A method and system for energy storage control for dru-hvdc

Abstract

The application discloses an energy storage control method and system for DRU-HVDC, and relates to the technical field of electrical engineering. The method comprises the following steps: obtaining an angular frequency instruction value by integrating and adjusting the deviation between the active power instruction value and the actual value of each energy storage unit, and forming an active-frequency control loop; selecting a leading energy storage from the energy storage units that meet preset conditions, constructing a virtual voltage prediction model, and obtaining a virtual voltage prediction value at the grid connection point of the diode rectifier unit; constructing a power imbalance trend quantity according to the local voltage value of the leading energy storage and the virtual voltage prediction value, and using the power imbalance trend quantity to determine whether to trigger additional voltage control; and when the triggering condition is met, generating a voltage instruction value compensation quantity by a proportional controller and superimposing the voltage instruction value compensation quantity on the voltage control loop. The application realizes local discrimination and adjustment of the power distribution state between the energy storage and the diode rectifier unit without real-time communication.

Description

Technical Field

[0001] This invention relates to the field of electrical engineering technology, and in particular to an energy storage control method and system for DRU-HVDC. Background Technology

[0002] With the large-scale integration of renewable energy into the power system, high-voltage direct current (HVDC) systems employing diode rectifier units (DRUs) are being used in renewable energy islanding and long-distance power transmission scenarios due to their simple structure, high reliability, and cost advantages. However, diode rectifier units are uncontrolled rectifier devices, and their active power transmission capacity is mainly affected by the AC side voltage amplitude and system operating status, lacking active power regulation capabilities. Under conditions of renewable energy output fluctuations or load changes, the system's power balance typically relies on controllable power sources or energy storage units on the AC side for regulation.

[0003] In DRU-HVDC systems comprising multiple energy storage units, existing technologies typically achieve power distribution among these units through active-frequency droop control or power closed-loop control. While these control strategies can coordinate the output of each energy storage unit to some extent, their primary focus is on the power distribution relationship between the units themselves; they cannot actively participate in regulating the power distribution relationship between energy storage and uncontrolled rectifier units. When the output of new energy sources fluctuates, system power may concentrate or shift towards the uncontrolled rectifier unit, and existing droop control struggles to identify and correct this trend in a timely manner. On the other hand, to achieve more precise power distribution, some technical solutions introduce communication mechanisms, enabling centralized or distributed power coordination through information exchange between energy storage units or with the upper-level control system. However, in scenarios with isolated operation or limited communication, control methods relying on real-time communication may face issues such as decreased reliability and increased system complexity. Furthermore, existing control strategies often construct closed-loop control targets based on steady-state power errors, continuously adjusting to bring the power closer to a preset reference value. These control methods typically require explicitly constructing a power reference or power error signal and continuously participating in voltage or frequency regulation. In systems containing uncontrolled rectifier units, if the control strategy intervenes in voltage regulation for a long period of time, it may affect the original steady-state power distribution characteristics of the system and reduce the system's adaptive capability.

[0004] Therefore, how to autonomously sense the changing trend of power distribution between energy storage and uncontrolled rectifier units based solely on local measurement information of the energy storage unit without real-time communication, and conditionally intervene in voltage regulation only when a significant imbalance trend is identified, in order to achieve adaptive coordination of the power distribution relationship between energy storage and uncontrolled rectifier units, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the challenge of achieving autonomous and coordinated power distribution between energy storage units and uncontrolled rectifier units in existing renewable energy islanded DC transmission systems with diode rectifier units without real-time communication, this invention proposes an energy storage control method and system for DRU-HVDC. While retaining the basic power distribution mechanism among multiple energy storage units, it introduces a local virtual observation and event triggering mechanism. By constructing a power imbalance index that reflects the power imbalance trend of the system, it achieves on-demand, directional, and adaptive adjustment of the power distribution relationship between energy storage and diode rectifier units.

[0006] This application discloses an energy storage control method for DRU-HVDC, characterized by comprising the following steps: S1. The deviation between the active power command value and the actual output active power of each energy storage unit is processed by the integral regulator and added to the angular frequency reference value to generate the angular frequency command value, which serves as the active-frequency control loop. S2. Based on the active-frequency control loop, select the dominant energy storage unit among the energy storage units that meet the preset conditions, and generate the virtual voltage prediction value at the grid connection point of the diode rectifier unit through the virtual voltage predictor based on the electrical quantity measured locally by the dominant energy storage unit. S3. Input the virtual voltage prediction value and the dominant energy storage local voltage value into the power imbalance observer to calculate the power imbalance trend quantity that reflects the power distribution imbalance trend of the system. S4. Subtract the power offset trend from the rated value to obtain the difference. When the absolute value of the difference exceeds the preset margin, trigger the additional voltage control loop in the main energy storage. S5. The additional voltage control loop generates a voltage command value compensation amount based on the power offset trend amount, and superimposes the voltage command value compensation amount onto the voltage control loop that dominates energy storage, so as to adjust the power transmission capability of the diode rectifier unit.

[0007] Preferably, the formula for calculating the angular frequency command value is as follows:

[0008] in, For the first The angular frequency command value of each energy storage unit For the first Reference value of angular frequency for each energy storage unit No. Integral controller parameters for each energy storage unit For the Laplace operator, For the first Reference value of active power for each energy storage unit. For the first The actual active power of each energy storage unit.

[0009] Preferably, the preset conditions include at least one of the following: the equivalent electrical distance between the energy storage unit and the diode rectifier unit, the active power sensitivity of the energy storage unit to changes in bus voltage, or the active power adjustment margin of the energy storage unit.

[0010] Preferably, the formula for calculating the virtual voltage prediction value is as follows:

[0011] in, This is the virtual voltage prediction value. For the primary energy storage unit, local voltage measurement. For the primary energy storage unit, local current measurement is performed. This is the equivalent impedance between the output of the dominant energy storage unit and the grid connection point of the diode rectifier unit.

[0012] Preferably, the formula for calculating the power offset trend is as follows:

[0013] in, The voltage amplitude measured locally by the primary energy storage unit. The magnitude of the virtual voltage prediction; In the formula:

[0014] in, The active power transmitted through the line. The reactive power transmitted by the line. The resistance of the circuit. This refers to the reactance of the line.

[0015] Preferably, the additional voltage control loop is a proportional controller, and voltage regulation is only intervened when the power imbalance trend meets the triggering condition, thereby changing the active power distribution tendency between the energy storage cluster and the diode rectifier unit by adjusting the proportional coefficient.

[0016] Preferably, the formula for calculating the voltage command value compensation is as follows:

[0017] in, This is the compensation amount for the voltage command value. This refers to the proportional coefficient of the proportional controller in the additional voltage control.

[0018] This application also discloses an energy storage control system for DRU-HVDC, characterized in that, for implementing the above-mentioned energy storage control method for DRU-HVDC, it includes: An active power-frequency control unit is installed in each energy storage unit. It is used to process the deviation between the active power command value and the actual output active power of the energy storage unit through an integral regulator, and then add it to the angular frequency reference value to generate the angular frequency command value. The virtual voltage prediction unit, located in the main energy storage, is used to generate a virtual voltage prediction value at the grid connection point of the diode rectifier unit based on locally measured voltage, current and preset electrical quantities. A power offset observation unit, located in the main energy storage, is used to calculate the system power offset trend based on the amplitude of locally measured voltage and the amplitude of virtual voltage prediction. An event triggering unit, located in the primary energy storage, is used to compare the absolute value of the difference between the power offset trend and the rated value with a preset margin, and generate an additional voltage control trigger signal. An additional voltage control unit, located in the main energy storage, is used to generate a voltage command value compensation amount based on the power imbalance trend amount when the trigger signal is received, and to superimpose the compensation amount onto the voltage control loop.

[0019] The beneficial effects of this invention are: (1) Based solely on the local measurement information of each energy storage unit, this invention achieves autonomous coordination of power distribution between the energy storage unit and the diode rectifier unit through virtual voltage prediction and power offset trend discrimination mechanism. It does not require real-time communication between energy storage units or with the upper-level system, which significantly improves the applicability and reliability of the system in isolated operation or communication-restricted scenarios.

[0020] (2) By constructing a power imbalance trend quantity and introducing an event triggering mechanism, this invention can identify the evolution direction of the system power distribution state and intervene in additional voltage control only when an imbalance trend occurs, thereby avoiding continuous intervention in the steady-state operation of the system, maintaining the stability of the bus voltage, and improving the system's operational stability and control economy.

[0021] (3) Based on the active power-frequency control, the present invention superimposes a dominant energy storage additional voltage control structure, which enables the system to adjust the power relationship between the energy storage and diode rectifier units under the condition of new energy output fluctuation, actively guides the transmission tendency of the active power of new energy fluctuation between the energy storage and diode rectifier units, and facilitates the coordinated exchange of active power within the system and between the system and other isolated systems. Attached Figure Description

[0022] Figure 1 This is a flowchart of an energy storage control method for DRU-HVDC according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the DRU-HVDC system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of an energy storage control system for DRU-HVDC according to an embodiment of the present invention; Figure 4 The waveform diagram shows the comparison between the predicted voltage value of the diode rectifier unit grid connection point calculated by the virtual voltage predictor in this embodiment of the invention and the actual voltage value. Figure 5 The diagram shows the power offset trend, threshold, and additional voltage control trigger signal waveforms under different disturbances in this embodiment of the invention. Figure 6 The active power waveform of the dominant energy storage and diode rectifier units is shown in the embodiment of the present invention when the parameters of the additional voltage controller are changed. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments.

[0024] One embodiment of this application discloses an energy storage control method for DRU-HVDC, the process of which is as follows: Figure 1 As shown, it includes the following S1-S5. The DRU-HVDC system mentioned in this embodiment is as follows: Figure 2 As shown, the system includes a new energy power generation station, an energy storage station, AC transmission lines, transformers, diode rectifier units, and DC transmission lines. Specifically, two new energy generation units, each with a rated capacity of 100 MW, and one energy storage unit ESS1 with a rated capacity of 100 MW are connected to a 35 kV AC bus; another energy storage unit ESS2 with a rated capacity of 100 MW is connected to a 110 kV AC bus. A DRU is connected to the 110 kV bus to rectify the AC power into DC power before sending it to the ±200 kV DC grid.

[0025] S1. For each energy storage unit, the difference between the active power command value and the sampled actual value is calculated, and the difference is passed through an integral regulator to obtain the angular frequency increment. This increment is then added to the angular frequency reference value to obtain the angular frequency command value for each energy storage unit, which serves as the active power-frequency control loop. The active power command value in the active power-frequency control loop is a fixed value preset locally in each energy storage unit, or it is generated autonomously by the local controller based on the unit's operating status.

[0026] The calculation formula is as follows:

[0027] in, For the first The angular frequency command value of each energy storage unit For the first Reference value of angular frequency for each energy storage unit No. Integral controller parameters for each energy storage unit For the Laplace operator, For the first Reference value of active power for each energy storage unit. For the first The actual active power value of each energy storage unit. The obtained angular frequency command value is used in processes such as coordinate transformation.

[0028] S2. Based on the active-frequency control loop, select the dominant energy storage unit from the energy storage units that meet the preset conditions. The preset conditions for the dominant energy storage unit include at least one of the following: the equivalent electrical distance between the energy storage unit and the diode rectifier unit, the active power sensitivity of the energy storage unit to changes in bus voltage, or the active power regulation margin of the energy storage unit.

[0029] Based on the voltage measured locally by the dominant energy storage system Current and the equivalent impedance between the output of the dominant energy storage unit and the grid connection point of the diode rectifier unit. The virtual voltage predictor is used to obtain the virtual voltage prediction at the grid connection point of the diode rectifier unit by adding the voltage at the local measurement point of the main energy storage unit to the line voltage drop. The virtual voltage predictor is a model built based on the equivalent impedance parameters between the output terminal of the main energy storage unit and the grid connection point of the diode rectifier unit. The virtual voltage prediction value is calculated from the locally measured electrical quantities using this model.

[0030] The formula for calculating the virtual voltage prediction value is as follows:

[0031] in, This is the virtual voltage prediction value. For the primary energy storage unit, local voltage measurement. For the primary energy storage unit, local current measurement is performed. This is the equivalent impedance between the output of the dominant energy storage unit and the grid connection point of the diode rectifier unit.

[0032] The virtual voltage prediction process is based on line electrical parameters and locally measured electrical quantities, and performs an equivalent estimation of the voltage state of remote nodes without relying on remote measurement information or real-time communication.

[0033] S3. Input the virtual voltage prediction value and the local voltage value of the dominant energy storage unit into the power offset observer to calculate the power offset trend quantity, which reflects the power distribution imbalance trend of the system. The power offset observer uses the locally measured voltage value of the dominant energy storage unit and the virtual voltage prediction value generated by the virtual voltage predictor as inputs. By analyzing the deviation relationship between the two, the power offset trend quantity is constructed. The power offset trend quantity is used as the criterion for local event triggering and the basis for voltage compensation direction.

[0034] In this embodiment, both the virtual voltage predictor and the power offset observer are constructed solely based on the voltage, current, and preset parameters measured locally by the dominant energy storage unit, without relying on real-time measurement information from other energy storage units or diode rectifier units.

[0035] Calculate the local measured voltage of the primary energy storage unit and virtual voltage prediction value Amplitude:

[0036]

[0037] in, The voltage amplitude measured locally by the primary energy storage unit. The magnitude of the virtual voltage prediction value. , The unit local measurement voltage is obtained from the Park transformation. of Axial components, , It is the virtual voltage prediction obtained from the Park transformation. of Axial components.

[0038] According to the power transfer theory of AC lines, the square difference of the voltage across the two ends of the line... With the active power transmitted through the line and reactive power Satisfying Relationship:

[0039] in, , These refer to the active power and reactive power transmitted through the line, respectively. These represent the resistance and reactance of the circuit, respectively. In this embodiment, the diode rectifier unit primarily consumes active power. Therefore, reactive power Negligible. Because the main energy storage unit is relatively short in distance from the diode rectifier unit, higher-order terms can be ignored. Therefore, the difference between the squares of the two voltages can approximate the active power transfer trend of the line.

[0040] Calculate the power offset trend The calculation formula is as follows:

[0041] in, This is a power imbalance trend measure used to achieve localized and autonomous sensing of the power distribution imbalance trend between the energy storage and diode rectifier units without directly measuring the remote active power. Its main function is to trigger subsequent local events and determine the direction of voltage compensation. The absolute value of the difference between the power imbalance trend measure and its rated value is compared with a margin value to determine whether to trigger an additional voltage control loop. Its sign determines the direction of the voltage command compensation amount. When the power imbalance trend measure does not meet the triggering conditions, the dominant energy storage unit does not participate in voltage regulation, which not only maintains the stability of the bus voltage but also avoids frequent energy storage operations caused by small voltage fluctuations, improving system operational stability and control economy.

[0042] S4. The absolute value of the power imbalance trend. With the rated value When comparing, When, the additional voltage control loop in the main energy storage is triggered; when At this time, the additional voltage control loop is not triggered. This can be achieved by setting a preset margin. It filters out minor voltage fluctuations and measurement noise, and only initiates regulation when there is a significant shift in the power transmission trend.

[0043] S5. After triggering the additional voltage control loop in the dominant energy storage, the additional voltage control loop generates a voltage command compensation value based on the power offset trend, and superimposes the voltage command compensation value onto the voltage control loop of the dominant energy storage to adjust the power transmission capability of the diode rectifier unit. In this embodiment, the additional voltage control loop is a proportional controller, and it only intervenes in voltage regulation when the power offset trend meets the triggering condition. By adjusting the proportional coefficient, it changes the active power distribution tendency between the energy storage cluster and the diode rectifier unit.

[0044] The formula for calculating the voltage command value compensation is as follows:

[0045] in, This is the compensation amount for the voltage command value. This refers to the proportional coefficient of the proportional controller in the additional voltage control. The voltage command compensation value acts on the dominant energy storage voltage control loop, affecting the power transfer capability of the diode rectifier unit by changing the magnitude of the energy storage output voltage, thereby adjusting the power distribution relationship between the energy storage and the diode rectifier unit. This is achieved by adjusting the proportional coefficient. It can change the power bearing tendency between energy storage and diode rectifier units, thereby guiding the flow of fluctuating power from new energy sources.

[0046] Another embodiment of this application discloses an energy storage control system for DRU-HVDC, used to implement the above-described energy storage control method for DRU-HVDC. Its structure is as follows: Figure 3 As shown, it includes: The active power-frequency control unit, located in each energy storage unit, is used to process the deviation between the active power command value and the actual output active power of the energy storage unit via an integral regulator, and then add it to the angular frequency reference value to generate the angular frequency command value. .

[0047] The virtual voltage prediction unit, located within the primary energy storage system, generates a virtual voltage prediction value at the grid connection point of the diode rectifier unit based on locally measured voltage, current, and preset electrical quantities. .

[0048] A power offset observation unit, located within the primary energy storage, is used to measure voltage amplitude locally. and the amplitude of the virtual voltage prediction Calculate the power offset trend of the system .

[0049] The event triggering unit, located in the primary energy storage, is used to detect power imbalance trends. With the rated value Subtract to get the difference , and the preset margin The comparison is performed to generate an additional voltage control trigger signal.

[0050] An additional voltage control unit, located in the primary energy storage, is used to generate a voltage command value compensation amount via a proportional controller based on the power imbalance trend when the trigger signal is received. This compensation is then added to the original voltage control loop, ultimately affecting the transmission power of the uncontrolled rectifier unit.

[0051] In one specific embodiment, the energy storage control method for DRU-HVDC proposed in this application is verified in MATLAB / Simulink software. Based on the electrical distance between each energy storage station and the DRU, energy storage station ESS2 is selected as the dominant energy storage, while energy storage station ESS1 is the general energy storage. ESS1 and ESS2 stations are each composed of two identical energy storage units connected in parallel.

[0052] The active power output of the two renewable energy power plants was set to increase by 0.2 pu at t=3s. Figure 4 The predicted voltage at the grid connection point of the diode rectifier unit, calculated by the virtual voltage predictor, is given. Compared with actual voltage value The comparison results show that during the disturbance process, It can reflect well The trend of change shows that the deviation between the two remains within an acceptable range. This result indicates that, without the need for real-time communication, an effective equivalent estimation of the DRU grid connection point voltage can be made solely based on the locally measured voltage, current, and equivalent impedance parameters of the dominant energy storage unit.

[0053] To verify the effectiveness of the power offset trend and event triggering mechanism, simulations were conducted under the same system parameters with two disturbance conditions. First, at t=2s, a small step change in the output active power of the renewable energy power plant was introduced, with an amplitude of 0.002 pu. The simulation waveform is shown below. Figure 5 As shown, the results indicate that the power imbalance trend... Although fluctuations occurred, Always less than the preset margin The additional voltage control was not triggered, and the system continued to operate under the active power-frequency base distribution mechanism. Subsequently, a large step disturbance of 0.2 pu was applied at t=3s. At this point, the absolute value of the power offset trend rapidly exceeded the threshold, triggering the intervention of the additional voltage control loop. The dominant energy storage affected the grid connection voltage level of the diode rectifier unit by adjusting the voltage reference value, thereby changing the power distribution relationship between the energy storage and the DRU. This result shows that the proposed power offset trend discrimination and event triggering mechanism can distinguish between small disturbances and significant power offsets, intervening only when necessary to achieve conditional control of the power distribution state.

[0054] To verify the effectiveness of the additional voltage control, the active power generated by the two renewable energy power stations was set to increase by 0.2 pu at t=3s. Figure 6 The waveforms showing the changes in active power of the primary energy storage and the DRU when the proportional regulator parameters of the additional voltage controller in the primary energy storage are changed. Figure 6 As can be seen from (a), when At this point, it's equivalent to not having an additional voltage control loop; the system will automatically complete the active power distribution. The change in active power of the stored energy at this time... The change in transmission power of the DRU This indicates that when only active power-frequency control exists, the system inherently possesses a power distribution pattern determined by its topology and parameters, making it impossible to control the power transmitted by the diode rectifier unit. However, by adding additional voltage control, changing the control parameters of the additional voltage loop allows for the redistribution of the varying portion of the energy storage active power. Figure 6 (a) and Figure 6 (b) and Figure 6 By comparing (c), we can see that increasing... This will increase the transmission power of the DRU and reduce the active power undertaken by the energy storage. This demonstrates that the energy storage control method for DRU-HVDC proposed in the embodiments of this application can guide the active power to be preferentially undertaken by the energy storage or the DRU.

[0055] This application, based on the multi-energy storage active-frequency power allocation mechanism, introduces a virtual voltage prediction and power offset trend discrimination mechanism based on the dominant energy storage, and conditionally superimposes an additional voltage control path through event triggering. This method relies solely on locally measured voltage, current, and equivalent impedance parameters of the dominant energy storage to perform an equivalent estimation of the voltage state at the grid connection point of the diode rectifier unit. It then constructs a power transmission trend using the squared difference of voltage amplitudes. When a power allocation offset is detected, it affects the active power transmission capability of the diode rectifier unit by adjusting the reference value of the dominant energy storage voltage, thereby changing the power sharing relationship between the energy storage and the uncontrolled rectifier unit. This control structure achieves local sensing and conditional adjustment of the power allocation state of the diode rectifier unit without introducing real-time communication.

[0056] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for energy storage control in DRU-HVDC, characterized in that, Includes the following steps: S1. The deviation between the active power command value and the actual output active power of each energy storage unit is processed by the integral regulator and added to the angular frequency reference value to generate the angular frequency command value, which serves as the active-frequency control loop. S2. Based on the active-frequency control loop, select the dominant energy storage unit among the energy storage units that meet the preset conditions, and generate the virtual voltage prediction value at the grid connection point of the diode rectifier unit through the virtual voltage predictor based on the electrical quantity measured locally by the dominant energy storage unit. S3. Input the virtual voltage prediction value and the dominant energy storage local voltage value into the power imbalance observer to calculate the power imbalance trend quantity that reflects the power distribution imbalance trend of the system. S4. Subtract the power offset trend from the rated value to obtain the difference. When the absolute value of the difference exceeds the preset margin, trigger the additional voltage control loop in the main energy storage. S5. The additional voltage control loop generates a voltage command value compensation amount based on the power offset trend amount, and superimposes the voltage command value compensation amount onto the voltage control loop that dominates energy storage, so as to adjust the power transmission capability of the diode rectifier unit.

2. The energy storage control method for DRU-HVDC according to claim 1, characterized in that, The formula for calculating the angular frequency command value is as follows: in, For the first The angular frequency command value of each energy storage unit For the first Reference value of angular frequency for each energy storage unit No. Integral controller parameters for each energy storage unit For the Laplace operator, For the first Reference value of active power for each energy storage unit. For the first The actual active power of each energy storage unit.

3. The energy storage control method for DRU-HVDC according to claim 2, characterized in that, The preset conditions include at least one of the following: the equivalent electrical distance between the energy storage unit and the diode rectifier unit, the active power sensitivity of the energy storage unit to changes in bus voltage, or the active power adjustment margin of the energy storage unit.

4. The energy storage control method for DRU-HVDC according to claim 3, characterized in that, The formula for calculating the virtual voltage prediction value is as follows: in, This is the virtual voltage prediction value. For the primary energy storage unit, local voltage measurement. For the primary energy storage unit, local current measurement is performed. This is the equivalent impedance between the output of the dominant energy storage unit and the grid connection point of the diode rectifier unit.

5. The energy storage control method for DRU-HVDC according to claim 4, characterized in that, The formula for calculating the power offset trend is as follows: in, The voltage amplitude measured locally by the primary energy storage unit. The magnitude of the virtual voltage prediction; In the formula: in, This refers to the active power transmitted through the line. The reactive power transmitted by the line. The resistance of the circuit. This refers to the reactance of the line.

6. The energy storage control method for DRU-HVDC according to claim 5, characterized in that, The additional voltage control loop is a proportional controller, and it only intervenes in voltage regulation when the power imbalance trend meets the triggering condition. By adjusting the proportional coefficient, it changes the active power distribution tendency between the energy storage cluster and the diode rectifier unit.

7. The energy storage control method for DRU-HVDC according to claim 6, characterized in that, The formula for calculating the voltage command value compensation is as follows: in, This is the compensation amount for the voltage command value. This refers to the proportional coefficient of the proportional controller in the additional voltage control.

8. An energy storage control system for DRU-HVDC, characterized in that, The energy storage control method for DRU-HVDC according to any one of claims 1-7 is characterized in that it comprises: An active power-frequency control unit is installed in each energy storage unit. It is used to process the deviation between the active power command value and the actual output active power of the energy storage unit through an integral regulator, and then add it to the angular frequency reference value to generate the angular frequency command value. The virtual voltage prediction unit, located in the main energy storage, is used to generate a virtual voltage prediction value at the grid connection point of the diode rectifier unit based on locally measured voltage, current and preset electrical quantities. A power offset observation unit, located in the main energy storage, is used to calculate the system power offset trend based on the amplitude of locally measured voltage and the amplitude of virtual voltage prediction. An event triggering unit, located in the primary energy storage, is used to compare the absolute value of the difference between the power offset trend and the rated value with a preset margin, and generate an additional voltage control trigger signal. An additional voltage control unit, located in the main energy storage, is used to generate a voltage command value compensation amount based on the power imbalance trend amount when the trigger signal is received, and to superimpose the compensation amount onto the voltage control loop.

Images