Alkaline electrolytic cell micro-grid system based on common alternating current bus and control method
By using a microgrid system based on a common AC bus, combined with bidirectional AC-DC and DC-DC converters and battery energy storage, the dynamic mismatch problem between alkaline electrolyzers and wind and solar power generation systems is solved, achieving a hydrogen production process with high stability, high efficiency and high reliability, avoiding equipment damage and frequent start-ups and shutdowns, and improving system robustness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ORDOS NEW ENERGY RESEARCH & APPLICATION CO LTD
- Filing Date
- 2026-02-10
- Publication Date
- 2026-05-15
AI Technical Summary
In existing technologies, the mismatch between the dynamic characteristics of alkaline electrolyzers and wind and solar power generation systems leads to safety risks, equipment damage and shortened lifespan. Traditional microgrid systems lack robustness, and high-frequency fluctuations affect hydrogen production efficiency and stability.
A microgrid system based on a common AC bus is adopted, which combines a bidirectional AC-DC converter, a DC-DC converter and battery energy storage. The battery energy storage is connected to the DC bus and configured with IGBT modules. The maximum power transfer (MPPT) control strategy and master-slave control method are adopted to achieve a hydrogen production process with high stability and high efficiency.
It effectively addresses millisecond- to minute-level fluctuations in wind and solar power generation, enhances system stability and reliability, prevents equipment damage, extends equipment lifespan, improves energy utilization and system robustness, and ensures the safe and efficient operation of the hydrogen production process.
Smart Images
Figure CN122052128A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of hydrogen production microgrids, specifically relating to a microgrid system and control method for alkaline electrolyzers based on a common AC bus. Background Technology
[0002] Driven by the "dual carbon" goal, wind, solar, and green hydrogen projects have become important energy transition paths. Alkaline electrolyzers, due to their significant advantages in technological maturity, cost, and large-scale hydrogen production capacity, have become the primary method for hydrogen production. However, wind and solar power generation is intermittent and highly random, often exhibiting millisecond- to minute-level fluctuations due to cloud movement or obstruction, wind speed changes, etc. Alkaline electrolyzers, on the other hand, have slow response speeds and limited dynamic adjustment capabilities. Power regulation is typically limited to a rate of 3%–5% / s, resulting in minute-level delays. Furthermore, safe and efficient operation usually requires maintaining power within 30%–110% of rated power. This severe mismatch in source-load dynamic characteristics raises a series of challenges, from operational safety to equipment lifespan.
[0003] First, there are safety risks under low-power operation. When insufficient wind and solar power output leads to low-load operation of the alkaline electrolyzer, insufficient electrolyte circulation causes bubble retention. At the same time, wind and solar fluctuations can also cause overshoot and high-frequency interference in the microgrid system, resulting in excessive current density, exacerbating side reactions such as oxygen evolution, and causing changes in the pressure difference between the anode and cathode chambers inside the electrolyzer. This can lead to hydrogen and oxygen gas cross-contamination, resulting in excessive oxygen content in hydrogen or hydrogen in oxygen, increasing the risk of explosion and threatening system safety.
[0004] Secondly, there is equipment damage caused by sudden power fluctuations. Sudden power fluctuations in wind and solar power can cause the electrolyzer to be passively or actively disconnected by triggering protection, resulting in a loss of power. However, the electrochemical process cannot be stopped instantly. At this time, the cathode electrode coating may be subjected to reverse current impact, and the roles of cathode and anode may be temporarily reversed, leading to corrosion, peeling, and deactivation of the electrode coating catalyst. In addition, frequent power fluctuations can also cause the diaphragm to be subjected to repeated pressure and temperature changes, accelerating its chemical degradation and physical damage. The sealing gaskets are also prone to aging and failure under frequent thermal expansion and contraction and alkaline corrosion.
[0005] Finally, frequent start-ups and shutdowns shorten the lifespan of the electrolyzer. The intermittent nature of wind and solar power generation forces alkaline electrolyzers to start and stop frequently, leading to accelerated corrosion and wear of nickel-based electrodes, deterioration of diaphragm performance, and other problems, significantly shortening equipment lifespan and increasing maintenance costs.
[0006] To alleviate the above contradictions, there are currently two main technical approaches: (i) Adopting a microgrid system with a shared AC bus for wind, solar, and hydrogen storage. For example... Figure 1As shown, this common AC bus microgrid system uses energy storage batteries to smooth out peak and valley loads and millisecond-level high-frequency power fluctuations, and equips the alkaline electrolyzer with both AC-DC and DC-DC converters for power management. However, this solution has inherent limitations: (1) Wind and solar fluctuations will still affect other main components of the microgrid through the AC-DC converter. Its transient adjustment process will cause DC bus voltage fluctuations, affecting the input stability and hydrogen production efficiency of the alkaline electrolyzer. (2) Meanwhile, the system energy needs to be converted multiple times between wind and solar power, energy storage and alkaline electrolyzers, the conversion link is long, and there is still room for optimization of the overall system efficiency; (3) The system has poor fault tolerance and insufficient robustness. On the one hand, once the bidirectional AC-DC converter of the battery energy storage fails or is repaired, alkaline hydrogen production will face the challenges of system operation safety, equipment wear and tear and lifespan reduction again. In the case of isolated microgrids, the system may even collapse and stop due to the loss of voltage / frequency grid support. On the other hand, once the AC-DC converter of the alkaline electrolyzer fails or is repaired, the alkaline electrolyzer will suffer the equipment damage mentioned above, and it will be unable to continue to use battery energy storage to maintain the alkaline electrolyzer to produce hydrogen or to stop in an orderly manner.
[0007] (ii) A hybrid system using alkaline electrolyzers and PEM electrolyzers. This approach aims to utilize the rapid response (seconds) of PEM to handle fluctuations, allowing the alkaline electrolyzers to bear the base load. However, this approach still faces challenges: the response speed of PEM is still insufficient to mitigate the millisecond-level instantaneous impacts of wind and solar power, thus energy storage remains indispensable; more importantly, the unit power cost of PEM electrolyzers is much higher than that of alkaline electrolyzers. While their introduction improves flexibility, it also significantly increases the total system investment, posing a challenge to the project's economic viability. Summary of the Invention
[0008] The purpose of this invention is to provide a microgrid system and control method for alkaline electrolyzers based on a common AC bus, aiming to solve the above-mentioned problems and achieve high stability, high efficiency and high reliability.
[0009] This invention is mainly achieved through the following technical solutions: A microgrid system for an alkaline electrolyzer based on a common AC bus includes a bidirectional AC-DC converter, a DC-DC converter, and battery energy storage. One side of the common AC bus is connected to a wind power unit, a photovoltaic unit, and a power grid system, respectively, and the other side of the common AC bus is connected to the bidirectional AC-DC converter. The bidirectional AC-DC converter is connected in parallel with the DC-DC converter, and the DC-DC converter is connected to the alkaline electrolyzer. The bidirectional AC-DC converter and the DC-DC converter are connected to the battery energy storage via a direct DC bus, and an IGBT module is installed between the bidirectional AC-DC converter and the direct-connected energy storage.
[0010] To better realize the present invention, a capacitor C0 is further provided in parallel between the bidirectional AC-DC converter and the battery energy storage; a load is also connected to the other side of the common AC bus, and the load is grounded.
[0011] To better realize the present invention, the wind power unit is further connected to the common AC bus via an AC-DC-AC inverter; the photovoltaic unit is connected to the common AC bus via a DC-AC inverter.
[0012] This invention is mainly achieved through the following technical solutions: A control method for a microgrid for an alkaline electrolyzer based on a common AC bus is implemented based on the aforementioned microgrid system for an alkaline electrolyzer based on a common AC bus. Both the wind power unit and the photovoltaic unit adopt a grid-following control strategy with maximum power transfer (MPPT). When the project does not require 100% zero-carbon certification, the microgrid system adopts a grid-connected configuration; When a project requires 100% zero-carbon certification or needs to improve its economic efficiency, the microgrid system adopts an off-grid configuration, with battery energy storage and grid-connected converters replacing the voltage / frequency support provided by the grid, and using master-slave control to drive the wind power and photovoltaic structures to operate in a grid-following control manner.
[0013] To better realize the present invention, if the microgrid system is configured as an island or can be switched between grid-connected and off-grid, then the bidirectional AC-DC converter adopts a grid-type converter to achieve grid support under off-grid conditions.
[0014] To better realize the present invention, furthermore, while meeting the load requirements of the microgrid system itself, the hydrogen production power is adjusted within a safe range of 30%-110% of the rated power of the alkaline electrolyzer, based on the wind and solar intensity. like P wind + P PV ≥ P load + PALK_min And if Battry_SOC≥90%, then the power of the alkaline electrolyzer is... P ALK = P ALK_max ; like P wind + P PV ≥ P load + P ALK_min If 70% ≤ Battry_SOC ≤ 90%, then the power of the alkaline electrolytic cell is:
[0015] like P wind + P PV ≥ P load + P ALK_min And if Battry_SOC < 70%, then the power of the alkaline electrolyzer is... P ALK = P ALK_min The battery is used for charging. P battery = P wind + P PV - P load - P ALK_min ; in: P wind Wind power output; P PV Light energy power; P load For the microgrid system's own load; P ALK_min This represents the minimum hydrogen production power of the microgrid system. P ALK_max This represents the maximum hydrogen production capacity of the microgrid system. Battry_SOC represents the battery's stored energy.
[0016] To better realize the present invention, further, if P wind + P PV< P load + P ALK_min ,but P ALK = P ALK_before This process continues for 5 minutes, during which the alkaline hydrogen production power is provided by battery energy storage. P wind + P PV + P Battery = P load + P ALK If after 5 minutes, and P wind + P PV < P load + P ALK_min ,but P ALK The value is 0 to ensure the continuous and stable operation of the microgrid system's own load.
[0017] The beneficial effects of this invention are as follows: (1) This invention avoids reliance on high-cost PEM electrolyzers and has the advantages of high stability, high efficiency, and high reliability. This invention can effectively cope with the millisecond to minute-level wideband fluctuations of wind and solar power generation (especially photovoltaic), providing a highly stable and efficient DC power environment for alkaline electrolyzers, avoiding their low-load safety risks, power surge damage, and frequent start-stop losses. This invention improves the fault tolerance robustness of traditional microgrid architectures. When the system faces extreme conditions such as grid failures and critical converter failures, it has the ability to isolate faults and perform orderly degradation, ensuring that the core hydrogen production load does not collapse instantly and can switch to safe operation or orderly shutdown, thereby comprehensively improving the availability and resilience of the system.
[0018] (2) This invention can achieve active support for DC bus voltage. When the SOC of the battery energy storage is between 20% and 80%, the battery voltage can be approximated as a DC voltage source due to its small fluctuations. This characteristic gives the DC bus voltage of the alkaline electrolyzer a natural stability, which can effectively isolate voltage fluctuations caused by sudden changes in wind and solar power or other AC-side disturbances from the front-end AC-DC converter, creating highly stable input conditions for the alkaline electrolyzer. At the same time, the DC bus capacitor of the traditional microgrid architecture only experiences current oscillation during fluctuations, and the DC bus capacitor current is 0 during steady state. However, the battery allows current to pass through during steady state. This means that under the microgrid system of this invention, the battery energy storage can still provide energy to other loads of the microgrid itself through the bidirectional AC-DC converter, rather than only serving the alkaline electrolyzer.
[0019] (3) The present invention can directly absorb high-frequency power fluctuations. The energy storage battery is generally lithium iron phosphate, which usually has excellent high-rate charge and discharge capabilities. This means that the high-frequency power fluctuations and corresponding peak currents generated by wind and solar power generation under extreme conditions can be quickly absorbed or replenished by the nearby directly connected energy storage battery before being transmitted to the alkaline electrolyzer, thereby avoiding the impact of high-frequency power fluctuations on the operating efficiency, safety and lifespan of the alkaline hydrogen production device.
[0020] (4) Compared with traditional wind-solar-hydrogen storage microgrids, this invention reduces the AC-DC device, thereby reducing system costs and the propagation path of battery energy storage to supply energy to the alkaline electrolyzer, thus improving energy utilization. This invention directly connects battery energy storage to the DC bus, and with the quasi-voltage source characteristics and high-frequency high-current absorption capacity of battery energy storage, it avoids the impact of frequent wind and solar fluctuations on the operating efficiency, equipment reliability and lifespan of the alkaline electrolyzer. This invention can flexibly disconnect the AC side from the electrolyzer when the bidirectional AC-DC converter or the microgrid as a whole fails, so that the hydrogen production load can continue to operate safely or be shut down in an orderly manner, thus improving the robustness and fault tolerance of the system. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the structure of a traditional wind-solar-hydrogen storage microgrid; Figure 2 This is a schematic diagram of the microgrid system for an alkaline electrolytic cell based on a common AC bus, according to the present invention. Figure 3 The curves show the system efficiency and hydrogen production rate of the alkaline electrolyzer as a function of hydrogen production power. Figure 4 This is a schematic diagram of the flow rate of the microgrid system for alkaline electrolyzers based on a common AC bus as a hydrogen production microgrid according to the present invention. Figure 5 A schematic diagram of the flow of a microgrid system when wind and solar power are sufficient and Battry_SOC < 70%; Figure 6 A schematic diagram of the flow rate of a microgrid system when wind and solar power fluctuate and alkaline hydrogen production power is provided by battery energy storage; Figure 7 This is a schematic diagram of the flow of traffic in a microgrid system when the bidirectional AC-DC converter is disconnected from the IGBT module. Detailed Implementation
[0022] Example 1: A microgrid system for alkaline electrolyzers based on a common AC bus, such as Figure 2 As shown, a novel microgrid with a common AC bus is constructed based on a two-stage converter in an alkaline electrolyzer and a direct-connected battery energy storage system on the DC bus. One side of the common AC bus is connected to a wind power unit, a photovoltaic unit, and the power grid system, respectively, while the other side is connected to a bidirectional AC-DC converter. The bidirectional AC-DC converter is connected in parallel with a DC-DC converter, and the DC-DC converter is connected to the alkaline electrolyzer. The bidirectional AC-DC converter and the DC-DC converter are connected to the direct-connected battery energy storage system via the DC bus, and an IGBT module is installed between the bidirectional AC-DC converter and the direct-connected energy storage system.
[0023] Specifically, based on the existing bidirectional AC-DC converter and DC-DC converter of the alkaline electrolyzer (where the bidirectional AC-DC converter is responsible for AC-DC conversion, and the DC-DC converter is responsible for fine-grained active regulation and optimization according to the temperature, pressure, efficiency, etc. of the alkaline electrolyzer), the battery energy storage adopts direct connection to the DC bus, instead of a separate DC-AC converter for battery energy storage in the traditional microgrid architecture; and an additional IGBT configuration is added between the bidirectional AC-DC converter of the alkaline electrolyzer and the direct-connected battery energy storage to improve the robustness and fault tolerance of the system.
[0024] Example 2: A control method for a microgrid in an alkaline electrolyzer based on a common AC bus is as follows: (1) Wind and solar green power (wind power and photovoltaic power) still use DC-AC inverters to connect to the AC bus, and the control strategy adopts the grid-following control of maximum power transmission MPPT; (2) Adopt a common AC bus architecture and decide whether to connect to the grid based on project requirements.
[0025] When a project does not require 100% zero-carbon certification, the microgrid system can be configured to be connected to the grid. Although many projects do not allow surplus electricity to be fed into the grid, they can draw power from the grid to cope with insufficient wind and solar power, thereby reducing the project's configuration of wind, solar and energy storage and other backup power sources. When a project aims to achieve 100% zero-carbon certification to address the challenges of foreign carbon barriers, or to improve the project's economics by avoiding grid backup service fees such as grid access fees / capacity fees and additional cable fees in remote areas, the microgrid system adopts an off-grid configuration. Battery energy storage and grid-connected converters replace the voltage / frequency support provided by the grid, and master-slave control drives the operation of wind and solar power in grid-connected control mode. (3) If the microgrid system is configured to be connected to the grid, the alkaline electrolyzer can still use a grid-connected bidirectional converter to reduce costs; if the microgrid system is configured to be isolated or can be switched between grid and off-grid, the bidirectional AC-DC converter of the alkaline electrolyzer needs to be a grid-connected converter to achieve grid support under off-grid conditions.
[0026] Preferably, since hydrogen energy can be fully utilized as long-term energy storage through hydrogen energy storage, hydrogen feedstock, and hydrogen power, however, the conversion of hydrogen into electricity requires additional energy loss. Therefore, the system's scheduling strategy prioritizes "ensuring the power supply to the microgrid's own load while maximizing the efficient utilization of green electricity." Figure 3 As shown, alkaline hydrogen production can adjust the hydrogen production power within a safe range of 30%-110% of the rated power based on the wind and solar intensity, while meeting the microgrid's own load requirements, thereby adjusting the relationship between its operating power, system efficiency, and hydrogen production rate.
[0027] a) To ensure power supply reliability and avoid frequent start-ups and shutdowns of the alkaline electrolyzer, the alkaline electrolyzer is only allowed to exceed the minimum hydrogen production power when Battry_SOC ≥ 70% (this threshold can be adjusted according to actual conditions). P ALK_min Run; such as Figure 4 As shown, if the microgrid itself is a hydrogen production microgrid, then the load of the microgrid system itself will be considered. P load Substitute 0 into the following scheduling conditions.
[0028] b) When the sum of wind and solar power is greater than or equal to the sum of the microgrid's own load and the alkaline hydrogen production power, i.e. P wind + P PV ≥ P load + P ALK_min : b1. If the battery stores enough energy, i.e., Battry_SOC ≥ 90%, then the power of the alkaline electrolyzer is... P ALK Because it can withstand the maximum power operation, that is P ALK = P ALK_max ; b2. If the battery's stored energy is in a relatively high state, i.e., 70% ≤ Battry_SOC ≤ 90%, then the power of the alkaline electrolyzer... P ALK The difference between the power output of wind and solar green electricity and the power of the additional load, and the alkaline electrolyzer does not exceed its maximum power handling capacity. P ALK_max ,Right now
[0029] b3. If the battery energy is low, i.e., Battry_SOC < 70%, then the alkaline electrolyzer will operate at minimum power. Figure 5 As shown, the battery stores energy for charging, that is... P ALK = P ALK_min , P battery = P wind + P PV - P load - P ALK_min .
[0030] in: P wind Wind power output; P PV Light energy power; P load For the microgrid system's own load; P ALK_min This represents the minimum hydrogen production power of the microgrid system. P ALK_max This represents the maximum hydrogen production capacity of the microgrid system. Battry_SOC represents the battery's stored energy.
[0031] c) When the sum of wind and solar power is less than the sum of the additional load and alkaline hydrogen production power, i.e. P wind + P PV < P load + P ALK_min The alkaline electrolyzer power (alkaline hydrogen production power) remains unchanged for 5 minutes (this duration can be adjusted according to actual conditions). P ALK = P ALK_before ,like Figure 6As shown, the alkaline hydrogen production power during this period is provided by battery energy storage, i.e. P wind + P PV + P Battery = P load + P ALK To avoid the impact of random fluctuations in wind and solar power on the operation of alkaline electrolyzers, the energy stored in the new microgrid architecture can be directly supplied to the alkaline electrolyzers through a single DC-DC converter instead of two bidirectional AC-DC converters when helping them respond to wind and solar power fluctuations. This greatly improves energy utilization. At the same time, due to the voltage source characteristics of the direct DC bus connection to the energy storage, frequent changes in wind and solar power will not affect the DC-DC side, thus avoiding the fluctuation impact of traditional microgrid architectures on alkaline electrolyzers.
[0032] If the sum of wind and solar power after 5 minutes is still less than the sum of the additional load and alkaline hydrogen production power, then the alkaline hydrogen production power is adjusted to 0, and hydrogen production is stopped to ensure the continuous and stable operation of the microgrid's own load.
[0033] This invention exhibits superior fault tolerance: In traditional architectures, a failure of the converter in the energy storage or alkaline electrolyzer leads to complete functional loss. However, for the novel microgrid system of this invention, even if the bidirectional AC-DC converter shared by the alkaline electrolyzer and battery energy storage fails, or if the microgrid as a whole experiences severe voltage / frequency imbalance or requires maintenance due to extreme conditions such as high / low voltage ride-through, communication failure, or line arcing, the system can still withstand the failure. Figure 7 As shown, by actively controlling the IGBT module Q1 to disconnect from the bidirectional AC-DC converter microgrid, the fault propagation is prevented from exceeding the battery's energy absorption capacity. Simultaneously, it ensures that the hydrogen production load does not instantly collapse, causing the previously mentioned equipment damage, thus allowing the hydrogen production load to continue operating safely or shut down in an orderly manner, thereby improving the system's robustness and fault tolerance. Energy flow at this time...
[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.
Claims
1. A microgrid system for an alkaline electrolytic cell based on a common AC bus, characterized in that, It includes a bidirectional AC-DC converter, a DC-DC converter, and battery energy storage; one side of the common AC bus is connected to a wind power unit, a photovoltaic unit, and a power grid system, and the other side of the common AC bus is connected to the bidirectional AC-DC converter. The bidirectional AC-DC converter is connected in parallel with the DC-DC converter, and the DC-DC converter is connected to an alkaline electrolytic cell; the bidirectional AC-DC converter and the DC-DC converter are connected to the battery energy storage via a direct DC bus, and an IGBT module is installed between the bidirectional AC-DC converter and the direct-connected energy storage.
2. The microgrid system for an alkaline electrolytic cell based on a common AC bus as described in claim 1, characterized in that, A capacitor C0 is connected in parallel between the bidirectional AC-DC converter and the battery energy storage; a load is also connected to the other side of the common AC bus, and the load is grounded.
3. The microgrid system for an alkaline electrolytic cell based on a common AC bus as described in claim 1, characterized in that, The wind power unit is connected to the common AC bus via an AC-DC-AC inverter; the photovoltaic unit is connected to the common AC bus via a DC-AC inverter.
4. A control method for a microgrid in an alkaline electrolyzer based on a common AC bus, implemented based on a microgrid system for an alkaline electrolyzer based on a common AC bus as described in any one of claims 1-3, characterized in that, Both the wind power system and the photovoltaic system adopt the grid-following control strategy of maximum power transmission (MPPT). When the project does not require 100% zero-carbon certification, the microgrid system adopts a grid-connected configuration; When a project requires 100% zero-carbon certification or needs to improve its economic efficiency, the microgrid system adopts an off-grid configuration, with battery energy storage and grid-connected converters replacing the voltage / frequency support provided by the grid, and using master-slave control to drive the wind power and photovoltaic structures to operate in a grid-following control manner.
5. The control method for a microgrid in an alkaline electrolytic cell based on a common AC bus according to claim 4, characterized in that, If the microgrid system is configured as an island or can be switched between grid-connected and off-grid, then the bidirectional AC-DC converter adopts a grid-type converter to achieve grid support under off-grid conditions.
6. A control method for a microgrid in an alkaline electrolytic cell based on a common AC bus, as described in claim 4 or 5, characterized in that, While meeting the load requirements of the microgrid system itself, the hydrogen production power is adjusted within a safe range of 30%-110% of the rated power of the alkaline electrolyzer, depending on the wind and solar intensity. like P wind + P PV ≥ P load + P ALK_min And if Battry_SOC≥90%, then the power of the alkaline electrolyzer is... P ALK = P ALK_max ; like P wind + P PV ≥ P load + P ALK_min If 70% ≤ Battry_SOC ≤ 90%, then the power of the alkaline electrolytic cell is: ； like P wind + P PV ≥ P load + P ALK_min And if Battry_SOC < 70%, then the power of the alkaline electrolyzer is... P ALK = P ALK_min The battery is used for charging. P battery = P wind + P PV - P load - P ALK_min ; in: P wind Wind power output; P PV Light energy power; P load For the microgrid system's own load; P ALK_min This represents the minimum hydrogen production power of the microgrid system. P ALK_max This represents the maximum hydrogen production capacity of the microgrid system. Battry_SOC represents the battery's stored energy.
7. The control method for a microgrid in an alkaline electrolytic cell based on a common AC bus as described in claim 6, characterized in that, like P wind + P PV < P load + P ALK_min ,but P ALK = P ALK_before This process continues for 5 minutes, during which the alkaline hydrogen production power is provided by battery energy storage. P wind + P PV + P Battery = P load + P ALK If after 5 minutes, and P wind + P PV < P load + P ALK_min ,but P ALK The value is 0 to ensure the continuous and stable operation of the microgrid system's own load.