91 results about "Multi machine system" patented technology

System and method for managing data fail-over for a computing system comprising a plurality of computers, e.g., computer blades, coupled through a network. A fail-over condition may indicate a component failure, an imminent failure, and / or a need to modify or replace some aspect of a computer. Computers in the system may back up their information to other computers in the system. If a fail-over condition is detected on a first computer, a replacement computer may be loaded with the information from the first computer, optionally from a backup copy stored on another computer (or distributed across multiple computers), and the first computer's peripheral devices (human interface) switched over to the replacement computer. The method may be used to replace a single computer, swap two computers, and / or perform a cascade move among multiple computers, and may be performed automatically in response to the fail-over condition, or initiated by a system administrator.

The invention discloses an online transient stability analysis method based on a concise expression form of electromagnetic power of a single generator in a multi-machine power system. Electromagnetic output power of any single generator in the power system is a multivariable nonlinear function of all generator load angles or a multivariable nonlinear function of a slip between all generator load angles and an inductor rotor, which is known by analyzing the traditional power system. A concise expression form of the electromagnetic output power of any single generator in the complex power system is obtained through expanding a Taylor series; a load angle swinging curve of a multi-machine power system and an electromagnetic power curve are obtained through time domain simulation, and a coefficient in a high-order polynomial function is obtained by using data fitting; the load angle curve obtained through the fitting is extended to obtain a predictive load angle curve of a future moment, and the stability margin of the single generator in the multi-machine system and the system can be obtained by using the obtained concise expression form of the single generator load angle curve. The invention can be used for the online transient stability analysis of the large-scale power system.

The invention discloses a multi-port memory controller based on block transmission comprising a detection address selection unit, a conflict detection unit, a conflict treatment unit correspondent to a plurality of ports, a selector correspondent to a plurality of ports and a plurality of module selectors. Said multi-port memory controller receives block transmission request from a plurality of independent ports, conducts conflict detection and conflict treatment to the request, controls multi-path request and conflict free accesses the memory in a synchronous parallel mode. The multi-port memory composed of the multi-port storage controller and a plurality of current mono-port storage chips supports synchronous parallel block transmission from a plurality of ports, when compared to the prior multi-port memory, the invention has low lost, favorable expansion and maintenance property and high share rate. The multi-port memory can be used as a data channel between the junctions in a multi-machine system to provide a high-speed, low-delay communication.

The invention discloses an air conditioning system and a method for detecting a liquid level of an air-liquid separator of the air conditioning system. The air conditioning system comprises a compressor, a four-way valve, an outdoor heat exchanger, a throttling device, an indoor heat exchanger, the air-liquid separator and a detecting pipeline. The detecting pipeline is connected among the compressor, the air-liquid separator and the four-way valve and is used for detecting the liquid level of the air-liquid separator. The air conditioning system and the method have the advantages that the internal liquid level of the air-liquid separator is detected and judged, corresponding control is executed by outer machines when the liquid level of the air-liquid separator is higher than a warning liquid level, the internal liquid level of the air-liquid separator is adjusted under output actions of the outer machines and adjustment actions of valves and is within a safety range, problems that return air of a compressor carries liquid, the compressor runs under an excessively wet condition and liquid impact occurs due to an excessively high internal liquid level of an air-liquid separator are solved, safe and reliable running of an outer machine system is guaranteed, and drifting among the outer machines in the multi-machine system can be effectively prevented.

The invention discloses a transient state power angle stability analysis method for a wind power plant-containing multi-machine system. The transient state power angle stability analysis method comprises the steps of disclosing a mutual synchronicity principle for influencing the power angle of a synchronous machine by a double-fed wind power plant by means of transferring active and reactive power to a power grid for realizing electrical interaction with the synchronous machine, and reflecting the externally output power characteristic of a double-fed fan by parallel connection grounding admittance; performing two times of contraction treatment on a node voltage equation of the double-fed fan-containing multi-machine system, combining the active and reactive information included in the double-fed fan into an admittance matrix of the synchronous machine nodes, namely, converting the influence of the double-fed fan on the electromagnetic power of the synchronous machine into changes on the electrical relation intensity between the synchronous machines; and performing analysis on the mutual synchronicity of the power angle of the synchronous machine of the multi-machine system and the transient state stability of the multi-machine system with wind power plant access, according to the contraction treatment result by combination with a node injection current formula and an expansion equal-area criterion.

The invention discloses a velocity synchronizing self-adapting inverse controlling means of IC material linear cutting machine multi-machine system for the problem existing in traditional PID controlling method. In multi-machine system linear velocity synchronous tracking controlling, the main electric machine system is identified in self-adaptive algorithm by using main electric machine as reference model, the main electric machine mathematical model obtained by identification self-adapting adjust the controller, and then the obtained self-adaptive controllers controls the linear speed of the driven electric machine to track the linear speed of main electric machine. The invention has advantages indicated by testing such as high control precision, stable operation and low tear string failure rate and so on.

The invention relates to a positioning and analyzing method of an oscillation center based on reactive power integral in a multi-machine system. The method comprises the following steps of 1, obtaining dynamic response data of a power grid; 2, extracting the data of a large power grid, so as to obtain the required generator power angle, bus voltage size, bus power and phase angle difference of voltages at the two ends of a connecting line; 3, grouping the system according to the relative power angle of a generator; 4, observing the fluctuation condition of the voltage of a critical branch; 5, carrying out reactive integral on the possible oscillation center; and 6, using the phase angle difference of the bus voltage to detect the obtained branch. The method has the advantages that the cross section of the oscillation center is determined by the reactive power integral of the branch under the assisting of the variation features of electric amount of the oscillation center and the relative power angle difference of the generator, the speed and the precision of the original reactive power integral method are improved, the effect by the running method and the structure change of the power grid is avoided, the method is visual and accurate, the implementation is easy, and the reliability is high.

The invention relates to the field of a multi-machine test system formed by multiple electronic devices, and discloses an electronic device whose internal part is integrated with a synchronization module. Each electronic device can be configured into the role of a master machine or a slave machine, wherein the master machine provides synchronization signals for other slave machines, the synchronization signals comprise synchronization clock signals and synchronization control signals, the slave machines receive and execute the synchronization signals sent by the master machine at the same time, and the operating state of the whole synchronization system is coordinated and allocated. The multi-machine system formed by the multiple electronic devices is simple in hardware connection, two types of synchronization signal terminals are only required to be sequentially connected, the master device and the slave device are configured on software, all of the slave devices are uniformly dispatched and controlled by the master device to operate, and the master device and the slave devices adopts the same clock source and the same control source, thereby ensuring synchronization control of the multiple machines, and realizing a synchronization function of the system.

The invention discloses a method for evaluating the new energy acceptance capacity of a grid-connected point by comprehensively considering the stability characteristic, and belongs to the technical field of automation of power systems. The influences of wind power generation variability and instability on a power grid, an external load level and the change condition thereof are combined; a multi-machine system is equivalent to a single-machine infinite bus system through an EEAC method by employing a static stability constraint, reactive power control and a transient constraint of the power system as conditions; the stability margin and the sampling yield are calculated; and the capability of connecting a wind power station of considering a transient stability constraint to the power grid to the maximum extent is evaluated by employing the specified range of the sampling yield as an index. By the method, the safe and stable operation level of the wind power station can be improved; the generating capacity of the wind power station is effectively ensured; and the benefits of energy conservation and emission reduction are improved.

The invention relates to a judging method for first two swaying stability of a transient state power angle of a wind power integration system. The judging method comprises steps of structuring an equivalent one machine infinity bus system model applicable to quantitative and qualitative analysis of the transient state power angle stability of a wind-power-containing multi-machine system; calculating the actual grid data by using the OMIB (one machine infinity bus) model; judging a second swaying stability according to sufficient and necessary conditions of the second swaying unstability of the transient sate power angle of the wind power integration system; confirming a relationship between the second swaying stability and the first swaying stability of the power angle in the wind power integration system and judging the stability of first two swaying of the transient state power angle. The judging method expands the transient state power angle stability analysis method which only concerns the unstability of the first swaying after the integration of wind power at present, and provides a theoretical guidance for the transient state stable control of the large scale wind power centralized grid-connected electricity system.

The invention discloses a mobile base station, a one-station multi-machine system, a communication method and a control method. The mobile base station comprises a base body, a GPS module arranged onthe base body, a base station data transmission station and a network communication module, and the network communication module is a public network wireless data transmission module or a WIFI module.According to the one-station multi-machine system, Accurate differential positioning is provided for the unmanned aerial vehicle by adopting the mobile base station, the GPS positioning precision ofthe unmanned aerial vehicle is ensured, redundant communication connection between the unmanned aerial vehicle and the background processing center is realized by utilizing the mobile base station, effective function realization in an area with poor signals is ensured, and a base station forwarding scheme is that redundancy is carried out on a control link by the aircraft in a weak network environment.the reliability of communications is improved.

The invention relates to a method for improving the transient stability of a system by combining a crowbar circuit and an energy storage device. The method is applied to a multi-machine system with afan; and a rotor-side crowbar protection circuit is employed and a superconducting energy storage device is installed at the exit of a wind power plant. The method comprises: when the system works normally, the superconducting energy storage device works in a work mode of stabilizing output fluctuation of the fan; when a short-circuit fault occurs at the system, the voltage at the grid-connected point of the fan is reduced, the rotor current reaches a set value, the rotor-side crowbar protection circuit starts to work, and the work mode of stabilizing output fluctuation of the fan is changed into a work mode with a fault after the superconducting energy storage device detects a crowbar signal change; the superconducting energy storage device starts detecting a power angle difference signalbetween two synchronous machines of the two-machine systems; and when the absolute value of a difference between a power angle difference signal at a current time and a power angle difference signalat a previous time is larger than a set value epsilon, the superconducting energy storage device works continuously in the work mode with a fault.

The invention discloses an unmanned aerial vehicle one-station multi-machine system air-ground data link channel allocation method, and aims to provide a link channel allocation method capable of reducing the operation complexity and improving the channel resource reuse degree. The method is realized through the following technical scheme: a ground control station obtains unmanned aerial vehicle platform position information, counts the number of air-ground data links, calculates included angles between every two air-ground data links, and performs descending order arrangement on all includedangle values; then, starting from the air-ground data link corresponding to the maximum included angle, a 'super link' is constructed according to the relation between the included angle between the links and a 'multiplexing threshold', and the number of the air-ground data links contained in the super link is taken as the weight of the super link; the ground control station iteratively performs the super link merging process until no super link which can be further merged exists, and the channel resources are evenly distributed to each super link; and after the distribution process is finished, the channel distribution result is sent to the unmanned aerial vehicle platform through the uplink air link.

The invention provides a low-frequency oscillation suppression strategy design method for a multi-machine system by a photovoltaic power station based on the VSG technology. The method comprises the steps of establishing a multi-machine system mathematical model containing the photovoltaic power station; establishing a VSG control strategy model of the grid-connected inverter of the photovoltaic power station by simulating a rotor motion equation of a synchronous generator; designing a self-adaptive virtual inertia control strategy for the VSG control strategy model of the grid-connected inverter of the photovoltaic power station; and designing a WPSS low-frequency oscillation suppression strategy based on wide-area signal control in the VSG control strategy model of the grid-connected inverter of the photovoltaic power station according to a power system stabilizer equipped for a power generator set. According to the invention, low-frequency oscillation in the multi-machine system andpower low-frequency oscillation on a tie line are suppressed.

The invention discloses a multi-machine system difference adjustment coefficient optimization method based on sensitivity analysis, and the method comprises the steps: firstly obtaining the track sensitivity of a difference adjustment coefficient R, an inertia time constant M and a load damping coefficient D to the frequency deviation of a power system, analyzing the impact on the maximum frequency deviation from the track sensitivity of all parameters, and determining a dominant parameter of the maximum frequency deviation as a difference adjustment coefficient R; establishing a mathematicalmodel of difference adjustment coefficient R optimization, and converting a nonlinear optimization problem of the established mathematical model into a linear programming problem by adopting a sensitivity analysis method; and optimizing and sequencing the units according to the sensitivity of the difference adjustment coefficients of the units of the power system, and optimizing the difference adjustment coefficients of the units in sequence. The method can guarantee the output stability of the synchronous unit while meeting the system frequency stability, and fully excavates the frequency modulation capability of the synchronous unit.

The invention discloses a multi-machine system speed governor PID parameter optimization method, comprising the steps of obtaining an initial optimization value range to obtain various particles and aparticle swarm according to the initial optimization value range; for each particle, the position variable of the particle is substituted for the PID parameter of the corresponding unit governor. Thefitness function is obtained according to the weighted sum of the system oscillation damping and the frequency modulation response speed of the generator set under the fault. According to the fitnessfunction, the fitness function value of each particle is obtained, and the fitness function value of the particle is compared with the optimal fitness function value of the particle swarm at the current time. When the fitness function value of the particle is better than the optimal fitness function value of the particle swarm, updating the optimal fitness function value of the particle swarm andthe optimal position of the particle swarm according to the position of the particle; And updating the state of the particles; When the optimal fitness function value of particle swarm satisfies thepreset precision, the optimal PID parameters are obtained. The convergence speed of a particle swarm and the optimization efficiency of the algorithm are improved.

The invention discloses an equivalent modeling method for an offshore wind power system suitable for reactive compensation. The equivalent modeling method comprises the following steps: I, grouping wind power generators in a wind power plant according to a topological structure of the offshore wind power system, wherein each group comprises at least one wind power generator; II, working out the total capacity of equivalent wind power generator sets by adopting a load flow calculation method, wherein a branch formed by multiple wind power generators of each group becomes a single-chain branch of the corresponding wind power generator set, and equivalent capacity is the sum of the capacity of all the wind power generator sets; III, performing equivalent analysis on transformers in the wind power generators of each group to obtain an equivalent multi-machine system; IV, performing the equivalent analysis on current collection systems of the multiple groups of wind power generators to obtain an equivalent multi-chain system; V, establishing a simulation model of the offshore wind power system suitable for the reactive compensation according to results obtained in the steps II, III and IV. The modeling method disclosed by the invention is simple, capable of establishing the model rapidly and better meets the requirement of practical application.

The invention discloses characteristic value analysis model and step for the subsynchronous resonance analysis of a multi-machine power system, relating to the field of characteristic value analysis models of the subsynchronous resonance analysis of the power system. The deducing and calculating process of a method comprises the following step of: respectively writing a rotor motion equation of amultimass block model of a shaft system of a steam turbine generator, an electromagnetic transient state equation of a magnetic chain and the voltage of a generator, an electromagnetic transient state equation of a power transmission line, an electromagnetic transient state equation of a series-connected compensation capacitor and a control system equation of an excitation controller and the like. The invention obtains a differential equation set related to a state quantity by linearizing the equations on a stable-state operating point and can solve the characteristic value and the characteristic vector of a state equation coefficient matrix on the basis, obtain much information related to resonance damping characteristics by judging the stability of the subsynchronous resonance of the multi-machine power system and can be used for designing a controller to inhibit the subsynchronous resonance of the multi-machine power system by combining with a control theory.

A method and a device for calculating that lowest frequency of a power system in the absence of high power are disclosed. The method comprises a construction step, Simplify Steps Once, Secondary Simplified Steps, Resolution Steps, Combined with the content of primary frequency modulation in frequency control system, the physical process of frequency response is analyzed, qualitative analysis of the frequency change trend after disturbance, the frequency response equivalent model of multi-machine system is constructed. Two simplification methods, frequency feedback loop decomposition and frequency response characteristic fitting, are used to simplify the complex multi-machine system. The time domain expressions of the lowest frequency and its corresponding time are derived by analytic method, Simple and practical calculation of the lowest frequency of the power system, and then through quantitative analysis to achieve better coordination with the relay protection, improve the frequencyresponse of the execution speed, change the frequency fluctuation transient process, so as to avoid the occurrence of low-frequency load shedding and other accidents, to better ensure the frequency stability of the system, to maintain the stability of the operation of the power system.

The invention provides a multicomputer system priority chain voting device applied to a space application. The device comprises a plurality of identical subsystems which are installed on computers respectively, each subsystem comprises a local machine Fv voting module and a local machine MC state control module, each local machine Fv voting module is valid in output when the situation that a local machine fault-tolerant software self-inspection result is right, a multicomputer communication comparative result is right, a local machine hardware watchdog signal is invalid, a local machine reset signal is invalid and other one-machine clear local machine Fv signals are invalid is met, and each local machine MC state control module is valid in output when the situations that a local machine operation result Fv is valid and a local priority is higher than a local one-machine MC state are invalid. The device can conveniently achieve independent redundant fault-tolerance of amulticomputer system and system reconfiguration, and has the advantages of being high in real-time performance and reliability and long in service life.

The invention provides a distributed multi-machine system, control method and a control device. The distributed multi-machine system forms a multi-level relationship of the tree structure, including the root node machine, the intermediate node machine, and the leaf node machine. The root node machine and the intermediate node machine are configured to receive the heartbeat status reported by the sub-node machines, and according to the heartbeat state of the sub-node machine, the downtime of the sub-node machine is determined. The intermediate node machine and the leaf node machine are also configured to report heartbeat status to the parent node machine. Thus the check by each task machine is improved to the check by the non-leaf node machine, and the check for all the task machines is improved to check their own sub-node machines, which reduces the consumption of downtime inspection, and achieve the purpose of reduction in computing resources waste, improve the distributed multi-machine performance.

The invention discloses a parameter tuning method of a PID controller for a speed regulating system to improve the dynamic response characteristics of primary frequency modulation. A mathematical model of primary frequency modulation of a multi-machine system is established according to that frequency response characteristic of the system in the primary frequency modulation process; based on the classical control theory, a sufficient condition for judging the stability of primary frequency modulation process is given by using the relationship between the eigenequation of primary frequency modulation closed loop of single machine system and that of multi machine system, and a method for tuning the parameters of PID controller by using the sufficient condition is proposed. The method of theinvention comprehensively considers the coupling relationship between each unit in the primary frequency modulation process, has strong adaptability to various operation modes of the system, is easy to be operated in engineering practice, can effectively avoid the ultra-low frequency oscillation problem in the area with a high proportion of hydroelectric units, and improves the dynamic response characteristics of the primary frequency modulation.

The invention discloses a method for solving a transient voltage stability safety region of an AC / DC system, which utilizes an energy function method and a singular induced bifurcation theory to analyze the transient voltage stability of the AC / DC system respectively. Based on the characteristics of transient potential energy of dynamic components in AC / DC system, the parameter space of key dynamic components used to describe the safety region is found. Furthermore, the boundary of the transient voltage stability security region determined by the stability manifold and singular surface of thetransient voltage instability-dependent dominant unstable equilibrium point is constructed. Then the boundary of the safety region determined by the stable manifold of the transient voltage instability-dependent dominant unstable equilibrium point and the boundary of the safety region determined by the singular surface are obtained by Q-linear approximation and second-order Taylor expansion respectively. By analyzing the influence of a plurality of dynamic components on the transient voltage stability in a multi-machine system, the invention selects key parameters to form a dynamic safety region space, which is favorable for an operator to quickly and effectively monitor the system.

The invention relates to a multi-point access regional load inertia time constant identification method. The method comprises the following steps: step 1, proposing a generalized inertia of a power system based on a synchronous generator inertia expression, giving a load inertia calculation formula based on a power fluctuation and frequency change relation, and calculating an inertia time constant of a load by taking load output as a reference; step 2, for a single-point access load, adopting a load grid-connected point voltage frequency curve and a load power curve, and adopting a least square method to identify a load inertia and an inertia time constant; and step 3, referring to a multi-machine system synchronous generator comprehensive inertia time constant calculation formula, and adopting a weighted conversion method to calculate a multi-point access regional load inertia time constant. According to the method, inertia identification is carried out by adopting the least square method, the optimal function matching between the load disturbed power and the grid-connected point voltage frequency can be searched through the quadratic sum of the minimum error, and the accuracy is improved; and a regional load inertia time constant conversion method is established for a multi-point access load.

The invention discloses a simplified calculation method and device for long-process frequency response of a power system. The method comprises the following steps of obtaining dynamic response data ofthe power system through a disturbance test or historical observation data; identifying a simplified model of the prime mover and speed regulator part of each synchronous generator according to the actually measured frequency response curve and the output mechanical power change curve; wherein a multi-machine system is equivalent to a single-machine equivalent system, the long-process frequency response of a power system is calculated, and the defects that accurate parameters of all links of the system cannot be obtained, the calculated amount is large and the calculation precision is poor inan existing method are overcome. The frequency domain simplified model of the prime motor and the speed regulator are optimized and identified through a least square method, the dynamic state of a boiler and a control system of the boiler is considered, the precision of the model is improved, and the order of the model is reduced; A multi-machine power system is equivalent to a single-machine equivalent model, so that the scale of the solved problem is reduced, the calculation amount is reduced, and the calculation speed is increased; Reference is provided for frequency analysis and safe andstable control of a power system.

The invention relates to an analysis method for the influence of wind farm access on a fault limit cut-off time of a multi-machine system. Based on a transient energy function theory, starting from anoriginal multi-machine system, a first integral method is used to construct a transient state energy function of the multi-machine system including a wind farm. On the basis, a relationship between acritical energy value of the system and the transient output power of the wind farm is derived, the change of a critical energy borne by the system brought by the change generated by a network topology structure due to the access of a DFIG is quantitatively analyzed, and the influence of the wind farm access on system stability margin is reflected from the perspective of critical energy. According to the influence of the DFIG on the equivalent electromagnetic power of the system during a fault period, the change of a system state variable and an energy accumulation process are analyzed, and the influence mode of the wind farm access system on the speed of the system transient energy accumulation is given. The fault limit cut-off time is calculated by the accumulation time from the transient energy to the system critical energy.

The invention relates to an online active splitting control method and system for an electric power system. The method comprises the steps of performing unit grouping prediction by combining neighborhood high-dimensional visualization and an M-mean root cluster polymerization method, then establishing a short-term power load prediction model combining an NRS theory and a global evolutionary optimization algorithm by taking island power balance constraints into consideration, and optimizing the load grouping; determining the number of split islands and initial search nodes through a dendrite deep learning algorithm by using the grouping results of units and loads on the basis; then solving the optimal splitting section by adopting a GA search algorithm so as to realize the quick solution of the whole network; and finally, optimizing and adjusting the output of a generator set of each island which does not meet the safety constraint so as to maintain the safe operation of each island. The invention realizes an online active splitting control algorithm, effectively solves a problem of cluster instability of a multi-machine system and ensures the stable operation of the islands.

The invention discloses a multi-machine infinite power system dynamic area division sliding mode controller with SVC. The implementation of the controller comprises the following steps: 1) modeling for a multi-machine infinite power system with SVC; 2) under a condition that an actuator fails, establishing a multi-machine system model containing a failure fault; 3) adopting an RBF neural network to approach an unknown function in the system model; and 4) combining a dynamic surface controller design method with an integral sliding mode, and designing the self-adaptive controller of the multi-machine power system with the SVC. In the invention, on the basis of parameter uncertainty and external disturbance of a multi-machine power system, a failure fault condition of the actuator is considered; and an adaptive fault-tolerant control method is adopted to finally form a dynamic area division sliding mode coordination controller of SVC and generator excitation, convergence of a state tracking error to zero in finite time is realized, an anti-interference capability, a convergence speed and tracking precision of the system are improved, and all signals of the whole control system are ensured to be semi-globally consistent and finally bounded.

The invention discloses an online stability analysis method, and aiming at solving the problem that the system transient stability online calculation is complex and low in speed, a method for piecewise linearization after power angle approximation polymerization is provided, and the stability margin of the system after a fault is calculated online. Firstly, the additional impedance of an asymmetric fault is calculated by means of a positive sequence equivalent rule; network simplification is completed under the condition that additional impedance is considered, and a network model is obtained,wherein all nodes except an internal potential node, of the network model are eliminated. On the basis, a relative acceleration equation of a multi-machine system is converted into an equivalent single-machine infinite high-power bus system equation form. By establishing a segmented linear model, an expression of a power angle of a generator and an analysis analytical expression of system stability margin are obtained. For the stability margin expression, the stability degree of the system can be quickly judged according to the calculated fault removal angle. The method has the technical effects that the calculation speed is high and the accuracy is high; and finally, the effectiveness of the method is verified through simulation.

The invention relates to a wind power plant configuration method being beneficial to the transient stability of a multi-machine power system. After wind power plant access, a system node voltage equation is corrected and shrunk; external characteristics, representing the low voltage ride-through performance, of the wind power plant power and position information of a connected multi-machine systemof the wind power plant are reflected to electrical connection of synchronous machines; on the basis of a node power equation, a relationship of the influence on the equivalent mechanical power of the system by a wind power plant access position and a transient output characteristic is deduced; and a rule beneficial to the transient power angle of the multi-machine system is obtained based on thechanging of the equivalent mechanical power and thus a wind power plant access position and a reasonable configuration plan of the corresponding low-voltage protection measure are provided based on the rule.