CN117595375A - Method for considering influence of grid-connected access mode of electrolytic cell on voltage stability of power grid - Google Patents
Method for considering influence of grid-connected access mode of electrolytic cell on voltage stability of power grid Download PDFInfo
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Abstract
The invention relates to a method for considering the influence of an electrolytic cell grid-connected access mode on the voltage stability of a power grid, which comprises the following steps: step S1: constructing a topological structure of a direct-hanging type electrobath hydrogen production system without a transformer based on an electrobath, wherein the topological structure comprises an electrobath module and a power conversion system; step S2: based on the voltage-current relation and steady-state model in the electrolytic cell, constructing a mathematical model of grid connection of a transformer-free direct hanging type electrolytic cell; step S3: calculating injection current and power of a system node after the electrolytic cell is connected, establishing a correction equation, and solving a partial derivative of the correction to the node voltage so that internal current of the hydrogen production system of the electrolytic cell participates in Newton-Lawson method iteration of continuous power flow calculation; step S4: and calculating continuous power flow of the system before and after the electrolytic cell is connected to obtain a static voltage stability margin of the system, and increasing the distance from the current operating point to the voltage breakdown point. The invention improves the stability margin of the system static voltage and the conversion efficiency of the system and improves the voltage stability of the power grid.
Description
Technical Field
The invention relates to the technical field of grid connection of power systems, in particular to a method for considering the influence of an electrolytic cell grid connection access mode on the voltage stability of a power grid.
Background
With the continuous development of society and economy, the requirements of people on electric energy and reliability are higher and higher. On the one hand, the traditional power grid faces the challenge of rapid load increase; on the other hand, the intermittence and fluctuation of renewable energy sources such as wind power, photovoltaic and the like bring serious influence to the safe and stable operation of a power grid, and hydrogen energy storage is an effective method for solving the problems.
The electrolytic cell hydrogen production system has good dynamic response characteristic and mainly comprises an electrolytic cell and a power conversion system. The power conversion system is used as an interface between the electrolytic tank and the power grid, so that the output electric energy quality and dynamic characteristics of the hydrogen production system of the electrolytic tank are determined, and the service life of the electrolytic tank is greatly influenced. Through the change of the circuit topology and the combination mode of the converter, the efficiency, the safety and the reliability of the electrolytic cell hydrogen production system can be effectively improved, and the cost is reduced. The electrolytic cell hydrogen production system is used for solving the problems of frequency modulation and peak shaving at the power grid side, renewable energy friendly grid connection at the power generation side, power grid access at the user side and the like, and has wide application, and the capacity of the electrolytic cell hydrogen production system is developed from the kW level at the user side to the hundred MW level scale at the power grid side. However, with the rapid development of the hydrogen energy storage capacity, the influence of the grid-connected access mode on the system safety is increasingly larger, and especially the voltage stability of the power grid faces a series of technical challenges, so that considering the influence of the grid-connected access mode of the electrolytic cell on the voltage stability of the power grid is of great importance.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for considering the influence of an electrolytic cell grid-connected access mode on the voltage stability of a power grid. Based on the operation characteristics and steady-state models of the electrolytic tank, the internal mathematical model of the grid connection of the electrolytic tank hydrogen production system is fully considered, a transformerless direct hanging type access mode is adopted for grid connection, node current of the electrolytic tank hydrogen production system is participated in Newton-Lafson method iteration of continuous power flow calculation after the electrolytic tank is accessed, a jacobian matrix is continuously corrected, a PV curve is obtained by respectively calculating continuous power flows before and after the electrolytic tank is accessed, a static voltage stability margin is obtained by calculating the distance from the current operation point of the system to a voltage collapse point of the PV curve, and the static voltage stability margin of the system is improved by adopting transformerless direct hanging type grid connection access of the electrolytic tank, so that the voltage stability of a power grid is improved.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a method for considering influence of an electrolytic cell grid-connected access mode on voltage stability of a power grid comprises the following steps:
step S1: constructing a topological structure of a direct-hanging type electrobath hydrogen production system without a transformer based on an electrobath, wherein the topological structure comprises an electrobath module and a power conversion system;
Step S2: based on the voltage-current relation and steady-state model inside the electrolytic tank module, constructing a mathematical model of a grid-connected access mode of the direct-hanging type electrolytic tank without a transformer;
step S3: calculating injection current and power of nodes of the electrolytic cell hydrogen production system after the electrolytic cell module is connected, establishing a correction equation, solving partial derivatives of correction to node voltages, and enabling internal current of the transformerless direct-hanging electrolytic cell hydrogen production system to participate in Newton-Lafson method iteration of continuous tide calculation;
step S4: and calculating continuous power flow of the electrolytic cell hydrogen production system before and after the electrolytic cell module is connected to obtain static voltage stability margin of the electrolytic cell hydrogen production system, and increasing the distance from the current operating point to the voltage collapse point according to the transformer-free direct hanging type electrolytic cell grid-connected connection mode.
Further, the step S1 specifically includes:
the power conversion system comprises a DC/AC (direct current/alternating current) converter and an internal power electronic device thereof, wherein the DC/AC converter adopts a two-level three-phase bridge converter, and the internal power electronic device is composed of an IGBT (insulated gate bipolar transistor) high-frequency switching device;
the electrolytic tank module comprises a plurality of series-parallel electrolytic tank stacks, the cathode and the anode of each electrolytic tank stack are respectively connected with the input end of a corresponding DC/AC converter, and the output end of the DC/AC converter is directly connected into a power grid without a transformer after being sequentially connected in series.
Further, the step S2 specifically includes:
step S21: based on the voltage-current relation and the steady-state model inside the electrolytic cell module, a voltage-current equation in a steady state is established, as shown in the following formula:
U el ＝U rev +U pol +U ohm
wherein U is el Is the terminal voltage of the electrolysis chamber; u (U) rev 、U pol And U ohm Reversible voltage, polarization overvoltage and ohmic overvoltage respectively; r, r 1 、r 2 、r 3 Is the polarization overvoltage coefficient; t is the temperature of the electrolyte; i el Is the electrolysis chamber current; s is the surface area of an electrode of the electrolytic cell; t is t 1 、t 2 And p 1 、p 2 Ohmic overvoltage temperature coefficient and pressure coefficient respectively; p is a pressure coefficient, taking 5bar;
step S22: multiple electrolytic chambers are connected in series and parallel to form an electrolytic cell stack, and the voltage U of the electrolytic cell stack els And consumed power P els The following formula is shown:
wherein n is 1 And n 2 The number of the electrolytic cells in series connection and the number of the electrolytic cells in parallel connection are respectively;
step S23: constructing a mathematical model of a grid-connected access mode of the direct-hanging type electrolytic tank without a transformer, connecting the electrolytic tank to the direct-current side of the DC/AC converter, and directly connecting the alternating-current side of the DC/AC converter to a power grid without a transformer;
the basic equation of the mathematical model of the grid-connected access mode of the transformerless direct hanging type electrolytic tank is shown as follows:
wherein U is sa 、U sb 、U sc The voltages of the phase a, the phase b and the phase c of the power grid are respectively; u (U) NO Is the voltage difference between the neutral point of the power grid and the reference point; i a 、I b 、I c A, b and c phases of alternating current respectively; l and R represent the inductance in the main circuit and the parasitic resistance thereof; the voltage U of the electrolytic cell stack can be reduced due to the slow change of the electrolytic cell voltage els Equivalent to an ideal voltage source; f (F) a 、F b 、F c A phase leg switching function for the DC/AC converter; f (F) a ＝1、F b ＝1、F c =1 indicates the upper tube of a, b, c phase bridge arm is on, the lower tube is off, F a ＝0、F b ＝0、F c =0 indicates that the upper tubes of the a, b and c phase bridge arms are turned off and the lower tube is turned on respectively;
summing the above, the voltage difference U between the neutral point and the reference point of the power grid can be obtained NO The following formula is shown:
further, the step S3 specifically includes:
step S31: after the electrolytic tank module is added, the node injection power of the transformerless direct hanging type electrolytic tank hydrogen production system is shown as follows:
P i ＝P G -P els
wherein P is i The injection power of the i node is 1,2, and n is a natural number; p (P) G Representing node generator injection power;
and establishing a correction equation according to the calculated node injection power of the direct hanging type electrolytic tank hydrogen production system without the transformer, wherein the correction equation is shown in the following formula:
ΔP i ＝P i -U i I i ＝P G -P els -U i I i
wherein DeltaP i A power correction amount for the i-th node; u (U) i Representing the voltage at node i; i i A current representing node i;
current I at node I i The following formula is shown:
wherein Y is ii Representing the self admittance of node i; y is Y ij Representing the transadmittance between node i and node j; n represents the number of nodes; y is Y ii U els Correction amount of current injection is performed on an access node of the transformer-free direct-hanging type electrolytic tank hydrogen production system for the access of the DC/AC converter; u (U) j Representing the voltage at node j;
step S32: injecting node generator into power P G Setting the current as a fixed value, solving the partial derivative of the node power correction quantity to the node voltage, and providing calculation support for the internal current of the electrolytic tank hydrogen production system to participate in the iteration of the Newton-Lawson method of continuous power flow calculation;
if the node i is connected to the electrolytic cell module, the following formula is shown:
wherein,and->The partial derivatives of the power correction quantity of the ith node to the voltages of the node i and the node j are respectively; />And->Power P respectively consumed by the stacks els Partial derivatives of the voltages at node i and node j.
Further, the step S4 specifically includes:
step S41: firstly, calculating an initial tide solution of a system when an electrolytic tank module is not connected, and obtaining an approximate value of a next solution according to a given step length from the initial tide solution in a tangential direction; substituting the obtained approximate value of the solution as an initial value into a power flow balance equation for iteration, and solving by adopting a Newton-Lapherson method to obtain a correction solution meeting the actual power flow balance equation; selecting a proper step length to enable the estimated approximation value to fall into a corrected convergence domain; at the flatter position of the PV (power-voltage) curve, a larger step length can be selected to improve the calculation speed, and at the position close to the inflection point of the PV curve, a smaller step length can be selected to ensure the convergence of calculation; stopping iteration until the tide balance equation is converged, and obtaining a PV curve of the system when the electrolytic tank module is not connected;
Step S42: after the continuous power flow calculation of the transformer-free direct hanging type electrolytic tank hydrogen production system is carried out after the electrolytic tank module is connected, when a jacobian matrix is formed, the jacobian matrix of the conventional power flow is increased by one step, and an augmented jacobian matrix is obtained;
the jacobian of the conventional power flow becomes a model of the load under consideration:
wherein Δu is the voltage correction amount of the node; Δp is the power correction of the node;
then carrying out iterative computation by adopting a Newton-Laportson method, and continuously modifying the jacobian matrix to obtain updated injection current I 'of the electrolytic cell' i I.e. cell current I' el Thereby obtaining the power value P' els ；
Step S43: after the electrolytic tank module is connected, starting from a given running state of the hydrogen production system of the direct-hanging type electrolytic tank without a transformer, a PV curve is obtained by gradually approaching a voltage collapse point through the increase of load or transmission power according to a certain step length, and the equation is shown as follows:
f(x)+λb＝0
x＝[δ U] T
wherein lambda is a load parameter variable; x is a state vector; f is a function vector and represents a tide equation; b is a constant vector, which represents a load increasing mode; delta is the voltage power angle vector; u is a voltage amplitude vector;
the distance from the current operating point of the system to the voltage breakdown point is a static voltage stability margin, and the static voltage stability margin is shown in the following formula:
λ VSM ＝[(λ+1)P 0 -P 0 ]/P 0
P 0 ＝P L0 -P els
Wherein lambda is VSM A static voltage stability margin for the system; p (P) 0 Is the original system payload; (lambda+1) P 0 Is the maximum payload that the system can withstand; p (P) L0 Is the initial load of the system;
the calculated electrolytic tank adopts the transformer-free direct hanging grid connection to improve the static voltage stability margin of the system, and the larger the static voltage stability margin is, the more stable the system is.
The invention also provides a device for considering the influence of the grid-connected access mode of the electrolytic cell on the voltage stability of the power grid, which comprises:
the model construction module comprises a topological structure for constructing a direct hanging type electrobath hydrogen production system without a transformer based on an electrobath, wherein the topological structure comprises an electrobath module and a power conversion system, and a mathematical model of a grid-connected access mode of the direct hanging type electrobath without the transformer is constructed based on a voltage-current relation and a steady-state model in the electrobath module, so that the electrobath module is connected to a direct current side of a DC/AC converter, and an alternating current side of the DC/AC converter is directly connected to a power grid without a transformer;
the correction calculation module comprises a step of calculating injection current and power of nodes of the direct-hanging type electrolytic cell hydrogen production system without a transformer after the electrolytic cell module is connected, establishing a correction equation, solving partial derivatives of correction to node voltages, enabling internal current of the electrolytic cell hydrogen production system to participate in Newton-Lafson method iteration of continuous tide calculation, and modifying a jacobian matrix;
The stability calculation module is used for respectively calculating continuous power flow of the electrolytic cell hydrogen production system before and after the electrolytic cell is connected into the electrolytic cell hydrogen production system and obtaining a PV curve, and obtaining a static voltage stability margin by calculating the distance from the current operating point of the system to the voltage collapse point of the PV curve.
Further, the power conversion system in the model building module comprises a DC/AC converter and an internal power electronic device thereof, wherein the DC/AC converter adopts a two-level three-phase bridge converter, and the internal power electronic device is composed of an IGBT high-frequency switching device;
the electrolytic tank module comprises a plurality of series-parallel electrolytic tank stacks, the cathode and the anode of each electrolytic tank stack are respectively connected with the input end of a corresponding DC/AC converter, and the output end of the DC/AC converter is directly connected into a power grid without a transformer after being sequentially connected in series.
Based on the voltage-current relation and the steady-state model inside the electrolytic cell module, a voltage-current equation in a steady state is established, as shown in the following formula:
U el ＝U rev +U pol +U ohm
wherein U is el Is the terminal voltage of the electrolysis chamber; u (U) rev 、U pol And U ohm Reversible voltage, polarization overvoltage and ohmic overvoltage respectively; r, r 1 、r 2 、r 3 Is the polarization overvoltage coefficient; t is the temperature of the electrolyte; i el Is the electrolysis chamber current; s is the surface area of an electrode of the electrolytic cell; t is t 1 、t 2 And p 1 、p 2 Ohmic overvoltage temperature coefficient and pressure coefficient respectively; p is the coefficient of pressure and,taking 5bar;
multiple electrolytic chambers are connected in series and parallel to form an electrolytic cell stack, and the voltage U of the electrolytic cell stack els And consumed power P els The following formula is shown:
wherein n is 1 And n 2 The number of the electrolytic cells in series connection and the number of the electrolytic cells in parallel connection are respectively;
constructing a mathematical model of a grid-connected access mode of the direct-hanging type electrolytic tank without a transformer, connecting the electrolytic tank to the direct-current side of the DC/AC converter, and directly connecting the alternating-current side of the DC/AC converter to a power grid without a transformer;
the basic equation of the mathematical model of the grid-connected access mode of the transformerless direct hanging type electrolytic tank is shown as follows:
wherein U is sa 、U sb 、U sc The voltages of the phase a, the phase b and the phase c of the power grid are respectively; u (U) NO Is the voltage difference between the neutral point of the power grid and the reference point; i a 、I b 、I c A, b and c phases of alternating current respectively; l and R represent the inductance in the main circuit and the parasitic resistance thereof; the voltage U of the electrolytic cell stack can be reduced due to the slow change of the electrolytic cell voltage els Equivalent to an ideal voltage source; f (F) a 、F b 、F c A phase leg switching function for the DC/AC converter; f (F) a ＝1、F b ＝1、F c =1 indicates the upper tube of a, b, c phase bridge arm is on, the lower tube is off, F a ＝0、F b ＝0、F c =0 indicates that the upper tubes of the a, b and c phase bridge arms are turned off and the lower tube is turned on respectively;
summing the above, the voltage difference U between the neutral point and the reference point of the power grid can be obtained NO The following formula is shown:
further, after the electrolytic tank module is added in the correction calculation module, the node injection power of the transformer-free direct hanging type electrolytic tank hydrogen production system is shown as the following formula:
P i ＝P G -P els
wherein P is i The injection power of the i node is 1,2, and n is a natural number; p (P) G Representing node generator injection power;
and establishing a correction equation according to the calculated node injection power of the direct hanging type electrolytic tank hydrogen production system without the transformer, wherein the correction equation is shown in the following formula:
ΔP i ＝P i -U i I i ＝P G -P els -U i I i
wherein DeltaP i A power correction amount for the i-th node; u (U) i Representing the voltage at node i; i i A current representing node i;
current I at node I i The following formula is shown:
wherein Y is ii Representing the self admittance of node i; y is Y ij Representing the transadmittance between node i and node j; n represents the number of nodes; y is Y ii U els Correction amount of current injection is performed on an access node of the transformer-free direct-hanging type electrolytic tank hydrogen production system for the access of the DC/AC converter; u (U) j Representing the voltage at node j;
injecting node generator into power P G Setting the current as a fixed value, solving the partial derivative of the node power correction quantity to the node voltage, and providing calculation support for the internal current of the electrolytic tank hydrogen production system to participate in the iteration of the Newton-Lawson method of continuous power flow calculation;
If the node i is connected to the electrolytic cell module, the following formula is shown:
wherein,and->The partial derivatives of the power correction quantity of the ith node to the voltages of the node i and the node j are respectively; />And->Power P respectively consumed by the stacks els Partial derivatives of the voltages at node i and node j.
Further, an initial tide solution of the system when the electrolytic tank module is not connected is calculated in the stability calculation module, and an approximation value of a next solution is obtained according to a given step length from the initial tide solution in the tangential direction; substituting the obtained approximate value of the solution as an initial value into a power flow balance equation for iteration, and solving by adopting a Newton-Lapherson method to obtain a correction solution meeting the actual power flow balance equation; selecting a proper step length to enable the estimated approximation value to fall into a corrected convergence domain; at the flatter position of the PV (power-voltage) curve, a larger step length can be selected to improve the calculation speed, and at the position close to the inflection point of the PV curve, a smaller step length can be selected to ensure the convergence of calculation; stopping iteration until the tide balance equation is converged, and obtaining a PV curve of the system when the electrolytic tank module is not connected;
after the continuous power flow calculation of the transformer-free direct hanging type electrolytic tank hydrogen production system is carried out after the electrolytic tank module is connected, when a jacobian matrix is formed, the jacobian matrix of the conventional power flow is increased by one step, and an augmented jacobian matrix is obtained;
The jacobian of the conventional power flow becomes a model of the load under consideration:
wherein Δu is the voltage correction amount of the node; Δp is the power correction of the node;
then carrying out iterative computation by adopting a Newton-Laportson method, and continuously modifying the jacobian matrix to obtain updated injection current I 'of the electrolytic cell' i I.e. cell current I' el Thereby obtaining the power value P' els ；
After the electrolytic tank module is connected, starting from a given running state of the hydrogen production system of the direct-hanging type electrolytic tank without a transformer, a PV curve is obtained by gradually approaching a voltage collapse point through the increase of load or transmission power according to a certain step length, and the equation is shown as follows:
f(x)+λb＝0
x＝[δ U] T
wherein lambda is a load parameter variable; x is a state vector; f is a function vector and represents a tide equation; b is a constant vector, which represents a load increasing mode; delta is the voltage power angle vector; u is a voltage amplitude vector;
the distance from the current operating point of the system to the voltage breakdown point is a static voltage stability margin, and the static voltage stability margin is shown in the following formula:
λ VSM ＝[(λ+1)P 0 -P 0 ]/P 0
P 0 ＝P L0 -P els
wherein lambda is VSM A static voltage stability margin for the system; p (P) 0 Is the original system payload; (lambda+1) P 0 Is the maximum payload that the system can withstand; p (P) L0 Is the initial load of the system;
the calculated electrolytic tank adopts the transformer-free direct hanging grid connection to improve the static voltage stability margin of the system, and the larger the static voltage stability margin is, the more stable the system is.
The invention also provides an electronic device comprising a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the processor executes the program to realize the steps of the method for considering the influence of the grid connection access mode of the electrolytic cell on the voltage stability of the power grid.
The invention also provides a non-transitory computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when executed by a processor, implements the steps of the method of taking into account the influence of the grid-connected access mode of the electrolysis cell on the voltage stability of the grid.
Compared with the prior art, the invention has the following beneficial effects:
1. the traditional electrolytic cell hydrogen production system is connected with the power frequency boosting access mode of a transformer in a grid mode, along with the rapid development of large-scale and large-capacity electrolytic cells, the inconsistency of the electrolytic cells leads the safety of the hydrogen production system to be rapidly reduced along with the increase of the serial-parallel number of the electrolytic cells, and the improvement of the stack capacity of the electrolytic cells is seriously restricted;
2. The traditional electrolytic tank hydrogen production system is mostly regarded as a power constant or current constant model when continuous tide is calculated, the influence of the access of the electrolytic tank on the node current cannot be reflected, the internal current of the electrolytic tank hydrogen production system is participated in the iteration of continuous tide calculation, the jacobian matrix in the iteration of the Newton-Lafson method is continuously modified, the static voltage stability margin is obtained by solving the distance from the current operating point of the system to the voltage collapse point after the PV curve is obtained, and the continuous tide calculation result can be more accurate.
Drawings
FIG. 1 is a flow chart of a method of considering the effect of an electrolyzer grid-tie access mode on grid voltage stability in an example of the invention;
FIG. 2 is a schematic diagram of the topology of a transformerless direct-hanging electrolyzer hydrogen production system in an example of the invention;
FIG. 3 is a schematic illustration of the access of a transformerless direct hanging electrolyzer in accordance with an embodiment of the present invention.
Detailed Description
The invention provides a method for considering the influence of an electrolytic cell grid-connected access mode on the voltage stability of a power grid, which adopts a transformerless direct hanging access mode to grid-connect based on the voltage-current relation and a steady-state model in an electrolytic cell hydrogen production system under the condition of large-scale grid connection, and participates the internal current of the electrolytic cell hydrogen production system in the Newton-Lafson method iterative computation in the continuous tide computation, so that the jacobian matrix is continuously updated, the static voltage stability margin of the system is obtained through the PV curve computation, and the accuracy of the continuous tide computation is improved.
The present invention will be further described in detail below with reference to the accompanying drawings by way of specific embodiments in order to make the objects, technical solutions and advantages of the present invention more apparent.
As shown in fig. 1, a method for considering the influence of an electrolytic cell grid-connected access mode on the voltage stability of a power grid provided by an embodiment of the invention includes the following steps:
step S1: constructing a topological structure of a direct-hanging type electrobath hydrogen production system without a transformer based on an electrobath, wherein the topological structure comprises an electrobath module and a power conversion system;
step S2: based on the voltage-current relation and steady-state model inside the electrolytic tank module, constructing a mathematical model of a grid-connected access mode of the direct-hanging type electrolytic tank without a transformer;
step S3: calculating injection current and power of nodes of the electrolytic cell hydrogen production system after the electrolytic cell module is connected, establishing a correction equation, solving partial derivatives of correction to node voltages, and enabling internal current of the transformerless direct-hanging electrolytic cell hydrogen production system to participate in Newton-Lafson method iteration of continuous tide calculation;
step S4: and calculating continuous power flow of the electrolytic cell hydrogen production system before and after the electrolytic cell module is connected to obtain static voltage stability margin of the electrolytic cell hydrogen production system, and increasing the distance from the current operating point to the voltage collapse point according to the transformer-free direct hanging type electrolytic cell grid-connected connection mode.
Specifically, the step S1 includes:
as shown in fig. 2, the power conversion system includes a DC/AC (direct current/alternating current) converter and internal power electronics thereof, the DC/AC converter adopts a two-level three-phase bridge converter, and the internal power electronics is composed of an IGBT (insulated gate bipolar transistor) high-frequency switching device;
the electrolytic tank module comprises a plurality of series-parallel electrolytic tank stacks, the cathode and the anode of each electrolytic tank stack are respectively connected with the input end of a corresponding DC/AC converter, and the output end of the DC/AC converter is directly connected into a power grid without a transformer after being sequentially connected in series.
Through the step S1, a topological structure of a direct hanging type electrobath hydrogen production system without a transformer based on an electrobath is provided, and structural support is provided for constructing a mathematical model of grid connection of the direct hanging type electrobath without the transformer.
Specifically, the step S2 includes:
step S21: based on the voltage-current relation and the steady-state model inside the electrolytic cell module, a voltage-current equation in a steady state is established, as shown in the following formula:
U el ＝U rev +U pol +U ohm
wherein U is el Is the terminal voltage of the electrolysis chamber; u (U) rev 、U pol And U ohm Reversible voltage, polarization overvoltage and ohmic overvoltage respectively; r, r 1 、r 2 、r 3 Is the polarization overvoltage coefficient; t is the electrolyte temperature A degree; i el Is the electrolysis chamber current; s is the surface area of an electrode of the electrolytic cell; t is t 1 、t 2 And p 1 、p 2 Ohmic overvoltage temperature coefficient and pressure coefficient respectively; p is a pressure coefficient, taking 5bar;
step S22: multiple electrolytic chambers are connected in series and parallel to form an electrolytic cell stack, and the voltage U of the electrolytic cell stack els And consumed power P els The following formula is shown:
wherein n is 1 And n 2 The number of the electrolytic cells in series connection and the number of the electrolytic cells in parallel connection are respectively;
step S23: as shown in fig. 2, a mathematical model of a grid-connected access mode of the direct-hanging type electrolytic cell without a transformer is constructed, so that the electrolytic cell is connected to the direct-current side of a DC/AC converter, and the alternating-current side of the DC/AC converter is directly connected to a power grid without a transformer;
the basic equation of the mathematical model of the grid-connected access mode of the transformerless direct hanging type electrolytic tank is shown as follows:
wherein U is sa 、U sb 、U sc The voltages of the phase a, the phase b and the phase c of the power grid are respectively; u (U) NO Is the voltage difference between the neutral point of the power grid and the reference point; i a 、I b 、I c A, b and c phases of alternating current respectively; l and R represent the inductance in the main circuit and the parasitic resistance thereof; the voltage U of the electrolytic cell stack can be reduced due to the slow change of the electrolytic cell voltage els Equivalent to an ideal voltage source; f (F) a 、F b 、F c A phase leg switching function for the DC/AC converter; f (F) a ＝1、F b ＝1、F c =1 indicates the upper tube of a, b, c phase bridge arm is on, the lower tube is off, F a ＝0、F b ＝0、F c =0 indicates that the upper tubes of the a, b and c phase bridge arms are turned off and the lower tube is turned on respectively;
summing the above, the voltage difference U between the neutral point and the reference point of the power grid can be obtained NO The following formula is shown:
and S2, constructing a transformer-free direct hanging type electrolytic cell access mode grid-connected mathematical model, and providing model support for calculating injection current and power of the electrolytic cell hydrogen production system node and establishing a correction equation.
Specifically, the step S3 includes:
step S31: as shown in fig. 3, after the addition of the electrolyzer module, the node injection power of the transformerless direct-hanging electrolyzer hydrogen production system is as follows:
P i ＝P G -P els
wherein P is i The injection power of the i node is 1,2, and n is a natural number; p (P) G Representing node generator injection power;
and establishing a correction equation according to the calculated node injection power of the direct hanging type electrolytic tank hydrogen production system without the transformer, wherein the correction equation is shown in the following formula:
ΔP i ＝P i -U i I i ＝P G -P els -U i I i
wherein DeltaP i A power correction amount for the i-th node; u (U) i Representing the voltage at node i; i i A current representing node i;
current I at node I i The following formula is shown:
wherein Y is ii Representing the self admittance of node i; y is Y ij Representing the transadmittance between node i and node j; n represents the number of nodes; y is Y ii U els Access pair invariant for DC/AC converterCorrection amount of current injection into an access node of a pressure direct-hanging type electrolytic cell hydrogen production system; u (U) j Representing the voltage at node j;
step S32: injecting node generator into power P G Setting the current as a fixed value, solving the partial derivative of the node power correction quantity to the node voltage, and providing calculation support for the internal current of the electrolytic tank hydrogen production system to participate in the iteration of the Newton-Lawson method of continuous power flow calculation;
if the node i is connected to the electrolytic cell module, the following formula is shown:
wherein,and->The partial derivatives of the power correction quantity of the ith node to the voltages of the node i and the node j are respectively; />And->Power P respectively consumed by the stacks els Partial derivatives of the voltages at node i and node j.
And step S3, obtaining partial derivatives of the node injection current and the power correction quantity on the node voltage, and providing calculation support for participating in iteration of continuous power flow calculation and modifying the jacobian matrix according to the partial derivatives.
Specifically, the step S4 includes:
step S41: firstly, calculating an initial tide solution of a system when an electrolytic tank module is not connected, and obtaining an approximate value of a next solution according to a given step length from the initial tide solution in a tangential direction; substituting the obtained approximate value of the solution as an initial value into a power flow balance equation for iteration, and solving by adopting a Newton-Lapherson method to obtain a correction solution meeting the actual power flow balance equation; selecting a proper step length to enable the estimated approximation value to fall into a corrected convergence domain; at the flatter position of the PV (power-voltage) curve, a larger step length can be selected to improve the calculation speed, and at the position close to the inflection point of the PV curve, a smaller step length can be selected to ensure the convergence of calculation; stopping iteration until the tide balance equation is converged, and obtaining a PV curve of the system when the electrolytic tank module is not connected;
Step S42: after the continuous power flow calculation of the transformer-free direct hanging type electrolytic tank hydrogen production system is carried out after the electrolytic tank module is connected, when a jacobian matrix is formed, the jacobian matrix of the conventional power flow is increased by one step, and an augmented jacobian matrix is obtained;
the jacobian of the conventional power flow becomes a model of the load under consideration:
wherein Δu is the voltage correction amount of the node; Δp is the power correction of the node;
then carrying out iterative computation by adopting a Newton-Laportson method, and continuously modifying the jacobian matrix to obtain updated injection current I 'of the electrolytic cell' i I.e. cell current I' el Thereby obtaining the power value P' els ；
Step S43: after the electrolytic tank module is connected, starting from a given running state of the hydrogen production system of the direct-hanging type electrolytic tank without a transformer, a PV curve is obtained by gradually approaching a voltage collapse point through the increase of load or transmission power according to a certain step length, and the equation is shown as follows:
f(x)+λb＝0
x＝[δ U] T
wherein lambda is a load parameter variable; x is a state vector; f is a function vector and represents a tide equation; b is a constant vector, which represents a load increasing mode; delta is the voltage power angle vector; u is a voltage amplitude vector;
the distance from the current operating point of the system to the voltage breakdown point is a static voltage stability margin, and the static voltage stability margin is shown in the following formula:
λ VSM ＝[(λ+1)P 0 -P 0 ]/P 0
P 0 ＝P L0 -P els
Wherein lambda is VSM A static voltage stability margin for the system; p (P) 0 Is the original system payload; (lambda+1) P 0 Is the maximum payload that the system can withstand; p (P) L0 Is the initial load of the system;
the calculated electrolytic tank adopts the transformer-free direct hanging grid connection to improve the static voltage stability margin of the system, and the larger the static voltage stability margin is, the more stable the system is.
Through the step S4, the internal current of the hydrogen production system of the electrolytic tank is participated in the iteration of the Newton-Lapherson method of continuous tide calculation, each element of the jacobian matrix is continuously corrected, the static voltage stability margin of the system before and after the electrolytic tank is connected is respectively obtained through the PV curve, and the transformer-free direct hanging grid connection mode is adopted to connect the electrolytic tank, so that the voltage stability of the power grid is improved.
The invention also provides an electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, which processor implements the steps of the method when executing the program.
The invention also provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the method.
The invention also provides a device for considering the influence of the grid-connected access mode of the electrolytic cell on the voltage stability of the power grid, which comprises:
The model construction module comprises a topological structure for constructing a direct hanging type electrobath hydrogen production system without a transformer based on an electrobath, wherein the topological structure comprises an electrobath module and a power conversion system, and a mathematical model of a grid-connected access mode of the direct hanging type electrobath without the transformer is constructed based on a voltage-current relation and a steady-state model in the electrobath module, so that the electrobath module is connected to a direct current side of a DC/AC converter, and an alternating current side of the DC/AC converter is directly connected to a power grid without a transformer;
the correction calculation module comprises a step of calculating injection current and power of nodes of the direct-hanging type electrolytic cell hydrogen production system without a transformer after the electrolytic cell module is connected, establishing a correction equation, solving partial derivatives of correction to node voltages, enabling internal current of the electrolytic cell hydrogen production system to participate in Newton-Lafson method iteration of continuous tide calculation, and modifying a jacobian matrix;
the stability calculation module is used for respectively calculating continuous power flow of the electrolytic cell hydrogen production system before and after the electrolytic cell is connected into the electrolytic cell hydrogen production system and obtaining a PV curve, and obtaining a static voltage stability margin by calculating the distance from the current operating point of the system to the voltage collapse point of the PV curve.
In summary, the invention discloses a method for considering the influence of an electrolytic cell grid-connected access mode on the voltage stability of a power grid, and aims to solve the problem that the current large-scale electric hydrogen production load grid connection causes fluctuation on the voltage stability of the power grid.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. The solutions in the embodiments of the present application may be implemented in various computer languages, for example, object-oriented programming language Java, and an transliterated scripting language JavaScript, etc.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the spirit or scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims and the equivalents thereof, the present application is intended to cover such modifications and variations.
Claims (11)
1. The method for considering the influence of the grid-connected access mode of the electrolytic cell on the voltage stability of the power grid is characterized by comprising the following steps:
step S1: constructing a topological structure of a direct-hanging type electrobath hydrogen production system without a transformer based on an electrobath, wherein the topological structure comprises an electrobath module and a power conversion system;
step S2: based on the voltage-current relation and steady-state model inside the electrolytic tank module, constructing a mathematical model of a grid-connected access mode of the direct-hanging type electrolytic tank without a transformer;
step S3: calculating injection current and power of nodes of the electrolytic cell hydrogen production system after the electrolytic cell module is connected, establishing a correction equation, solving partial derivatives of correction to node voltages, and enabling internal current of the transformerless direct-hanging electrolytic cell hydrogen production system to participate in Newton-Lafson method iteration of continuous tide calculation;
step S4: and calculating continuous power flow of the electrolytic cell hydrogen production system before and after the electrolytic cell module is connected to obtain static voltage stability margin of the electrolytic cell hydrogen production system, and increasing the distance from the current operating point to the voltage collapse point according to the transformer-free direct hanging type electrolytic cell grid-connected connection mode.
2. The method according to claim 1, wherein the step S1 specifically includes:
the power conversion system comprises a direct current/alternating current (DC/AC) converter and an internal power electronic device thereof, wherein the DC/AC converter adopts a two-level three-phase bridge converter, and the internal power electronic device is composed of an Insulated Gate Bipolar Transistor (IGBT) high-frequency switching device;
the electrolytic tank module comprises a plurality of series-parallel electrolytic tank stacks, the cathode and the anode of each electrolytic tank stack are respectively connected with the input end of a corresponding DC/AC converter, and the output end of the DC/AC converter is directly connected into a power grid without a transformer after being sequentially connected in series.
3. The method according to claim 2, wherein the step S2 specifically includes:
step S21: based on the voltage-current relation and the steady-state model inside the electrolytic cell module, a voltage-current equation in a steady state is established, as shown in the following formula:
U el ＝U rev +U pol +U ohm
wherein U is el Is the terminal voltage of the electrolysis chamber; u (U) rev 、U pol And U ohm Reversible voltage, polarization overvoltage and ohmic overvoltage respectively; r, r 1 、r 2 、r 3 Is the polarization overvoltage coefficient; t is the temperature of the electrolyte; i el Is the electrolysis chamber current; s is the surface area of an electrode of the electrolytic cell; t is t 1 、t 2 And p 1 、p 2 Ohmic overvoltage temperature coefficient and pressure coefficient respectively; p is a pressure coefficient, taking 5bar;
step S22: multiple electrolytic chambers are connected in series and parallel to form an electrolytic cell stack, and the voltage U of the electrolytic cell stack els And consumed power P els The following formula is shown:
wherein n is 1 And n 2 The number of the electrolytic cells in series connection and the number of the electrolytic cells in parallel connection are respectively;
step S23: constructing a mathematical model of a grid-connected access mode of the direct-hanging type electrolytic tank without a transformer, connecting the electrolytic tank to the direct-current side of the DC/AC converter, and directly connecting the alternating-current side of the DC/AC converter to a power grid without a transformer;
the basic equation of the mathematical model of the grid-connected access mode of the transformerless direct hanging type electrolytic tank is shown as follows:
wherein U is sa 、U sb 、U sc The voltages of the phase a, the phase b and the phase c of the power grid are respectively; u (U) NO Is the voltage difference between the neutral point of the power grid and the reference point; i a 、I b 、I c A, b and c phases of alternating current respectively; l and R represent the inductance in the main circuit and the parasitic resistance thereof; the voltage U of the electrolytic cell stack can be reduced due to the slow change of the electrolytic cell voltage els Equivalent to an ideal voltage source; f (F) a 、F b 、F c A phase leg switching function for the DC/AC converter; f (F) a ＝1、F b ＝1、F c =1 indicates the upper tube of a, b, c phase bridge arm is on, the lower tube is off, F a ＝0、F b ＝0、F c =0 indicates that the upper tubes of the a, b and c phase bridge arms are turned off and the lower tube is turned on respectively;
summing the above, the voltage difference U between the neutral point and the reference point of the power grid can be obtained NO The following formula is shown:
4. a method according to claim 3, wherein the step S3 specifically comprises:
step S31: after the electrolytic tank module is added, the node injection power of the transformerless direct hanging type electrolytic tank hydrogen production system is shown as follows:
P i ＝P G -P els
wherein P is i The injection power of the i node is 1,2, and n is a natural number; p (P) G Representing node generator injection power;
and establishing a correction equation according to the calculated node injection power of the direct hanging type electrolytic tank hydrogen production system without the transformer, wherein the correction equation is shown in the following formula:
ΔP i ＝P i -U i I i ＝P G -P els -U i I i
wherein DeltaP i A power correction amount for the i-th node; u (U) i Representing the voltage at node i; i i A current representing node i;
current I at node I i The following formula is shown:
wherein Y is ii Representing the self admittance of node i; y is Y ij Representing the transadmittance between node i and node j; n represents the number of nodes; y is Y ii U els Correction amount of current injection is performed on an access node of the transformer-free direct-hanging type electrolytic tank hydrogen production system for the access of the DC/AC converter; u (U) j Representing the voltage at node j;
step S32: injecting node generator into power P G Setting the current as a fixed value, solving the partial derivative of the node power correction quantity to the node voltage, and providing calculation support for the internal current of the electrolytic tank hydrogen production system to participate in the iteration of the Newton-Lawson method of continuous power flow calculation;
if the node i is connected to the electrolytic cell module, the following formula is shown:
wherein,and->The partial derivatives of the power correction quantity of the ith node to the voltages of the node i and the node j are respectively;and->Power P respectively consumed by the stacks els Partial derivatives of the voltages at node i and node j.
5. The method according to claim 4, wherein the step S4 specifically includes:
step S41: firstly, calculating an initial tide solution of a system when an electrolytic tank module is not connected, and obtaining an approximate value of a next solution according to a given step length from the initial tide solution in a tangential direction; substituting the obtained approximate value of the solution as an initial value into a power flow balance equation for iteration, and solving by adopting a Newton-Lapherson method to obtain a correction solution meeting the actual power flow balance equation; selecting a proper step length to enable the estimated approximation value to fall into a corrected convergence domain; at the flatter position of the power-voltage PV curve, a larger step size can be selected to improve the calculation speed, and at the position close to the inflection point of the PV curve, a smaller step size can be selected to ensure the calculation convergence; stopping iteration until the tide balance equation is converged, and obtaining a PV curve of the system when the electrolytic tank module is not connected;
Step S42: after the continuous power flow calculation of the transformer-free direct hanging type electrolytic tank hydrogen production system is carried out after the electrolytic tank module is connected, when a jacobian matrix is formed, the jacobian matrix of the conventional power flow is increased by one step, and an augmented jacobian matrix is obtained;
the jacobian of the conventional power flow becomes a model of the load under consideration:
wherein Δu is the voltage correction amount of the node; Δp is the power correction of the node;
then carrying out iterative computation by adopting a Newton-Laporton method, and continuously modifying the Jacobian matrix to obtain updated injection current I of the electrolytic cell i ' i.e. cell current I e ' l Thereby obtaining the power value P' els ；
Step S43: after the electrolytic tank module is connected, starting from a given running state of the hydrogen production system of the direct-hanging type electrolytic tank without a transformer, a PV curve is obtained by gradually approaching a voltage collapse point through the increase of load or transmission power according to a certain step length, and the equation is shown as follows:
f(x)+λb＝0
x＝[δ U] T
wherein lambda is a load parameter variable; x is a state vector; f is a function vector and represents a tide equation; b is a constant vector, which represents a load increasing mode; delta is the voltage power angle vector; u is a voltage amplitude vector;
the distance from the current operating point of the system to the voltage breakdown point is a static voltage stability margin, and the static voltage stability margin is shown in the following formula:
λ VSM ＝[(λ+1)P 0 -P 0 ]/P 0
P 0 ＝P L0 -P els
Wherein lambda is VSM A static voltage stability margin for the system; p (P) 0 Is the original system payload; (lambda+1) P 0 Is the maximum payload that the system can withstand; p (P) L0 Is the initial load of the system;
the calculated electrolytic tank adopts the transformer-free direct hanging grid connection to improve the static voltage stability margin of the system, and the larger the static voltage stability margin is, the more stable the system is.
6. A device for considering the effect of an electrolytic cell grid-connected access mode on the voltage stability of a power grid, comprising:
the model construction module comprises a topological structure for constructing a direct hanging type electrobath hydrogen production system without a transformer based on an electrobath, wherein the topological structure comprises an electrobath module and a power conversion system, and a mathematical model of a grid-connected access mode of the direct hanging type electrobath without the transformer is constructed based on a voltage-current relation and a steady-state model in the electrobath module, so that the electrobath module is connected to a direct current side of a DC/AC converter, and an alternating current side of the DC/AC converter is directly connected to a power grid without a transformer;
the correction calculation module comprises a step of calculating injection current and power of nodes of the direct-hanging type electrolytic cell hydrogen production system without a transformer after the electrolytic cell module is connected, establishing a correction equation, solving partial derivatives of correction to node voltages, enabling internal current of the electrolytic cell hydrogen production system to participate in Newton-Lafson method iteration of continuous tide calculation, and modifying a jacobian matrix;
The stability calculation module is used for respectively calculating continuous power flow of the electrolytic cell hydrogen production system before and after the electrolytic cell is connected into the electrolytic cell hydrogen production system and obtaining a PV curve, and obtaining a static voltage stability margin by calculating the distance from the current operating point of the system to the voltage collapse point of the PV curve.
7. The device for considering influence of grid-connected access mode of an electrolytic cell on voltage stability of a power grid according to claim 6, wherein the power conversion system in the model building module comprises a DC/AC converter and an internal power electronic device thereof, the DC/AC converter adopts a two-level three-phase bridge converter, and the internal power electronic device is composed of an IGBT high-frequency switching device;
the electrolytic tank module comprises a plurality of series-parallel electrolytic tank stacks, wherein the cathode and the anode of each electrolytic tank stack are respectively connected with the input end of a corresponding DC/AC converter, and the output end of the DC/AC converter is directly connected into a power grid without a transformer after being sequentially connected in series;
the model construction module is used for establishing a voltage-current equation in a steady state based on a voltage-current relation and a steady state model in the electrolytic tank module, wherein the voltage-current equation is shown in the following formula:
U el ＝U rev +U pol +U ohm
wherein U is el Is the terminal voltage of the electrolysis chamber; u (U) rev 、U pol And U ohm Reversible voltage, polarization overvoltage and ohmic overvoltage respectively; r, r 1 、r 2 、r 3 Is the polarization overvoltage coefficient; t is the temperature of the electrolyte; i el Is the electrolysis chamber current; s is the surface area of an electrode of the electrolytic cell; t is t 1 、t 2 And p 1 、p 2 Ohmic overvoltage temperature coefficient and pressure coefficient respectively; p is a pressure coefficient, taking 5bar;
multiple electrolytic chambers are connected in series and parallel to form an electrolytic cell stack, and the voltage U of the electrolytic cell stack els And consumed power P els The following formula is shown:
wherein n is 1 And n 2 The number of the electrolytic cells in series connection and the number of the electrolytic cells in parallel connection are respectively;
constructing a mathematical model of a grid-connected access mode of the direct-hanging type electrolytic tank without a transformer, connecting the electrolytic tank to the direct-current side of the DC/AC converter, and directly connecting the alternating-current side of the DC/AC converter to a power grid without a transformer;
the basic equation of the mathematical model of the grid-connected access mode of the transformerless direct hanging type electrolytic tank is shown as follows:
wherein U is sa 、U sb 、U sc The voltages of the phase a, the phase b and the phase c of the power grid are respectively; u (U) NO Is the voltage difference between the neutral point of the power grid and the reference point; i a 、I b 、I c A, b and c phases of alternating current respectively; l and R represent the inductance in the main circuit and the parasitic resistance thereof; the voltage U of the electrolytic cell stack can be reduced due to the slow change of the electrolytic cell voltage els Equivalent to an ideal voltage source; f (F) a 、F b 、F c A phase leg switching function for the DC/AC converter; f (F) a ＝1、F b ＝1、F c =1 indicates the upper tube of a, b, c phase bridge arm is on, the lower tube is off, F a ＝0、F b ＝0、F c =0 indicates that the upper tubes of the a, b and c phase bridge arms are turned off and the lower tube is turned on respectively;
summing the above, the voltage difference U between the neutral point and the reference point of the power grid can be obtained NO The following formula is shown:
8. the device for considering the influence of the grid-connected access mode of the electrolytic cell on the voltage stability of the power grid as claimed in claim 6, wherein the correction calculation module comprises, after adding the electrolytic cell module, the node injection power of the transformerless direct-hanging type electrolytic cell hydrogen production system is as follows:
P i ＝P G -P els
wherein P is i The injection power of the i node is 1,2, and n is a natural number; p (P) G Representing node generator injection power;
and establishing a correction equation according to the calculated node injection power of the direct hanging type electrolytic tank hydrogen production system without the transformer, wherein the correction equation is shown in the following formula:
ΔP i ＝P i -U i I i ＝P G -P els -U i I i
wherein DeltaP i A power correction amount for the i-th node; u (U) i Representing the voltage at node i; i i A current representing node i;
current I at node I i The following formula is shown:
wherein Y is ii Representing the self admittance of node i; y is Y ij Representing the transadmittance between node i and node j; n represents the number of nodes; y is Y ii U els Correction amount of current injection is performed on an access node of the transformer-free direct-hanging type electrolytic tank hydrogen production system for the access of the DC/AC converter; u (U) j Representing the voltage at node j;
injecting node generator into power P G Setting the current as a fixed value, solving the partial derivative of the node power correction quantity to the node voltage, and providing calculation support for the internal current of the electrolytic tank hydrogen production system to participate in the iteration of the Newton-Lawson method of continuous power flow calculation;
if the node i is connected to the electrolytic cell module, the following formula is shown:
wherein,and->The partial derivatives of the power correction quantity of the ith node to the voltages of the node i and the node j are respectively;and->Power P respectively consumed by the stacks els Partial derivatives of the voltages at node i and node j.
9. The device for considering influence of grid-connected access mode of an electrolytic cell on voltage stability of a power grid according to claim 6, wherein the stability calculation module firstly calculates an initial power flow solution of a system when the electrolytic cell module is not accessed, and obtains an approximate value of a next solution according to a given step length from the initial power flow solution in a tangential direction; substituting the obtained approximate value of the solution as an initial value into a power flow balance equation for iteration, and solving by adopting a Newton-Lapherson method to obtain a correction solution meeting the actual power flow balance equation; selecting a proper step length to enable the estimated approximation value to fall into a corrected convergence domain; at the flatter position of the PV (power-voltage) curve, a larger step length can be selected to improve the calculation speed, and at the position close to the inflection point of the PV curve, a smaller step length can be selected to ensure the convergence of calculation; stopping iteration until the tide balance equation is converged, and obtaining a PV curve of the system when the electrolytic tank module is not connected;
After the continuous power flow calculation of the transformer-free direct hanging type electrolytic tank hydrogen production system is carried out after the electrolytic tank module is connected, when a jacobian matrix is formed, the jacobian matrix of the conventional power flow is increased by one step, and an augmented jacobian matrix is obtained;
the jacobian of the conventional power flow becomes a model of the load under consideration:
wherein Δu is the voltage correction amount of the node; Δp is the power correction of the node;
then carrying out iterative computation by adopting a Newton-Laportson method, and continuously modifying the jacobian matrix to obtain updated injection current I 'of the electrolytic cell' i I.e. cell current I' el Thereby obtaining the power value P' els ；
After the electrolytic tank module is connected, starting from a given running state of the hydrogen production system of the direct-hanging type electrolytic tank without a transformer, a PV curve is obtained by gradually approaching a voltage collapse point through the increase of load or transmission power according to a certain step length, and the equation is shown as follows:
f(x)+λb＝0
x＝[δ U] T
wherein lambda is a load parameter variable; x is a state vector; f is a function vector and represents a tide equation; b is a constant vector, which represents a load increasing mode; delta is the voltage power angle vector; u is a voltage amplitude vector;
the distance from the current operating point of the system to the voltage breakdown point is a static voltage stability margin, and the static voltage stability margin is shown in the following formula:
λ VSM ＝[(λ+1)P 0 -P 0 ]/P 0
P 0 ＝P L0 -P els
Wherein lambda is VSM A static voltage stability margin for the system; p (P) 0 Is the original system payload; (lambda+1) P 0 Is the maximum payload that the system can withstand; p (P) L0 Is the initial load of the system;
the calculated electrolytic tank adopts the transformer-free direct hanging grid connection to improve the static voltage stability margin of the system, and the larger the static voltage stability margin is, the more stable the system is.
10. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor when executing the program implements a method of taking into account the effect of the grid connection access mode of an electrolysis cell on the voltage stability of a grid as claimed in any one of claims 1 to 5.
11. A non-transitory computer readable storage medium having stored thereon a computer program, which when executed by a processor implements a method according to any of claims 1-5 taking into account the influence of the grid-connected access mode of an electrolysis cell on the voltage stability of the grid.
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