Diesel generator set energy storage collaborative power supply method

Abstract

This invention relates to the field of energy storage and power supply coordination methods for diesel generator sets. The method collects operating data from the load, online diesel generator sets, and energy storage devices. Based on the historical load response, thermal state, and speed regulation margin of the diesel generator sets, it determines the upper boundary of transient load acceptance and the upper limit of steady-state available power. The power supply gap is divided into transient response gap and continuous capacity gap, which are rapidly supported and compensated for by the energy storage device, respectively. A standby diesel generator set is then activated based on power and energy constraints. After the standby diesel generator set is connected, the energy storage discharge power is gradually reduced according to its actual net connection power. After the load stabilizes, the compensation power is determined based on the amount of support energy to be replenished and the accumulated low load of the diesel generator set. This application can improve the continuity of power supply and the accuracy of diesel-energy storage coordinated control under load abrupt changes.

Description

Technical Field

[0001] This invention relates to the field of power supply control technology for power systems, and specifically to a method for co-powering diesel generator sets with energy storage. Background Technology

[0002] Diesel generator sets are characterized by flexible starting, strong environmental adaptability, and high power supply independence, and are widely used in isolated power supply, emergency backup, engineering construction, and critical load backup power supply scenarios. To improve the problems of slow response speed and large bus frequency fluctuations when the load changes suddenly, existing power supply systems usually configure energy storage devices on the diesel generator side. The energy storage devices discharge rapidly when the load suddenly increases and recharge when the load decreases or when the output power of the diesel generator set exceeds the load demand.

[0003] Existing coordinated control of diesel generator sets and energy storage devices often uses fixed control thresholds based on the energy storage device's state of charge, load demand power, or the diesel generator set's rated power. The charging and discharging power of the energy storage device is determined by a fixed ramp rate, a fixed power range, or the difference between the load demand power and the actual output power of the diesel generator set. However, the actual load-bearing capacity of a diesel generator set is affected by current output power, coolant temperature, exhaust temperature, speed regulation margin, operating time, and changes in the unit's status. Fixed ramp parameters cannot accurately reflect the load that the diesel generator set can accept under current operating conditions. When the actual response capability of the unit is lower than the set value, insufficient energy storage support is likely to occur; conversely, when the actual response capability is higher than the set value, the energy storage device may be over-utilized.

[0004] Furthermore, existing control methods typically combine the power gap caused by the temporary inability of diesel generator sets to increase load with the power gap caused by insufficient steady-state capacity of online diesel generator sets, allocating the compensation to energy storage devices. This makes it difficult to distinguish the causes of energy storage discharge. After the diesel generator set takes over the load, the withdrawal and recharging of the energy storage device are often executed based on power commands, state of charge, or fixed times, without fully considering the actual takeover power of the diesel generator set, the energy storage support margin required for subsequent load surges, and the low-load operating state of the diesel generator set. This can easily lead to premature withdrawal of the energy storage device, untimely start-up of the standby diesel generator set, or new power disturbances caused during the recharging process. Therefore, it is necessary to coordinate and control the actual load-bearing capacity of the diesel generator set, the type of energy storage support, the takeover process of the standby unit, and the energy storage recharge process. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a diesel generator set energy storage-assisted power supply method to solve the technical problems existing in the prior art.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A diesel generator set energy storage coordinated power supply method, applied to a power supply system including an AC bus, load, energy storage device, controller, at least one online diesel generator set and at least one standby diesel generator set, includes the following steps: S1: Collect the load demand power, the actual output power, speed, speed regulator status, coolant temperature and exhaust temperature of each online diesel generator set, as well as the state of charge, current available energy and allowable charging and discharging power of the energy storage device, and form a load power sequence based on the load demand power collected in the continuous control cycle, and determine the predicted load power from the load power sequence. S2: Record the power command, actual output power and response time of each online diesel generator set during load change process, and select qualified load response events from the load change process where the actual output power continuously follows the power command, the absolute difference between the actual output power and the power command continuously decreases and the AC bus frequency recovers to the allowable frequency range. S3: Determine the reliable load increase rate based on the qualified load response events corresponding to each online diesel generator set, and combine the current actual output power, speed regulation margin, coolant temperature and exhaust temperature of each online diesel generator set to determine the upper boundary of the single unit transient load acceptance and the upper limit of the single unit steady-state available power in the next control window. The sum of the upper boundaries of the single unit transient load acceptance is determined as the upper boundary of the total transient load acceptance, and the sum of the upper limits of the single unit steady-state available power is determined as the upper limit of the total steady-state available power. S4: Based on the current load demand power, the upper limit of the total transient load acceptance and the upper limit of the total steady-state available power, the power supply power that the online diesel generator set cannot cover is divided into transient response gap and continuous capacity gap. The energy storage device is controlled to compensate for the transient response gap and temporarily compensate for the continuous capacity gap within the dispatchable discharge power. The energy storage device supports the amount of energy to be replenished based on the actual discharge power and discharge time used to compensate for the transient response gap. S5: Based on the predicted load power and the start-up time, synchronization time and load ramp-up time of the standby diesel generator set, determine the reserved support power and reserved support energy that the energy storage device needs to retain. The remaining power after deducting the reserved support power from the allowable discharge power of the energy storage device is determined as the dispatchable discharge power. The remaining energy after deducting the reserved support energy from the current available energy of the energy storage device is determined as the dispatchable energy. S6: When the continuous capacity gap is greater than the dispatchable discharge power, or when the gap energy formed before the standby diesel generator set completes the load increase is greater than the dispatchable energy, start a standby diesel generator set; after the standby diesel generator set completes synchronization and is connected to the AC bus, it is treated as a newly added online diesel generator set, and the discharge power of the energy storage device used to compensate for the continuous capacity gap is reduced according to the increase in its actual output power. S7: Based on the power difference, duration, coolant temperature and exhaust temperature of each online diesel generator set below the corresponding restored load power, a low load accumulation is formed; when the difference between the maximum and minimum load demand power within the continuous control window is not greater than the load stability threshold, the continuous capacity gap is zero, there is remaining load increase space at the upper boundary of the total transient load acceptance, and the energy storage device has reserved support power and reserved support energy, the recovery power is determined based on the remaining load increase space, the allowable charging power of the energy storage device, the amount of support energy to be recovered, and the low load accumulation, and the online diesel generator set is controlled to increase the output power and charge the energy storage device according to the recovery power; S8: During the charging process of the energy storage device, when the increase in load demand power in the adjacent control cycle reaches the load rise threshold, or when the predicted load power exceeds the current total transient load acceptance upper boundary, the charging of the energy storage device is stopped, the unreplenished support energy is retained, and the transient response gap and continuous capacity gap are reclassified.

[0007] Preferably, determining the predicted load power based on the load power sequence includes: Calculate the power change at adjacent sampling points in the load power sequence, and determine the current load change rate based on the continuous power changes in the same direction and their corresponding sampling periods; Based on the current load demand power, the current load change rate, and the duration of the next control window, determine the predicted load power within the next control window; If the current power change has the opposite sign to the power change in the previous sampling period, or if the current positive load change rate decreases for two consecutive sampling periods, shorten the length of the load power sequence used to calculate the current load change rate, and use the shortened load power sequence to redetermine the predicted load power.

[0008] Preferably, the qualified load response events to be screened include: The moment when the increase in power command of the online diesel generator set reaches the command change threshold is determined as the start time of the load response event. The command change threshold is determined based on the rated power and power sampling resolution of the online diesel generator set. After the start time, determine whether the actual output power of the online diesel generator set increases continuously for no less than two sampling periods, whether the absolute difference between the actual output power and the power command decreases continuously for no less than two sampling periods, whether the speed controller is in an unsaturated state, and whether the AC bus frequency has recovered to the allowable frequency range. A load response event that simultaneously meets the following conditions is defined as a qualified load response event: the actual output power continuously increases, the absolute difference continuously decreases, the speed control actuator is in an unsaturated state, and the AC bus frequency recovers to the allowable frequency range. The response delay and actual load increase rate are determined based on the start time of each qualified load response event, the moment when the actual output power begins to increase continuously, and the moment when the absolute difference between the actual output power and the power command decreases to within the tracking deviation threshold. The tracking deviation threshold is determined based on the rated power and power sampling resolution of the online diesel generator set.

[0009] Preferably, determining the reliable load ramp rate, the upper limit of the transient load acceptance of a single unit, and the upper limit of the steady-state available power of a single unit for each online diesel generator set includes: Select at least three qualified load response events for the same online diesel generator set, arranged from the most recent to the oldest occurrence time, and determine the minimum value among the actual load rate corresponding to the selected qualified load response events as the base load rate. The thermal state correction factor is determined based on the deviation of the current coolant temperature and exhaust temperature of the online diesel generator set from their respective allowable temperature ranges. The product of the basic load rate and the thermal state correction factor is then determined as the reliable load rate. The sum of the current actual output power of the online diesel generator set and the power that can be increased within the next control window at the reliable load rate is determined as the ramp limit power; The thermal state limiting power is obtained by subtracting the derating power determined by the deviation between coolant temperature and exhaust temperature from the rated power of the online diesel generator set. The sum of the current actual output power and the power that can be increased corresponding to the remaining stroke of the speed controller is determined as the speed controller limiting power. The minimum value among the ramp-up limit power, thermal limit power, and speed regulation execution limit power is determined as the upper boundary of the transient load acceptance of a single unit, and the smaller value among the thermal limit power and speed regulation execution limit power is determined as the upper limit of the steady-state available power of a single unit.

[0010] Preferably, the transient response gap and the sustained capacity gap are divided into: When the current load demand power is greater than the upper limit of the total transient load acceptance but not greater than the upper limit of the total steady-state available power, the power difference between the current load demand power and the upper limit of the total transient load acceptance is determined as the transient response gap, and the continuous capacity gap is determined as zero. When the current load demand power is greater than the upper limit of the total steady-state available power, the positive power difference between the upper limit of the total steady-state available power and the upper limit of the total transient load acceptance is determined as the transient response gap, and the power difference between the current load demand power and the upper limit of the total steady-state available power is determined as the continuous capacity gap. When the current load demand power is not greater than the upper limit of the total transient load acceptance, both the transient response gap and the continuous capacity gap are set to zero; The first target discharge power of the energy storage device is determined based on the transient response gap, and the second target discharge power of the energy storage device is determined based on the continuous capacity gap. The sum of the first target discharge power and the second target discharge power is limited to the dispatchable discharge power.

[0011] Preferably, the cumulative amount of support energy to be replenished and the determination of reserved support power and reserved support energy include: When the energy storage device compensates for the transient response gap according to the first target discharge power, the product of the actual discharge power used to compensate for the transient response gap and the sampling period is accumulated to the amount of supporting energy to be replenished, and the discharge energy used by the energy storage device to compensate for the continuous capacity gap is excluded from the amount of supporting energy to be replenished. The takeover period is determined based on the takeover time required for the standby diesel generator set to complete synchronization and reach the target output power from receiving the start command. The reserved support power is determined based on the maximum positive power difference between the predicted load power during the takeover period and the upper boundary of the total transient load acceptance corresponding to each control window. The positive power difference between the predicted load power and the total transient load acceptance upper boundary corresponding to each control window during the takeover period is accumulated according to the control window duration to obtain the reserved support energy; When the energy storage device is charged according to the replenishment power, the amount of supporting energy to be replenished is reduced according to the actual charging energy generated according to the replenishment power, and the lower limit of the amount of supporting energy to be replenished is set to zero.

[0012] Preferably, determining whether to start the standby diesel generator set includes: Based on the predicted load power, the upper limit of total steady-state available power, and the reserved support power of each control window during the takeover period, the predicted continuous capacity gap in each control window is determined. The predicted continuous capacity gap in each control window is summed with the product of the corresponding control window duration to obtain the gap energy before the standby diesel generator set completes the takeover. The remaining power after deducting the reserved support power from the allowable discharge power of the energy storage device is determined as the dispatchable discharge power, and the remaining energy after deducting the reserved support energy from the current available energy of the energy storage device is determined as the dispatchable energy. When the current continuous capacity gap is greater than the dispatchable discharge power, or the gap energy is greater than the dispatchable energy, a start command is sent to a standby diesel generator set that is in a shutdown state. When the current continuous capacity gap is not greater than the dispatchable discharge power and the gap energy is not greater than the dispatchable energy, the standby diesel generator set is kept in a shutdown state, and the current continuous capacity gap, gap energy, dispatchable discharge power and dispatchable energy are redefined in the next control window.

[0013] Preferably, reducing the discharge power of the energy storage device based on the actual output power of the standby diesel generator set includes: After the standby diesel generator set that receives the start command completes synchronization and is connected to the AC bus, the standby diesel generator set is treated as a newly added online diesel generator set. The actual increase in output power of the newly added online diesel generator set in adjacent control cycles is collected. The actual increase in output power is compared with the actual discharge power of the energy storage device currently used to compensate for the continuous capacity gap. The second target discharge power of the energy storage device is reduced according to the smaller of the two values. When the actual output power of the newly added online diesel generator set does not increase for two consecutive control cycles, the actual output power drops, or the absolute difference between the actual output power and the power command is greater than the tracking deviation threshold, the reduction of the second target discharge power of the energy storage device will be stopped. Based on the actual output power, speed governor actuator status, coolant temperature, exhaust temperature, and qualified load response events of the newly added online diesel generator set, determine the upper limit of the single-unit transient load acceptance and the upper limit of the single-unit steady-state available power of the newly added online diesel generator set, and update the upper limit of the total transient load acceptance and the upper limit of the total steady-state available power.

[0014] Preferably, forming a low load accumulation and determining the compensation power includes: Based on the historical output power and exhaust temperature correspondence of each online diesel generator set, the output power required to bring the exhaust temperature to the lower limit of the recovery temperature is determined, and the larger value between this output power and the minimum stable operating power of the corresponding online diesel generator set is determined as the recovery load power. When the actual output power of the online diesel generator set is lower than the corresponding recovery load power and the exhaust temperature is lower than the lower limit of the recovery temperature, the power difference between the recovery load power and the actual output power and the corresponding duration are multiplied and accumulated to the low load accumulation of the online diesel generator set. When the actual output power of the online diesel generator set is not lower than the corresponding recovery load power, and the exhaust temperature is not lower than the lower limit of the recovery temperature and continues to reach the temperature holding time, the low load accumulation of the online diesel generator set is reduced according to the power difference between the actual output power and the recovery load power and the corresponding duration. The ratio of the amount of supporting energy to be replenished to the replenishment time is determined as the energy replenishment demand power, and the sum of the positive power differences between the corresponding restored load power of each online diesel generator set and the current actual output power is determined as the low load recovery demand power. The minimum value among the following is determined as the upper limit of the replenishment power: the power difference between the upper limit of the total transient load acceptance and the sum of the current actual output power of each online diesel generator set, the allowable charging power of the energy storage device, and the energy replenishment demand power required to reduce the amount of supporting energy to be replenished within the replenishment period. Within the upper limit of the replenishment power, the replenishment power is determined according to the larger value between the energy replenishment demand power and the low load recovery demand power.

[0015] Preferably, the process of detecting new load increase events and handling interruptions includes: During the charging process of the energy storage device, the increase in load demand power in adjacent control cycles is calculated. A new load rise event is determined when the increase in load demand power reaches the load rise threshold, or when the predicted load power exceeds the upper limit of the current total transient load acceptance. The load rise threshold is determined based on the load rated power and power sampling resolution. In the next control cycle after a new load increase event is identified, the replenishment power will be reduced to zero, the amount of support energy that has not yet been reduced will be retained for replenishment, and the transient response gap and continuous capacity gap will be re-determined based on the new current load demand power, the predicted load power, the upper limit of the total transient load acceptance, and the upper limit of the total steady-state available power. The control energy storage device compensates for the redefined transient response gap, adds the actual discharge energy corresponding to this compensation to the remaining support energy to be replenished, and re-executes the start-up judgment of the standby diesel generator set based on the redefined continuous capacity gap, gap energy, dispatchable discharge power, and dispatchable energy.

[0016] In summary, the present invention has the following main beneficial effects: By collecting data on the actual output power, speed regulator status, coolant temperature, exhaust temperature, and recent qualified load response events of each online diesel generator set, the reliable load ramp rate, transient load acceptance upper limit, and steady-state available power upper limit of each unit are dynamically determined. Furthermore, the total transient load acceptance upper limit and total steady-state available power upper limit are updated in real time based on the actual operating status of each unit. This avoids using a fixed ramp rate or rated power to judge the load-bearing capacity of the diesel generator set, enabling energy storage power control to adapt to changes in the thermal state, speed regulation margin, and actual response capability of the diesel generator set. This reduces the risk of excessive load ramping, bus power imbalance, and frequency fluctuations during sudden load changes.

[0017] By dividing the power supply that online diesel generator sets cannot cover into transient response gaps and continuous capacity gaps, the energy storage device prioritizes compensating for transient response gaps and only accumulates the actual discharge energy of this part as the supporting energy to be replenished. At the same time, the standby diesel generator sets are started according to the continuous capacity gap, the capacity support dispatchable power, the gap energy during the takeover period, and the energy storage dispatchable energy. This achieves the effect of distinguishing between the temporary response insufficiency of diesel generator sets and the steady-state power supply capacity insufficiency, avoiding the mistaken treatment of continuous capacity insufficiency as short-term support by energy storage. This ensures that the start-up of standby diesel generator sets meets both power constraints and energy constraints, and improves the continuity of power supply under continuous load conditions.

[0018] By gradually reducing the discharge power of the energy storage device to compensate for the continuous capacity gap after the standby diesel generator set is connected to the AC bus, based on the net takeover power after deducting the increase in load during the same period from the actual increase in output power, the power of the energy storage device to compensate for the continuous capacity gap is gradually reduced. After the load stabilizes, the power of the energy to be replenished is determined based on the amount of support energy to be replenished, the amount of low load accumulation, the remaining load increase space of the diesel generator set, and the allowable charging power of the energy storage, so as to avoid prematurely withdrawing the energy storage support according to the target power. When a new load increase event occurs, the power of the energy storage is stopped and the amount of support energy to be replenished that has not yet been reduced is retained, so as to form an interruptible and resumable collaborative power supply closed loop that enables the rapid support of energy storage, the actual takeover of the diesel generator set, the recovery of energy storage, and the recovery of the diesel generator set from the low load state. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present 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 embodiments of the present invention, and not all embodiments. 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] Example 1 refer to Figure 1 A diesel generator set energy storage coordinated power supply method, applied to a power supply system including an AC bus, load, energy storage device, controller, at least one online diesel generator set and at least one standby diesel generator set, includes the following steps: S1: Collect the load demand power, the actual output power, speed, speed regulator status, coolant temperature and exhaust temperature of each online diesel generator set, as well as the state of charge, current available energy and allowable charging and discharging power of the energy storage device, and form a load power sequence based on the load demand power collected in the continuous control cycle, and determine the predicted load power from the load power sequence. S2: Record the power command, actual output power and response time of each online diesel generator set during load change process, and select qualified load response events from the load change process where the actual output power continuously follows the power command, the absolute difference between the actual output power and the power command continuously decreases and the AC bus frequency recovers to the allowable frequency range. S3: Determine the reliable load increase rate based on the qualified load response events corresponding to each online diesel generator set, and combine the current actual output power, speed regulation margin, coolant temperature and exhaust temperature of each online diesel generator set to determine the upper boundary of the single unit transient load acceptance and the upper limit of the single unit steady-state available power in the next control window. The sum of the upper boundaries of the single unit transient load acceptance is determined as the upper boundary of the total transient load acceptance, and the sum of the upper limits of the single unit steady-state available power is determined as the upper limit of the total steady-state available power. S4: Based on the current load demand power, the upper limit of the total transient load acceptance and the upper limit of the total steady-state available power, the power supply power that the online diesel generator set cannot cover is divided into transient response gap and continuous capacity gap. The energy storage device is controlled to compensate for the transient response gap and temporarily compensate for the continuous capacity gap within the dispatchable discharge power. The energy storage device supports the amount of energy to be replenished based on the actual discharge power and discharge time used to compensate for the transient response gap. S5: Based on the predicted load power and the start-up time, synchronization time and load ramp-up time of the standby diesel generator set, determine the reserved support power and reserved support energy that the energy storage device needs to retain. The remaining power after deducting the reserved support power from the allowable discharge power of the energy storage device is determined as the dispatchable discharge power. The remaining energy after deducting the reserved support energy from the current available energy of the energy storage device is determined as the dispatchable energy. S6: When the continuous capacity gap is greater than the dispatchable discharge power, or when the gap energy formed before the standby diesel generator set completes the load increase is greater than the dispatchable energy, start a standby diesel generator set; after the standby diesel generator set completes synchronization and is connected to the AC bus, it is treated as a newly added online diesel generator set, and the discharge power of the energy storage device used to compensate for the continuous capacity gap is reduced according to the increase in its actual output power. S7: Based on the power difference, duration, coolant temperature and exhaust temperature of each online diesel generator set below the corresponding restored load power, a low load accumulation is formed; when the difference between the maximum and minimum load demand power within the continuous control window is not greater than the load stability threshold, the continuous capacity gap is zero, there is remaining load increase space at the upper boundary of the total transient load acceptance, and the energy storage device has reserved support power and reserved support energy, the recovery power is determined based on the remaining load increase space, the allowable charging power of the energy storage device, the amount of support energy to be recovered, and the low load accumulation, and the online diesel generator set is controlled to increase the output power and charge the energy storage device according to the recovery power; S8: During the charging process of the energy storage device, when the increase in load demand power in the adjacent control cycle reaches the load rise threshold, or when the predicted load power exceeds the current total transient load acceptance upper boundary, the charging of the energy storage device is stopped, the unreplenished support energy is retained, and the transient response gap and continuous capacity gap are reclassified.

[0022] The power supply system used in this embodiment includes an AC bus, loads connected to the AC bus, an energy storage device, a controller, at least one online diesel generator set, and at least one standby diesel generator set.

[0023] Online diesel generator sets refer to diesel generator sets that output active power to the AC bus when the grid connection switch is closed; standby diesel generator sets refer to diesel generator sets that can sequentially complete diesel engine start-up, generator voltage building, synchronization, and load increase after receiving a start command when the grid connection switch is open.

[0024] The energy storage device includes a battery pack, a battery management system (BMS), and an energy storage converter. The AC side of the energy storage converter is connected to the AC bus and is used to perform discharge or charge operations according to the active power commands issued by the controller. The BMS outputs the energy storage device's state of charge, state of health, battery temperature, current available energy, allowable charging power, and allowable discharging power.

[0025] Each diesel generator set includes a diesel engine, a synchronous generator, a generator set controller, a speed governor actuator, an automatic voltage regulator, a synchronizing device, and a grid connection switch. The generator set controller receives power commands and outputs the generator set's speed, actual output power, speed governor actuator status, coolant temperature, exhaust temperature, grid connection switch status, and fault status to the grid connection switch.

[0026] The controller communicates with the AC bus metering device, energy storage converter, battery management system, and the generator controllers of each diesel generator set. The controller can be a standalone microgrid controller or integrated into the energy management controller of the power supply system.

[0027] The AC bus metering device collects the three-phase voltage, three-phase current, active power, reactive power, and frequency of the AC bus. The current load demand is calculated using the actual active power output from the AC bus to the load side.

[0028] The actual output power of each diesel generator set is preferentially based on the measurement results of the corresponding unit's outlet-side energy metering device, while the power data uploaded by the unit controller is used for cross-verification. The speed governor actuator status can be based on the fuel rack position, fuel injection quantity command, engine torque command, or the normalized speed governor output. The speed governor execution margin is determined by the difference between the maximum allowable position of the speed governor actuator and the current actual position.

[0029] The rated power, minimum stable operating power, allowable coolant temperature range, allowable exhaust temperature range, temperature derating starting value, temperature protection limit value, and maximum allowable position of the speed controller of the diesel generator set can be obtained from the nameplate of the unit, the manufacturer's technical documents, or the valid configuration parameters in the unit controller.

[0030] The rated energy, upper and lower limits of state of charge, permissible charge and discharge power, battery temperature correction relationship, and charge and discharge efficiency of the energy storage device are obtained from the technical documents or valid configuration parameters of the battery pack, energy storage converter, and battery management system manufacturers.

[0031] When the battery management system directly outputs the current available energy, the controller uses that output value. When the battery management system does not directly output the current available energy, the controller determines the current available energy based on the energy storage device's rated energy, state of health, current state of charge, allowable discharge state limit, battery temperature, and discharge efficiency.

[0032] The controller collects operating data according to the sampling period and performs load forecasting, load acceptance boundary updating, power supply gap division, energy storage power control, and standby diesel generator start-stop control according to the control period.

[0033] The sampling period is determined based on the data refresh cycle of the AC bus metering device, the generator controller, and the energy storage converter. The control cycle consists of one or several consecutive sampling cycles, and is no greater than the minimum effective response delay of the diesel generator set measured in the field step load test, so that the controller can identify the actual power changes of the diesel generator set in adjacent control cycles.

[0034] The controller saves the current load demand power collected in consecutive control cycles in chronological order to form a load power sequence.

[0035] The initial length of the load power sequence was determined using field trial operation data. Specifically, different sequence lengths were used to predict the load power of the next control window, and the prediction error corresponding to each sequence length was calculated. When the decrease in prediction error due to further increasing the sequence length was not greater than the load power measurement resolution, the corresponding shortest sequence length was determined as the initial sequence length.

[0036] When field trial operation data is lacking, the load power sequence should include at least three consecutive sampling points, and the sequence length should be adjusted according to the actual prediction error.

[0037] The controller determines the current load change rate based on the continuously changing power data in the load power sequence, and determines the predicted load power according to the following formula: ; In the formula: For the first Predicted load power for each control cycle; For the first Current load demand power for each control cycle; This represents the current load change rate; This represents the number of prediction steps relative to the current control cycle. To control the cycle duration.

[0038] When the load power change in the current control cycle is opposite in sign to the load power change in the previous control cycle, the controller deletes the sampling points before the load change direction changed and uses the continuous sampling points after the change direction changed to reconstruct the load power sequence.

[0039] When the positive load change rate decreases for two consecutive control cycles, the controller sequentially deletes the earliest sampling point in the load power sequence until the positive load change rate corresponding to the remaining sampling points no longer decreases continuously.

[0040] The shortened load power sequence retains at least three consecutive sampling points. If fewer than three sampling points remain, the current load change rate is set to zero, and the current load demand power is used as the predicted load power for the next control window.

[0041] The predicted load power is used to determine the reserved support power, reserved support energy, predicted continuous capacity gap, and the start-up timing of standby diesel generator sets within the future control window. The discharge power of the energy storage device in the current control cycle is still determined based on the current load demand power, avoiding the direct conversion of prediction errors into AC bus power deviation.

[0042] The controller continuously records the power command, actual output power, speed controller status, and AC bus frequency for each online diesel generator set.

[0043] The command change threshold is used to distinguish between valid load increase commands and governor steady-state fine-tuning. For any online diesel generator set, the natural fluctuation range of its actual output power is first recorded under stable load conditions, and then the power command change is gradually increased. The minimum command change that causes the actual output power to exceed the natural fluctuation range for at least two consecutive sampling periods is determined as the command change threshold for that generator set. This threshold must not be less than twice the power measurement resolution.

[0044] When the increase in power command of the online diesel generator set reaches the corresponding command change threshold, the controller determines this moment as the start time of a load response event.

[0045] After the load response event begins, the controller sequentially checks: Does the actual output power increase continuously for at least two sampling periods? Whether the absolute difference between the actual output power and the power command decreases continuously for at least two sampling periods; Is the speed control actuator below the maximum permissible position? Has the AC bus frequency returned to the allowable frequency range?

[0046] The permissible frequency range is the intersection of the permissible frequency range of the load, the permissible frequency range of the diesel generator set, and the design frequency range of the power supply system.

[0047] The tracking deviation threshold is determined based on the steady-state power regulation error and power measurement resolution of the diesel generator set. If the manufacturer's technical documents specify the steady-state power regulation error, the manufacturer's stated error is used; otherwise, the maximum absolute difference between the power command and the actual output power is recorded through a stable load test. The tracking deviation threshold is the larger of this steady-state power regulation error and twice the power measurement resolution.

[0048] When the actual output power increases continuously, the absolute difference of power tracking decreases continuously, the speed control actuator is in an unsaturated state, and the AC bus frequency recovers to the allowable frequency range, the load response event is determined as a qualified load response event.

[0049] The corresponding load response event should not be used to determine the reliable load-carrying capacity of the diesel generator set if any of the following conditions are met: Power measurement data was interrupted; The grid connection switch status has changed; Diesel generator sets are subject to manual power intervention; The protection device performs a power limiting action; The speed-regulating actuator reaches its maximum permissible position; Actual output power continues to decline; The AC bus frequency has not recovered to the permissible frequency range.

[0050] The controller records the start time of the qualified load response event, the moment when the actual output power begins to increase continuously, and the moment when the absolute difference between the actual output power and the power command decreases to within the tracking deviation threshold.

[0051] Response delay is the time difference between the start of the load response event and the start of the continuous increase in actual output power. Actual load increase rate is the ratio of the increase in actual output power to the corresponding duration from the start of the continuous increase in actual output power until the absolute difference in power tracking decreases to within the tracking deviation threshold.

[0052] For each online diesel generator set, the controller selects no fewer than three qualified load response events in order of their occurrence time from most recent to oldest, and determines the minimum value among the actual load increase rates of the selected qualified load response events as the base load increase rate.

[0053] When the system has not accumulated three qualified load response events in the early stage of operation, the smaller value between the allowable load rate given by the manufacturer and the actual load rate obtained from the field step load test shall be determined as the base load rate.

[0054] The controller determines the thermal state correction factor based on the current coolant temperature and exhaust temperature of the online diesel generator set.

[0055] For any temperature parameter, when the current temperature does not exceed the corresponding temperature derating start value, the correction factor for that temperature is 1; when the current temperature is between the temperature derating start value and the temperature protection limit value, the correction factor decreases linearly as the current temperature increases; when the current temperature reaches the temperature protection limit value, the correction factor is 0.

[0056] The smaller of the coolant temperature correction factor and the exhaust temperature correction factor is used as the thermal state correction factor.

[0057] No. The reliable load ramp rate, the upper limit of transient load acceptance for a single unit, and the upper limit of steady-state available power for a single unit of an online diesel generator set are determined according to the following relationships: ; ; ; In the formula: For the first The online diesel generator set is in the first The reliable load rate for each control cycle; This is a thermal state correction factor; This is the set of recent qualified load response events for this unit; For the first The actual load ramp rate corresponding to the sub-qualified load response event; This represents the unit's current actual output power. Duration of the next control window; Power is limited for thermal conditions; Power is limited to regulate speed; The upper boundary is for accepting transient loads on a single machine; This represents the upper limit of the power available in steady state for a single unit.

[0058] The thermal limiting power is determined based on the coolant temperature derating curve and exhaust temperature derating curve provided by the manufacturer. The speed control actuator limiting power is determined based on the remaining stroke of the speed control actuator and the correspondence between the speed control actuator position and the stable output power.

[0059] The correspondence can be provided by the manufacturer, or it can be formed by running the diesel generator set stably at different load points during on-site commissioning and recording the position of the speed regulator actuator and the actual output power.

[0060] The controller adds up the upper limits of the transient load acceptance of each online diesel generator set to obtain the upper limit of the total transient load acceptance; it also adds up the upper limits of the steady-state available power of each online diesel generator set to obtain the upper limit of the total steady-state available power.

[0061] When the coolant temperature or exhaust temperature of any online diesel generator set reaches the protection limit, the unit is no longer allowed to generate additional load capacity. When the actual output power of the unit is higher than the allowable derating power, the controller will implement load reduction, and the power gap caused by the load reduction will be compensated by the energy storage device or other online diesel generator sets.

[0062] This embodiment does not use the fixed gradeability rate on the diesel generator set's nameplate, but instead uses recent actual load increases, current thermal conditions, and speed control margin to jointly determine the load that the diesel generator set can accept in the next control window. When the unit ages, its speed control capability decreases, or its temperature approaches the protection limit, the resulting load acceptance boundary automatically decreases.

[0063] The controller classifies the power supply that the online diesel generator set cannot cover based on the current load demand power, the upper limit of the total transient load acceptance, and the upper limit of the total steady-state available power.

[0064] The transient response gap and the sustained capacity gap are determined according to the following formula: ; ; In the formula: For transient response gap; There is a persistent capacity gap. The upper boundary is accepted for the total transient load; This represents the upper limit of the total steady-state available power. .

[0065] The transient response gap represents the power that the online diesel generator set can handle under steady-state conditions, but cannot provide in a timely manner within the current control window due to the limitation of the actual load-up speed.

[0066] A persistent capacity gap indicates that the current load demand has exceeded the upper limit of the total steady-state available power of the online diesel generator set, and this gap cannot be eliminated by continuing to increase the load on the existing online diesel generator set.

[0067] The first target discharge power of the energy storage device is used to compensate for the transient response gap. The first target discharge power is taken as the smaller value between the transient response gap and the current allowable discharge power of the energy storage device.

[0068] The power used by the energy storage device to compensate for continuous capacity shortages is called the second target discharge power. To prevent continuous capacity support from consuming the rapid support capacity reserved by the energy storage device for subsequent load shocks, the upper limit of the second target discharge power is determined in the following order: First, subtract the portion of the first target discharge power already occupied from the current allowable discharge power of the energy storage device; When the first target discharge power is less than the reserved support power, the portion of the reserved support power that has not yet been occupied by the first target discharge power shall be retained. The remaining discharge capacity after deducting the above power is used as the capacity-supported dispatchable power. The second target discharge power is the smaller of the continuous capacity gap and the capacity support dispatchable power.

[0069] The controller uses the sum of the first target discharge power and the second target discharge power as the active power command for the energy storage converter. The actual discharge power of the energy storage device is based on the metering value on the AC side of the energy storage converter.

[0070] When the current allowable discharge power of the energy storage device is insufficient to compensate for both types of gaps at the same time, the transient response gap is compensated first, the remaining discharge capacity is used to temporarily compensate for the continuous capacity gap, and the standby diesel generator set start-up judgment is executed immediately.

[0071] The actual discharge power of the energy storage device used to compensate for transient response gaps is called the transient support actual power. The controller only includes the discharge energy corresponding to the transient support actual power in the support energy to be replenished.

[0072] The discharge energy used by energy storage devices to compensate for the continuous capacity gap is not included in the supporting energy to be replenished. The continuous capacity gap originates from insufficient steady-state power supply capacity of online diesel generator sets and cannot be automatically replenished by the currently online diesel generator sets after the load stabilizes.

[0073] The amount of supporting energy to be replenished is updated according to the following formula: ; In the formula: This represents the amount of support energy to be replenished at the end of the current control cycle. This is the amount of support energy to be replenished at the end of the previous control cycle. This is the actual discharge power used by the energy storage device to compensate for transient response gaps; This refers to the actual charging power absorbed by the energy storage device during the recharge process.

[0074] Only the actual charging energy that meets the replenishment access conditions of this embodiment is used to reduce the amount of support energy to be replenished. Charging energy generated by normal economic charging, manual charging, or other scheduling strategies does not directly reduce the amount of support energy to be replenished.

[0075] Therefore, the amount of supporting energy to be replenished can reflect the energy provided by the energy storage device to compensate for the lag in the dynamic response of the diesel generator set, but which has not yet been restored, without mixing in the energy supply from the energy storage during periods of continuous capacity shortage.

[0076] The controller determines the takeover period based on the time required for the target standby diesel generator set to complete synchronization and reach the target output power from receiving the start command.

[0077] The takeover period includes the diesel engine start-up time, generator pressure build-up time, synchronization time, and the time required to increase the load to the target output power.

[0078] When the standby diesel generator set has no less than three valid start records, the maximum time required from the issuance of the start command to the actual output power reaching the target output power among the three most recent valid start records shall be used as the takeover period.

[0079] A valid startup record should simultaneously meet the following conditions: no faults occurred during the startup process, the synchronization device worked normally, the grid connection switch closed normally, the startup process was not subject to manual intervention, and the actual output power continuously increased to the target output power.

[0080] If there are fewer than three valid start-up records, the sum of the manufacturer's maximum start-up time, the on-site synchronous test time, and the on-site load increase test time shall be used as the takeover period.

[0081] Reserved support power and reserved support energy are determined solely based on the predicted transient response gap during the takeover period. The predicted continuous capacity gap is not included in the reserved support power and reserved support energy, but is used separately for the start-up judgment of the standby diesel generator set.

[0082] During the takeover period, the controller calculates the predicted load power, the upper limit of the predicted total transient load acceptance, and the upper limit of the predicted total steady-state available power for each control window. The portion of the smaller of the predicted load power and the upper limit of the predicted total steady-state available power that exceeds the upper limit of the predicted total transient load acceptance is determined as the predicted transient response gap for the corresponding control window.

[0083] The maximum value of each predicted transient response gap during the takeover period is the reserved support power; the sum of the products of each predicted transient response gap and the corresponding control window duration is the reserved support energy.

[0084] The dispatchable energy of an energy storage device is the remaining energy after deducting the reserved support energy from the current available energy. The amount of support energy to be replenished is no longer deducted from the current available energy, because the current available energy already reflects the energy reduction caused by previous energy storage discharges, and repeated deduction would cause the dispatchable energy of the energy storage to be underestimated.

[0085] The controller determines the predicted continuous capacity gap for each control window based on the predicted load power and the upper limit of the total steady-state available power of the online diesel generator set during the takeover period.

[0086] The sum of the products of each predicted continuous capacity gap and the corresponding control window duration during the takeover period constitutes the continuous capacity gap energy before the target standby diesel generator set completes the takeover.

[0087] The target output power of the standby diesel generator set is determined based on the maximum value of the predicted continuous capacity gap during the takeover period, and shall not exceed the upper limit of the steady-state available power of the standby diesel generator set under the current environmental conditions.

[0088] The controller outputs a start command to a standby diesel generator set that is in a stopped state when any of the following conditions are met: The current continuous capacity gap is greater than the capacity of energy storage devices to support dispatchable power; The continuous capacity gap during the takeover period is greater than the dispatchable energy of the energy storage device.

[0089] The first judgment is used to identify situations where the total energy of the energy storage device is still available but the current discharge power is insufficient; the second judgment is used to identify situations where the current discharge power of the energy storage device can cover the gap but the sustainable energy is insufficient.

[0090] If neither of the above two conditions is met, the standby diesel generator set remains in a shutdown state, and the continuous capacity gap, capacity support dispatchable power, continuous capacity gap energy, and dispatchable energy are recalculated in the next control window.

[0091] When the power supply system is equipped with two or more standby diesel generator sets, priority should be given to selecting the units with a shorter takeover period and a steady-state available power limit that can cover the predicted continuous capacity gap.

[0092] If the steady-state available power of a single standby diesel generator set is insufficient to cover the predicted continuous capacity gap, one standby diesel generator set shall be started first, and the continuous capacity gap shall be recalculated after it is connected to the AC bus; if the recalculation result still meets the starting conditions, the next standby diesel generator set that is in a shutdown state shall be started.

[0093] After the standby diesel generator set completes synchronization and is connected to the AC bus, the controller updates its status to indicate that a new online diesel generator set has been added.

[0094] Instead of reducing the discharge power of the energy storage device in advance based on the power command or target output power of the newly added online diesel generator set, the controller reduces the second target discharge power of the energy storage device to compensate for the continuous capacity gap based on the actual net take-off power already formed by the newly added online diesel generator set.

[0095] The actual net overhead power of the newly added online diesel generator set is determined according to the following formula: ; In the formula: This refers to the actual net takeover power generated during the current control cycle of the newly added online diesel generator set; and These represent the actual output power of the newly added online diesel generator set in the current control cycle and the previous control cycle, respectively.

[0096] When the actual output power of the newly added online diesel generator sets increases, but the power demand of the load also increases, only the remaining part after deducting the increase in load from the actual increase in power of the newly added units can be used to reduce the second target discharge power of the energy storage device.

[0097] The energy storage device is allowed to reduce the second target discharge power within a control cycle, not exceeding the actual net control power, nor the actual discharge power used to compensate for the continuous capacity gap in the previous control cycle.

[0098] When the actual output power of the newly added online diesel generator set does not increase for two consecutive control cycles or decreases, or when the absolute difference between the actual output power and the power command exceeds the tracking deviation threshold, the reduction of the second target discharge power of the energy storage device will be stopped.

[0099] After a new online diesel generator set is connected to the AC bus, the controller updates the upper limit of the total transient load acceptance and the upper limit of the total steady-state available power based on its actual output power, thermal state, speed regulation margin and actual load increase record, and redefines the transient response gap and continuous capacity gap.

[0100] The temporary power shortage caused by newly added online diesel generator sets not yet completing their load ramp-up is classified as a transient response gap based on the recalculated results. The actual discharge energy of the energy storage device used to compensate for this transient response gap continues to be included in the supporting energy replenishment amount.

[0101] The controller establishes a relationship between output power and exhaust temperature based on the historical output power and stable exhaust temperature of each online diesel generator set.

[0102] During on-site commissioning, the diesel generator set was operated stably at different load points. When the difference between the maximum and minimum exhaust temperature during the continuous observation period was not greater than the larger of the exhaust temperature measurement resolution and the natural fluctuation range during stable operation, the exhaust temperature was determined to have reached a stable state, and the corresponding actual output power and stable exhaust temperature were recorded.

[0103] The lower limit of the recovery temperature should preferably be the lower limit of the normal combustion temperature range given by the manufacturer. If the manufacturer does not provide this data, it should be determined by combustion stability, exhaust conditions, and allowable long-term operating loads at different stable load points.

[0104] The controller determines the output power required to bring the exhaust temperature to the lower limit of the recovery temperature based on the relationship between output power and exhaust temperature, and determines the larger value between this output power and the minimum stable operating power of the diesel generator set as the recovery load power.

[0105] When the actual output power of the online diesel generator set is lower than the corresponding recovery load power and the exhaust temperature is lower than the lower limit of the recovery temperature, the low load accumulation of the unit is increased according to the power difference between the recovery load power and the actual output power and its duration.

[0106] When the actual output power of the online diesel generator set is not lower than the corresponding recovery load power, and the exhaust temperature reaches the lower limit of the recovery temperature and remains at that temperature for a certain duration, the low load accumulation is reduced based on the power difference between the actual output power and the recovery load power and its duration.

[0107] The temperature holding time was determined through on-site load testing. The diesel generator set was brought up from an operating state below the recovery load power to the recovery load power, and the time required for the temperature change to remain within the stable temperature range after the exhaust temperature reached the lower limit of the recovery temperature was recorded. The maximum value among no fewer than three test results was determined as the temperature holding time.

[0108] Low load accumulation is the cumulative result of power difference and duration. It is used to indicate the degree and duration of a diesel generator set deviating from the restored load power. It is not directly equivalent to fuel consumption or pollutant emissions.

[0109] The controller enters the recovery phase when the following conditions are met simultaneously: The difference between the maximum and minimum load power demand within the continuous control window shall not exceed the load stability threshold. The current continuous capacity gap is zero; The absolute difference between the actual output power and the power command of each online diesel generator set is no greater than the corresponding tracking deviation threshold. The speed control actuators of all online diesel generator sets did not reach their maximum permissible position; The upper limit of the total transient load acceptance is greater than the sum of the current actual output power of the online diesel generator sets; The current allowable discharge power of the energy storage device shall not be less than the reserved support power; The energy storage device currently has an available energy level that is not less than the reserved support energy level; The amount of supporting energy to be replenished is greater than zero, or the low load accumulation of at least one online diesel generator set is greater than zero.

[0110] The load stability threshold is determined based on the maximum natural fluctuation range of the load demand power during the stable operation of the power supply system and the load power measurement resolution, taking the larger of the two values, and it shall not be less than twice the load power measurement resolution.

[0111] The recovery time is determined based on the time when the next predicted load increase event may occur, the allowable charging power of the energy storage device, and the remaining load capacity of the online diesel generator set.

[0112] When the predicted load power exceeds the upper limit of the total transient load acceptance during the prediction period, the time between the current time and the predicted time exceeding the limit is used as the upper limit of the recovery time.

[0113] When no new load increase event is predicted, the shortest time required to reduce the current supporting energy to be replenished is calculated based on the allowable charging power of the energy storage device and the remaining load capacity of the online diesel generator set. The smaller of this shortest time and the longest continuous replenishment period allowed by the power supply system is taken as the replenishment duration.

[0114] The required power for energy replenishment is determined by the ratio of the amount of supporting energy to be replenished to the replenishment time.

[0115] The power required for low-load recovery is determined by the sum of the positive power difference between the recovery load power corresponding to the online diesel generator set with a low-load accumulation greater than zero and the current actual output power.

[0116] The final replenishment power is determined according to the following formula: ; In the formula: To compensate for power; This represents the current allowed charging power of the energy storage device. To make up for lost time; To restore the required power for low load.

[0117] When the amount of supporting energy to be replenished is zero and the amount of low load accumulation is greater than zero, the controller can still perform power replenishment based on the power required for low load recovery.

[0118] When the low load accumulation is zero and the supporting energy to be replenished is greater than zero, the controller performs energy replenishment based on the power required for energy replenishment.

[0119] When both conditions exist simultaneously, the larger value is used as the replenishment requirement, and it is subject to the combined limitations of the remaining load capacity of the online diesel generator set and the allowable charging power of the energy storage device.

[0120] The replenished power is preferentially allocated to online diesel generator sets with a low load accumulation greater than zero. The increased power allocated to any generator set shall not exceed the positive power difference between the restored load power and the current actual output power of the generator set, nor shall it exceed the difference between the upper limit of the transient load acceptance of the generator set and the current actual output power.

[0121] If there is still residual power after the power allocation required for low-load recovery is completed, it shall be allocated according to the proportion of the remaining load capacity of each online diesel generator set.

[0122] The controller reduces the amount of supporting energy to be replenished based on the actual charging power fed back from the energy storage converter. Charging energy generated due to low load recovery that exceeds the current amount of supporting energy to be replenished will not cause the amount of supporting energy to be replenished to fall below zero.

[0123] Through the above processing, the increased actual output power of the diesel generator set is used to restore the energy consumed by the energy storage device to meet the transient response gap, and to provide a controlled loading channel for the diesel generator set that has been in a low-load state for a long time.

[0124] During the recovery process, the controller continuously calculates the increase in load demand power in adjacent control cycles and updates the predicted load power.

[0125] The load rise threshold is determined based on the maximum natural fluctuation range of load power during stable operation, the load power measurement resolution, and on-site load input tests.

[0126] In the field load input test, the input load power was gradually increased, and the minimum load increase that enabled the online diesel generator set to produce a continuous load increase response was determined as the minimum effective load increase.

[0127] The load increase threshold is the larger of the minimum effective load increase and the natural fluctuation amplitude of stable operation plus twice the power measurement resolution.

[0128] When the increase in load demand power in an adjacent control cycle reaches the load rise threshold, or when the predicted load power exceeds the upper limit of the current total transient load acceptance, the controller determines that a new load rise event has occurred.

[0129] Upon determining that a new load increase event has occurred, the controller reduces the charging power command to zero according to the power change rate allowed by the energy storage converter.

[0130] The zero-power allowable range is determined based on the maximum steady-state power fluctuation amplitude of the energy storage converter when it is under zero-power command and the energy storage power measurement resolution, taking the larger of the two values, and it shall not be less than twice the energy storage power measurement resolution.

[0131] When the actual power fed back by the energy storage converter enters the zero power allowable zone, the controller sends a discharge power command to the energy storage converter.

[0132] When the energy storage converter has a fast power reverse control mode, the maximum charge-discharge conversion time given by the manufacturer is used as the direction switching time, and the predicted transient response gap within this direction switching time is included in the reserved support energy.

[0133] After the replenishment process stops, the remaining support energy to be replenished is retained. The controller reclassifies the transient response gap and the continuous capacity gap based on the new current load demand power.

[0134] The energy storage device is used to compensate for the actual discharge energy of the new transient response gap, which continues to accumulate to the original supporting energy to be replenished.

[0135] If the redefined continuous capacity gap is greater than the capacity support dispatchable power, or if the continuous capacity gap energy during the takeover period is greater than the dispatchable energy, the controller will re-execute the standby diesel generator set start-up judgment.

[0136] When the actual output power, speed governor status, coolant temperature, or exhaust temperature data of any online diesel generator set fails, the controller stops using that unit to update the reliable load rate and limits the upper limit of the unit's single-unit transient load acceptance to the most recent valid actual output power.

[0137] When the coolant temperature or exhaust temperature reaches the protection limit, the controller sets the unit's additional load capacity to zero and performs load reduction according to the unit's protection requirements.

[0138] When the state of charge, current available energy, allowable charging power, or allowable discharging power data of the energy storage device become invalid, the controller stops recharging and no longer includes the energy storage device in the capacity support dispatchable power and dispatchable energy.

[0139] When the load forecast data fails, the controller will use the current load demand power as the forecast load power for the next control window, and use the maximum takeover period in the effective start-up record of the target standby diesel generator set to perform the standby diesel generator set start-up judgment.

[0140] When the upper limit of the total transient load or the upper limit of the total steady-state available power decreases due to increased unit temperature, reduced speed control margin, data failure, or unit malfunction, the controller immediately uses the updated boundaries to redefine the transient response gap and the continuous capacity gap.

[0141] The power supply system initially relies on online diesel generator sets to provide a stable load, and the energy storage device is in a state where charging and discharging are permitted.

[0142] When the first batch of loads is put into operation, the current load demand exceeds the upper limit of the total transient load acceptance, but does not exceed the upper limit of the total steady-state available power. The controller identifies the portion exceeding the upper limit of the total transient load acceptance as the transient response gap and controls the energy storage device to output power according to the first target discharge power.

[0143] The energy storage device is used to compensate for the transient response gap by accumulating the actual discharge energy to support the amount of energy to be replenished. As the actual output power of the online diesel generator set increases, the transient response gap gradually decreases, and the energy storage device simultaneously reduces the first target discharge power.

[0144] When the second batch of load continues to be added, causing the current load demand power to exceed the total steady-state available power limit, the controller will identify the portion within the total steady-state available power limit but exceeding the total transient load acceptance upper limit as the transient response gap, and the portion exceeding the total steady-state available power limit as the continuous capacity gap.

[0145] Energy storage devices prioritize compensating for transient response gaps and temporarily compensate for continuous capacity gaps within the capacity support dispatchable power range.

[0146] When the continuous capacity gap exceeds the dispatchable power supported by the capacity, or when the continuous capacity gap energy during the takeover period exceeds the dispatchable energy of the energy storage device, the controller starts the standby diesel generator set.

[0147] After the standby diesel generator set completes synchronization and is connected to the AC bus, the controller gradually reduces the second target discharge power of the energy storage device to compensate for the continuous capacity gap, based on the actual net power of the actual increase in output power minus the increase in load during the same period.

[0148] Once the load stabilizes and the continuous capacity gap disappears, the controller determines the replenishment power based on the amount of supporting energy to be replenished and the low load accumulation of each online diesel generator set, thereby increasing the actual output power of the online diesel generator sets and charging the energy storage device through the energy storage converter.

[0149] When the load is applied again during the replenishment period, the controller stops charging, retains the remaining support energy to be replenished, and re-enters the process of classifying and handling transient response gaps and continuous capacity gaps.

[0150] This application does not directly control the start and stop of the diesel generator set based on a fixed state of charge threshold, nor does it simply allocate all the difference between the load demand power and the actual output power of the diesel generator set to the energy storage device. Instead, it forms a dynamic load acceptance boundary based on the recent actual response of the online diesel generator set, the current thermal state, and the speed regulation margin, and divides the power supply gap into transient response gap and continuous capacity gap.

[0151] The transient response gap is used to generate the amount of supporting energy to be replenished, while the continuous capacity gap is used to determine the start-up and takeover of the standby diesel generator set. After the standby diesel generator set is connected, the energy storage support is withdrawn according to its actual net takeover power. After the load stabilizes, the replenishment is carried out jointly based on the amount of supporting energy to be replenished and the accumulated low load. This forms a continuous and interruptible coordinated power supply process between rapid energy storage support, actual takeover of the diesel generator set, energy storage recovery, and recovery of the diesel generator set from low load.

[0152] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for coordinated power supply of diesel generator sets and energy storage, applied to a power supply system including an AC bus, load, energy storage device, controller, at least one online diesel generator set and at least one standby diesel generator set, characterized in that, Includes the following steps: S1: Collect the load demand power, the actual output power, speed, speed regulator status, coolant temperature and exhaust temperature of each online diesel generator set, as well as the state of charge, current available energy and allowable charging and discharging power of the energy storage device, and form a load power sequence based on the load demand power collected in the continuous control cycle, and determine the predicted load power from the load power sequence. S2: Record the power command, actual output power and response time of each online diesel generator set during load change process, and select qualified load response events from the load change process where the actual output power continuously follows the power command, the absolute difference between the actual output power and the power command continuously decreases and the AC bus frequency recovers to the allowable frequency range. S3: Determine the reliable load increase rate based on the qualified load response events corresponding to each online diesel generator set, and combine the current actual output power, speed regulation margin, coolant temperature and exhaust temperature of each online diesel generator set to determine the upper boundary of the single unit transient load acceptance and the upper limit of the single unit steady-state available power in the next control window. The sum of the upper boundaries of the single unit transient load acceptance is determined as the upper boundary of the total transient load acceptance, and the sum of the upper limits of the single unit steady-state available power is determined as the upper limit of the total steady-state available power. S4: Based on the current load demand power, the upper limit of the total transient load acceptance and the upper limit of the total steady-state available power, the power supply power that the online diesel generator set cannot cover is divided into transient response gap and continuous capacity gap. The energy storage device is controlled to compensate for the transient response gap and temporarily compensate for the continuous capacity gap within the dispatchable discharge power. The energy storage device supports the amount of energy to be replenished based on the actual discharge power and discharge time used to compensate for the transient response gap. S5: Based on the predicted load power and the start-up time, synchronization time and load ramp-up time of the standby diesel generator set, determine the reserved support power and reserved support energy that the energy storage device needs to retain. The remaining power after deducting the reserved support power from the allowable discharge power of the energy storage device is determined as the dispatchable discharge power. The remaining energy after deducting the reserved support energy from the current available energy of the energy storage device is determined as the dispatchable energy. S6: When the continuous capacity gap is greater than the dispatchable discharge power, or when the gap energy formed before the standby diesel generator set completes the load increase is greater than the dispatchable energy, start a standby diesel generator set; after the standby diesel generator set completes synchronization and is connected to the AC bus, it is treated as a newly added online diesel generator set, and the discharge power of the energy storage device used to compensate for the continuous capacity gap is reduced according to the increase in its actual output power. S7: Based on the power difference, duration, coolant temperature and exhaust temperature of each online diesel generator set below the corresponding restored load power, a low load accumulation is formed; when the difference between the maximum and minimum load demand power within the continuous control window is not greater than the load stability threshold, the continuous capacity gap is zero, there is remaining load increase space at the upper boundary of the total transient load acceptance, and the energy storage device has reserved support power and reserved support energy, the recovery power is determined based on the remaining load increase space, the allowable charging power of the energy storage device, the amount of support energy to be recovered, and the low load accumulation, and the online diesel generator set is controlled to increase the output power and charge the energy storage device according to the recovery power; S8: During the charging process of the energy storage device, when the increase in load demand power in the adjacent control cycle reaches the load rise threshold, or when the predicted load power exceeds the current total transient load acceptance upper boundary, the charging of the energy storage device is stopped, the unreplenished support energy is retained, and the transient response gap and continuous capacity gap are reclassified.

2. The method for co-powering a diesel generator set with energy storage according to claim 1, characterized in that, Determining the predicted load power based on the load power sequence includes: Calculate the power change at adjacent sampling points in the load power sequence, and determine the current load change rate based on the continuous power changes in the same direction and their corresponding sampling periods; Based on the current load demand power, the current load change rate, and the duration of the next control window, determine the predicted load power within the next control window; If the current power change has the opposite sign to the power change in the previous sampling period, or if the current positive load change rate decreases for two consecutive sampling periods, shorten the length of the load power sequence used to calculate the current load change rate, and use the shortened load power sequence to redetermine the predicted load power.

3. The method for co-powering a diesel generator set with energy storage according to claim 2, characterized in that, Qualified load response events are selected, including: The moment when the increase in power command of the online diesel generator set reaches the command change threshold is determined as the start time of the load response event. The command change threshold is determined based on the rated power and power sampling resolution of the online diesel generator set. After the start time, determine whether the actual output power of the online diesel generator set increases continuously for no less than two sampling periods, whether the absolute difference between the actual output power and the power command decreases continuously for no less than two sampling periods, whether the speed controller is in an unsaturated state, and whether the AC bus frequency has recovered to the allowable frequency range. A load response event that simultaneously meets the following conditions is defined as a qualified load response event: the actual output power continuously increases, the absolute difference continuously decreases, the speed control actuator is in an unsaturated state, and the AC bus frequency recovers to the allowable frequency range. The response delay and actual load increase rate are determined based on the start time of each qualified load response event, the moment when the actual output power begins to increase continuously, and the moment when the absolute difference between the actual output power and the power command decreases to within the tracking deviation threshold. The tracking deviation threshold is determined based on the rated power and power sampling resolution of the online diesel generator set.

4. The method for coordinated power supply of diesel generator sets with energy storage according to claim 3, characterized in that, Determine the reliable load ramp rate, the upper limit of transient load acceptance for a single unit, and the upper limit of steady-state available power for a single unit for each online diesel generator set, including: Select at least three qualified load response events for the same online diesel generator set, arranged from the most recent to the oldest occurrence time, and determine the minimum value among the actual load rate corresponding to the selected qualified load response events as the base load rate. The thermal state correction factor is determined based on the deviation of the current coolant temperature and exhaust temperature of the online diesel generator set from their respective allowable temperature ranges. The product of the basic load rate and the thermal state correction factor is then determined as the reliable load rate. The sum of the current actual output power of the online diesel generator set and the power that can be increased within the next control window at the reliable load rate is determined as the ramp limit power; The thermal state limiting power is obtained by subtracting the derating power determined by the deviation between coolant temperature and exhaust temperature from the rated power of the online diesel generator set. The sum of the current actual output power and the power that can be increased corresponding to the remaining stroke of the speed controller is determined as the speed controller limiting power. The minimum value among the ramp-up limit power, thermal limit power, and speed regulation execution limit power is determined as the upper boundary of the transient load acceptance of a single unit, and the smaller value among the thermal limit power and speed regulation execution limit power is determined as the upper limit of the steady-state available power of a single unit.

5. The method for coordinated power supply of diesel generator sets with energy storage according to claim 4, characterized in that, The transient response gap and the sustained capacity gap are distinguished, including: When the current load demand power is greater than the upper limit of the total transient load acceptance but not greater than the upper limit of the total steady-state available power, the power difference between the current load demand power and the upper limit of the total transient load acceptance is determined as the transient response gap, and the continuous capacity gap is determined as zero. When the current load demand power is greater than the upper limit of the total steady-state available power, the positive power difference between the upper limit of the total steady-state available power and the upper limit of the total transient load acceptance is determined as the transient response gap, and the power difference between the current load demand power and the upper limit of the total steady-state available power is determined as the continuous capacity gap. When the current load demand power is not greater than the upper limit of the total transient load acceptance, both the transient response gap and the continuous capacity gap are set to zero; The first target discharge power of the energy storage device is determined based on the transient response gap, and the second target discharge power of the energy storage device is determined based on the continuous capacity gap. The sum of the first target discharge power and the second target discharge power is limited to the dispatchable discharge power.

6. The method for coordinated power supply of diesel generator sets with energy storage according to claim 5, characterized in that, The cumulative amount of support energy to be replenished and the reserved support power and reserved support energy are determined, including: When the energy storage device compensates for the transient response gap according to the first target discharge power, the product of the actual discharge power used to compensate for the transient response gap and the sampling period is accumulated to the amount of supporting energy to be replenished, and the discharge energy used by the energy storage device to compensate for the continuous capacity gap is excluded from the amount of supporting energy to be replenished. The takeover period is determined based on the takeover time required for the standby diesel generator set to complete synchronization and reach the target output power from receiving the start command. The reserved support power is determined based on the maximum positive power difference between the predicted load power during the takeover period and the upper boundary of the total transient load acceptance corresponding to each control window. The positive power difference between the predicted load power and the total transient load acceptance upper boundary corresponding to each control window during the takeover period is accumulated according to the control window duration to obtain the reserved support energy; When the energy storage device is charged according to the replenishment power, the amount of supporting energy to be replenished is reduced according to the actual charging energy generated according to the replenishment power, and the lower limit of the amount of supporting energy to be replenished is set to zero.

7. The method for coordinated power supply of diesel generator sets with energy storage according to claim 6, characterized in that, Determining whether to start the standby diesel generator set includes: Based on the predicted load power, the upper limit of total steady-state available power, and the reserved support power of each control window during the takeover period, the predicted continuous capacity gap in each control window is determined. The predicted continuous capacity gap in each control window is summed with the product of the corresponding control window duration to obtain the gap energy before the standby diesel generator set completes the takeover. The remaining power after deducting the reserved support power from the allowable discharge power of the energy storage device is determined as the dispatchable discharge power, and the remaining energy after deducting the reserved support energy from the current available energy of the energy storage device is determined as the dispatchable energy. When the current continuous capacity gap is greater than the dispatchable discharge power, or the gap energy is greater than the dispatchable energy, a start command is sent to a standby diesel generator set that is in a shutdown state. When the current continuous capacity gap is not greater than the dispatchable discharge power and the gap energy is not greater than the dispatchable energy, the standby diesel generator set is kept in a shutdown state, and the current continuous capacity gap, gap energy, dispatchable discharge power and dispatchable energy are redefined in the next control window.

8. A diesel generator set energy storage and coordinated power supply method according to claim 7, characterized in that, The discharge power of the energy storage device is reduced based on the actual output power of the standby diesel generator set, including: After the standby diesel generator set that receives the start command completes synchronization and is connected to the AC bus, the standby diesel generator set is treated as a newly added online diesel generator set. The actual increase in output power of the newly added online diesel generator set in adjacent control cycles is collected. The actual increase in output power is compared with the actual discharge power of the energy storage device currently used to compensate for the continuous capacity gap. The second target discharge power of the energy storage device is reduced according to the smaller of the two values. When the actual output power of the newly added online diesel generator set does not increase for two consecutive control cycles, the actual output power drops, or the absolute difference between the actual output power and the power command is greater than the tracking deviation threshold, the reduction of the second target discharge power of the energy storage device will be stopped. Based on the actual output power, speed governor actuator status, coolant temperature, exhaust temperature, and qualified load response events of the newly added online diesel generator set, determine the upper limit of the single-unit transient load acceptance and the upper limit of the single-unit steady-state available power of the newly added online diesel generator set, and update the upper limit of the total transient load acceptance and the upper limit of the total steady-state available power.

9. A diesel generator set energy storage and coordinated power supply method according to claim 6, characterized in that, Forming low load accumulation and determining compensation power includes: Based on the historical output power and exhaust temperature correspondence of each online diesel generator set, the output power required to bring the exhaust temperature to the lower limit of the recovery temperature is determined, and the larger value between this output power and the minimum stable operating power of the corresponding online diesel generator set is determined as the recovery load power. When the actual output power of the online diesel generator set is lower than the corresponding recovery load power and the exhaust temperature is lower than the lower limit of the recovery temperature, the power difference between the recovery load power and the actual output power and the corresponding duration are multiplied and accumulated to the low load accumulation of the online diesel generator set. When the actual output power of the online diesel generator set is not lower than the corresponding recovery load power, and the exhaust temperature is not lower than the lower limit of the recovery temperature and continues to reach the temperature holding time, the low load accumulation of the online diesel generator set is reduced according to the power difference between the actual output power and the recovery load power and the corresponding duration. The ratio of the amount of supporting energy to be replenished to the replenishment time is determined as the energy replenishment demand power, and the sum of the positive power differences between the corresponding restored load power of each online diesel generator set and the current actual output power is determined as the low load recovery demand power. The minimum value among the following is determined as the upper limit of the replenishment power: the power difference between the upper limit of the total transient load acceptance and the sum of the current actual output power of each online diesel generator set, the allowable charging power of the energy storage device, and the energy replenishment demand power required to reduce the amount of supporting energy to be replenished within the replenishment period. Within the upper limit of the replenishment power, the replenishment power is determined according to the larger value between the energy replenishment demand power and the low load recovery demand power.

10. A diesel generator set energy storage and coordinated power supply method according to claim 9, characterized in that, The process of detecting new load spikes and handling interruptions includes: During the charging process of the energy storage device, the increase in load demand power in adjacent control cycles is calculated. A new load rise event is determined when the increase in load demand power reaches the load rise threshold, or when the predicted load power exceeds the upper limit of the current total transient load acceptance. The load rise threshold is determined based on the load rated power and power sampling resolution. In the next control cycle after a new load increase event is identified, the replenishment power will be reduced to zero, the amount of support energy that has not yet been reduced will be retained for replenishment, and the transient response gap and continuous capacity gap will be re-determined based on the new current load demand power, the predicted load power, the upper limit of the total transient load acceptance, and the upper limit of the total steady-state available power. The control energy storage device compensates for the redefined transient response gap, adds the actual discharge energy corresponding to this compensation to the remaining support energy to be replenished, and re-executes the start-up judgment of the standby diesel generator set based on the redefined continuous capacity gap, gap energy, dispatchable discharge power, and dispatchable energy.

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