Cooperative control and comprehensive regulation method and system for on-load tap changing transformer and energy storage system

Abstract

The invention discloses a cooperative control and comprehensive regulation method and system for an on-load tap changing transformer and an energy storage system. The method comprises the following steps: constructing a Zbus linearization power flow model based on single fixed point iteration; determining the node voltage sensitivity in the power grid based on a Zbus linearization power flow model; determining the voltage regulation quantity of the on-load voltage regulation transformer and the maximum and minimum charging and discharging power of the energy storage system; determining the real-time charging and discharging power of the energy storage system based on the node voltage sensitivity and the maximum and minimum charging and discharging power of the energy storage system; and determining the voltage regulation range of the transformer substation based on the node voltage sensitivity, the voltage regulation quantity of the on-load voltage regulation transformer and the real-time charging and discharging power of the energy storage system so as to realize the voltage regulation capability regulation of the transformer substation under the cooperative control of the on-load voltage regulation transformer and the energy storage system. According to the invention, the system voltage can be maintained in a reasonable range, so that the reliability and continuity of power supply can be guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of power system operation and control, and in particular to a method and system for coordinated control and comprehensive regulation of an on-load voltage-regulating transformer and an energy storage system. Background Art

[0002] With the rapid development of renewable energy and the growing demand for electricity, the power system is facing increasingly complex challenges. These challenges mainly include voltage stability, load fluctuations, and power supply quality. In traditional power systems, voltage stability usually relies on static power generation and supply methods. However, with the widespread access to renewable energy such as wind and solar energy, this static mode has been severely impacted. Due to the volatility and randomness of new energy, the active power balance of the system is often affected, and the widespread distribution of distributed new energy often leads to over-limit voltage at the end of the feeder. In order to meet these challenges, existing studies have suggested that by tapping the regulation potential of load-side resources, broadening the means of grid regulation, and improving the source-load interaction capability, the research focus is on how to aggregate and manage a large number of distributed resources.

[0003] In this context, energy storage technology and on-load tap changer (OLTC) as key technologies to improve the flexibility and stability of power systems have gradually become the focus of research and application. Energy storage systems can quickly release energy during peak periods of power demand, thereby balancing power supply and demand; when power supply is sufficient, these systems can absorb excess power and provide necessary support for the power grid. This rapid response capability enables energy storage systems to play an important role in dynamic power regulation. At the same time, OLTC can accurately control the output voltage of the power grid and ensure the quality of power supply by adjusting the tap position of the transformer. The combination of these two technologies, which uses energy storage systems to quickly respond to short-term fluctuations and uses on-load tap changers to complete long-term steady-state regulation, can not only improve the regulation accuracy and response speed of the power system, but also improve the economy and reliability of the entire power system. Therefore, it is necessary to provide a comprehensive regulation and control method for substation voltage and capacity under the coordinated control of on-load tap changers and energy storage systems. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the first object of the present invention is to provide a method for coordinated control and comprehensive regulation of an on-load tap-changing transformer and an energy storage system, which can ensure that the system voltage is maintained within a reasonable range, thereby facilitating the guarantee of reliability and continuity of power supply.

[0005] The second object of the present invention is to provide a comprehensive regulation system for coordinated control of an on-load tap-changing transformer and an energy storage system.

[0006] A third object of the present invention is to provide a computer-readable storage medium.

[0007] A fourth object of the present invention is to provide an electronic device.

[0008] To achieve the above object, the present invention is implemented through the following technical solutions:

[0009] A method for coordinated control and comprehensive regulation of an on-load voltage-regulating transformer and an energy storage system, comprising:

[0010] Construct a Zbus linearized power flow model based on single fixed point iteration;

[0011] Determine the node voltage sensitivity in the power grid based on the Zbus linearized power flow model;

[0012] Determine the voltage regulation of the on-load tap-changing transformer and the maximum and minimum charging and discharging power of the energy storage system;

[0013] Determine the real-time charging and discharging power of the energy storage system based on the node voltage sensitivity and the maximum and minimum charging and discharging power of the energy storage system;

[0014] The voltage regulation range of the substation is determined based on the node voltage sensitivity, the voltage regulation amount of the on-load tap-changing transformer and the real-time charging and discharging power of the energy storage system, so as to achieve the substation voltage regulation capacity adjustment under the coordinated control of the on-load tap-changing transformer and the energy storage system.

[0015] Preferably, the method further comprises formulating an on-load tap-changing transformer and an energy storage system coordinated control optimization strategy, wherein the on-load tap-changing transformer and an energy storage system coordinated control optimization strategy comprises:

[0016] determining node voltage deviations;

[0017] When the node voltage deviation is less than the first voltage deviation threshold value, controlling the energy storage system to perform response adjustment;

[0018] When the node voltage deviation is greater than a second voltage deviation threshold value and the voltage deviation duration exceeds the trigger time of the on-load tap-changing transformer, the on-load tap-changing transformer is controlled to intervene in regulation, and the second voltage deviation threshold value is greater than the first voltage deviation threshold value.

[0019] Preferably, the method further includes determining the capacity adjustable range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system, so as to implement the capacity adjustable capability evaluation of the substation under the coordinated control of the system.

[0020] Preferably, determining the adjustable capacity range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system includes:

[0021] Determine the CVR coefficient and the power regulation of the on-load tap-changing transformer;

[0022] The capacity adjustment range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system is determined based on the real-time charging and discharging power of the energy storage system, the power adjustment amount of the on-load tap-changing transformer, and the CVR coefficient.

[0023] To achieve the above object, the second aspect of the present invention provides a coordinated control integrated regulation system for an on-load voltage-changing transformer and an energy storage system, comprising:

[0024] Construction module for constructing Zbus linearized power flow model based on single fixed point iteration;

[0025] A solution module is used to determine the node voltage sensitivity in the power grid based on the Zbus linearized power flow model; and determine the voltage regulation amount of the on-load tap-changing transformer and the maximum and minimum charging and discharging power of the energy storage system, and determine the real-time charging and discharging power of the energy storage system based on the node voltage sensitivity and the maximum and minimum charging and discharging power of the energy storage system; and determine the voltage regulation range of the substation based on the node voltage sensitivity, the voltage regulation amount of the on-load tap-changing transformer and the real-time charging and discharging power of the energy storage system, so as to realize the voltage regulation capacity adjustment of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system.

[0026] Preferably, the on-load voltage-changing transformer and energy storage system coordinated control integrated regulation system further includes a strategy formulation module for formulating an optimization strategy for coordinated control of the on-load voltage-changing transformer and the energy storage system. The optimization strategy for coordinated control of the on-load voltage-changing transformer and the energy storage system includes:

[0027] determining node voltage deviations;

[0028] When the node voltage deviation is less than the first voltage deviation threshold value, controlling the energy storage system to perform response adjustment;

[0029] When the node voltage deviation is greater than a second voltage deviation threshold value and the voltage deviation duration exceeds the trigger time of the on-load tap-changing transformer, the on-load tap-changing transformer is controlled to intervene in regulation, and the second voltage deviation threshold value is greater than the first voltage deviation threshold value.

[0030] Preferably, the solution module is also used to determine the capacity adjustable range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system, so as to realize the capacity adjustable capability evaluation of the substation under the coordinated control of the system.

[0031] Preferably, when determining the adjustable capacity range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system, the solution module is specifically used to:

[0032] Determine the CVR coefficient and the power regulation of the on-load tap-changing transformer;

[0033] The capacity adjustment range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system is determined based on the real-time charging and discharging power of the energy storage system, the power adjustment amount of the on-load tap-changing transformer, and the CVR coefficient.

[0034] To achieve the above-mentioned purpose, the third aspect of the present invention provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned on-load tap-changing transformer and energy storage system coordinated control comprehensive regulation method is implemented.

[0035] To achieve the above-mentioned purpose, the fourth aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the above-mentioned on-load tap-changing transformer and energy storage system coordinated control comprehensive regulation method is implemented.

[0036] The present invention has at least the following technical effects:

[0037] The present invention constructs a Zbus linearized power flow model of a single fixed point iteration, and the model can be used to calculate the partial derivative of each node voltage relative to the injected power, thereby obtaining an expression of the node voltage sensitivity. In this way, the analytical relationship between the node voltage and the injected power can be quantified, greatly reducing the computational complexity. Subsequently, the energy storage system charging and discharging power calculation formula can be comprehensively obtained according to the node voltage sensitivity and the power-limited condition of the energy storage system, and then the voltage regulation capability of the substation can be determined. Finally, the power adjustment range of the substation, that is, the capacity adjustable range, can be evaluated by combining the CVR coefficient and the system control optimization strategy, thereby realizing the comprehensive regulation and control of the substation voltage and capacity under the coordinated control of the on-load tap-changing transformer and the energy storage system. In addition, the energy storage system of the present invention cooperates with OLTC to adjust the capacity of the substation, uses the energy storage system to quickly respond to short-term fluctuations, and completes long-term steady-state regulation with the help of the on-load tap-changing transformer, thereby improving the flexibility and stability of the power system to cope with increasingly complex power supply and demand issues. The present invention enables the power system to respond quickly to the ever-changing load and renewable energy output changes, ensuring that the voltage is maintained within a reasonable range, thereby ensuring the reliability and continuity of power supply.

[0038] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a flowchart of a method for coordinated control and comprehensive regulation of an on-load tap-changing transformer and an energy storage system according to an embodiment of the present invention.

[0040] Figure 2It is a structural block diagram of the on-load tap-changing transformer and energy storage system coordinated control integrated regulation system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The present embodiment is described in detail below, and examples of the embodiment are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0042] The following describes the on-load tap-changing transformer and energy storage system coordinated control integrated regulation method and system of this embodiment with reference to the accompanying drawings.

[0043] Figure 1 Flow chart of the on-load voltage-changing transformer and energy storage system coordinated control comprehensive regulation method according to an embodiment of the present invention. Figure 1 As shown, the method includes:

[0044] Step S101: constructing a Zbus linearized power flow model based on a single fixed point iteration.

[0045] Step S102: Determine node voltage sensitivity in the power grid based on the Zbus linearized power flow model.

[0046] Step S103: Determine the voltage regulation amount of the on-load tap-changing transformer and the maximum and minimum charging and discharging powers of the energy storage system.

[0047] Step S104: determining the real-time charge and discharge power of the energy storage system based on the node voltage sensitivity and the maximum and minimum charge and discharge powers of the energy storage system.

[0048] Step S105: Determine the voltage regulation range of the substation based on the node voltage sensitivity, the voltage regulation amount of the on-load tap-changing transformer and the real-time charging and discharging power of the energy storage system, so as to achieve the substation voltage regulation capacity adjustment under the coordinated control of the on-load tap-changing transformer and the energy storage system.

[0049] In this embodiment, a Zbus (power flow calculation method based on node impedance matrix) linearized power flow model with a single fixed point iteration is constructed, and the partial derivative of each node voltage relative to the injected power can be calculated using this model to determine the node voltage sensitivity. Subsequently, the charging and discharging power of the energy storage system can be comprehensively obtained based on the node voltage sensitivity and the power limitation condition of the energy storage system, and then the voltage regulation capacity of the substation can be determined based on the node voltage sensitivity, the charging and discharging power of the energy storage system, and the voltage regulation amount of the on-load tap-changing transformer.

[0050] In one embodiment of the present invention, the method also includes formulating an optimization strategy for coordinated control of an on-load tap-changing transformer and an energy storage system, and the optimization strategy for coordinated control of an on-load tap-changing transformer and an energy storage system includes: determining a node voltage deviation; when the node voltage deviation is less than a first voltage deviation threshold value, controlling the energy storage system to respond and adjust; when the node voltage deviation is greater than a second voltage deviation threshold value, and the voltage deviation duration exceeds the trigger time of the on-load tap-changing transformer, controlling the on-load tap-changing transformer to intervene in the adjustment, and the second voltage deviation threshold value is greater than the first voltage deviation threshold value.

[0051] Furthermore, the method also includes determining the adjustable capacity range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system, so as to realize the capacity adjustment capability evaluation of the substation under the coordinated control of the system. Determining the adjustable capacity range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system includes: determining the CVR (a parameter used to quantify the impact of voltage reduction on power consumption) coefficient and the power adjustment amount of the on-load tap-changing transformer; determining the adjustable capacity range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system based on the real-time charging and discharging power of the energy storage system, the power adjustment amount of the on-load tap-changing transformer, and the CVR coefficient.

[0052] In order to enable those skilled in the art to clearly understand the on-load voltage-regulating transformer and energy storage system coordinated control comprehensive regulation method of this embodiment, the on-load voltage-regulating transformer and energy storage system coordinated control comprehensive regulation method is described in detail below. The on-load voltage-regulating transformer and energy storage system coordinated control comprehensive regulation method specifically includes the following steps:

[0053] Step 1: Construct a Zbus linearized power flow model based on a single fixed point iteration.

[0054] Step 2: Based on the Zbus linearized power flow model in step 1, the partial derivative of each node voltage with respect to the injected power can be calculated to obtain the node voltage sensitivity under different regulation modes, and the voltage regulation amount of the on-load tap-changing transformer can be calculated.

[0055] Step 3: According to the node voltage sensitivity and the power limitation of the energy storage system, the real-time charging and discharging power of the energy storage system is comprehensively obtained.

[0056] Step 4: Determine the voltage regulation capacity of the substation based on the results obtained in steps 2 and 3, and formulate a system collaborative control optimization strategy;

[0057] Step 5: Combine the CVR coefficient to evaluate the capacity adjustment range of the substation under the coordinated control of the energy storage system and OLTC.

[0058] Step 1.1: Zbus linearized power flow model

[0059] Power flow calculation is a method used in power systems to analyze the distribution of parameters such as voltage, phase angle and power at each node in the power system to determine the steady-state working state of the power system, where nodes represent the connection points between components in the power system such as generators, transformers, lines, loads, etc. Its goal is to solve the voltage and phase angle of each node in the power system so that each component in the power system (generator, transformer, line, load, etc.) satisfies constraints such as power balance and power flow balance. A Zbus power flow model based on single fixed point iteration is proposed here to improve the solution efficiency.

[0060] In a typical distribution network system, it is usually assumed that the voltage of the balancing node remains unchanged, and other nodes can be regarded as PQ nodes (load nodes in the power grid). According to the superposition principle, the voltage U of node i is i It is composed of two parts: the voltage U generated by the root node at node i i1 The voltage U generated by the other PQ nodes at node i i2 For a system with 1 equilibrium node and N PQ nodes, the power flow equation is as follows:

[0061]

[0062] Among them, S1 is the node injection power vector, U is the node voltage vector, I1 is the node injection current vector, The conjugate matrix of the node injection power vector, The conjugate matrix of the node voltage vector, Y is the system node admittance matrix.

[0063] By dividing each matrix according to the balance node and PQ node, the following form can be obtained:

[0064]

[0065] Among them, the matrix is ​​divided into blocks based on whether it is a balanced node. I0, S0 and V0 are the balanced node injection current vector, balanced node injection power vector and balanced node voltage vector respectively; I, S and V are the PQ node injection current vector, PQ node injection power vector and PQ node voltage vector respectively. The conjugate matrix of the power vector injected into the equilibrium node, is the conjugate matrix of the equilibrium node voltage vector, The conjugate matrix of the power vector injected into the PQ node, is the conjugate matrix of the voltage vector of the PQ node, diag represents the construction of a diagonal matrix, Y 00 is the self-admittance of the balanced node, Y 0L , Y L0 are the two mutual admittance matrices of the balancing node and the PQ node, Y LLis the admittance matrix of all PQ nodes. 00 is a 1*1 matrix, Y 0L is a 1*n matrix, Y L0 is an n*1 matrix, Y LL It is an n*n matrix, where n is the matrix order.

[0066] According to the above power flow equation, the PQ node injection power equation and the injection current equation are combined to eliminate the injection current vector I of the PQ node, thereby obtaining an implicit expression of the PQ node voltage, including the current source part affected by the PQ node injection power and the voltage source part affected by the equilibrium node voltage.

[0067]

[0068] Wherein, the first term is the voltage generated by each PQ node (current source), and the second term is the voltage generated by the root node (voltage source), which is approximately a constant set to W.

[0069] Therefore, the Zbus power flow model is: The Zbus power flow model has clear physical concepts and uses the Y matrix with sparse characteristics, namely the system node admittance matrix and the equivalent current source injection form, which can reduce the calculation memory and improve the calculation efficiency.

[0070] Step 1.2: Zbus linearized power flow model based on single fixed point iteration

[0071] For any nonlinear function y1 = f(x), when solving its zero point x0, f(x0) = 0. At this time, it can be written in another equivalent form x0 = Ψ(x0). x0 is called the fixed point of the function Ψ(x0), where Ψ(x0) is the fixed point function. The actual fixed point is the intersection of the original function and another function y2 = x. The process of calculating the zero point of a nonlinear function by calculating the fixed point is called fixed point iteration. The iteration formula is shown in formula (6).

[0072] X(k h )=Ψ(X(k h -1)) (6)

[0073] Among them, X(k h ) is the kth h The fixed point obtained by round iteration, X(k h -1) is the kth h -1 fixed point obtained after 1 round of iteration.

[0074] From the Zbus power flow model expression, it can be seen that the Zbus power flow equation has obvious iterative function characteristics. The left side of the equation is the voltage V of each PQ node, and the right side is a function of V. Therefore, it can be solved by fixed point iteration. However, fixed point iteration requires multiple calculations and the algorithm complexity is high. Therefore, a linear approximation method based on single fixed point iteration (FFPI) is used here to construct a linearized power flow model of the Zbus nonlinear model about the reference power flow point through single-step iteration. At this time, the latest operating point V of the system is selected. 0 'As a reference power flow point, when the system power flow changes, the PQ node power is updated, and the PQ node voltage vector V is obtained according to the following formula.

[0075]

[0076] Where A is the coefficient matrix, Once the line topology, parameters and reference flow points are determined, A and W can be calculated offline. The above formula constructs a linear relationship between the PQ node voltage vector V and the injected power vector S of each PQ node in the system, which significantly reduces the complexity of the solution process.

[0077] The essence of this single fixed point iteration method is to use the two power flow points (0, W) and (S 0 ',V 0 '), S 0 ' represents the reference point used for interpolation in the linearization method. This is fundamentally different from the standardized linearization method that cuts the plane at a feasible solution, such as the Taylor first-order expansion, which allows the linear approximation method based on a single fixed point iteration to maintain high accuracy over a larger interval.

[0078] Step 2 is to derive the above Zbus linearized power flow model and calculate the node voltage sensitivity under different regulation modes. The specific steps include:

[0079] Step 2.1: Quick calculation of the voltage sensitivity of PQ nodes to node injection power

[0080] The voltage sensitivity of the PQ node refers to the sensitivity of the PQ node voltage to the changes in the node injection power of each PQ node. The adjustable resources in the distribution network include active and reactive resources, so the voltage-active sensitivity and voltage-reactive sensitivity are calculated separately. The power voltage sensitivity can be obtained by calculating the derivative of the PQ node voltage for factors such as load power changes, generator output power changes, or line parameter changes. The traditional voltage sensitivity is obtained by inverting the Jacobian matrix, but this method is difficult to use for real-time control due to its large amount of calculation, and the voltage sensitivity of the balancing node cannot be obtained. Based on the Zbus linearized power flow model, the PQ node voltage is a linear function of the injected power, so the partial derivative of the active injected power and the reactive injected power can be obtained to obtain the expression of the node voltage sensitivity (PQ node voltage sensitivity) as follows, which can quantify the analytical relationship between the PQ node voltage and the injected power, realize the rapid calculation of the PQ node voltage sensitivity, and greatly reduce the computational complexity.

[0081]

[0082] Where P and Q are the active power and reactive power matrices of each PQ node, respectively. Running point for the latest trend.

[0083] Step 2.2: Quick calculation of PQ node voltage sensitivity to the balance node

[0084] In addition to the fact that the power injected into each PQ node will cause the voltage of each PQ node to change, the voltage change of the root node will also affect the voltage of each PQ node. In the Zbus linearized power flow model, the node voltage of each PQ node is also linearly related to the voltage vector of the balance node. Therefore, the voltage vector V0 of the balance node can also be derived according to the linearized power flow equation, thereby realizing the rapid calculation of the sensitivity of the PQ node to the balance node voltage. According to the Zbus linearized power flow model, the voltage sensitivity of each PQ node voltage with respect to the root node is solved as follows:

[0085]

[0086] The above formula establishes a linear relationship between the voltage of each PQ node and the root node voltage. Using this relationship, the impact of the balance node voltage change on the voltage change of each PQ node can be quantitatively determined.

[0087] In the distribution network, the voltage of the PQ node is mainly affected by two aspects. First, the gear adjustment of the substation on-load tap changer (OLTC) will cause the change of the balancing node voltage, which will lead to the change of each PQ node voltage. Second, the change of load power will also cause the change of PQ node voltage. Since the distribution network line has a high resistance to reactance ratio, there is a strong coupling relationship between the PQ node voltage and the active power and reactive power.

[0088] In summary, the voltage of each PQ node is closely related to the voltage of the balancing node and the active and reactive power of each PQ node. Through the analysis based on the Zbus linearized power flow model, the node voltage sensitivity can be obtained, and then the linear relationship between these variables can be established, which provides theoretical support for the boundary calculation of substation voltage regulation.

[0089] Step 2.3: Calculation method of voltage regulation of on-load tap-changing transformer

[0090] The on-load tap-changing transformer is a typical traditional discrete voltage regulating device that needs to meet the constraints of its tap adjustment range. In order to achieve accurate voltage regulation, it is necessary to calculate and optimize its voltage regulation according to the operating constraints of the on-load tap-changing transformer. The size of the voltage regulation is not only related to the current voltage deviation, but also needs to consider factors such as the number of equipment taps, step size, and operating frequency. Through the operating constraints of the on-load tap-changing transformer, its voltage regulation can be calculated. The corresponding constraints are as follows:

[0091] ΔV t OLTC =ΔkΔV tap (11)

[0092] k min ≤k2≤k 0,t ≤k1≤k max (12)

[0093] Where, ΔV t OLTC is the voltage regulation of the on-load tap-changing transformer, Δk is the number of times the on-load tap-changing transformer tap position is changed, ΔV tap represents the voltage adjustment step of the on-load tap-changing transformer tap, that is, the voltage change corresponding to the unit tap position change; k1 and k2 are the tap positions of the on-load tap-changing transformer in two scenarios, respectively. min and k max are the minimum and maximum positions of the on-load tap-changing transformer, k 0,t It is the position of the tap of the on-load tap-changing transformer after adjustment at a specific time t.

[0094] In step 3, the real-time charging and discharging power of the energy storage system is comprehensively obtained based on the node voltage sensitivity and the power limitation condition of the energy storage system. The specific steps include:

[0095] Step 3.1: Calculation of node voltage deviation

[0096] In the power system, node voltage deviation refers to the difference between the actual voltage and the target or set voltage. The calculation of node voltage deviation is usually to evaluate the operation status of the power grid and ensure that the node voltage is maintained within a reasonable range, thereby ensuring the safety and stability of the system. The node voltage deviation calculation is shown in the following formula.

[0097] ΔV (t) =V set -V (t) (13)

[0098] Where, ΔV (t) is the voltage deviation, that is, the voltage deviation of the PQ node; V set The target voltage value preset by the system; V (t) is the real-time PQ node voltage of the system at time t. (t) >0, indicating that the node voltage is lower than the target value and needs to be increased; when ΔV (t) When <0, it means that the node voltage is too high and needs to be reduced.

[0099] Step 3.2: Calculation of charging and discharging power and charging and discharging status considering power limitation of energy storage system

[0100] In order to achieve accurate regulation of node voltage in the coordinated control of the energy storage system and the on-load tap-changing transformer, it is necessary to calculate the charging and discharging power of the energy storage system at time t, that is, the real-time charging and discharging power P. storage (t), which depends on the node voltage deviation, node voltage sensitivity, power limitation of the energy storage system, and the power demand of the system. The basic formula for the real-time charging and discharging power of the energy storage system is:

[0101]

[0102] In the formula, k storage is the regulation gain coefficient of the energy storage system, which is used to control the response degree of the energy storage system to the node voltage deviation. is the inverse matrix of the node voltage sensitivity matrix, which is used to convert the node voltage deviation into power demand.

[0103] However, the charging and discharging power of the energy storage system is limited by its maximum power capacity and the current SOC (State Of Charge), ensuring that the system does not exceed its physical limits. The charging and discharging power calculation formula taking into account these limiting conditions is as follows:

[0104]

[0105] When ΔV (t) >0, indicating that the node voltage is lower than the target value, and the energy storage system needs to discharge to increase the voltage. In the formula, P maxis the maximum charging and discharging power of the energy storage system, P min is the minimum charging and discharging power of the energy storage system. If the calculated power exceeds the charging and discharging capacity of the energy storage system, it will be limited to P min and P max between.

[0106] The state of charge (SOC) of the energy storage system at time t is a key indicator for describing the available energy in the energy storage device. SOC changes with the charging and discharging process, and the change of SOC directly affects the operating efficiency and reliability of the energy storage system. The expression of the charging and discharging state of the energy storage system at time t is as follows:

[0107]

[0108] In the formula, SOC(t) is the charge and discharge state of the energy storage system at time t, E (t) is the energy stored in the energy storage system at time t, E max is the maximum energy storage capacity of the energy storage system.

[0109] During the charging and discharging process of the energy storage system, the SOC of the energy storage system will continue to change with the inflow and outflow of energy. The change of SOC is affected by multiple factors, including: charging and discharging power, environmental factors, usage strategy, etc. Among them, the power of charging or discharging directly affects the rate of change of SOC. The greater the power, the faster the SOC changes. The calculation formula for the change of the charging and discharging state of the energy storage system is as follows:

[0110]

[0111] In the formula, SOC(t+Δt) is the charge and discharge state of the energy storage system at time t+Δt, and Δt is the time step.

[0112] When the energy storage system is charged, the SOC gradually increases to its maximum value until it reaches the full charge state; when the energy storage system is discharged, the SOC gradually decreases until it reaches the set minimum SOC threshold to protect the energy storage system from over-discharge. The minimum SOC threshold is usually set to 20%. Therefore, the charging and discharging process is subject to the upper and lower limits of SOC, that is, 20% ≤ SOC(t) ≤ 100%.

[0113] The specific steps of determining the voltage regulation capacity of the substation and formulating the system collaborative control optimization strategy in step 4 include:

[0114] Step 4.1: CVR coefficient and load regulation

[0115] The CVR coefficient is an important parameter used in power systems to measure the impact of voltage changes on load regulation. By moderately reducing the voltage level in the power grid, the power load can be effectively reduced, thereby achieving more efficient use of energy without compromising the user's power experience. With the access to emerging power-consuming devices such as renewable energy and electric vehicles, the operation of the power system faces increasingly complex challenges. Therefore, reasonable voltage management has become a key measure to improve system flexibility and efficiency.

[0116] In practice, the effective application of the CVR coefficient can significantly improve energy efficiency. By real-time monitoring and adjusting the voltage, a voltage reduction strategy can be implemented during peak load periods, thereby reducing the need for additional power generation capacity. Voltage regulation can also reduce line losses, optimize power transmission efficiency, and thus reduce overall energy consumption. By properly managing the relationship between voltage and load, CVR can promote the effectiveness of load regulation. When CVR>0, it means that the load changes in the same direction as the voltage changes. When CVR<0, it means that the load and voltage changes are inversely related. In actual systems, the CVR coefficient is usually between 0.5% and 1%, which means that when the voltage drops by 1%, the load power decreases by about 0.5% to 1%. The change in load power ΔP caused by the voltage change in the system load load (t) is:

[0117]

[0118] Where P load is the base power of the load.

[0119] Step 4.2: Determine the voltage regulation range of the substation

[0120] The principle of voltage regulation by energy storage system and on-load tap-changing transformer is mainly based on the precise coordinated control of on-load tap-changing function of transformer and energy storage system, so as to achieve real-time dynamic stability of system voltage. This process fully combines the advantages of both: on-load tap-changing transformer can gradually adjust the output voltage by changing the tap position of winding to adapt to load changes and power demand; while energy storage system has the characteristics of fast response, and can quickly intervene when voltage fluctuates for a short time, and provide instant voltage support for the power grid through charging or discharging.

[0121] When the system voltage deviates, the energy storage system first detects this change and immediately adjusts the charge and discharge according to the size and direction of the voltage deviation to prevent further voltage fluctuations. At the same time, if the voltage deviation lasts for a long time or exceeds the regulation capability of the energy storage system, the control system will start the on-load tap-changing transformer and change its tap position to achieve a wider range of voltage adjustment, ensuring that the voltage of the power grid or substation is stable within the target range.

[0122] Since the resistance in the distribution network is much larger than the reactance, the coupling between voltage and active power is more obvious. Therefore, the substation can indirectly adjust the active power by adjusting the voltage. Therefore, by adjusting the on-load tap-changing transformer, not only can the bus voltage be adjusted, but also the active power can be indirectly controlled. In order to ensure the safe and stable operation of the power grid, it is necessary to calculate the upper and lower limits of the substation voltage regulation, that is, the voltage regulation range. In practical applications, to evaluate the voltage regulation range of the substation, it is usually necessary to calculate the voltage sensitivity of each node for evaluation. The node voltage is affected by the changes in load power and the charging and discharging power of the energy storage system. The active power of the load and the charging and discharging power of the energy storage system have put forward new requirements for maximizing the voltage regulation range.

[0123] To determine the voltage regulation capability of a substation, the following formula can be used:

[0124]

[0125] Where, ΔV range Indicates the voltage regulation range parameters of the substation.

[0126] Therefore, the voltage regulation range of the substation can be determined based on the voltage regulation amount of the on-load tap-changing transformer, the node voltage sensitivity, the real-time charging and discharging power of the energy storage system, and the change in load power caused by the voltage change of the system load, thereby realizing the substation voltage regulation and control under the coordinated control of the system.

[0127] Step 4.3: Coordinated control optimization strategy of energy storage system and on-load tap-changing transformer

[0128] The principle of the energy storage system and the on-load tap-changing transformer working together to regulate voltage mainly relies on the on-load tap-changing function of the on-load tap-changing transformer and the precise coordinated control of the energy storage system, so as to achieve real-time dynamic stability of the system voltage. This process fully combines the advantages of both: the on-load tap-changing transformer can gradually adjust the output voltage by changing the tap position of the winding to adapt to load changes and power demand; while the energy storage system has the characteristics of fast response, and can quickly intervene when the voltage fluctuates for a short time, and provide instant voltage support to the power grid through charging or discharging.

[0129] When the system voltage deviates, the energy storage system first detects this change and immediately adjusts the charge and discharge according to the size and direction of the voltage deviation to prevent further voltage fluctuations. At the same time, if the voltage deviation persists for a long time or exceeds the regulation capability of the energy storage system, the control system will start the on-load tap-changing transformer and change its tap position to achieve a wider range of voltage adjustment to ensure that the voltage of the power grid or substation is stable within the target range. In order to further optimize the coordinated control and ensure that the substation voltage is stably controlled within the set range, the system adds a voltage deviation response threshold. Based on the characteristics of the two, the following optimization strategies can be formulated:

[0130] Energy storage system priority threshold: When |ΔV (t) When |<∈1, only the energy storage system responds.

[0131] OLTC intervention regulation threshold: When |ΔV (t) |>∈2, and the voltage deviation lasts longer than Δt OLTC OLTC intervenes to adjust.

[0132] Among them, ∈1, ∈2 are the first and second voltage deviation thresholds, Δt OLTC The energy storage system and OLTC collaborative control optimization strategy has the advantages of fast response speed, high stability, energy saving and high efficiency. Specifically, the energy storage system makes up for the slow response speed of the on-load tap-changing transformer, avoids frequent switching of transformer taps by OLTC, and reduces equipment wear. Through hierarchical control, fast response and fine response are combined to ensure the voltage stability of the system and improve the system operation efficiency.

[0133] In step 5, the capacity adjustment range of the substation under the coordinated control of the energy storage system and OLTC is evaluated in combination with the CVR coefficient. The specific steps include:

[0134] Step 5.1: Calculation method of power regulation of on-load tap-changing transformer

[0135] According to step 2.3, the on-load tap-changing transformer is a typical traditional discrete voltage regulating device, which needs to meet the constraints of its tap adjustment range. Through the operation constraints of the on-load tap-changing transformer, the voltage regulation amount ΔV of the on-load tap-changing transformer can be calculated. t OLTC Combined with the node voltage sensitivity, the power regulation value P of the on-load tap-changing transformer can be obtained. OLTC (t):

[0136]

[0137] Step 5.2: Calculation method for adjustable substation capacity under coordinated control of energy storage system and OLTC

[0138] The calculation of the adjustable range of substation capacity is a key step in the voltage regulation process. Through the rapid response of the energy storage system and the steady-state regulation capability of OLTC, combined with the impact of the CVR coefficient on the load, the entire system can be flexibly regulated. The coordinated regulation strategy of the two improves the operating efficiency of the system, while also enhancing the grid's ability to adapt to load fluctuations and renewable energy fluctuations, providing important support for the realization of smart grids and sustainable energy development. The calculation formula for the adjustable range of substation capacity jointly regulated by the energy storage system and OLTC is as follows:

[0139]

[0140] Where P range (t) represents the adjustable range of substation capacity.

[0141] It should be noted that during periods of high grid load, the load can be reduced by lowering the voltage (CVR strategy). The energy storage system and OLTC can work together to ensure that the voltage is maintained within a reasonable range while reducing power consumption and the risk of equipment overload. In the case of large fluctuations in wind and photovoltaic power generation, the energy storage system and OLTC work together to quickly respond to voltage fluctuations and achieve stable operation of the system. The CVR coefficient is particularly important in this scenario because it can reduce the impact of fluctuations on the load through voltage regulation.

[0142] Figure 2 FIG. 1 is a structural block diagram of the on-load voltage-changing transformer and energy storage system coordinated control integrated regulation system according to an embodiment of the present invention. Figure 2 As shown, the on-load tap-changing transformer and energy storage system coordinated control integrated regulation system 100 includes a construction module 10 and a solution module 20.

[0143] Among them, the construction module 10 is used to construct a Zbus linearized power flow model based on a single fixed point iteration; the solution module 20 is used to determine the node voltage sensitivity in the power grid based on the Zbus linearized power flow model; and, determine the voltage regulation amount of the on-load tap-changing transformer and the maximum and minimum charging and discharging power of the energy storage system, and determine the real-time charging and discharging power of the energy storage system based on the node voltage sensitivity and the maximum and minimum charging and discharging power of the energy storage system; and, determine the voltage regulation range of the substation based on the node voltage sensitivity, the voltage regulation amount of the on-load tap-changing transformer and the real-time charging and discharging power of the energy storage system, so as to realize the substation voltage regulation capacity adjustment under the coordinated control of the on-load tap-changing transformer and the energy storage system.

[0144] In one embodiment of the present invention, the on-load tap-changing transformer and energy storage system coordinated control integrated regulation system also includes a strategy formulation module 30, which is used to formulate an optimization strategy for the coordinated control of the on-load tap-changing transformer and the energy storage system. The optimization strategy for the coordinated control of the on-load tap-changing transformer and the energy storage system includes: determining the node voltage deviation; when the node voltage deviation is less than the first voltage deviation threshold value, controlling the energy storage system to respond and adjust; when the node voltage deviation is greater than the second voltage deviation threshold value, and the voltage deviation duration exceeds the trigger time of the on-load tap-changing transformer, controlling the on-load tap-changing transformer to intervene in the regulation, and the second voltage deviation threshold value is greater than the first voltage deviation threshold value.

[0145] In one embodiment of the present invention, the solution module 20 is also used to determine the capacity adjustable range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system, so as to realize the capacity adjustable capability evaluation of the substation under the coordinated control of the system.

[0146] In one embodiment of the present invention, when determining the adjustable capacity range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system, the solution module 20 is specifically used to: determine the CVR coefficient and the power adjustment amount of the on-load tap-changing transformer; determine the adjustable capacity range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system based on the real-time charging and discharging power of the energy storage system, the power adjustment amount of the on-load tap-changing transformer, and the CVR coefficient.

[0147] It should be noted that the specific implementation methods of the on-load tap-changing transformer and energy storage system collaborative control comprehensive regulation system of the embodiment of the present invention can refer to the specific implementation methods of the on-load tap-changing transformer and energy storage system collaborative control comprehensive regulation method mentioned above. To avoid redundancy, they will not be repeated here.

[0148] In summary, the present invention constructs a Zbus linearized power flow model of a single fixed point iteration, and the model can be used to calculate the partial derivative of each node voltage relative to the injected power, thereby obtaining an expression for the node voltage sensitivity. In this way, the analytical relationship between the node voltage and the injected power can be quantified, greatly reducing the computational complexity. Subsequently, the energy storage system charging and discharging power calculation formula can be comprehensively obtained based on the node voltage sensitivity and the power-limited conditions of the energy storage system, and then the voltage regulation capability of the substation can be determined. Finally, the power adjustment range of the substation, that is, the capacity adjustable range, can be evaluated by combining the CVR coefficient and the system control optimization strategy, thereby realizing the comprehensive regulation and control of the substation voltage and capacity under the coordinated control of the on-load tap-changing transformer and the energy storage system. In addition, the energy storage system of the present invention cooperates with the OLTC to adjust the capacity of the substation, uses the energy storage system to quickly respond to short-term fluctuations, and completes long-term steady-state regulation with the help of the on-load tap-changing transformer, thereby improving the flexibility and stability of the power system to cope with increasingly complex power supply and demand issues. The present invention can adjust the charging and discharging power and OLTC ratio of the energy storage system by monitoring the grid status and load changes in real time. This adjustment mechanism enables the power system to respond quickly to rapidly changing loads and renewable energy output changes, thereby ensuring that the system voltage is maintained within a reasonable range, thereby ensuring the reliability and continuity of power supply.

[0149] Furthermore, the present invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned on-load tap-changing transformer and energy storage system coordinated control integrated regulation method is implemented.

[0150] Furthermore, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the above-mentioned on-load tap-changing transformer and energy storage system coordinated control integrated regulation method is implemented.

[0151] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0152] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A method for coordinated control and comprehensive regulation of an on-load voltage-regulating transformer and an energy storage system, characterized in that: include: Construct a Zbus linearized power flow model based on single fixed point iteration; Determine the node voltage sensitivity in the power grid based on the Zbus linearized power flow model; Determine the voltage regulation of the on-load tap-changing transformer and the maximum and minimum charging and discharging power of the energy storage system; Determine the real-time charging and discharging power of the energy storage system based on the node voltage sensitivity and the maximum and minimum charging and discharging power of the energy storage system; The voltage regulation range of the substation is determined based on the node voltage sensitivity, the voltage regulation amount of the on-load tap-changing transformer and the real-time charging and discharging power of the energy storage system, so as to achieve the substation voltage regulation capacity adjustment under the coordinated control of the on-load tap-changing transformer and the energy storage system.

2. The on-load voltage-changing transformer and energy storage system coordinated control comprehensive regulation method according to claim 1, characterized in that: The method further includes formulating an on-load voltage-changing transformer and an energy storage system coordinated control optimization strategy, wherein the on-load voltage-changing transformer and an energy storage system coordinated control optimization strategy includes: determining node voltage deviations; When the node voltage deviation is less than the first voltage deviation threshold value, controlling the energy storage system to perform response adjustment; When the node voltage deviation is greater than a second voltage deviation threshold value and the voltage deviation duration exceeds the trigger time of the on-load tap-changing transformer, the on-load tap-changing transformer is controlled to intervene in regulation, and the second voltage deviation threshold value is greater than the first voltage deviation threshold value.

3. The on-load voltage-changing transformer and energy storage system coordinated control comprehensive regulation method according to claim 1, characterized in that: The method also includes determining the capacity adjustable range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system, so as to implement the capacity adjustable capability evaluation of the substation under the coordinated control of the system.

4. The on-load voltage-changing transformer and energy storage system coordinated control comprehensive regulation method according to claim 3, characterized in that: Determine the adjustable capacity range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system, including: Determine the CVR coefficient and the power regulation of the on-load tap-changing transformer; The capacity adjustment range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system is determined based on the real-time charging and discharging power of the energy storage system, the power adjustment amount of the on-load tap-changing transformer, and the CVR coefficient.

5. A coordinated control integrated regulation system for an on-load voltage-regulating transformer and an energy storage system, characterized in that: include: Construction module for constructing Zbus linearized power flow model based on single fixed point iteration; A solution module is used to determine the node voltage sensitivity in the power grid based on the Zbus linearized power flow model; and determine the voltage regulation amount of the on-load tap-changing transformer and the maximum and minimum charging and discharging power of the energy storage system, and determine the real-time charging and discharging power of the energy storage system based on the node voltage sensitivity and the maximum and minimum charging and discharging power of the energy storage system; and determine the voltage regulation range of the substation based on the node voltage sensitivity, the voltage regulation amount of the on-load tap-changing transformer and the real-time charging and discharging power of the energy storage system, so as to realize the voltage regulation capacity adjustment of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system.

6. The on-load voltage-changing transformer and energy storage system coordinated control integrated regulation system according to claim 5, characterized in that: It also includes a strategy formulation module for formulating an optimization strategy for coordinated control of on-load tap-changing transformers and energy storage systems. The optimization strategy for coordinated control of on-load tap-changing transformers and energy storage systems includes: determining node voltage deviations; When the node voltage deviation is less than the first voltage deviation threshold value, controlling the energy storage system to perform response adjustment; When the node voltage deviation is greater than a second voltage deviation threshold value and the voltage deviation duration exceeds the trigger time of the on-load tap-changing transformer, the on-load tap-changing transformer is controlled to intervene in regulation, and the second voltage deviation threshold value is greater than the first voltage deviation threshold value.

7. The on-load voltage-changing transformer and energy storage system coordinated control integrated regulation system according to claim 5, characterized in that: The solution module is also used to determine the capacity adjustable range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system, so as to realize the capacity adjustable capability evaluation of the substation under the coordinated control of the system.

8. The on-load voltage-changing transformer and energy storage system coordinated control integrated regulation system according to claim 7, characterized in that: When determining the adjustable capacity range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system, the solution module is specifically used to: Determine the CVR coefficient and the power regulation of the on-load tap-changing transformer; The capacity adjustment range of the substation under the coordinated control of the on-load tap-changing transformer and the energy storage system is determined based on the real-time charging and discharging power of the energy storage system, the power adjustment amount of the on-load tap-changing transformer, and the CVR coefficient.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, the on-load tap-changing transformer and energy storage system coordinated control comprehensive regulation method as described in any one of claims 1-4 is implemented.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, it implements the on-load tap-changing transformer and energy storage system coordinated control comprehensive regulation method according to any one of claims 1-4.

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