the first A controllable power supply with adjustable capacity and reduced power output. To support the active power requirements of frequency modulation events. This represents the total number of controllable power sources.

[0070] when and At that time, the target active power regulation of the controllable power supply is:

[0071]

[0072] In the formula, This is the controllable power supply serial number. For the first The target active power regulation of a controllable power supply. For the first The adjustable power reduction capacity of each controllable power source. This relationship ensures that when the negative demand exceeds the total power reduction capacity of all controllable power sources, the target active power adjustment of each controllable power source remains at its corresponding adjustable power reduction capacity.

[0073] The target active power regulation is determined by adjusting the adjustable capacity of the controllable power source for either increasing or decreasing power. Controllable power sources with different remaining regulation capacities share the regulation responsibility according to their respective adjustable capacities for increasing or decreasing power, while ensuring that the target active power regulation does not require any controllable power source to exceed its adjustable power limit. The algebraic sum of all target active power regulation values ​​formed by the above allocation relationship is in the same direction as the active power demand supported by the frequency of the frequency modulation event, and its absolute value does not exceed the absolute value of the active power demand supported by the frequency of the frequency modulation event.

[0074] Based on the initial active power and target active power adjustment of the frequency regulation event of the controllable power source, calculate the target active power command of the controllable power source:

[0075]

[0076] In the formula, This is the controllable power supply serial number. For the first The target active power command of a controllable power source. For the first The frequency modulation event of a controllable power supply starts with active power. For the first The target active power adjustment amount of a controllable power source. The controller outputs an active power adjustment command to the corresponding controllable power source according to the target active power command. The target active power command represents the target active power value of the controllable power source, and the active power adjustment command represents the control signal sent by the controller to the controllable power source carrying the target active power command. The two have different object types.

[0077] S4. Determine the transient adjustment amount of the smelting load based on the active power demand of the frequency support of the frequency modulation event, and have the power unit perform fast frequency support.

[0078] After a frequency regulation event is initiated, the transient adjustment of the smelting load directly references the active power demand supported by the frequency of the frequency regulation event, and is subject to bidirectional limiting by both the adjustable capacity for load reduction and the adjustable capacity for load increase in the smelting load. Therefore, the smelting load first undertakes the frequency support it can currently handle, without waiting for multiple controllable power sources to complete their actual output changes.

[0079] when At the start of the frequency modulation event, the transient adjustment of the smelting load is:

[0080]

[0081] In the formula, This represents the transient adjustment of the smelting load at the start of the frequency modulation event. To support the active power requirements of frequency modulation events. Adjustable capacity for reducing smelting load. Adjustable capacity for increasing smelting load. This condition indicates that the active power demand supported by the frequency modulation event is within the bidirectional adjustable capacity of the smelting load.

[0082] when At the start of the frequency modulation event, the transient adjustment of the smelting load is:

[0083]

[0084] In the formula, This represents the transient adjustment of the smelting load at the start of the frequency modulation event. Adjustable capacity for reducing smelting load. This relationship limits the transient adjustment of the smelting load in the positive direction to the allowable reduction range of the lower limit of the adjustable power of the smelting load.

[0085] when At the start of the frequency modulation event, the transient adjustment of the smelting load is:

[0086]

[0087] In the formula, This represents the transient adjustment of the smelting load at the start of the frequency modulation event. Adjustable capacity for increasing smelting load. This relationship limits the negative smelting load transient adjustment to within the allowable increase range of the adjustable power limit of the smelting load.

[0088] Based on the smelting load baseline active power and the smelting load transient adjustment at the start of the frequency regulation event, calculate the smelting load active power control command at the start of the frequency regulation event:

[0089]

[0090] In the formula, This is the active power control command for the smelting load at the start of the frequency modulation event. The active power is the reference value for the smelting load. This represents the transient adjustment of the smelting load at the start of the frequency modulation event. Since the positive transient adjustment of the smelting load indicates a load reduction, subtraction can be used to convert the positive frequency support into a reduction in the active power of the smelting load.

[0091] The controller sends active power control commands for the smelting load to the power unit, which then adjusts the active power of the smelting load. During the current frequency regulation event, the transient adjustment of the smelting load is executed by the power unit's power electronic power conversion, independent of the electrode control system driving electrode position changes. The electrode control system maintains the smelting control logic corresponding to the current smelting stage. This execution relationship utilizes the power unit's electrical regulation process to provide rapid power support at the beginning of the frequency regulation event.

[0092] S5. Determine the actual response quantity of the controllable power source based on the actual active power of the controllable power source and form the multi-source actual response increment.

[0093] After multiple controllable power sources receive the active power adjustment command, the controller continuously acquires the actual active power of the controllable power sources in subsequent control cycles. The actual response of the controllable power source takes the active power at the start of the frequency modulation event as the reference zero point and is simultaneously limited by the adjustment direction of the active power adjustment command and the absolute value of the target active power adjustment amount.

[0094] No. The controllable power supply in the first The actual response of the controllable power supply in one control cycle is expressed as: ,when hour:

[0095]

[0096] In the formula, This is the controllable power supply serial number. To control the cycle number, For the first The controllable power supply in the first The actual response of the controllable power supply in each control cycle. This refers to the actual active power of the controllable power supply corresponding to the control cycle. The active power at the start of the frequency modulation event. The target active power adjustment amount; through First, exclude reverse changes. Then, the amount included should be limited to the target active power adjustment amount.

[0097] when hour:

[0098]

[0099] In the formula, This is the controllable power supply serial number. To control the cycle number, For the first The controllable power supply in the first The actual response of the controllable power supply in each control cycle. This refers to the actual active power of the controllable power supply corresponding to the control cycle. The active power at the start of the frequency modulation event. The target active power adjustment. First, exclude positive changes that are the opposite of the power reduction command. Then, the negative input amount is limited to within the target active power adjustment amount.

[0100] when hour:

[0101]

[0102] In the formula, This is the controllable power supply serial number. To control the cycle number, For the first The controllable power supply in the first The actual response of the controllable power supply in each control cycle. When the target active power adjustment is zero, the corresponding controllable power supply does not contribute the actual response of the controllable power supply to the current frequency regulation event.

[0103] For example, in the direction of increasing active power, if the target active power adjustment is 0.60MW, and the actual active power of the controllable power source increases by 0.30MW relative to the initial active power of the frequency regulation event, then the actual response of the controllable power source is 0.30MW; if the actual increase is 0.80MW, then the current frequency regulation event only counts 0.60MW. As another example, in the direction of decreasing active power, if the target active power adjustment is -0.50MW and the actual decrease is 0.20MW, then the actual response of the controllable power source is -0.20MW; if the actual active power of the controllable power source increases instead, then the actual response of the controllable power source is zero.

[0104] Summing the actual responses of all controllable sources, calculate the multi-source actual response increment:

[0105]

[0106] In the formula, To find the controllable power supply number in the summation, To control the cycle number, For the first Multi-source actual response increment for each control cycle. For the first The controllable power supply in the first The actual response of the controllable power supply in each control cycle. This represents the total number of controllable power sources.

[0107] The actual response increment of the multi-source system only summarizes the actual active power changes that are consistent with the active power adjustment direction of the current frequency regulation event and do not exceed the target active power adjustment amount. Therefore, the reverse fluctuation of the controllable power supply will not be mistaken for the completed frequency support, and the change of the controllable power supply exceeding the target active power adjustment amount will not further push the smelting load to cross the smelting load benchmark active power.

[0108] S6. Based on the frequency support active power demand of the frequency modulation event and the actual response increment of multiple sources, determine the remaining frequency support active power demand and update the transient adjustment of the smelting load.

[0109] The difference between the frequency-supported active power demand of the frequency modulation event and the current multi-source actual response increment is determined as the remaining frequency-supported active power demand. The remaining frequency-supported active power demand represents the portion of active power support that has not yet been actually borne by multiple controllable power sources in the current frequency modulation event. The smelting load only bears the amount that can be borne within the adjustable power range of the smelting load for this remaining portion.

[0110] when At that time, the transient adjustment of the smelting load is:

[0111]

[0112] In the formula, To control the cycle number, For the first Transient adjustment of smelting load per control cycle To support the active power requirements of frequency modulation events. For the first Multi-source actual response increment for each control cycle. Adjustable capacity for reducing smelting load. Adjustable capacity is added to the smelting load. At this time, the remaining frequency supports the active power demand within the bidirectional adjustable capacity of the smelting load.

[0113] when At that time, the transient adjustment of the smelting load is:

[0114]

[0115] In the formula, To control the cycle number, For the first Transient adjustment of smelting load per control cycle Adjustable capacity for reducing smelting load. When the remaining frequency-supported active power demand exceeds the forward load adjustable capacity, the transient adjustment of the smelting load remains at the adjustable capacity for reducing smelting load.

[0116] when At that time, the transient adjustment of the smelting load is:

[0117]

[0118] In the formula, To control the cycle number, For the first Transient adjustment of smelting load per control cycle Adjustable capacity for increasing smelting load. When the remaining frequency-supported active power demand exceeds the negative load adjustable capacity, the transient adjustment of the smelting load remains at the adjustable capacity for increasing smelting load.

[0119] Based on the smelting load baseline active power and the smelting load transient adjustment, calculate the smelting load active power control command:

[0120]

[0121] In the formula, To control the cycle number, For the first Active power control commands for smelting load in each control cycle The active power is the reference value for the smelting load. For the first The transient adjustment of the smelting load in each control cycle. As the actual response increment of the multi-source increases, the demand for active power supported by the remaining frequency decreases, and the transient adjustment of the smelting load returns to zero. As a result, the active power of the smelting load recovers to the reference active power of the smelting load.

[0122] Configuration power handover tolerance ,when Furthermore, when the deviation between the isolated bus frequency and the rated isolated frequency does not exceed the allowable deviation of the isolated frequency, the transient adjustment of the smelting load is set to zero and the current frequency regulation event is terminated; where, To support the active power requirements of frequency modulation events. For the first Multi-source actual response increment for each control cycle. This is the allowable error for power handover. This judgment requires both the basic completion of power handover and the return of the islanded bus frequency to the allowable range, to avoid prematurely ending the current frequency modulation event if only one condition is met.

[0123] When the remaining frequency-supported active power demand is positive and greater than the adjustable capacity for reducing the smelting load, the active power control command for the smelting load remains at the lower limit of the adjustable power of the smelting load. When the remaining frequency-supported active power demand is negative and its absolute value is greater than the adjustable capacity for increasing the smelting load, the active power control command for the smelting load remains at the upper limit of the adjustable power of the smelting load. In both cases, control results exceeding the adjustable power range of the smelting load are not output.

[0124] If the current frequency regulation event has not yet ended and the islanded bus frequency exceeds the rated islanded frequency and further exceeds the allowable deviation of the islanded frequency in the opposite direction, the current frequency regulation event ends, and a frequency regulation event in the opposite direction is re-established using the current islanded bus frequency, the actual active power of the current controllable power source, the current smelting stage, the reference active power of the smelting load, the allowable active power range of the smelting stage, and the allowable active power range of the power unit. This re-entry process uses the new frequency regulation event's initial active power and the new frequency regulation event frequency to support the active power demand, avoiding the continued use of the active power change already formed in the previous direction as the power handover reference in the opposite direction.

[0125] This invention also discloses a frequency-coordinated power control system for multi-source isolated grid smelting, including a controller, a frequency acquisition interface, a power acquisition interface, multiple controllable power supplies, power units, and an electrode control system. The frequency acquisition interface is connected to the isolated grid bus signal and provides the isolated grid bus frequency to the controller. The power acquisition interface is connected to the signals of the multiple controllable power supplies and provides the controller with the actual active power of each controllable power supply.

[0126] The controller obtains the current smelting stage, the reference active power of the smelting load, and the allowable active power range for the smelting stage from the smelting process control program. It also obtains the allowable active power range for each power unit from the power unit and the adjustable power boundaries of each controllable power source. The controller outputs active power adjustment commands to multiple controllable power sources and outputs active power control commands for the smelting load to the power units. The power units adjust the active power of the smelting load according to the active power control commands.

[0127] The electrode control system is connected to the electrode actuator of the smelting load. During the period when the transient adjustment of the smelting load is executed by the power unit, the electrode control system maintains the smelting control logic corresponding to the current smelting stage. After the current frequency modulation event ends, the electrode control system continues to adjust the electrode position according to the smelting control logic corresponding to the current smelting stage.

[0128] In one specific embodiment, taking the example of three controllable power sources supplying power to a smelting load with a power unit, the implementation path of the above method is explained as follows:

[0129] Assume rated island frequency Island network frequency tolerance Frequency adjustment coefficient The frequency of the isolated bus at the start of the FM event The frequency deviation of the isolated network is:

[0130]

[0131] In the formula, the island frequency deviation is 0.20Hz, which exceeds the allowable island frequency deviation of 0.05Hz. Therefore, the current frequency modulation event belongs to the positive frequency support.

[0132]

[0133] In the formula, the active power requirement supported by the frequency of the frequency regulation event is 1.5MW, which serves as the power handover reference before the end of the current frequency regulation event.

[0134] Let the reference active power of the smelting load corresponding to the current smelting stage be... The permissible active power range during the smelting stage is: The allowable active power range of the power unit is Therefore, the adjustable power range of the smelting load is .

[0135]

[0136] In the formula, the adjustable capacity for smelting load reduction is 1.5MW, which is equal to the active power demand supported by the frequency of the current frequency regulation event. Therefore, at the start of the frequency regulation event, the power unit can undertake all positive transient support.

[0137] The transient adjustment of the smelting load at the start of the frequency modulation event is The active power control command for the smelting load is:

[0138]

[0139] In the formula, the active power of the smelting load is reduced from 12MW to 10.5MW, and the reduction of 1.5MW corresponds to the net active power support of the isolated grid in the positive direction.

[0140] The initial active power of the frequency modulation events of the three controllable power supplies are respectively , and The adjustable power boost capacity of the three controllable power supplies are respectively , and After allocating power according to the adjustable capacity ratio of the controllable power supply:

[0141]

[0142]

[0143]

[0144] In the formula, the sum of the three target active power adjustment amounts is 1.5MW, and each does not exceed the controllable power increase adjustable capacity of the corresponding controllable power source.

[0145] In the subsequent control cycle, the actual active power of the three controllable power sources becomes respectively... , and All three changes occur along the direction of increasing active power, and their absolute values ​​do not exceed the absolute value of the corresponding target active power adjustment. Therefore, the actual multi-source response increment is:

[0146]

[0147] In the formula, the actual response increment of multiple sources is 0.75MW, which means that 0.75MW of the active power demand supported by the frequency of the 1.5MW frequency regulation event has been actually undertaken by multiple controllable power sources.

[0148]

[0149] In the formula, the remaining frequency supports an active power requirement of 0.75MW, so the transient adjustment of the smelting load is updated to 0.75MW.

[0150]

[0151] In the formula, the active power control command of the smelting load is restored from 10.5MW to 11.25MW, and the equivalent power transfer is completed with the 0.75MW multi-source actual response increment formed by multiple controllable power sources.

[0152] In subsequent control cycles, when the actual active power of the three controllable power sources reaches respectively , and At that time, the actual increase in multi-source response reached With the remaining frequency supporting zero active power demand, the transient adjustment of the smelting load also returns to zero, and the active power control command of the smelting load is restored to normal. The current frequency regulation event ends when the frequency of the isolated network bus simultaneously recovers to within the allowable deviation of the isolated network frequency and meets the allowable error condition for power handover.

[0153] The specific embodiments described above, along the implementation path, complete the establishment of frequency regulation events, rapid support for the smelting load, formation of actual output from multiple controllable power sources, reduction of active power demand supported by remaining frequency, and recovery of active power for the smelting load. When multiple controllable power sources have received active power adjustment commands but have not yet formed actual controllable power source responses, the transient adjustment of the smelting load will not be prematurely cancelled simply because the commands have been issued; as the incremental increase in the actual responses from multiple sources increases, the transient adjustment of the smelting load gradually recedes according to the active power demand supported by remaining frequency.

[0154] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A frequency-coordinated power control method for multi-source isolated grid smelting, characterized in that, include: Obtain the isolated bus frequency, rated isolated frequency, allowable deviation of isolated frequency, reference active power of smelting load, allowable active power range of smelting stage, allowable active power range of power unit, and actual active power of each controllable power source. The adjustable power range of the smelting load is determined based on the allowable active power range of the smelting stage and the allowable active power range of the power unit. When the frequency of the isolated grid bus exceeds the allowable deviation of the isolated grid frequency corresponding to the rated isolated grid frequency for the first time, the corresponding control time is determined as the start time of the frequency modulation event, and the active power demand supported by the frequency modulation event frequency is determined based on the frequency of the isolated grid bus at the start time of the frequency modulation event. Based on the active power demand supported by the frequency modulation event, the target active power adjustment amount of each controllable power source is determined, so that the algebraic sum of each target active power adjustment amount is in the same direction as the active power demand supported by the frequency modulation event and the absolute value does not exceed the absolute value of the active power demand supported by the frequency modulation event. An active power adjustment command is output, and the transient adjustment amount of the smelting load is determined within the adjustable power range of the smelting load based on the active power demand supported by the frequency modulation event. The power unit changes the active power of the smelting load according to the transient adjustment amount of the smelting load. During the execution of the active power adjustment command, the actual active power of the controllable power source is continuously acquired. The actual active power of the controllable power source at the start of the frequency modulation event is taken as the start active power of the frequency modulation event. The actual response amount of the controllable power source formed along the adjustment direction corresponding to the active power adjustment command and whose absolute value does not exceed the absolute value of the target active power adjustment amount is determined. The actual response amounts of the controllable power source are summarized to form a multi-source actual response increment. The remaining frequency support active power demand is determined based on the difference between the frequency support active power demand of the frequency modulation event and the actual response increment of the multi-source, and the transient adjustment of the smelting load is updated based on the remaining frequency support active power demand, so that the active power of the smelting load recovers to the reference active power of the smelting load.

2. The frequency-coordinated power control method for multi-source isolated grid smelting according to claim 1, characterized in that, Obtain the current smelting stage, and retrieve the smelting load reference active power and the allowable active power range of the smelting stage from the smelting process control program; The common range of the allowable active power range of the smelting stage and the allowable active power range of the power unit is taken as the adjustable power range of the smelting load. When there is no common range or the reference active power of the smelting load is not within the adjustable power range of the smelting load, the transient adjustment of the smelting load is determined to be zero.

3. The frequency-coordinated power control method for multi-source isolated grid smelting according to claim 1, characterized in that, Configure a frequency adjustment coefficient, determine the frequency support active power requirement of the frequency modulation event based on the degree to which the island bus frequency exceeds the allowable deviation of the island frequency at the start time of the frequency modulation event and the frequency adjustment coefficient, and keep the frequency support active power requirement of the frequency modulation event unchanged before the end of the frequency modulation event.

4. The frequency-coordinated power control method for multi-source isolated grid smelting according to claim 1, characterized in that, Obtain the adjustable power boundary of each controllable power source. Determine the adjustable capacity of the controllable power source for increasing power or decreasing power based on the adjustment direction of the active power demand supported by the frequency modulation event and the initial active power of the frequency modulation event. When the active power demand supported by the frequency modulation event is positive, if the sum of the adjustable capacity of the increased power of all controllable power sources is zero, then the target active power adjustment amount is determined to be zero. Otherwise, the active power demand supported by the frequency modulation event is allocated according to the proportion of the adjustable capacity of the increased power of each controllable power source to the sum of the adjustable capacity of the increased power of all controllable power sources, and the corresponding adjustable capacity of the increased power of the controllable power source is used as the upper limit of the target active power adjustment amount. When the frequency-controlled event frequency supports a negative active power demand, if the sum of the adjustable power reduction capacity of all controllable power sources is zero, then the target active power adjustment amount is set to zero. Otherwise, the absolute value of the frequency-controlled event frequency supports active power demand is allocated according to the proportion of the adjustable power reduction capacity of each controllable power source to the sum of the adjustable power reduction capacity of all controllable power sources. The corresponding adjustable power reduction capacity of the controllable power source is used as the upper limit of the absolute value of the target active power adjustment amount, and the target active power adjustment amount is made negative.

5. The frequency-coordinated power control method for multi-source isolated grid smelting according to claim 1, characterized in that, When the target active power adjustment amount is positive, the change in the actual active power of the controllable power source relative to the active power source at the start of the frequency modulation event along the direction of increasing active power, and whose absolute value does not exceed the absolute value of the target active power adjustment amount, is determined as the actual response amount of the controllable power source. When the target active power adjustment is negative, the change in the actual active power of the controllable power source relative to the active power at the start of the frequency modulation event along the direction of decreasing active power, and whose absolute value does not exceed the absolute value of the target active power adjustment, is determined as the actual response of the controllable power source.

6. The frequency-coordinated power control method for multi-source isolated grid smelting according to claim 1, characterized in that, The adjustable power range of the smelting load includes a lower limit and an upper limit. The adjustable capacity for load reduction and increase is determined based on the reference active power of the smelting load and the adjustable power range. The active power control command for the smelting load is determined based on the difference between the reference active power and the transient adjustment of the smelting load, and a power handover allowable error is configured. When the absolute value of the active power demand supported by the remaining frequency does not exceed the power handover allowable error, and the islanded bus frequency... When the absolute value of the deviation from the rated island frequency does not exceed the allowable deviation of the island frequency, the transient adjustment of the smelting load is set to zero; when the remaining frequency supports a positive active power demand and is greater than the adjustable capacity of the smelting load reduction, the active power control command of the smelting load is set to the lower limit of the adjustable power of the smelting load; when the remaining frequency supports a negative active power demand and its absolute value is greater than the adjustable capacity of the smelting load expansion, the active power control command of the smelting load is set to the upper limit of the adjustable power of the smelting load.

7. The frequency-coordinated power control method for multi-source isolated grid smelting according to claim 1, characterized in that, The current smelting stage is obtained; the transient adjustment of the smelting load is executed by the power electronic power conversion of the power unit, and is formed without relying on the electrode control system to drive the electrode position change; after the frequency modulation event ends, the electrode control system adjusts the electrode position according to the smelting control logic corresponding to the current smelting stage.

8. A frequency-coordinated power control system for multi-source isolated grid smelting, characterized in that, The system includes a controller, a frequency acquisition interface, a power acquisition interface, multiple controllable power supplies, and power units connected to the smelting load. The frequency and power acquisition interfaces are connected to the controller signals, providing the controller with the islanded bus frequency and the actual active power of the controllable power supplies. The controller acquires the rated islanded frequency and the allowable deviation of the islanded frequency to determine the adjustable power range of the smelting load. The start time of the frequency modulation event is determined when the deviation of the islanded bus frequency from the rated islanded frequency first exceeds the allowable deviation. The active power demand supported by the frequency modulation event is determined based on the islanded bus frequency at the start time of the frequency modulation event. The frequency-supported active power demand of the frequency-modulated event determines the transient adjustment amount of the smelting load within the adjustable power range of the smelting load. It outputs active power adjustment commands to multiple controllable power sources and causes the power units to change the active power of the smelting load according to the transient adjustment amount of the smelting load. Based on the change of the actual active power of each controllable power source relative to the start time of the frequency-modulated event along the direction of the active power adjustment command, it determines the actual response amount of the controllable power source and summarizes it into the multi-source actual response increment. The remaining frequency-supported active power demand is determined by the difference between the frequency-supported active power demand of the frequency-modulated event and the multi-source actual response increment, and the transient adjustment amount of the smelting load is updated.

9. The frequency-coordinated power control system for multi-source isolated grid smelting according to claim 8, characterized in that, It also includes an electrode control system; the controller is further used to obtain the current smelting stage, and the electrode control system is connected to the electrode actuator of the smelting load; during the period when the power unit performs power electronic power conversion according to the transient adjustment amount of the smelting load, the electrode control system maintains the smelting control logic corresponding to the current smelting stage, and after the frequency modulation event ends, the electrode control system adjusts the electrode position according to the smelting control logic corresponding to the current smelting stage.

10. The frequency-coordinated power control system for multi-source isolated grid smelting according to claim 8, characterized in that, The controller is also used to determine the target active power adjustment amount of each controllable power source, and to determine the actual active power change of each controllable power source formed along the adjustment direction corresponding to the active power adjustment command and whose absolute value does not exceed the absolute value of the target active power adjustment amount as the actual response amount of the controllable power source.

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