A power distribution network optimization system based on multi-element energy coordination

Abstract

The application relates to the technical field of electric energy storage, in particular to a power distribution network optimization system based on multi-element energy cooperation, which is applied to a main line containing distributed photovoltaic equipment, electrochemical energy storage equipment, an intelligent charging pile network and a small hydropower unit, and specifically comprises a state monitoring module, an energy storage control module, a load control module and a hydropower control module; the state monitoring module generates a trigger instruction when confirming that the power distribution network forms an island microgrid; the energy storage control module responds to the instruction, uses a converter to output transient compensation power, suppresses bus voltage and frequency drop and provides transient support; the load control module executes stepwise flexible power reduction control on the intelligent charging pile network according to the battery state of charge and charging power in a transient window period to reduce the active power shortage; the hydropower control module regulates and controls the small hydropower to increase the output, and after judging that the small hydropower overcomes the water hammer effect and enters a steady state climbing, the converter is controlled to proportionally reduce the compensation power until the water-light complementation meets the regional load demand.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, specifically to a power distribution network optimization system based on multi-energy synergy. Background Technology

[0002] When existing distribution networks disconnect from the main grid due to faults in the main lines, they often face significant power supply-demand imbalances, easily leading to widespread blackouts. Traditional off-grid control strategies typically rely on the passive response of a single backup power source. Because the dynamic adjustment timescales of various power generation entities are highly inconsistent, the system faces severe voltage and frequency over-limit risks during the initial transient phase of sudden power changes. Furthermore, traditional load shedding methods often employ the crude approach of directly tripping circuit breakers, lacking refined demand-side management. This not only severely impacts the electricity experience for end users but also introduces severe secondary electrical shocks into the microgrid, making it difficult to ensure a smooth transition and long-term stability of regional power supply.

[0003] How to overcome the physical barriers of inconsistent response time scales of various regulatory resources in the initial stage of transient impact when a sudden power outage forms an island in the distribution network, fill the huge transient power gap in the early stage without causing abrupt power outage impact on the user side, and eliminate the secondary disturbance to the power grid caused by the reverse power drop caused by the mechanical lag of slow-speed rotating generator sets, so as to achieve seamless connection of microgrid from transient emergency support to steady-state complementary power supply.

[0004] To address this, a power distribution network optimization system based on multi-energy synergy is proposed. Summary of the Invention

[0005] The present invention aims to provide a distribution network optimization system based on multi-energy synergy, which ensures the stability of voltage and frequency of the distribution network under islanded conditions through the time-series decoupling and control handover of energy storage transient support, flexible load reduction and hydropower steady-state ramp-up.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A power distribution network optimization system based on multi-energy synergy, the system comprising: Status monitoring module: After a fault is segmented on the main line, based on the mechanical position change signal of the tie switch, the status of the auxiliary contacts of the associated circuit breaker, and the voltage, frequency change rate and ride power at the grid connection point, it confirms the formation of an islanded microgrid and generates a trigger command containing an island confirmation timestamp and an electrical quantity snapshot. Energy storage control module: In response to the trigger command, it generates a compensation command based on the frequency deviation, frequency change rate and voltage deviation of the isolated microgrid bus, and limits the state of charge of the energy storage and the rated power of the converter, and controls the converter to inject the corresponding compensation power into the bus. Load control module: It is used to calculate the real-time active power deficit based on the real-time total output of distributed power sources, regional base load power and energy storage compensation power, and determine the load shedding priority based on the power battery state of charge and real-time charging power of each smart charging pile. It issues dynamic power limiting instructions according to the load shedding priority, so that the smart charging pile reduces the charging power with a stepped current reference. The hydropower control module is used to generate a steady-state power gap benchmark when it detects an increase in the guide vane opening of the small hydropower unit and the rate of change of the filtered active power at the generator end turns from negative to positive and remains greater than the positive slope threshold within the confirmation window. The module then adjusts the compensation power of the converter according to the increase in the active power of the small hydropower unit and the deviation correction amount until the actual active power of the small hydropower unit and the current active power output of the distributed photovoltaic system meet the steady-state power gap benchmark.

[0007] Preferably, the step of the status monitoring module generating the trigger command specifically includes: The system collects mechanical position signals of the tie switches at the connection point between the main line and the distribution network in real time, as well as the status of the auxiliary contacts of the associated circuit breakers, to monitor the physical topology connection status of the distribution network. Simultaneously, it collects the instantaneous values ​​of the three-phase voltage and current at the bus side of the connection point, extracts the effective value of the three-phase voltage, the voltage phase angle jump degree, and the system frequency change rate, and calculates the flow state of active power and reactive power at the connection point. When the physical topology connection is disconnected through the mechanical displacement signal and the status monitoring of the auxiliary contact, and within the preset anti-interference delay window period, the effective value of the three-phase voltage exceeds the lower limit of the undervoltage protection setting and / or the system frequency change rate exceeds the system frequency steady-state dead zone, and the active power and reactive power at the grid connection point both fall to the zero dead zone range, it is confirmed that the distribution network has been passively disconnected from the main grid and has officially formed the islanded microgrid, and a trigger command is generated.

[0008] Preferably, the step of the energy storage control module generating the active transient compensation power command specifically includes: The actual voltage and frequency at the bus of the isolated microgrid are collected in real time, and the dynamic voltage deviation between the actual voltage and the preset rated voltage, as well as the dynamic frequency deviation between the actual frequency and the preset rated frequency and the instantaneous frequency change rate, are calculated respectively. A virtual inertia and damping adjustment mechanism simulating the electromechanical characteristics of a synchronous generator is established. Based on the instantaneous frequency change rate and the preset virtual inertia coefficient, the inertia support part of the active power is calculated, and based on the dynamic frequency deviation and the preset droop adjustment coefficient, the damping adjustment part of the active power is calculated. The inertia support part and the damping adjustment part are superimposed to generate an active transient compensation power command.

[0009] Preferably, the specific steps for suppressing voltage and frequency drops on the islanded microgrid bus include: The reactive transient compensation power command is calculated synchronously based on the voltage dynamic deviation and the preset voltage droop gain; the active transient compensation power command and the reactive transient compensation power command are converted into the converter's intrinsic voltage amplitude and phase angle modulation signal, and the electrochemical energy storage device is driven to dynamically inject the corresponding active and reactive power in the four quadrants by controlling the conduction and cutoff of the power switching tubes inside the converter, so as to suppress the voltage and frequency drop of the islanded microgrid bus.

[0010] Preferably, the step of the load control module determining the load shedding call priority specifically includes: The system continuously monitors the total output of distributed power sources and the total power of regional base load within the isolated microgrid, and calculates the real-time active power deficit of the isolated microgrid by combining the transient compensation power output of the converter. The system also collects the state of charge of the power batteries of the vehicles currently mounted on each smart charging pile concurrently through the distribution area communication network, as well as the real-time charging power. Smart charging piles with a state of charge of power batteries higher than a preset adequacy threshold are classified into adjustable clusters. Within the controllable cluster, load shedding priorities are assigned in descending order according to the cross-weighted order of the power battery state of charge from high to low and the real-time charging power from large to small.

[0011] Preferably, the specific process by which the load control module performs the stepped flexible power reduction control is as follows: A total load-cutting power target is generated based on the real-time active power deficit; dynamic power-limiting operation instructions are sequentially issued to the corresponding smart charging piles in the adjustable cluster according to the load-cutting call priority from high to low. The intelligent charging pile that receives the dynamic power limiting operation command adjusts the output current reference value of the internal AC-DC conversion link to perform continuous step-by-step active power reduction until the sum of the active power reduced by each intelligent charging pile matches the total load reduction target, thereby smoothing out the active power deficit.

[0012] Preferably, the specific execution process of the water and electricity control module includes: The guide vane opening and actual active power at the turbine end of the small hydropower unit are collected in real time, and the real-time rate of change of the actual active power is calculated. When the guide vane opening is detected to increase, and after experiencing an initial reverse drop in power, the real-time rate of change of the actual active power changes from negative to positive and remains above the preset positive slope value, it is determined that the small hydropower unit has overcome the water hammer effect and entered the steady-state ramping stage. Subsequently, the real-time demand of the regional load within the isolated microgrid is obtained, and the current active power output of the distributed photovoltaic equipment is deducted to generate a steady-state power gap benchmark. With the steady-state power gap benchmark as the target, the transient compensation power of the converter is synchronously reduced at a decay rate equal to the real-time change rate of the actual active power until the actual active power of the small hydropower unit completely covers the steady-state power gap benchmark, and the transient compensation power smoothly falls back to zero.

[0013] Preferably, when the state of charge of the electrochemical energy storage device is lower than the warning threshold, the compensation power is reduced according to the power contraction rate, and the reduction amount is written into the additional deficit.

[0014] Preferably, when the state of charge is below the emergency threshold or the available load capacity of the charging pile is insufficient, the secondary interruptible load is scheduled to take over according to the release capacity.

[0015] Preferably, after the power handover is completed, the secondary interruptible load is restored in reverse order.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention reduces the probability of false triggering caused by instantaneous disturbances through dual verification of multi-dimensional electrical characteristics and physical topology. Simultaneously, based on virtual inertia and damping mechanisms, the converter is controlled to provide immediate active and reactive power compensation at the moment of grid disconnection, mitigating voltage and frequency drops on the bus during the initial islanding phase and creating a critical operating window for subsequent slow resource adjustments.

[0017] 2. This invention utilizes smart charging piles as flexible resources, establishing dynamic priorities based on battery state of charge and charging power. When the system faces a power shortage, the AC / DC conversion links within the charging pile are adjusted sequentially to execute a step-by-step power reduction. Compared to direct tripping and load shedding, this method reduces the power step amplitude and the risk of secondary impacts, approaching the load reduction target in a real-time closed-loop manner while still meeting basic charging needs.

[0018] 3. This invention deeply integrates the rapid response of energy storage, the flexible load shedding of the charging network, and the slow ramp-up characteristics of small hydropower units. The system can effectively identify the power recovery phase after water hammer hysteresis, and after confirming that the unit has entered steady-state ramp-up, the energy storage compensation power is reduced proportionally to the rate of increase of the hydropower unit's active power. By applying multi-source coordination across time scales, the power surge during the handover process is reduced, achieving a transient steady-state handover. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the steps of a power distribution network optimization system based on multi-energy synergy according to the present invention. Figure 2 This is a flowchart illustrating the execution logic of the status monitoring module of the present invention; Figure 3This is a flowchart illustrating the load reduction logic of the load control module 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] Please see Figures 1 to 3 This invention provides a power distribution network optimization system based on multi-energy synergy, referring to... Figure 1 Step-by-step flowchart Figure 2 A flowchart illustrating the execution logic of the status monitoring module, and Figure 3 A flowchart illustrating the load shedding logic of the load control module; the technical solution is as follows: Status monitoring module: After a fault is segmented on the main line, based on the mechanical position change signal of the tie switch, the status of the auxiliary contacts of the associated circuit breaker, and the voltage, frequency change rate and ride power at the grid connection point, it confirms the formation of an islanded microgrid and generates a trigger command containing an island confirmation timestamp and an electrical quantity snapshot. Energy storage control module: In response to the trigger command, it generates a compensation command based on the frequency deviation, frequency change rate and voltage deviation of the isolated microgrid bus, and limits the state of charge of the energy storage and the rated power of the converter, and controls the converter to inject the corresponding compensation power into the bus. Load control module: It is used to calculate the real-time active power deficit based on the real-time total output of distributed power sources, regional base load power and energy storage compensation power, and determine the load shedding priority based on the power battery state of charge and real-time charging power of each smart charging pile. It issues dynamic power limiting instructions according to the load shedding priority, so that the smart charging pile reduces the charging power with a stepped current reference. The hydropower control module is used to generate a steady-state power gap benchmark when it detects an increase in the guide vane opening of the small hydropower unit and the rate of change of the filtered active power at the generator end turns from negative to positive and remains greater than the positive slope threshold within the confirmation window. The module then adjusts the compensation power of the converter according to the increase in the active power of the small hydropower unit and the deviation correction amount until the actual active power of the small hydropower unit and the current active power output of the distributed photovoltaic system meet the steady-state power gap benchmark.

[0022] Example 1: This implementation method targets islanded distribution networks containing distributed photovoltaic (PV) equipment, electrochemical energy storage devices, smart charging pile networks, and small hydropower units. It achieves accurate islanding identification through joint verification of dual electrical characteristics and physical topology. Through three stages of time-sequential decoupling and coordination—including the instantaneous transient support of the energy storage control module's virtual inertia mechanism, the stepped flexible load shedding of the charging pile network by the load control module, and the steady-state power replacement by the hydropower control module—it ensures voltage and frequency stability throughout the entire process of the islanded microgrid from the impact of grid disconnection to the steady-state power supply of the hydro-solar complementary system. The specific implementation steps are as follows: First, the steps for the status monitoring module to generate trigger commands specifically include: real-time acquisition of mechanical displacement signals of the tie switches at the connection point between the main line and the distribution network, as well as the status of auxiliary contacts of the associated circuit breakers, to monitor the physical topology connection status of the distribution network; synchronous acquisition of instantaneous three-phase voltage and current values ​​at the bus side of the connection point, extraction of effective three-phase voltage values, voltage phase angle jump degree, and system frequency change rate, and calculation of the flow status of active and reactive power at the connection point; when the physical topology connection is detected to be disconnected through the mechanical displacement signals and the status of the auxiliary contacts, and within the preset anti-interference delay window period, the effective three-phase voltage value exceeds the lower limit of the undervoltage protection setting and / or the system frequency change rate exceeds the system frequency steady-state dead zone, and the active and reactive power at the connection point both fall to the zero dead zone range, it is confirmed that the distribution network has passively disconnected from the main grid and formally formed the islanded microgrid, and a trigger command is generated.

[0023] Specifically, the status monitoring module deploys hard-wired digital quantity acquisition units at each tie switch node and grid connection point on the main line. The normally open contact of the travel limit sensor built into the tie switch is hard-wired to the digital input terminal of the acquisition unit. When the tie switch performs a tripping action, the normally open contact closes, and the terminal detection level changes from low to high. The acquisition unit synchronously reads the status of the auxiliary normally closed contact of the circuit breaker corresponding to the same tie switch. After the circuit breaker trips, the auxiliary normally closed contact immediately opens, and the terminal detection level changes from high to low. The acquisition unit stores the current logic level of each of the above signals into a dual register comparison buffer with a fixed polling period of 20ms. It performs a bitwise XOR operation on the current value and the value stored in the previous period. When the tie switch displacement signal and the circuit breaker auxiliary contact signal are detected to change simultaneously in the same polling period, the buffer writes a "topology disconnection event" record containing the event type, occurrence timestamp, and involved device number to the physical event detector. This record serves as the physical dimension input of the islanding comprehensive judgment logic and synchronously triggers the electrical quantity comprehensive judgment start process.

[0024] Specifically, the analog outputs of the secondary sides of the voltage transformers and current transformers configured on the bus side of the grid connection point are digitized by an analog-to-digital converter at a rate of 64 sampling points per power frequency cycle. The outputs a three-phase voltage instantaneous sampling sequence and a three-phase current instantaneous sampling sequence, which are temporarily stored in a circular sampling buffer. At the end of each power frequency cycle, the three-phase voltage effective value calculation module reads the most recent 64 voltage instantaneous values ​​from the buffer, squares each sampling point, and accumulates them all. The result is divided by 64 and the arithmetic square root is taken to obtain the effective value of each equivalent voltage. With the rated bus voltage of 10kV as the reference benchmark, when the effective value of any phase is lower than the undervoltage protection setting (set to 9kV in this embodiment), the undervoltage over-limit flag is set and the continuous over-limit cycle count is accumulated simultaneously. The flag and the count value are written into the flag register inside the status monitoring module for subsequent reading by the islanded integrated judgment logic unit.

[0025] Specifically, the phase-locked loop (PLL) tracking module takes the 64-point instantaneous sampling sequence of phase A voltage in the current power frequency cycle in the cyclic sampling buffer as input, continuously tracks the real-time phase angle of the fundamental component of phase A voltage, and calculates the difference between the estimated phase angle at the end of the current cycle and the steady-state locked phase angle at the end of the previous cycle. The absolute value of the difference is the voltage phase angle jump degree of the current cycle and is stored in the historical buffer for later use. The frequency calculation submodule continuously extracts the frequency measurement values ​​of two adjacent power frequency cycles from the PLL phase angle estimation output, and divides the difference between the two measurement values ​​by the duration of a single power frequency cycle to obtain the system frequency change rate. When the absolute value of the change rate exceeds the preset steady-state dead zone upper limit (set to 0.2Hz / s in this embodiment), the frequency over-limit flag is set. The frequency over-limit flag and the undervoltage over-limit flag are synchronously refreshed with the power frequency cycle and then uniformly written into the flag register for reading by the islanded synthesis criterion logic unit.

[0026] Specifically, the power calculation module uses the instantaneous sampling sequences of three-phase voltage and three-phase current in the cyclic sampling buffer as dual inputs. At the end of each power frequency cycle, it performs a single-cycle integral averaging operation on the product sequence of three-phase instantaneous power, and extracts the active power ride-through P and reactive power ride-through Q at the grid connection point. When the absolute values ​​of P and Q are simultaneously lower than their respective zero dead zone judgment thresholds (in this embodiment, the active power threshold is taken as 1% of the installed capacity and the reactive power threshold is taken as 0.5% of the installed capacity), the power drop-to-zero flag is set. This flag is refreshed with the power frequency cycle and written synchronously to the flag register along with the undervoltage over-limit and frequency over-limit flags, completing the unified storage and synchronous update of the three-dimensional electrical characteristic quantities, and providing complete data input for the multi-condition joint judgment of the islanding comprehensive criterion.

[0027] Specifically, upon receiving a "topology disconnection event" record, the islanding integrated criterion logic unit immediately starts an anti-interference delay timer with a preset duration of 100ms. During the timer's operation, the logic unit continuously polls the three flags in the flag register—undervoltage limit, frequency limit, and power drop to zero—at the power frequency cycle. The criterion logic relationship is: (the undervoltage limit flag is valid, or the frequency limit flag is valid), and the power drop to zero flag is valid simultaneously. When the above composite criteria are met for three consecutive power frequency cycles before the timer expires, the logic unit writes the islanding confirmation status into the system status register and then synchronously broadcasts a trigger command message to the energy storage control module and the hydropower control module via the internal message bus. The message data payload includes the islanding confirmation timestamp and snapshots of the current electrical measurements. Once the trigger command is generated, the subsequent multi-source collaborative control process is activated. In other embodiments, the aforementioned undervoltage protection settings, steady-state dead zone upper limit, active / reactive power thresholds, and timing duration can all be adjusted based on grid connection point protection settings, installed capacity, sampling frequency, and malfunction test results.

[0028] By employing a dual closed-loop verification of physical topology displacement signals and multi-dimensional electrical characteristics, coupled with a dual filtering mechanism of anti-interference delay window and continuous periodic confirmation, the system effectively eliminates false triggering due to instantaneous disturbances while ensuring accurate identification of islanded states, thus providing timely activation trigger signals for energy storage and hydropower control modules.

[0029] Furthermore, the step of the energy storage control module generating the active transient compensation power command specifically includes: real-time acquisition of the actual voltage and actual frequency at the bus of the islanded microgrid, and calculation of the voltage dynamic deviation between the actual voltage and the preset rated voltage, as well as the frequency dynamic deviation between the actual frequency and the preset rated frequency and the instantaneous rate of change of frequency; establishing a virtual inertia and damping adjustment mechanism simulating the electromechanical characteristics of a synchronous generator, calculating the inertia support part of the active power based on the instantaneous rate of change of frequency and the preset virtual inertia coefficient, and calculating the damping adjustment part of the active power based on the frequency dynamic deviation and the preset droop adjustment coefficient, and superimposing the inertia support part and the damping adjustment part to generate the active transient compensation power command.

[0030] Specifically, the energy storage control module continuously collects the bus electrical quantities through voltage transformers and frequency measurement units installed at the bus measurement points of the isolated microgrid. The analog output of the secondary side of the voltage transformer is digitized by an analog-to-digital converter, and the resulting instantaneous sampling sequence of the three-phase voltage is sent to the effective value calculation module. This module squares all sampling points within the most recent complete power frequency cycle and accumulates them. The result is divided by the number of sampling points and the arithmetic square root is taken to obtain the current effective value of the three-phase bus voltage. The rated voltage value is pre-stored in the controller parameter register as an offline setting parameter. The calculation module calculates the difference between the actual effective value and the rated value to obtain the electrical value. The dynamic deviation of the voltage is written into the voltage-dedicated channel of the deviation buffer register in signed floating-point format for later use. The phase-locked tracking module extracts the real-time phase angle of the fundamental wave of phase A voltage from the same voltage sampling sequence. At the end of each control cycle, the frequency measurement value of this cycle is subtracted from the rated frequency of 50Hz pre-stored in the parameter register to obtain the frequency dynamic deviation. The difference between the frequency measurement values ​​of two adjacent control cycles is divided by the control cycle duration to obtain the instantaneous frequency change rate. Both quantities are written into the frequency-dedicated channel of the deviation buffer register in signed floating-point format, completing the full acquisition and deviation quantification of the bus electrical quantities.

[0031] Specifically, within each control cycle, the virtual inertia calculation module and the damping adjustment calculation module use the instantaneous rate of change of frequency and the dynamic frequency deviation from the frequency-dedicated channel of the deviation buffer register as inputs to establish a virtual inertia and damping adjustment mechanism simulating the electromechanical characteristics of a synchronous generator. At the end of each control cycle, the power synthesis module synchronously performs algebraic addition on the inertia support and damping adjustment and sends the results to the limiting processing module. The specific calculation formula for the active transient compensation power command is as follows: ; in, The virtual inertia coefficient, whose physical meaning simulates the inertial energy storage size of the equivalent virtual synchronous generator rotor; The frequency droop adjustment coefficient is used to simulate the differential regulation characteristics of a synchronous generator speed governor. To preset the rated frequency, This is the actual frequency; The instantaneous rate of change of frequency; This indicates that the output upper limit is set based on the maximum available discharge power corresponding to the current state of charge (SOC) of the electrochemical energy storage device, and the output lower limit is set based on the maximum allowable charging power. Values ​​exceeding these limits are truncated, and the truncated value becomes the active transient compensation power command for this control cycle. This value is written to the command output register in signed floating-point format. Within the same control cycle, the modulation unit reads this value from the command output register and converts it into the conduction timing drive signal for the converter power switch via internal modulation logic. This drives the electrochemical energy storage device to inject the corresponding active power into the isolated microgrid bus, achieving a complete data closed loop from generation to execution of the active transient compensation power command.

[0032] By using a decoupled superposition design of virtual inertia support and droop damping adjustment, the energy storage converter can accurately simulate the electromechanical response characteristics of a synchronous generator at the moment of island formation, thereby achieving instantaneous injection of active power, effectively curbing the precipitous drop in bus frequency, and winning a critical action window for subsequent slow regulation resources.

[0033] Furthermore, the specific steps for suppressing the voltage and frequency drops of the isolated microgrid bus include: synchronously calculating reactive transient compensation power commands based on the voltage dynamic deviation and a preset voltage droop gain; converting the active transient compensation power commands and the reactive transient compensation power commands into the converter's intrinsic voltage amplitude and phase angle modulation signals; and driving the electrochemical energy storage device to dynamically inject corresponding active and reactive power in the four quadrants by controlling the conduction and cutoff of the power switching transistors inside the converter, thereby suppressing the voltage and frequency drops of the isolated microgrid bus.

[0034] Specifically, the reactive power calculation module uses the voltage dynamic deviation in the voltage-specific channel of the deviation buffer register as the sole input in each control cycle. It multiplies this signed floating-point value with the voltage droop gain pre-stored in the parameter register to obtain the reactive transient compensation power command. The physical meaning of the voltage droop gain is the incremental reactive power that needs to be injected or absorbed per unit voltage deviation. The setting principle is: when the effective value of the bus voltage drops by 5% of the rated value, the reactive transient compensation power command value falls within the range of 20% to 30% of the rated reactive capacity of the energy storage converter to form effective voltage support. The reactive transient compensation power command is written to the reactive channel of the command synthesis register in signed floating-point format. At the same time, the active transient compensation power command value is synchronously read from the command output register into the active channel of the command synthesis register. The two commands are converged in the command synthesis register as the complete input of the endogenous voltage synthesis module.

[0035] Specifically, the endogenous voltage synthesis module synchronously reads the signed floating-point instruction values ​​of the active and reactive power channels from the instruction synthesis register, and performs calculations according to the power-voltage regulation mechanism of the virtual synchronous generator. The active power channel instruction value is sent to the virtual rotor angular velocity integration unit, which performs numerical integration on the time axis of the estimated virtual angular velocity value in the current control cycle and updates the integration result to the state variable register to obtain the real-time phase angle reference value of the converter's endogenous voltage. The reactive power channel instruction value is sent to the automatic voltage amplitude regulation unit, which uses the rated output voltage amplitude pre-stored in the parameter register as a reference, maps the reactive power instruction value to the amplitude regulation increment through proportional conversion, and superimposes it on the reference amplitude to obtain the real-time amplitude reference value of the converter's endogenous voltage. The phase angle reference value and the amplitude reference value are written to the phase angle channel and amplitude channel of the modulation signal register in floating-point format, respectively, to complete the decoupling conversion of active and reactive power instructions into endogenous voltage amplitude and phase angle modulation parameters.

[0036] Specifically, the three-phase reference wave synthesis module reads the phase angle reference value and amplitude reference value from the phase angle channel and amplitude channel of the modulation signal register. Using the amplitude reference value as the peak amplitude and the phase angle reference value as the initial phase, it sequentially superimposes 120° phase differences according to the three-phase symmetrical relationship to generate three sets of sinusoidal reference voltage instantaneous values ​​and stores them in the carrier comparison buffer. The pulse width modulation module synchronously scans the three reference values ​​with a fixed frequency triangular carrier as the comparison reference. When the reference value of a certain phase is higher than the carrier value at the same moment, the corresponding upper bridge arm power switch is given a turn-on command and the lower bridge arm is given a turn-off command. When it is lower than the carrier value, the command is flipped. The switching time of the upper and lower bridge arms is symmetrically delayed according to the preset dead time to avoid shoot-through short circuit. Finally, six pulse width modulation drive timing sequences with dead time protection are generated and written into the drive signal output register. After being amplified by the voltage and current of the isolation drive circuit, they are connected to the gates of the six power switches of the three-phase full bridge of the converter to realize precise physical control of the turn-on and turn-off timing of each switch.

[0037] Specifically, under the aforementioned drive timing control, the three-phase full-bridge converter converts the DC power of the DC-side electrochemical energy storage device to the AC side. The direction and magnitude of active power injection are determined by the difference between the intrinsic voltage phase angle reference value and the real-time phase angle of the bus voltage: when the difference is positive, the converter injects active power into the bus and the corresponding energy storage device discharges; when the difference is negative, the converter absorbs active power from the bus and the corresponding energy storage device charges. The direction and magnitude of reactive power injection are determined by the difference between the intrinsic voltage amplitude reference value and the effective value of the bus voltage. The difference determines the voltage difference: when the amplitude reference value is higher than the effective value of the bus voltage, the converter injects reactive power into the bus to support the bus voltage drop; when the amplitude reference value is lower than the effective value of the bus voltage, the converter absorbs reactive power from the bus to suppress the local voltage rise. The direction and magnitude of the above-mentioned active and reactive power injection are updated independently and executed in parallel in each control cycle, covering the full range of power regulation in the four quadrants. This achieves synchronous transient suppression of the bus voltage and frequency of the islanded microgrid, preventing both from falling below the protection action setting and triggering an expanded power outage.

[0038] By synchronously decoupling the generation of active and reactive power commands and designing independent four-quadrant drives, the energy storage converter can synchronously support the bus voltage and frequency within a single control cycle, stabilizing both above the protection action setpoints, thus gaining a critical operating window for subsequent load regulation and hydropower ramp-up.

[0039] Furthermore, the step of determining charging priority by the load control module specifically includes: real-time statistical analysis of the total instantaneous output of distributed power sources and the total power of regional base load within the islanded microgrid, and calculation of the real-time active power deficit of the islanded microgrid in conjunction with the transient compensation power output of the converter; concurrently collecting the state of charge (SBC) of the power batteries of the currently mounted vehicles and the real-time charging power of each smart charging pile through the distribution area communication network, and classifying smart charging piles with SBCs higher than a preset adequacy threshold into adjustable clusters; within the adjustable clusters, assigning charging priorities in descending order according to the cross-weighted order of SBC from high to low and real-time charging power from large to small.

[0040] Specifically, the load control module has a built-in power deficit calculation unit. This unit reads the real-time active power output data reported by the distributed photovoltaic inverter and the active power data reported by the small hydropower unit monitoring and control device through the distribution area communication network. It accumulates the active power output values ​​of each distributed power source in the power summary register to obtain the real-time total output of the distributed power sources in the islanded microgrid. At the same time, it reads the total regional base load power (excluding charging pile charging load) collected by the grid-connected point power metering device and reads the current actual output transient compensation power measurement value from the AC side power measurement module of the energy storage converter. The above three data are written sequentially into the distributed power source channel, base load channel and compensation power channel of the power calculation buffer. The power deficit calculation unit performs a subtraction operation with the base load channel value as the minuend and the sum of the distributed power source channel and compensation power channel values ​​as the subtrahend. The calculated difference is written into the power deficit register in signed floating-point format to complete the quantitative calculation of real-time active power deficit.

[0041] Specifically, after receiving the acquisition trigger signal from the load control module, the main control unit of the distribution area communication network synchronously sends standard data read request frames to the embedded communication controllers of all registered smart charging piles in the distribution area in a broadcast concurrent manner. The request frame header contains a data type identifier field, specifying two types of data requested: state of charge and real-time charging power. After receiving the request frame, each charging pile communication controller reads the current power battery state of charge percentage integer value from the battery management system and the current real-time charging power floating-point value from the charging metering module. The two data streams are then packaged in the standard response frame format and transmitted back to the load control module via the distribution area communication network. The load control module writes the response data of each charging pile into the charging pile status data table in sequence according to the charging pile number index. Each row of the data table contains three fields: charging pile number, state of charge percentage, and real-time charging power. The row of a charging pile that does not respond within the specified response time limit is marked as "offline" and skipped in subsequent processing.

[0042] Specifically, the adjustable cluster partitioning module traverses all valid rows in the charging pile status data table, reads the state of charge percentage field value row by row, and compares it with the adequacy threshold (set to 30% in this embodiment) pre-stored in the parameter register. Rows with a state of charge percentage higher than the threshold are extracted and written into the adjustable cluster data table, while rows with a state of charge lower than or equal to the threshold are marked as "protected" and removed from the subsequent sorting process. For example, when 8 charging piles in the area complete this round of response and 5 of them have a state of charge higher than 30%, the adjustable cluster data table contains 5 valid records, retaining the original number, state of charge percentage, and real-time charging power fields of each row, which serve as the input dataset for the charging priority sorting module.

[0043] Specifically, the load shedding priority sorting module takes the adjustable cluster data table as input, performs a descending single-dimensional ranking of the state of charge percentage column to obtain the state of charge ranking value of each charging pile (the highest state of charge has a ranking value of 1), and performs a descending single-dimensional ranking of the real-time charging power column to obtain the charging power ranking value of each charging pile (the highest power has a ranking value of 1). Then, the state of charge ranking value and charging power ranking value of each charging pile are weighted by a preset cross-weighting coefficient and summed to obtain the comprehensive priority score of each charging pile. The lower the comprehensive score, the higher the state of charge and the greater the charging power of the charging pile, that is, the more abundant its power reserve and the more significant its current contribution to the active power deficit, and therefore it is assigned a higher load shedding priority. The sorting module arranges each record in the adjustable cluster data table from low to high according to the comprehensive priority score, assigns load shedding priority numbers from highest to lowest, and writes the final load shedding priority queue into the priority management register in a format that maps charging pile numbers to priority numbers one-to-one. One charging pile has a state of charge of 82% and a real-time charging power of 35kW, while another charging pile has a state of charge of 55% and a real-time charging power of 20kW. The former ranks higher in both dimensions and has a lower overall score than the latter. Therefore, it is given a higher priority for load shedding and is given priority in the subsequent load shedding process for power limiting control.

[0044] By cross-weighting the state of charge and charging power, the system accurately identifies the adjustable charging piles that contribute the most to the power deficit and have the most abundant power reserves, while fully protecting the charging needs of users with urgent power needs. This provides an orderly and quantifiable basis for subsequent tiered flexible power reduction control.

[0045] Furthermore, the specific process of the load control module executing the stepped flexible power reduction control is as follows: generating a total load reduction power target based on the real-time active power deficit; issuing dynamic power limiting operation commands to the corresponding smart charging piles in the adjustable cluster in sequence according to the charging priority from low to high; controlling the smart charging piles that receive the dynamic power limiting operation commands to adjust the output current reference value of the internal AC-DC conversion link to execute continuous stepped active power reduction actions until the sum of the cumulative active power reduction of each smart charging pile matches the total load reduction power target, thereby achieving the smoothing of the active power deficit.

[0046] Specifically, the load reduction target generation module reads the current real-time active power deficit floating-point value from the power deficit register, and multiplies it with the load reduction margin coefficient pre-stored in the parameter register (in this embodiment, it is taken as 1.05 to 1.1 to cover the dynamic fluctuation of the deficit during the period from instruction issuance to execution completion). The product result is the total load reduction power target for this load reduction cycle. This target value is written to the load reduction target register in floating-point format. At the same time, the load reduction progress accumulator is cleared and the scheduling cursor is reset to the first position of the priority queue, completing the initialization of this step-by-step flexible power reduction control process. The target value in the load reduction target register is used as a unified termination criterion in subsequent instruction issuance rounds.

[0047] Specifically, the instruction scheduling module reads the charging pile numbers sequentially according to the charging priority in the priority management register, from low to high. For each charging pile, it obtains its current real-time charging power from the charging pile status data table. Using the minimum reserved power per pile (set to 10% of the rated power of the pile in this embodiment) stored in the parameter register as the lower limit, it calculates the maximum power that can be reduced for the current round. The maximum power that can be reduced is compared with the current remaining load to be reduced in the load reduction target register (i.e., the total target minus the current value of the load reduction progress accumulator). When the maximum power that can be reduced does not exceed the remaining load to be reduced, the maximum power that can be reduced is used. The target power limit for a charging pile is generated based on the remaining load to be reduced. When the maximum power that can be reduced exceeds the remaining load to be reduced, the target power limit is generated based on the remaining load to be reduced. The dynamic power limiting operation instruction frame contains the target power limit field, the instruction number field, and the effective time field. It is unicast to the corresponding charging pile communication controller via the area communication network. After receiving the confirmation response frame of the pile, the reduction amount issued in this round is written into the load reduction progress accumulator for accumulation. When the accumulator value reaches the total load reduction power target in the load reduction target register, the scheduling module stops reading the subsequent pile number and exits the scheduling loop. Higher priority charging piles that have not been called maintain their current charging power unchanged.

[0048] Specifically, after receiving the dynamic power limiting operation command, each smart charging pile communication controller parses the target power upper limit field, reads the current actual charging power from the charging pile real-time metering module, divides the target power upper limit by the charging pile DC bus voltage to obtain the new DC output current reference value corresponding to the target power, divides the change range from the initial current reference value to the new current reference value into several adjustment levels, and writes the current reference value corresponding to the current level to the current setting register of the AC / DC converter module's built-in controller at preset step time intervals. The current closed-loop tracking control loop of the AC / DC converter module responds in real time to each update of the current setting register, driving the output current to converge to the new current reference value step by step along a stepped trajectory. The charging power then continuously and smoothly decreases from the initial value to the target power upper limit. After the output current of the AC / DC converter module stabilizes, the charging pile communication controller sends back a status confirmation frame containing the current actual charging power to the load control module. The load control module writes the actual power value in the confirmation frame into the power field of the corresponding row of the charging pile status data table to complete the refresh.

[0049] Specifically, after receiving each charging pile status confirmation frame, the cumulative verification module extracts the power difference before and after load reduction from the charging pile status data table, adds it to the load reduction progress accumulator, and performs a real-time comparison between the current value of the accumulator and the total load reduction power target in the load reduction target register. When the total cumulative reduction reaches the total load reduction power target, the cumulative verification module writes a "load reduction completed" flag to the instruction scheduling module. After the scheduling module confirms the flag, it stops issuing instructions to subsequent charging piles, and the charging network in the distribution area then enters a hierarchical power-limited operation steady state: the regulated charging piles continue to charge at their respective target power limits, and the unregulated charging piles maintain their original charging power operation. The total active power load of the distribution area is significantly reduced compared to before load reduction, the active power deficit of the islanded microgrid is effectively mitigated, and the transient compensation pressure of the energy storage converter decreases accordingly.

[0050] By coordinating a priority-based, step-by-step scheduling mechanism with smooth, step-by-step current adjustment within each pile, the power surge caused by direct circuit breaker tripping and load shedding is completely avoided. Under the premise of ensuring basic charging needs, the power deficit is precisely mitigated, ensuring the smooth transition of the isolated microgrid to steady-state operation.

[0051] Furthermore, the specific execution process of the hydropower control module includes: real-time acquisition of the guide vane opening and actual active power at the turbine end of the small hydropower unit, and calculation of the real-time rate of change of the actual active power; when the guide vane opening is detected to increase, and after experiencing an initial reverse power drop, the real-time rate of change of the actual active power changes from negative to positive and remains above the preset positive slope setpoint, it is determined that the small hydropower unit has overcome the water hammer effect and entered the steady-state ramp-up stage; subsequently, the real-time demand of the regional load in the isolated microgrid is acquired, and the current active power output of the distributed photovoltaic equipment is deducted to generate a steady-state power gap benchmark; with the steady-state power gap benchmark as the target, the transient compensation power of the converter is synchronously reduced at a decay rate equal to the real-time rate of change of the actual active power, until the actual active power of the small hydropower unit completely covers the steady-state power gap benchmark, and the transient compensation power smoothly falls back to zero.

[0052] Specifically, upon receiving the trigger command, the hydropower control module immediately activates the unit status monitoring process. The guide vane opening acquisition unit reads the guide vane opening percentage value from the displacement sensor installed on the water guide mechanism of the small hydropower unit at a fixed control cycle. The current value and the value stored in the previous cycle are sequentially written into the opening comparison buffer. When the current value is continuously higher than the previous value, the opening increase flag is set and maintained. At the same time, the generator power measurement unit extracts the actual active power measurement value from the secondary side sampling output of the generator current transformer and voltage transformer at the power frequency cycle. The difference between the current power measurement value and the historical value stored in the previous control cycle is divided by the control cycle duration to obtain the real-time change rate of the actual active power. The opening increase flag, the actual active power at the generator, and its real-time change rate are all written into the opening channel, power channel, and change rate channel of the hydropower status register in signed floating-point format, respectively. The water hammer effect determination module continues to read in subsequent processes.

[0053] Specifically, the water hammer effect determination module takes the hydropower status register as input and continuously monitors the real-time rate of change in the rate of change channel, provided that the opening increase flag is valid. When the guide vane opening increases and the real-time rate of change of the active power at the generator end after low-pass filtering turns from negative to positive for the first time, this moment is recorded as the "candidate moment for the end of water hammer" and written to the time record register. The determination module then starts a continuous confirmation timing window. In the timing window, the value of the rate of change channel after low-pass filtering is read sequentially in the control cycle and compared with the value of the positive slope setpoint stored in the parameter register. If all the continuously read rates of change in the timing window are maintained above the positive slope setpoint, it is determined that the small hydropower unit has overcome the water hammer effect and confirmed that it has entered the steady-state ramp-up stage. The "steady-state ramp-up confirmation" flag is written to the hydropower status register. If the rate of change in any control cycle in the timing window is lower than the positive slope setpoint, the "candidate moment for the end of water hammer" record is cleared, the timing window is closed, and it is reset to the initial monitoring state of waiting for the rate of change to turn from negative to positive.

[0054] Specifically, upon receiving the "steady-state ramp-up confirmation" flag, the steady-state power gap reference calculation module immediately triggers a single reference calculation. It sends demand reading requests to the load metering devices in each area of ​​the isolated microgrid through the distribution area communication network, and accumulates the real-time demand values ​​responded by each device in the area load summary register to obtain the total real-time demand of the area load. At the same time, it sends active power output reading requests to each distributed photovoltaic inverter, and accumulates the current active power output values ​​responded by each inverter in the photovoltaic output summary register to obtain the total photovoltaic active power output. It performs a subtraction operation with the total real-time demand of the area load as the minuend and the total photovoltaic active power output as the subtrahend. The difference is written into the steady-state gap reference register in signed floating-point format. This reference value serves as the target endpoint that the hydropower output needs to cover during the subsequent compensation power coordination withdrawal process.

[0055] Specifically, after the "steady-state ramp-up confirmation" flag is valid, the compensation power coordination exit module continuously executes two parallel operations in a control cycle: On the one hand, it reads the current real-time positive value of the actual active power change rate from the hydropower status register change rate channel, and based on the filtered and limited hydropower active power increment, it combines the bus frequency and voltage deviation closed-loop correction of the energy storage reduction amount, reads the current compensation power command value from the energy storage control module command output register, subtracts the downward adjustment amount of this cycle to obtain the new command value, and writes it back to the command output register to overwrite the previous value; if the bus frequency or voltage exceeds the limit again during the handover period, it suspends the energy storage exit or resumes transient compensation to ensure that the total injected power on the bus side of the islanded microgrid remains stable throughout the handover process; on the other hand, it reads the current compensation power command value from the generator end. The power measurement unit reads the current actual active power of the hydropower unit and compares it with the benchmark value in the steady-state gap benchmark register. At the same time, it monitors whether the current compensation power command value in the command output register approaches zero (when the command value is less than 1% of the rated capacity of the energy storage, it is considered to be approaching zero). When the sum of the actual active power of the small hydropower unit and the current active power output of the distributed photovoltaic reaches the steady-state power gap benchmark, the module writes the "power handover completed" flag to the hydropower status register, forces the compensation power command value in the command output register to zero, and the system enters the hydropower-photovoltaic complementary steady-state power supply mode, in which the output of the small hydropower and the output of the distributed photovoltaic work together to meet the continuous power supply needs of the nearby load in the region; otherwise, it will maintain the energy storage compensation output or trigger the secondary load takeover process.

[0056] By identifying the end of the water hammer effect and coordinating the attenuation of energy storage compensation power at the same rate, the secondary power impact was offset throughout the handover of multi-source power across time scales, realizing a seamless and smooth transition of the islanded microgrid from transient energy storage support to steady-state hydro-solar complementary power supply.

[0057] In summary, this embodiment constructs a complete multi-source collaborative control link from fault disconnection impact to steady-state hydro-solar complementary power supply by accurately identifying islanded microgrids through dual verification of multi-dimensional electrical characteristics and physical topology, providing instantaneous transient support through virtual inertia damping mechanism, implementing stepped flexible load shedding of charging piles based on cross-weighting of state of charge and charging power, and seamlessly handing over energy storage compensation power and steady-state hydropower output at the same rate. This effectively ensures the continuous and reliable power supply of islanded microgrids.

[0058] Example 2: In extreme conditions where isolated microgrids have a large initial active power deficit and electrochemical energy storage devices have a low state of charge, the state of charge of the power battery of the energy storage converter may drop to the safe operating boundary before the small hydropower unit completes steady-state ramp-up while continuously outputting transient compensation power. At the same time, when the total reducible capacity of the adjustable cluster of smart charging piles in the area is insufficient to cover the entire active power deficit, simply relying on the flexible load shedding of charging piles will not be able to completely suppress the deficit. This embodiment addresses the combined extreme conditions of limited energy storage capacity and insufficient charging pile load shedding capacity, and refines the adaptive contraction of compensation power under the protection of the energy storage state of charge boundary and the coordinated replacement process of secondary adjustable load.

[0059] Specifically, during islanded operation, the charge protection monitoring unit continuously reads the current state of charge percentage from the battery management system in control cycles and compares it with the pre-stored warning and emergency protection values ​​in the parameter register. When the state of charge is lower than the warning threshold, a "charge warning" flag is written to the energy storage control module. Upon receiving the flag, the energy storage control module writes a decreasing active transient compensation power command value to the command output register in each control cycle at a preset power reduction rate. The reduction in compensation power in each control cycle is synchronously written to the supplementary deficit register in an incremental format. This increment represents the new active power gap caused by the active de-rating of the energy storage. When the state of charge further drops to the emergency protection threshold, the compensation power command value in the command output register is forcibly set to zero and a "energy storage exit" flag is broadcast to the secondary load management module. The energy storage device then stops active power output and enters a protection standby state.

[0060] Specifically, the secondary load management module pre-establishes an interruptible load resource file within its jurisdiction that has signed demand response agreements through the distribution area communication network. The file is stored in the local storage unit of the load control module in a structured table format. Each record contains four fields: load node number, agreement interruptible capacity limit, current minimum guaranteed capacity, and current measured power. After receiving the additional gap value or energy storage exit flag from the additional gap supplement register, the module reads all file records, calculates the release capacity based on the difference between the current measured power and the minimum guaranteed capacity of each node, sorts the release capacity from largest to smallest, and sends power limit instruction frames to the nodes ranked first in sequence. The instruction frame contains the target power limit and effective time fields and is unicast to the corresponding load control terminal through the distribution area communication network. After receiving the instruction, the terminal adjusts the output setting value of the local power regulation device and sends back a confirmation frame. The secondary load management module accumulates the confirmed release capacity of each node into the additional gap compensation accumulator. When the accumulator value is not lower than the total additional gap in the additional gap supplement register, the module stops sending instructions to subsequent nodes. Nodes that are not called maintain their original working settings.

[0061] Furthermore, when the small hydropower unit triggers the "power handover completed" flag, the secondary load management module sends power recovery command frames to all restricted load nodes in reverse order of call. Each node gradually restores its power to the original working set value according to the command and sends back a confirmation frame. If the energy storage device's state of charge has been restored to the safe operating range through charging, the energy storage control module returns to standby mode after receiving the "restore allowed" flag. After all interruptible load nodes have been restored and the energy storage device has completed its state reset, the complete multi-source collaborative control process under the islanding condition officially ends.

[0062] In summary, this embodiment constructs a complete multi-source collaborative control link from fault disconnection impact to steady-state hydro-solar complementary power supply by accurately identifying islands through dual verification of multi-dimensional electrical characteristics and physical topology, providing real-time transient support through virtual inertia damping mechanism, implementing stepped flexible load shedding of charging piles based on cross-weighting of state of charge and charging power, and seamlessly handing over energy storage compensation power and steady-state hydropower output at the same rate. This eliminates voltage and frequency over-limits and secondary disturbance impacts throughout the process, effectively ensuring the continuous and reliable power supply of islanded microgrids.

[0063] 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 distribution network optimization system based on multi-energy synergy, characterized in that, The system includes; Status monitoring module: After a fault is segmented on the main line, based on the mechanical position change signal of the tie switch, the status of the auxiliary contacts of the associated circuit breaker, and the voltage, frequency change rate and ride power at the grid connection point, it confirms the formation of an islanded microgrid and generates a trigger command containing an island confirmation timestamp and an electrical quantity snapshot. Energy storage control module: In response to the trigger command, it generates a compensation command based on the frequency deviation, frequency change rate and voltage deviation of the isolated microgrid bus, and limits the state of charge of the energy storage and the rated power of the converter, and controls the converter to inject the corresponding compensation power into the bus. Load control module: It is used to calculate the real-time active power deficit based on the real-time total output of distributed power sources, regional base load power and energy storage compensation power, and determine the load shedding priority based on the power battery state of charge and real-time charging power of each smart charging pile. It issues dynamic power limiting instructions according to the load shedding priority, so that the smart charging pile reduces the charging power with a stepped current reference. The hydropower control module is used to generate a steady-state power gap benchmark when it detects an increase in the guide vane opening of the small hydropower unit and the rate of change of the filtered active power at the generator end turns from negative to positive and remains greater than the positive slope threshold within the confirmation window. The module then adjusts the compensation power of the converter according to the increase in the active power of the small hydropower unit and the deviation correction amount until the actual active power of the small hydropower unit and the current active power output of the distributed photovoltaic system meet the steady-state power gap benchmark.

2. The distribution network optimization system based on multi-energy synergy according to claim 1, characterized in that, The steps for the status monitoring module to generate trigger commands specifically include: The system collects mechanical position signals of the tie switches at the connection point between the main line and the distribution network in real time, as well as the status of the auxiliary contacts of the associated circuit breakers, to monitor the physical topology connection status of the distribution network. Simultaneously, it collects the instantaneous values ​​of the three-phase voltage and current at the bus side of the connection point, extracts the effective value of the three-phase voltage, the voltage phase angle jump degree, and the system frequency change rate, and calculates the flow state of active power and reactive power at the connection point. When the physical topology connection is disconnected through the mechanical displacement signal and the status monitoring of the auxiliary contact, and within the preset anti-interference delay window period, the effective value of the three-phase voltage exceeds the lower limit of the undervoltage protection setting and / or the system frequency change rate exceeds the system frequency steady-state dead zone, and the active power and reactive power at the grid connection point both fall to the zero dead zone range, it is confirmed that the distribution network has been passively disconnected from the main grid and has officially formed the islanded microgrid, and a trigger command is generated.

3. The distribution network optimization system based on multi-energy synergy according to claim 1, characterized in that, The steps for the energy storage control module to generate active transient compensation power commands specifically include: The actual voltage and frequency at the bus of the isolated microgrid are collected in real time, and the dynamic voltage deviation between the actual voltage and the preset rated voltage, as well as the dynamic frequency deviation between the actual frequency and the preset rated frequency and the instantaneous frequency change rate, are calculated respectively. A virtual inertia and damping adjustment mechanism simulating the electromechanical characteristics of a synchronous generator is established. Based on the instantaneous frequency change rate and the preset virtual inertia coefficient, the inertia support part of the active power is calculated, and based on the dynamic frequency deviation and the preset droop adjustment coefficient, the damping adjustment part of the active power is calculated. The inertia support part and the damping adjustment part are superimposed to generate an active transient compensation power command.

4. The distribution network optimization system based on multi-energy synergy according to claim 3, characterized in that, The specific steps for suppressing voltage and frequency drops on the isolated microgrid bus include: The reactive transient compensation power command is calculated synchronously based on the voltage dynamic deviation and the preset voltage droop gain; the active transient compensation power command and the reactive transient compensation power command are converted into the converter's intrinsic voltage amplitude and phase angle modulation signal, and the electrochemical energy storage device is driven to dynamically inject the corresponding active and reactive power in the four quadrants by controlling the conduction and cutoff of the power switching tubes inside the converter, so as to suppress the voltage and frequency drop of the islanded microgrid bus.

5. The distribution network optimization system based on multi-energy synergy according to claim 1, characterized in that, The specific steps by which the load control module determines the load shedding call priority include: The system continuously monitors the total output of distributed power sources and the total power of regional base load within the isolated microgrid, and calculates the real-time active power deficit of the isolated microgrid by combining the transient compensation power output of the converter. The system also collects the state of charge of the power batteries of the vehicles currently mounted on each smart charging pile concurrently through the distribution area communication network, as well as the real-time charging power. Smart charging piles with a state of charge of power batteries higher than a preset adequacy threshold are classified into adjustable clusters. Within the controllable cluster, load shedding priorities are assigned in descending order according to the cross-weighted order of the power battery state of charge from high to low and the real-time charging power from large to small.

6. The distribution network optimization system based on multi-energy synergy according to claim 5, characterized in that, The specific process by which the load control module performs the stepped flexible power reduction control is as follows: A total load-cutting power target is generated based on the real-time active power deficit; dynamic power-limiting operation instructions are sequentially issued to the corresponding smart charging piles in the adjustable cluster according to the load-cutting call priority from high to low. The intelligent charging pile that receives the dynamic power limiting operation command adjusts the output current reference value of the internal AC-DC conversion link to perform continuous step-by-step active power reduction until the sum of the active power reduced by each intelligent charging pile matches the total load reduction target, thereby smoothing out the active power deficit.

7. The distribution network optimization system based on multi-energy synergy according to claim 1, characterized in that, The specific execution process of the hydropower control module includes: The guide vane opening and actual active power at the turbine end of the small hydropower unit are collected in real time, and the real-time rate of change of the actual active power is calculated. When the guide vane opening is detected to increase, and after experiencing an initial reverse drop in power, the real-time rate of change of the actual active power changes from negative to positive and remains above the preset positive slope value, it is determined that the small hydropower unit has overcome the water hammer effect and entered the steady-state ramping stage. Subsequently, the real-time demand of the regional load within the isolated microgrid is obtained, and the current active power output of the distributed photovoltaic equipment is deducted to generate a steady-state power gap benchmark. With the steady-state power gap benchmark as the target, the transient compensation power of the converter is synchronously reduced at a decay rate equal to the real-time change rate of the actual active power until the actual active power of the small hydropower unit completely covers the steady-state power gap benchmark, and the transient compensation power smoothly falls back to zero.

8. The distribution network optimization system based on multi-energy synergy according to claim 1, characterized in that, When the state of charge of the electrochemical energy storage device is lower than the warning threshold, the compensation power is reduced according to the power contraction rate, and the reduction is written into the additional deficit.

9. The distribution network optimization system based on multi-energy synergy according to claim 8, characterized in that, When the state of charge is below the emergency threshold or the available capacity of the charging pile is insufficient, the secondary interruptible load is scheduled to take over according to the available capacity.

10. The distribution network optimization system based on multi-energy synergy according to claim 9, characterized in that, After the power handover is completed, the secondary interruptible load is restored in reverse order.

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