Efficient localization of ground faults in energized power systems such as photovoltaic arrays

Abstract

The present disclosure provides a method for efficiently localizing ground faults in an electrical circuit. To implement this method, a transmitter device ("transmitter") is electrically coupled to a first connection location of the electrical circuit. The transmitter is capable of transmitting a trace signal into the electrical circuit. This trace signal can be followed to identify the location of a ground fault within the circuit.

Description

EFFICIENT LOCALIZATION OF GROUND FAULTS IN ENERGIZED POWERSYSTEMS SUCH AS PHOTOVOLTAIC ARRAYSFIELD

[0001] The present disclosure relates generally to localization of ground faults. More particularly, the present disclosure relates to systems and methods for the efficient localization of ground faults in energized DC power systems such as photovoltaic arrays.BACKGROUND

[0002] A ground fault is an unintended electrical connection between an energized conductor and a grounded element, usually the metal framework of a system or earth ground. A ground fault can occur when the insulation on a wire gets damaged or when a live wire comes into contact with a conductive, grounded object. Ground faults are problematic as they allow current to flow along unintended paths, which can result in overheating, safety hazards, system malfunctions, or electrical fires.

[0003] As one example, in a photovoltaic (PV) system, ground faults can disrupt energyproduction and pose risks to system components and personnel due to the hazardous voltages involved. For example, when a ground fault occurs in a photovoltaic (PV) solar array, the inverter of the PV array may shut down, halting energy production until the fault is resolved. The task of locating a ground fault is often challenging, time-consuming, and potentially hazardous. Technicians may spend hours using different tools and workflows to detect the fault, manipulating numerous hazardous-voltage disconnection / connection locations.

[0004] Specifically, a range of factors makes ground fault detection difficult. The large scale of many solar arrays, particularly utility-scale solar farms, complicates the search for a fault that could be situated anywhere among thousands of panels connected to a single inverter. Additionally, the electrical topology of these arrays, featuring numerous parallel branches of strings and feeders tied to a common bus, means that an abnormal voltage resulting from a fault on one string may be seen across many other parts of the system. These issues, combined with the laborious process of disconnecting branches to isolate the fault, contribute to the complexity and time-consuming nature of the task.

[0005] The physical demands of the process further complicate matters. Making the necessary disconnections and connections can be laborious, particularly when it involves manual fastening of lugs or wire terminals. The often tricky process of accessing or identifying the specific wires between array elements due to their close bundling or obscurepositioning is also time-consuming. The need to effectively manage this intricate process of search and elimination requires significant training and skill, potentially leading to errors or additional wasted time if handled by less-trained technicians.

[0006] Beyond the practical difficulties, the above factors also increase the exposure to hazards. As solar sites typically produce hazardous voltages, even during daylight hours, technicians repeatedly face exposure to dangerous voltage levels, especially when they must make connections or disconnections at energized terminals. These connections or disconnections bring the technician into close proximity to dangerous electrical potential. With every' wire that is disconnected, a risk exists that the wire may be incorrectly reconnected in an unsafe configuration. Additionally, the often challenging terrain and extreme weather conditions can lead to an increased likelihood of injury, particularly when technicians are reaching for wires or attempting to lift panels while simultaneously encountering hazardous voltage.SUMMARY

[0007] Aspects and advantages of embodiments of the present disclosure will be set forth in part in the following description, or can be learned from the description, or can be learned through practice of the embodiments.

[0008] One example aspect of the present disclosure is directed to a method for efficiently localizing ground faults in an electrical circuit. To implement this method, a transmitter device (“transmitter”) is electrically coupled to a first connection location of the electrical circuit. The transmitter is capable of producing a trace signal within an electrical circuit. This trace signal can be followed to identify the location of a ground fault within the circuit.

[0009] Other aspects of the present disclosure are directed to various systems, apparatuses, non-transitory computer-readable media, user interfaces, and electronic devices.

[0010] These and other features, aspects, and advantages of various embodiments of the present disclosure will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate example embodiments of the present disclosure and, together with the description, serve to explain the related principles.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Detailed discussion of embodiments directed to one of ordinary skill in the art is set forth in the specification, which makes reference to the appended figures, in which:

[0012] Figure 1 depicts a block diagram of an example system for detecting the location of ground faults according to example embodiments of the present disclosure.

[0013] Figure 2 depicts a flowchart diagram of an example method for localizing ground faults according to example embodiments of the present disclosure.

[0014] Figures 3A-B depict graphical diagrams of performance of an example method for localizing ground faults according to example embodiments of the present disclosure.

[0015] Figures 4A-B depict graphical diagrams of performance of an example method for localizing ground faults according to example embodiments of the present disclosure.

[0016] Figure 5 depicts a graphical diagram of performance of an example method for localizing ground faults according to example embodiments of the present disclosure.

[0017] Figures 6A-D depict graphical diagrams of example configurations for localizing ground faults according to example embodiments of the present disclosure.

[0018] Figures 7A-D depict graphical diagrams of example configurations for localizing ground faults according to example embodiments of the present disclosure.

[0019] Figures 8 A and 8B depict schematic diagrams of example transmitter circuitry' according to example embodiments of the present disclosure.DETAILED DESCRIPTION

[0020] Example aspects of the present disclosure are directed to a method for efficiently localizing ground faults in an electrical circuit. To implement this method, a transmitter device (“transmitter”) is electrically coupled to a first connection location of the electrical circuit. The transmitter is capable of transmitting a trace signal into the conductors of an electrical circuit. This trace signal can be followed to identify the location of a ground fault within the circuit.

[0021] For example, in a photovoltaic (PV) system, the transmitter can be connected in parallel to the PV array at a certain location of connection. The trace signal is then coupled onto the array, allowing it to propagate through the circuit. The trace signal can be a specific frequency and / or waveform that is distinguishable from the normal operating signals in the circuit.

[0022] To trace the trace signal, a signal detector with a proximity-based sensor can be used. This device can be a hand-held wireless receiver or a signal analyzer that is capable ofdetecting and analyzing the trace signal. A technician or other operator can use the signal detector to follow the trace signal through the electrical circuit, identifying the location at which one or more characteristics of the trace signal change. For example, the change in the one or more characteristics can be or include a change in strength, frequency spectrum, phase, or polarity of the trace signal. This location of change indicates the location of the ground fault within the circuit.

[0023] For instance, in a PV system, the technician can walk through the array field with the signal detector, monitoring the strength of the trace signal along a wire. As the technician arrives at the location of the ground fault, a signal strength of the trace signal will decrease, terminate, or otherwise have a detectable change in one or more characteristic(s) as some of the trace signal will travel to electrical ground via the ground fault, rather than propagating through the remainder of the circuit. Specifically, as examples, the strength or polarity of the trace signal may change at or near the location of the ground fault because the trace signal may be propagating from the circuit conductors to the system ground. Detecting this change in the characteristic(s) of the trace signal allows the technician to pinpoint the exact location of the ground fault in a more efficient manner.

[0024] The proposed method of identifying ground faults offers several advantages. First, it significantly reduces the time required to locate a ground fault. Instead of manually inspecting and testing each section of the circuit, the technician can quickly trace the trace signal to the fault location. Second, it reduces the number of times a technician must manipulate, connect, or disconnect high-voltage contacts. The proposed trace signal method significantly reduces the need to physically access wire pairs or directly interact with exposed hazards voltage, minimizing the risk of electrical accidents. Lastly, this method enables a workflow that is relatively simple for a less trained technician. The trace signal provides clear guidance, allowing even entry -level technicians to effectively locate ground faults in electrical circuits.

[0025] According to one aspect of the present disclosure, in some implementations, the signal detector comprises one or more wireless detection device(s) that is configured to wirelessly detect the presence of the trace signal. The wireless detector can be a current clamp that is positioned around circuit conductors, such as wiring betw een components. As an improvement, the wireless detection device(s) can also be a proximity-based sensor that is capable of wirelessly detecting the trace signal without the need for any physical connection or specific physical orientation. For example, a proximity-based sensor may be distinguished from a clamp-based device that requires a clamp to be placed in a position that physicallysurrounds one or more conductors. Thus, the proximity-based sensor can be capable of detecting the trace signal radiating from the conductor(s) without physical access to the conductor(s) or other physical contact with the electrical circuit.

[0026] For example, the signal detector device can be a portable signal analyzer that is equipped with an antenna or inductive detection coil. The detector device can be tuned to the specific frequency or waveform of the trace signal, allowing it to detect the presence of the signal as it propagates through the PV circuit. The signal detector can also be equipped with a display or indicator to provide the technician with visual feedback on the strength and / or direction of the trace signal.

[0027] By using a signal detector with a proximity-based sensor, the technician can easily move around the electrical circuit and follow the trace signal without the constraints of physical contact or access to wires. This increases the flexibility and convenience of the fault localization process, allowing the technician to quickly and accurately locate ground faults in the circuit. The proximity-based signal detector also allows the technician to follow the trace signal on conductors that are not wires and cannot be clamped, such as the conductors internal to a PV panel. As an example, if solar panels are mounted against a roof surface, it would be difficult to gain access to the conductor wires to inspect with a clamp-based sensor and the technician would have to remove panels to access the wires. In this case of limited access, a proximity-based sensor can detect the trace signal radiating from the conductors internal to the panel or from the wiring below the panel.

[0028] According to one aspect of the present disclosure, the proposed method for efficient localization of ground faults in an electrical circuit is applicable to energized electrical circuits that include one or more voltage sources (e.g., solar panels). For example, the techniques described herein can be applied to a direct current voltage supply circuit that includes one or more energized direct current voltage sources (e.g., solar panels). The ability to operate on circuits with energized voltage sources is important because, in some instances, voltage sources cannot be easily de-energized disconnected from the circuit. For example, solar panels within a solar array will always produce voltage when illuminated (e.g., during the daytime) and would have to be disconnected or fully shaded to remove the voltage source from the array. The presence of active voltage sources within a circuit can make it more challenging to efficiently and safely locate ground faults.

[0029] To address this challenge, the disclosed method utilizes a trace signal that is produced by the transmitter. The trace signal serves as a marker that can be followed toidentify the location of a ground fault within the circuit, even in the presence of active voltage sources.

[0030] For example, in an energized electrical circuit such as a power generation system, the transmitter can be connected to a single circuit or to a central location or bus that is connected to multiple circuit branches that make up a larger overall circuit. When the trace signal is transmitted into the circuit, the signal propagates as a current through the conductors and components, passes to the ground through the ground fault, and returns on the ground to the transmitter creating a current loop.

[0031] By applying the method to energized electrical circuits, the proposed method offers a valuable solution for fault localization in these types of circuits. It eliminates the need for power shutdowns or other complex procedures that may be required to locate ground faults in energized circuits and / or which may be infeasible in certain power generating circuits such as PV arrays. Instead, the technician can rely on the trace signal to efficiently and safely locate ground faults, minimizing interruptions to the operation of the electrical system.

[0032] According to another aspect of the present disclosure, the proposed method for efficient localization of ground faults in an electrical circuit is particularly applicable to ungrounded electrical circuits. In an ungrounded system, also known as a floating system, no conductors are intentionally connected to earth ground (or only a high impedance connection is made to earth ground).

[0033] In some instances, when a PV array is producing power, one side of the system (positive or negative) is intentionally tied to ground. When a ground fault occurs, however, the load is removed, the ground fault protection circuit removes the tie to ground, and the array conductors float relative to the ground. Therefore, in the ground fault troubleshooting state, a PV array can be considered as one type of ungrounded power system.

[0034] In various industries, some AC power systems are configured as ungrounded power system and are also referred to as “Isole-terre” (IT) designs. Sometimes IT designs are used for industries with sensitive equipment or where shutdown due to a ground fault would be very costly. One of the key characteristics of such systems is that a single ground fault does not result in a large ground fault current as there’s no return path to the source. At the same time, it is important to locate faults in these systems before they become hazardous or a second fault arises that could create an uncontrolled current loop. Detecting and locating faults in these systems where the circuit remains energized is challenging.

[0035] To address this challenge, the disclosed method utilizes the trace signal produced by the transmitter as an electrical current on a circuit conductor. When the trace signal encounters a ground fault, the signal current passes from the conductor, through the fault, and returns along a path through the ground. This path creates a closed loop or fault path that can be detected and followed by the proximity -based signal detector, allowing the technician to pinpoint the location of the ground fault where the signal passes from the conductor to the ground.

[0036] For example, in a system such as an ungrounded PV array, the technician can connect the transmitter to a bus or terminal of the array and the system ground. The transmitter then transmits the trace signal into the array. As the technician uses the signal detector to trace the trace signal, they can follow its path through the array conductors that are part of the fault path. When the technician reaches the point at which the trace signal fades from the conductor, the lost signal indicates the presence of a ground fault at that location.

[0037] By applying the method to ungrounded electrical circuits, the proposed method offers a valuable solution for fault localization in these types of circuits. It eliminates the need for complex and time-consuming testing methods that may be required in ungrounded circuits. Instead, the technician can rely on the trace signal to efficiently locate ground faults, saving time and effort in fault identification and repair.

[0038] With reference now to the Figures, example embodiments of the present disclosure will be discussed in further detail.

[0039] Figure 1 depicts a block diagram of an example system for detecting the location of ground faults according to example embodiments of the present disclosure. The example system can include an example transmitter device ("‘transmitter”) (100) and an example signal detection device (“signal detector”) (200). The example transmitter device (100) can include a controller (110), a signal generation circuit (120), a user interface (130), a first connection terminal (140), and a second connection terminal (150). The example signal detector (200) can include a controller (210), one or more detection sensors (220). a signal processing unit (240), and a user interface (250).

[0040] Referring to the transmitter (100), the signal generation circuit (120) can produce a unique trace signal that circulates as a current within a circuit that is connected to the device terminals (e.g., (140) and (150)). In some implementations, the trace signal current can be produced by injecting a switched voltage into the circuit. In some other implementations, the transmitter (100) can use the voltage of the energized circuit as the source and can produce acurrent by acting as a switched load. Thus, in some implementations, when a sufficient source voltage is present within the energized circuit, then the transmitter (100) can produce the trace signal by acting as a switched load. However, in situations where a sufficient source voltage is not present within the circuit, then the transmitter (100) can actively inject voltage into the circuit to produce the trace signal. In some implementations, this function can be facilitated by a frequency generator producing an alternating (e g. sinusoidal or square) waveform and a modulator that modifies this waveform, resulting in a trace signal with a distinct frequency and modulation pattern. In some implementations, the frequency can be on the order of 100Hz-50kHz. A specific frequency may be selected based on various considerations, such as reducing coupling between conductors, reducing coupling with other circuit elements, or increasing detectability with the signal detector (200). The unique pattern of the trace signal can also help differentiate this signal from other signals in an energized circuit.

[0041] In general, the relationship between the frequency of a trace signal and its detectability by a proximity-based signal detector (e.g., such as signal detector (200)) can be characterized by the principle that higher frequencies tend to enhance the sensitivity of detection. Proximity -based signal detectors often utilize magnetic field sensors, such as induction coils or flux gates, which are more responsive to higher frequency electromagnetic fields. A higher frequency trace signal generates a more rapidly changing electromagnetic field, which induces a larger voltage in an inductive sensor. This results in more distinct and detectable variations that the proximity-based detectors can more easily identify and track, even when the magnetic field produced by the trace signal is relatively small at a distance.

[0042] This increased sensitivity can be beneficial as the trace signal current is typically very small, for example ranging from about 1-100mA, and the proximity-based sensor needs to effectively detect the signal even at a significant distance from the signal current path. In particular, some example implementations control the amplitude of the trace signal to be small to limit power dissipation and / or avoid damage to the circuit being traced. This further underscores the benefit of high sensitivity in the detection method. Thus, using a high- frequency trace signal enhances the overall effectiveness of the proximity-based detection, allowing for more accurate and efficient localization of ground faults within an electrical circuit.

[0043] In view of the above, example implementations of the transmitter (100) can be configured to produce a trace signal that has a frequency that is detectable by a proximitybased signal detector. In some implementations, the trace signal’s frequency can be adjustedto match the operational characteristics of the detection equipment used. In some implementations, the transmitter (100) can be configured to produce a trace signal with a minimum frequency of 10Hz. As another example, it can also be configured to produce a trace signal with a frequency of 50Hz, which may be more effective in environments with higher electrical noise. As yet another example, the transmitter (100) can produce a trace signal with a frequency of 1kHz. As another example, the transmitter (100) can produce a trace signal with a frequency of 6kHz or greater (e.g.. 6.25kHz). As another example, the transmitter (100) can produce a trace signal with a frequency of up to 50kHz. Thus, the transmitter (100) can provide a higher resolution of signal detection by the proximity-based signal detectors, which are typically more responsive to these higher frequencies. These configurations ensure that the transmitter (100) can adapt to various detection needs and environmental conditions, optimizing the fault localization process.

[0044] In some implementations, an interface and protection circuit (170) can be positioned electrically between the signal generation circuit (120) and any of the device terminals (140), (150), (160). The interface and protection circuit (170) can be configured to protect the device electronics from high voltages of the energized circuit and to protect from transients without impeding the trace signal. In some implementations, the interface and protection circuit (170) may include a voltage divider to divide a voltage present between any of the device terminals when connected to the energized circuit. Example interface and protection circuits (170) are described with reference to Figures and 8B.

[0045] Referring still to Figure 1 , the transmitter (100) can feature a controller (110) designed to manage the operation of the signal generation circuit (120). The controller (110) can also act as an intermediary between the user interface (130) and the signal generation circuit (120). The controller (110) can receive user inputs from the interface (130), process these inputs, and generate corresponding control signals for the signal generation circuit (120). This process allows the user to manipulate the parameters of the trace signal, such as its frequency and amplitude, according to their specific needs.

[0046] In some implementations, the controller (110) can include a microprocessor or a microcontroller unit (MCU). This unit can execute firmware or software instructions that govern the operation of the signal generation circuit (120). For example, the controller (110) can be programmed to control the frequency generator and the modulator, adjusting their operational parameters to generate the desired trace signal.

[0047] To ensure proper functioning and to maintain the performance of the signal generation circuit (120), the controller (110) can be designed to continuously monitor thestatus of the circuit elements. It might include feedback mechanisms to detect issues such as overheating, signal distortion, or operational errors. Upon detecting any such issues, the controller (110) can implement corrective actions, like reducing the power supply, altenng the operating frequency, or initiating a shutdown to prevent potential damage.

[0048] In one example, controller (110) can detect an active voltage source in a circuit to which the transmitter is connected. This detection can be based, for example, on measuring electrical characteristics of signals (e.g.. voltage levels) received at the first connection terminal (140). For example, the controller (110) can continuously monitor the voltage at the first connection terminal (140), which is connected to a point in the electrical circuit, and compare it against a predefined threshold that indicates the presence of an active voltage source. If the measured voltage exceeds this threshold, the controller (110) identifies it as an indication of an active voltage source, such as, for example, a photovoltaic panel producing electricity. Additionally or alternatively, the controller (110) may also monitor the stability' and consistency of the voltage over time to distinguish betw een constant voltage sources and transient voltage spikes.

[0049] Upon detecting an active voltage source, the controller can then initiate further actions, such as engaging the signal generation circuit (120) to produce a trace signal for fault localization. For example, when an active voltage source is detected in the photovoltaic circuit, the controller (110) can be configured to selectively connect a load from the signal generation circuit (120). This connection can occur between the first and second connection terminals (140) and (150) of the transmitter (100). The selective connection of the load allows the transmitter (100) to sink current from the active voltage source. The sinking of current can produce a trace signal on the circuit. As described throughout the present disclosure, the trace signal generated by this action can be utilized as a diagnostic tool. It can propagate through the circuit. It can be used to identify the location of a ground fault w ithin the circuit.

[0050] The controller (110) can also communicate with a battery management system to optimize the power consumption of the signal generation circuit (120). By monitoring the battery level, the controller (110) can adapt the performance of the signal generation circuit (120) to extend the battery life. For example, it can lower the signal strength when the battery level is low; thereby conserving powder.

[0051] In addition, in some implementations, the controller (110) can interface with wireless connectivity systems, allowing remote control over the signal generation circuit (120). Through a dedicated application on a smartphone or computer or via user inputreceived at the signal detector (200). users can adjust the settings of the transmitter (100), receiving real-time feedback about and / or providing real-time control of the operational status of the transmitter (100). This feature enhances the user’s control over the transmitter (100) and facilitates remote operation and monitoring.

[0052] The user interface (130) can include a power switch that activates the signal generation circuit (120) and the controller (110) that controls adjustments to the strength and frequency of the trace signal. An indicator light can also be incorporated, indicating when the transmitter (100) is actively transmitting the trace signal.

[0053] The transmitter (100) can include a power source like an integrated rechargeable battery or capability to be powered externally. A battery' management system can be incorporated to monitor the batters’ level and optimize power usage. This system can alert the user when the battery is low, encouraging the user to recharge or replace it.

[0054] A display screen can be integrated into the user interface (130) to provide more detailed information and control. The display might show key settings like the selected frequency, signal strength, battery status, or error messages. User interface elements, such as buttons or touch-sensitive controls, can help users navigate through settings and adjust parameters conveniently.

[0055] To aid signal tracing and identification, the transmitter (100) can incorporate signal detection and analysis features. This can involve adding a receiver circuit or sensor to detect and analyze nearby signals. The device can show data about the detected signals like their frequency, strength, and waveform characteristics, helping users differentiate the trace signal from other environmental signals.

[0056] In some implementations, the transmitter (100) can provide the option to record and log signal data for further analysis or documentation. This feature can store data about transmitted signals, such as frequency patterns, signal strengths, and timestamps. Users can access this data later for troubleshooting or generating reports related to circuit tracing or testing. The storage of the data and / or the interface to access that data can be on the signal detector (200) and / or the transmitter (100).

[0057] The transmitter (100) can offer signal filtering options to cater to various tracing scenarios. These filters can allow users to refine the trace signal by adjusting parameters like frequency range, modulation type, or signal bandwidth. Customization features might include presets or user-defined profiles to suit specific circuit tracing needs, promoting flexibility' and accuracy in signal identification.

[0058] The transmiter (100) can also measure the voltage and current present between any of the device terminals (140), (150). (160). In some implementations the transmiter (100) can measure these values when the trace signal is not being produced, and in some other implementations the transmiter (100) can measure these values when the trace signal is being produced. These values can indicate the presence of a fault in the system, and this information can be communicated or displayed on the user interface (130) of the transmiter (100) or the user interface (250) of the signal detector (200).

[0059] The system illustrated in Figure 1 also includes the signal detector (200). The signal detector (200) is configured to operate in conjunction with the transmiter (100), as described herein. The signal detector (200) allows users to accurately locate and identify signals produced by the transmiter device, making circuit tracing and troubleshooting more efficient. While Figure 1 illustrates a single signal detector (200), it is certainly possible that the system can include or interoperate with multiple different signal detectors, for example which may have different sensors, different sensing ranges, and / or other operational characteristics which render them more useful for certain situations or operations.

[0060] The signal detector (200) can comprise a compact housing that encloses various components designed to detect and analyze signals emited by the transmitter (100).

[0001] According to an aspect of the present disclosure, the signal detector (200) comprises one or more detection sensors (220). In some implementations, the detection sensor (220) can be a proximity-based sensor. In this case, the signal detector (200) can be referred to as a proximity -based signal detector. This proximity-based signal detector can operate on a proximity-based principle, detecting the trace signal without the requirement for any physical connection to the electrical circuit, or the need to maintain a specific physical orientation relative to the circuit.

[0062] Such a proximity-based detection sensor offers a distinct advantage over traditional detection methods, such as clamp-based devices. While the later often require a clamp to be situated in a manner that physically encircles one or more conductors of the electrical circuit, the proximity-based signal detector eliminates such necessity. The proximity-based sensor can detect the trace signal without necessitating physical access to the conductor(s), or making any direct physical contact with the electrical circuit.

[0063] This capability to wirelessly detect the trace signal enhances the efficiency and safety of the fault localization process. Technicians can easily maneuver around the circuit, tracing the signal without the limitations imposed by physical contact. This not only saves time but also reduces the risk of any electrical hazards that might arise from direct interactionwith the electrical circuit. Technicians can also detect the trace signal on parts of the system that are not individual wires, such as the internal traces of a PV panel.

[0064] In some implementations, the proximity -based sensor can include one or more sensitive devices that can accurately identify the trace signal within a certain range. Such sensors can be configured to detect the specific frequency or waveform of the trace signal, ensuring precise and reliable detection. This feature allows the proximity -based signal detector to provide an effective solution for tracking and localizing ground faults in the electrical circuit. In some implementations, the proximity-based detection sensor may comprise one or more of other such sensors, such as an induction coil, flux-gate, or a magnetoresistance sensor. In some implementations, more than one sensor can be used to form an array and the signal from the array can be analyzed to estimate the position of the signal source with respect to the signal detector. In other implementations, a particular detection sensor or combination of sensors can be used to cover a broad frequency range and to capture signals effectively.

[0065] In some implementations, the detection sensor (220) can include an antenna system. The antenna system can utilize different types of antennas, such as dipole, monopole, or loop antennas, to cover a broad frequency range and capture the signals effectively.

[0066] In some implementations, the detection sensor (220) can include a clamp-based detection sensor. The clamp-based detection sensor can enhance measurement of the trace signal. In particular, clamp-based sensors may be used to more exactly quantify if two conductors exhibit residual current in order to identify a faulted portion of the circuit based on principals known in the art as residual current detection (RCD).

[0067] In some implementations, signal amplification circuitry within the signal detector (200) can boost weak signals received by the detection sensor (220). The circuitry can use low-noise amplifiers and appropriate gain control mechanisms to enhance the received signals, promoting optimal signal detection and accurate tracing of the trace signal.

[0068] The signal detector (200) can also include a signal processing unit (240) that analyzes and interprets the signals received by the detection sensor (220). This signal processing unit (240) can employ digital signal processing techniques and algorithms to extract relevant signal information like frequency, modulation characteristics, and strength. It might also incorporate filtering mechanisms to minimize interference from ambient noise and other undesired signals.

[0069] The signal detector (200) can also include a user interface (250) that includes a display screen providing visual feedback to the user. This display might present informationabout the detected signals, including frequency, signal strength, and waveform representation. User interface (250) can also include buttons or touch-sensitive controls can help users navigate menus, adjust settings, and select operation modes. In some implementations, a communications system can be included to enable bi-directional communication between the signal detector (200) and transmitter (100). In some implementations, the communications system can perform various communications protocols such as WiFi, Bluetooth, or by signals coupled to the conductors of the circuit being evaluated. Bi-directional communication can be used for various purposes such as allowing the user to adjust settings on the transmitter from the signal detector device interface or allowing parameters measured by the transmitter (e.g. the voltage and current between terminals) to be displayed on the signal detector.

[0070] In some implementations, to provide audio feedback, the signal detector (200) can integrate an audio output system in the user interface (250). This system might include a speaker or a headphone jack to deliver audible signals corresponding to the detected signal. The audio output can help users quickly identify the presence and characteristics of the traced signal, even in noisy environments. Haptic vibrations may be used to replace or supplement audio outputs.

[0071] The signal detector (200) can incorporate signal localization features to assist users in pinpointing the source of the detected signal. These features can include signal strength indicators, such as LED bars or a graphical representation on the display, offering visual cues guiding users towards the highest signal intensity.

[0072] The signal detector (200) can include a power source like a rechargeable battery and a battery7management system. This system can ensure efficient power usage and alert the user when the battery needs charging or replacement.

[0073] Used in conjunction with the transmitter (100), the signal detector (200) provides a comprehensive solution for efficient circuit tracing and signal identification. Its compact and portable design, along with the integration of these components, provides users with a powerful tool for detecting, analyzing, and locating signals emitted by the transmitter (100). This device is particularly useful for professionals in various fields of electrical engineering such as photovoltaic system maintenance.

[0074] According to another aspect of the present disclosure, in some implementations, the transmitter (100) can be equipped with an additional connection terminal, thus enhancing the versatility of the device and allowing for more complex tracing scenarios. In particular, three connection terminals can include the first connection terminal (140), the second connection terminal (150), and an optional third connection terminal (160). Each of theseterminals can be configured to establish an electrical connection with specific points in the electrical circuit.

[0075] As an example, the first connection terminal (140) can be designed to be electrically coupled to a first connection location of the electrical circuit. The second connection terminal (150) can be configured to be electrically coupled to the system ground. The trace signal can be produced on the first and second terminal to create a trace signal current that will travel through the electrical circuit until it reaches the ground fault and returns to the second connection terminal (150) that is connected to the ground. Connecting the second connection terminal (150) to ground can also create a ground reference and help ensure the stability of the trace signal, reducing the likelihood of signal distortion or interference.

[0076] The third connection terminal (160) can be designed to be electrically coupled to a second connection location within the electrical circuit. This terminal can allow for the introduction of a secondary' or additional trace signal or the reception of signal feedback from the circuit. This can aid in advanced tracing techniques, such as residual current detection, differential signal tracing, or bidirectional tracing, which can provide more detailed information about the circuit’s condition and layout.

[0077] By providing three connection terminals, the transmitter (100) can offer more flexibility and adaptability in the tracing process. It can cater to a wider range of circuit configurations and tracing requirements. Additionally, this embodiment can support more robust and comprehensive fault detection and circuit analysis, thus enhancing the effectiveness of the system in maintaining and troubleshooting electrical circuits.

[0078] As an example, in some implementations, the transmitter (100) can be configured to generate separate trace signals for the positive-to-ground path and the negative-to-ground path. By dividing the signal in this manner, the system can provide a more detailed and accurate picture of the electrical circuit’s condition. These trace signals can be distinguished by their frequency or can be multiplexed (interleaved) with a time gap betw een the signals. For instance, the transmitter (100) can emit a trace signal on the positive-to-ground path for 500ms. wait for 500ms, then emit a trace signal on the negative-to-ground path for 500ms. wait for 500ms, and repeat this sequence.

[0079] The value of this approach becomes evident in different example fault scenarios. For instance, if the fault is located on a string in a combiner, the negative-to-ground trace signal would lead the technician directly to the correct combiner box. However, if the fault is located on the positive feeder to the combiner, the negative-to-ground trace signal would failto detect this fault. In this scenario, transmitting a trace signal on the positive-to-ground pair allows for quick and efficient location of the fault. By transmitting signals on both paths simultaneously, the system can locate faults efficiently in either scenario.

[0080] In some implementations, the transmitter (100) can be designed to control the phase of the signals transmitted on the two paths. By intentionally phasing the signals to combine destructively or constructively, the system can enhance the identification of the fault path. This method of phase manipulation can provide a more precise indication of the fault location, thereby further improving the efficiency and accuracy of the fault detection process.

[0081] As another example, in addition to its primary' function of wire tracing, the transmitter (100) with three connection terminals (140, 150, 160) can be configured to provide several additional functionalities that can assist the technician in locating and characterizing faults more effectively, and in identifying potential safety hazards. For instance, by measuring voltages between the positive-to-ground (+ / G), the negative-to- ground (- / G), and the positive-to-negative (+ / -) pairs, the device can calculate and display vital information to the user.

[0082] One such functionality can involve the calculation of the voltage ratio. This ratio can be utilized to estimate the location of the fault to the nearest panel, thereby enabling the technician to bypass the trace path and proceed directly to the near vicinity of the fault. For example, if a string contains 20 panels and each panel has a voltage of 30V, voltage readings of (+ / G) = 60V and (- / G) = 540V would indicate that the fault is located between the second and third panel from the positive end of the string. Therefore, this feature can significantly reduce the time and effort involved in fault detection, improving the overall efficiency of the tracing process.

[0083] In another implementation, the presence of a voltage differential between the + / G and / or - / G pairs can indicate the existence of a ground fault. This information can be used not only to confirm the presence of a fault but also to alert the user of the voltage differential or hazard present on the ground. Such warnings can be provided visually or audibly. An audible beep can be particularly useful in instances where a fault is intermittent, thereby alerting the user when a fault suddenly appears or disappears. This information may also be communicated between the transmitter (100) and signal detector (200) using the bidirectional communication system and methods mentioned previously.

[0084] Furthermore, voltage measurements can be used to detect less common faults, such as a short circuit between the positive and negative conductors or an open circuit. Inresponse to such detections, tracing signals can be automatically imposed on the positive to negative path, thereby facilitating the tracing of these faults.

[0085] In yet another implementation, the transmitter ( 100) can switch in a test load to measure the current through it, thereby enabling the measurement of leakage current and fault resistance between any of the three pairs. This feature can be particularly beneficial in scenarios where multiple faults exist in the system. Integrating this functionality into the transmitter (100) can simplify user operation and automate the calculation of fault parameters or the optimization of tracing signal parameters.

[0086] The addition of a third terminal (160) can also enable the transmitter (100) to function as a residual current detection (RCD) fault analyzer. This feature can facilitate a combined workflow where some tracing steps use a residual current clamp measurement instead of the wireless sensor. This combined functionality can significantly enhance the versatility of the device and provide users with a more comprehensive and efficient solution for circuit tracing and fault detection.

[0087] In particular, in some implementations to operate as an RCD fault analyzer, the transmitter can be connected at an inverter or other combination point where multiple circuits are combined in parallel on a positive and negative bus. The transmitter can cause a trace signal to circulate between the ground and one of the bus terminals. A technician can then use a current sensor to detect the trace signal on each parallel circuit, checking the positive and negative wires for each circuit. If a circuit branch has no ground fault, the positive and negative wires for that branch should have no residual trace current between the positive and negative pairs, i.e. any trace signal current going into the positive side should be balanced by the trace signal current exiting the negative side. The absence of residual trace signal current on an unfaulted branch can be understood as indicated that there is no point at which the trace signal current can leak out to ground. Alternatively, if a circuit branch does contain a ground fault, trace signal current can leak out to ground, and the current flowing into the positive side of the branch can be different from the current flowing out the negative side of the branch. Using the current sensor to compare the residual current on positive and negative pairs for each branch, a technician can determine which branch contains the ground fault.

[0088] Thus, according to another aspect of the present disclosure, in some implementations the transmitter (100) can integrate the dual functionality of a wire tracer and a RCD fault analyzer into a single device, thereby automating and optimizing the process of fault detection and localization in an electrical circuit. This embodiment can offer acomprehensive solution for efficient circuit tracing and fault identification, providing users with a versatile and user-friendly tool for electrical circuit maintenance and troubleshooting.

[0089] For example, in some implementations, the transmitter (100) can be designed to switch between two operational modes: a residual current detection (RCD) mode and a tracing mode. In the RCD-mode, the transmitter (100) can emit a signal that is optimized for RCD fault locating and that can be detected by a residual current clamp. This mode allows for the detection and location of residual current, which can indicate the presence of a ground fault in the circuit.

[0090] In the tracing mode, on the other hand, the transmitter (100) emits a distinct trace signal that can be followed to locate the exact position of the ground fault within the circuit. This mode can be particularly useful for tracing the path of the fault through the circuit and pinpointing its exact location.

[0091] Switching between these two modes can be performed physically on the transmitter (100), or it can be controlled wirelessly through the bi-directional communication methods mentioned previously or a dedicated application on a smartphone or computer. In some implementations, the transmitter (100) can automatically alternate betw een the two modes in an interleaved manner, emitting signals that are appropriate for each mode based on frequency or timing synchronization.

[0092] The integration of the RCD-mode and tracing-mode into the transmitter (100) can significantly simplify the workflow for locating ground faults in electrical circuits. For example, the transmitter (100) can be connected in parallel at an inverter. A technician can then use a current sensor capable of clamping wire pairs to detect residual current associated with the RCD-mode signal.

[0093] Once the correct feeder is identified, the technician can switch to the tracing mode and use a wireless signal detector to trace along the feeder to locate any faults present on the feeder line. At the combiner box, with all strings connected, the clamp can be used again to test for residual current and find the faulted string. Once the faulted string is identified, the string can be disconnected, and the tracing mode can be used to pinpoint the exact location of the fault on the string.

[0094] By integrating these functionalities into a single device, the transmitter (100) can streamline the process of fault detection and localization, saving time and effort for the technician. This embodiment offers a valuable solution for efficient and accurate fault detection in electrical circuits, enhancing the overall performance and reliability of electrical system maintenance and troubleshooting.

[0095] According to another aspect of the present disclosure, the transmitter’s functionality can be further improved by integrating an innovative RCD clamp design. Current clamps used in conventional CGFL systems may not be suitable for solar installations where wires are tightly packed, have various dimensions (e.g., ranging from 10AWG to 1000AWG), and where the wire pairs (e.g., positive and negative) may be separated by a significant distance. To address these challenges, the novel RCD clamp design can incorporate several improvements.

[0096] One such improvement can be the integration of a flexible coil in the clamp, such as a Rogowski coil . The flexible design of this large loop allows it to access tightly crowded spaces and enclose separated wires within its loop, thereby overcoming the access issues associated with tightly crowded wires and large wire distances. The clamp may also have an “open-fork” design, as is used in some handheld AC current clamp testers.

[0097] In another implementation, two separate clamps can be used to measure the current in separated cables independently. The signals from these clamps can then be combined using either analog circuitry or digital processing techniques. The two clamps can interface with the receiving unit either through wires or wirelessly. This flexibility in data communication enables easier access to separated wires in a pair, thereby enhancing the effectiveness of the fault detection process.

[0098] Further, the clamps can be designed to interface with a separate RCD receiver unit. Alternatively, the wireless signal detector used in the “tracing-mode” can be designed to include electronics that support connection to clamp sensors. This integration results in a single multi-function sensor required for tracing, thereby streamlining the process of fault detection and localization.

[0099] These improvements to the clamp design significantly enhance the versatility’ and efficiency of the system in detecting and localizing ground faults in electrical circuits. By providing a flexible and adaptable solution for accessing and measuring current in separated and crowded wires, the innovative RCD clamp design contributes to improving the overall performance and reliability’ of electrical system maintenance and troubleshooting.

[0100] Figure 2 depicts a flowchart diagram of an example method for localizing ground faults according to example embodiments of the present disclosure.

[0101] The method begins at step 2002, where a transmitter is electrically coupled to a system ground and to a first connection location of the electrical circuit. In some implementations, the electrical circuit can be an energized electrical circuit comprising one or more active voltage sources. The coupling of the transmitter to the electrical circuit allowsthe transmitter to interact directly with the electrical circuit and provides a pathway for the transmitter to introduce a trace signal into the circuit. In some implementations, the coupling may be provided through direct galvanic connection to a conductor, but coupling may also be provided by other means, such as inductive coupling or capacitive coupling.

[0102] At step 2004, the transmitter is caused to produce trace signal circulating as a current within a portion of the electrical circuit between the system ground and the first connection location. For example, the trace signal can be or have a specific frequency and / or w aveform that is distinguishable from normal operating signals in the circuit. This trace signal can serve as a marker that can be followed to identify the location of a ground fault within the circuit, even in the presence of active voltage sources. By introducing this trace signal into the circuit, the method provides a means for tracking and tracing the path of the electrical current through the circuit, which can be used to identify locations of ground faults.

[0103] Following step 2004, at step 2006, the trace signal is traced through the electrical circuit with a proximity -based signal detector to identify' a location at which one or more characteristics of the trace signal change. The proximity-based signal detector can be a wireless detection device that is configured to wirelessly detect the presence of the trace signal. The location at w hich one or more characteristics of the trace signal change can be indicative of a location of a ground fault within the electrical circuit. For example, the change in the one or more characteristics can be or include a change in amplitude, frequency, phase, or polarity of the trace signal. The location of the change indicates the location of the ground fault within the circuit. By detecting this change in the characteristic(s) of the trace signal, the technician is able to pinpoint the exact location of the ground fault in a more efficient manner.

[0104] This method offers a valuable solution for fault localization in energized electrical circuits, significantly reducing the time required to locate a ground fault and minimizing interruptions to the operation of the electrical system. For example, the use of a w ireless detection device can increase the flexibility and convenience of the fault localization process, allowing a technician to quickly and accurately locate ground faults in the circuit without the constraints of physical contact.

[0105] Figures 3A and 3B demonstrate an example scenario where a wire tracer transmitter is connected to a single photovoltaic (PV) string within a PV array. In particular, Figure 3A shows a PV string 300 that includes four PV panels 302-308 in series. The PV panels 302-308 may be active voltage sources. A ground fault 310 exists at a location between panels 304 and 306.

[0106] As shown in Figure 3B, a transmiter 312 establishes a first connection to the positive terminal 314 of the string 300 and a second connection to the system ground 316. In the event of the fault 310, a voltage difference between the positive terminal 314 and the ground 316 creates a loop of the energized system. The transmiter 312 can automatically detect this voltage difference and subsequently enter an “energized mode”, using specialized circuitry to safely induce a trace signal current into the energized circuit. This trace signal current travels along the string conductor up to the point of the fault 310. where it then flows back through the ground 316, forming a trace signal loop (shown as a doted line).

[0107] A wireless signal detector 318 can be used to localize the ground fault 310 in the PV string 300. The user activates the tracing mode on the wireless signal detector 318 and positions it near the terminals of the transmiter 312. In proximity to the trace signal loop, the wireless signal detector 318 can produce audible and / or visual responses, alerting the user of its proximity to the trace signal. The user can detect the trace signal radiating from the wiring between panels and can also detect the trace signal through the face of the PV panels. The user then moves the sensor along the string 300. following the path of the trace signal to identity' the fault location 310.

[0108] For example, when the wireless signal detector 318 is moved beyond the point of the fault 310 (to the right of the fault as shown), the trace signal ceases to continue along the wire (or otherw ise attenuates or demonstrates changes in one or more characteristic(s)), indicating that the signal detector 318 has passed the fault location 310. The user can interpret this change in character! stic(s) of the trace signal as a sign that they have moved past the fault point 310. To pinpoint the exact fault location, the user can move the detector 318 back and forth around the area where the signal terminates.

[0109] Figures 3 A and 3B collectively provide a visual guide for implementing the described method to localize a fault within a single string 300 of a PV array. This technique is applicable even if feeder wares are connected to the string. Later discussion describes techniques when other closed loops or circuit branches are present, such as when multiple strings are connected in parallel. The method thus provides a generalized, efficient approach to identifying and localizing ground faults in PV arrays or similar electrical circuits.

[0110] As another example, Figure 4A illustrates the initial steps of an example method for localizing ground faults in an electrical circuit using a transmiter and a handheld signal detector. In Figure 4A, a transmiter 412 is connected to a circuit 400 and then pow ered on. Once the transmiter 412 is powered on. it indicates the presence of a fault 410 within the circuit 400. The transmiter 412 then produces a trace signal through the fault path. This tracesignal serves as a marker that can be followed to identify the location of the ground fault 410 within the circuit.

[0111] Figure 4B further illustrates the subsequent steps of the example method for localizing ground faults. A handheld signal detector 418 is used to detect the trace signal. The handheld detector 418 may include an indicator such as a light or a tone that signals the proximity to the trace signal.

[0112] In some implementations, the handheld detector may also include a pole or other extension method so the user can trace signals on conductors or strings that may be far from reach. Extended reach can be helpful for example in the case of strings that are elevated far above ground, strings that are on the other side of an obstacle, or wiring that may be difficult to access by hand. In some implementations, the signal detector can be placed at the end of an extended pole. In other implementations, the detection sensor can be extended from the main signal detector so that the main signal detector can remain in the hands of the user to observe any indications on the unit.

[0113] The operator can then follow the trace signal through the circuit to locate the fault 410. The location of the fault is identified where the characteristics of the trace signal change (e g., as indicated automatically by the indicator such as the light or tone).

[0114] Figures 4A and 4B depict an efficient and effective process for localizing ground faults in an electrical circuit. This approach can be applied in a number of different scenarios, including identification of ground faults in the following settings: on feeders or homeruns; in junction boxes; along string wiring; and / or on failed panels.

[0115] Figure 5 is a graphical diagram illustrating an example method for localizing ground faults in an electrical circuit according to certain embodiments of the present disclosure. The Figure uses "‘single-line” schematic representation, where positive and negative wiring are represented as a single line. In particular. Figure 5 demonstrates an approach to locate a ground fault when there are many parallel groups of strings in a photovoltaic (PV) system. Figure 5 includes a representation of a solar array and the connections that can exist between multiple groups of strings.

[0116] As depicted in Figure 5. at the upstream side of the diagram is an array of multiple PV panels, such as, for example, PV panels 5100 and 5101. Each PV panel is a voltage source. Panels can be connected in series to form a string. As an example, the PV panels 5100 and 5101 are connected in series with two other panels to form a string 5102.

[0117] A string can be connected in parallel with any number of other strings to form a group of strings. For example, a group of strings can be connected in parallel at a combinerbox. As an example, string 5102 is connected in parallel with a string 5104 and two other strings at combiner box 5106 to form a group of strings 5108.

[0118] The physical electrical connection that connects the group of strings in parallel (thereby forming the group of strings) can be referred to as a branch combination point. The branch combination point can be located inside the combiner box. The branch combination point can, in some cases, take the form of (1) a positive combiner bus to which one side (e.g., the positive side) of all of the strings in the group are connected; and (2) a negative combiner bus to which the other side (e.g., the negative side) of all of the strings in the group are connected.

[0119] Groups of strings can also be connected in parallel to other groups of strings. For example, groups of strings can be connected in parallel at an inverter or recombiner. As an example, the group of strings 5108 is connected in parallel with a group of strings 5110 and one other group of strings at an inverter 502.

[0120] The physical conductors that exist between the combiner boxes and the inverter 502 can be referred to as combined branches (sometimes alternatively referred to as "‘feeder wires”). As an example, a combined branch 5112 conducts electricity between the inverter 502 and the combiner box 5106.

[0121] As an example, the upstream side of the combiner box 5106 can be referred to as the branch-side or string-side and the downstream side of the combiner box 5106 can be referred to as the combined side. The downstream side can be connected to the rest of the circuit using the combined branch 5112.

[0122] The physical electrical connection that connects the multiple groups of strings in parallel can be referred to as a branch recombination point. The branch recombination point can be located inside the inverter 502 or a recombiner box. The branch recombination point can, in some cases, take the form of (1) a positive common bus to which one side (e.g., the positive side) of all of the combined branches are connected; and (2) a negative common bus to which the other side (e.g., the negative side) of all of the combined branches are connected.

[0123] The many layers of parallel branching in a PV array allows modest amounts of current from individual panels or strings to be combined for large-scale power generation. However, these many layers of parallel branching can make it more challenging to identify and locate ground faults within the circuit.

[0124] Figure 5 illustrates a simplified electric schematic of a PV array as a “single-line” drawing where only one conductor is shown rather than both positive and negative conductor pairs As shown in Figure 5, a transmitter 512 can be connected to the inverter 502 or branchrecombination point of the PV system. This connection allows the transmitter 512 to transmit a trace signal into the electrical circuit. The trace signal can propagate through any branch of the circuit to reach the location of the ground fault.

[0125] In Figure 5, an operator, such as a technician or engineer, uses a handheld proximity -based signal detector 518 to trace the signal. The operator can follow the trace signal through any of the parallel branches of the circuit, even though these branches are not disconnected from each other. By monitoring the amplitude, frequency, phase or other characteristic(s) of the trace signal as they move along the circuit, the operator can identify which branch of the circuit is associated with the fault. Once the operator has isolated the fault to a single branch, the operator can identify the location at which characteristic(s) of the trace signal change. This location indicates the presence of the ground fault within the circuit.

[0126] The depiction in Figure 5 therefore illustrates an efficient and safe method for localizing ground faults in an electrical circuit, such as a photovoltaic system, without the need to make disconnections of parallel circuits. This method reduces the time and effort required to locate ground faults, minimizes the risk of electrical hazards, and simplifies the fault localization process.

[0127] Figures 6A-D depict graphical diagrams of example configurations for localizing ground faults according to example embodiments of the present disclosure.

[0128] Referring first to Figure 6A, Figure 6A provides a simplified representation of a photovoltaic (PV) system comprising 100 panels that are interconnected and coupled to an inverter. The configuration of the system is such that five panels are serially connected in a string, resulting in the total string voltage being five times that of a single panel. This is due to the additive property of voltages in series circuits.

[0129] In the depicted configuration, each combiner box receives input from five grouped strings that are connected in parallel at a branch connection point, on the combiner bus terminals inside a combiner box. The positive side of each string is connected in parallel to a positive combiner bus and the negative side of each string is connected to a negative combiner bus. On the upstream side of the bus, there is a positive-string-to-combiner-bus connection point between the positive side of each string and the positive combiner bus. A corresponding negative string-to-combiner-bus connection point exists for the negative sides of each string and the negative combiner bus.

[0130] As an example, referring to Figure 6A, a PV panel 602 is included in a string 604. The string 604 is connected in parallel with four other strings at a combiner 608 to form a group of strings 606. One side of the strings in the group of strings 606 are physicallyconnected in the combiner 608 at a positive combiner bus 610. The other side of the strings in the group of strings 606 are physically connected in the combiner 608 at a negative combiner bus 612. In some instances, the positive combiner bus 610 and the negative combiner bus 612 can be referred to as or be representative connection points for first and second sides of the group of strings 606. The combiner 608 is electrically connected to an inverter 614 via a combined branch 615. The inverter 614 includes a positive common bus 616 and a negative common bus 618. In some instances, the positive common bus 616 and anegative common bus 618 can be referred to as or be representative connection points for first and second sides of the inverter 614.

[0131] In real PV systems, the sty le of device used at the string-to-combiner-bus connections (e.g. the connections at 610 and 612) can vary. In some systems, the connection device may a “finger safe” fuse holder, MC4 connector pair, manual load-break disconnect, or other connection that can be easily connected and disconnected by hand. In other cases, the connection device may be a wire and screw terminal, a bolted wire lug, or other device that is more time consuming and hazardous to disconnect. Often, the positive string-to-combiner- bus connectors are “finger safe” fuse holders that can be opened and closed relatively easily without tools, and the negative string-to-combiner-bus connectors are screwed or bolted terminals that require tools and take more time to open or close.

[0132] On the downstream side of each combiner bus, there is a bus-to-combined-branch connector that can be of the aforementioned connector device types. For example, combiner 608 includes a positive bus-to-combined-branch connector 620 and anegative bus-to- combined-branch connector 622. Often the device on the positive bus-to-combined-branch connector is a manual load-break disconnect, sometimes referred to as a “DC disconnect” that can be connected or disconnected by hand. On the negative side, the connector is often a bolted or screw ed connection that requires tools.

[0133] The bus-to-combined-branch connector connects the positive combiner bus to the positive combined branch and negative combiner bus to the negative combined branch, sometimes referred to as the positive and negative feeders. A group of feeders from multiple combiner boxes are combined in parallel at another downstream branch combination point, typically on the common bus of a recombiner box or the common bus of the inverter (e.g., 616 and 618).

[0134] Figure 6A further shows that there are four combiner boxes, each carrying the output from its respective strings to the central inverter 614 through feeder wires. At the central inverter 614, the outputs from all the combiner boxes are joined onto the positivecommon bus 616 and the negative common bus 618. In effect, this creates a parallel connection of 100 strings through a branched topology, thus allowing for efficient power conversion and transmission to the load or grid. This representation is simply provided as an example.

[0135] Specifically, while Figure 6A depicts a relatively small-scale PV system, it is worth noting that the principles and configurations described herein can be scaled up for use in larger, utility-scale systems. This flexible and scalable approach to system design allows for the efficient localization of ground faults in PV systems of various sizes and complexities.

[0136] Some aspects of the topology in which strings are connected can vary between solar installations. For example, some solar PV systems use a trunk bus system where strings are connected directly to the feeder wire without combiner boxes. As another example, some solar fields use string inverters, and the first branch combination point for a group of strings is the bus of the inverter. PV systems that use panel-level devices, such as optimizers, can also have differences in topology and connections.

[0137] Figure 6B illustrates a process of identifying which combined branch or combiner box is downstream of the fault in the photovoltaic (PV) system represented in Figure 6A. In this process, the positive combiner bus for every combiner box is opened at the connection to the positive feeder (i.e. on the downstream side). For example, this can be accomplished by disconnecting the positive bus-to-combined-branch connector. In Figure 6B, an opened connection is shown with shaded fill. By opening the positive bus on each combiner, the parallel electrical connection between combiners and the connection from the combiners to the inverter is interrupted.

[0138] The next step in the fault localization process, as represented in Figure 6B, involves the successful identification of the faulted combiner. With the positive combiner bus opened on all combiners, a fault detection and localization method, such as the tracing signal method discussed earlier, can be used. For example, using a first connection from the transmitter to the negative common bus of the inverter and a second connection from the transmitter to the ground, the transmitter can produce the trace signal between the ground and the negative common bus of the inverter. For example, in Figure 6A. the [S] terminal of the transmitter is connected to the conductor while the [G] terminal is connected to ground. With all positive combiner buses disconnected, the trace signal will only flow to the combiner box containing the fault. It can be noted that the trace signal also flows through all of the strings that remain connected to the same combiner bus as the faulted string. The user can identifywhich combined branch is faulted by moving the signal detector across each of the negative feeders and observing on which feeder the trace signal is detected.

[0139] In this manner, Figure 6B depicts a fault detection and localization method that can be applied systematically across the PV system. By opening the positive combiner bus on all combiners (e.g., by disconnecting the positive bus-to-combined-branch connector) and moving the signal detector, the change in the trace signal across the system can be analyzed to efficiently identify and locate which feeder or combined branch contains the fault. This method also allows the user to physically follow the feeder wire associated with the fault without knowing the path or layout of that wire ahead of time. This method significantly reduces the time and effort required to locate faults, while also minimizing the need for physical interaction with high-voltage components, thereby enhancing the safety of the process.

[0140] Figure 6C illustrates the steps that can be taken to pinpoint the location of the fault once the user knows which combined branch is connected to the fault. For example, these steps may be taken after the combined branch containing the fault has been identified according to the steps illustrated in Figure 6B. In this example, the transmitter can be connected using the steps described for Figure 6B or can be left in place after the steps of 6B are completed. As noted with reference to Figure 6B, if all string-to-combiner-bus connectors for the string group containing the fault remain connected, the trace signal will flow through all strings in this group.

[0141] As shown in Figure 6C additional disconnections and steps can be used to find the exact location of the fault. If the string-to-combiner-bus connection is opened on the positive side for all strings in the string group containing the fault (e.g., open string-to- combiner connections shown with shaded fill within the circles), the trace signal will only flow through the one faulted string. Further, within the faulted string, the signal will fade or disappear from the conductor and wall return on the ground at the point of the ground fault. With the disconnections shown in Figure 6C, and using a proximity-based sensor, the user can identify the faulted string by checking which string contains the trace signal and can pinpoint the fault by following the trace signal to the location where it fades from the conductor.

[0142] Collectively following the steps described with reference to Figure 6A-C, the location of the fault is determined by following the trace signal and detecting a significant change or termination of the trace signal. For all steps, the transmitter can be connected onetime and left in one location. No other connections to high-voltage terminals are required, so this method significantly mitigates the risk of exposing or connecting high voltage terminals.

[0143] In these steps described with reference to Figures 6A-C, some disconnections are made in the system, but these disconnections are made systematically (e.g. on all strings in a combiner box). The same systematic disconnection can be made without requiring the user to have prior knowledge of which branch is associated with the fault. In the example illustrated, disconnections are made on the positive side and the trace signal is produced between the ground and negative side. Alternatively, the same steps can be taken disconnecting on the negative side and producing the trace signal between the ground and positive side. Often in a PV system, either the positive or negative-side connectors are finger-safe and can be quickly opened or closed without tools. This method reduces the complexity of disconnections and enables an efficient and accurate localization of the fault, allowing for a timely and targeted response to the issue, thereby minimizing downtime and enhancing the overall reliability' of the photovoltaic system.

[0144] Turning now to Figure 6D, this figure illustrates another configuration that makes use of an example transmitter that includes three terminals. This additional terminal significantly enhances the functionality of the system, particularly in terms of fault localization. This addresses a key deficiency in existing wire tracers, which are ty pically designed with only two inputs, limiting the functions and automation that can be provided by the apparatus.

[0145] In contrast to conventional wire tracers, the improved transmitter applied in the system of Figure 6D is designed with three connection terminals. These connections can simultaneously be connected to the positive, negative, and ground terminals of the sy stem. This unique configuration enables a number of novel functions that enhance safety and efficiency in fault localization.

[0146] The operational advantages of this improved configuration are demonstrated in Figure 6D with two hypothetical scenarios “A” and “B”. In scenario “A”, a fault is located on a string upstream of combiner box 2. By transmitting a trace signal on the negative-to-ground path, the technician can follow the path of the signal to the correct combiner box. However, in scenario “B”, the fault is located on the positive feeder to combiner 2. In this case, a trace signal on the negative-to-ground path does not reach this fault for detection. Instead, by simultaneously transmitting trace signals on both the positive-to-ground and the negative-to- ground paths, the fault can be quickly and efficiently located, irrespective of its location.

[0147] In further embodiments, the signals transmitted on the two paths can be intentionally phased in such a way as to combine destructively or constructively. This phasing can be used to highlight the path to the fault, providing an additional layer of precision in fault localization.

[0148] Figures 7A-D depict graphical diagrams of example configurations for localizing ground faults according to example embodiments of the present disclosure. In particular. Figures 7A-D illustrate an improved method for tracing faults in a circuit with multiple energized branches connected in parallel. The DC voltage sources in the energized branches have some source voltage V and some impedance Z. In some embodiments, the schematic and methods can represent a PV array, or could represent a battery storage bank, or could represent another configuration of voltage sources with some impedance. In the following discussion, the diagrams are described with reference to a PV array.

[0149] In the scenario depicted in Figures 7A-D, there is an array with multiple parallel strings, each string having multiple PV panels in series. Three strings are joined in parallel on the combiner bus terminals of a combiner box. For ease of reference, the connections of the combiner bus terminals outside of the combiner box are not illustrated. Each string contains three panels, represented as voltage sources and impedance for each panel. A fault to ground with impedance y occurs on the first string, between the second and third panels.

[0150] In this example combiner box, the strings are connected in parallel to a positive combiner bus bar on the positive side with fuse holders, which can be easily opened. On the negative side, the strings are connected to the negative combiner bus with lugs that are difficult to disconnect. If all strings are left connected in parallel, the trace signal will not only flow on the first string but also along every other closed loop in the system that is connected to the first string. This dispersion of the trace signal could make it difficult to efficiently locate the fault.

[0151] Figure 7A includes strings 702, 704, and 706. String 702 contains a ground fault. As Figure 7A shows, by disconnecting all strings from the positive combiner bus (e.g., strings 704 and 706), except for the faulted string 702, the trace signal only significantly flows on the faulted string 702 in a short path. This limited path allows the trace signal to guide the technician directly to the fault location, resulting in successful tracing. This improvement generalizes the workflow- for tracing faults in parallel branched circuits, minimizing the time required to locate a fault and increasing the overall efficiency of the process.

[0152] Figure 7B includes strings 712, 714, and 716. String 712 contains a ground fault. Figure 7B depicts another scenario where a trace signal is successfully traced, even though a random string 714, rather than the faulted string 712, is the only one connected at the positive combiner bus. In this setup, the trace signal is still able to guide the technician to the fault location, albeit in a longer path.

[0153] In this scenario, as in the previous, the three strings 712, 714. and 716 are connected in parallel within a combiner box, with each string consisting of three panels represented as voltage sources and impedance for each panel. A fault to ground with impedance Z^ is present on the first string 712, between the second and third panels.

[0154] In this case, all strings (e.g., 712 and 716) except for a random one 714 are disconnected from the positive combiner bus on the positive side. In the situation depicted in Figure 7B, the trace signal flows in a longer path as an incorrect (i.e., non-faulted) string 714 is left as the only one connected. Despite this, tracing is still successful as the trace signal path eventually terminates. The technician would follow the trace signal along the second (still connected) string 714 towards the negative combiner bus, and then back out along the first string 712 towards the point of the fault. Alternatively, after the technician checks all strings at the upstream side of the negative bus, the technician would recognize that the trace signal is present on both the first and second string 712 and 714 and could choose to trace along the first string 712 without exploring the second string 714. Consequently, the tracing process may take longer compared to when the faulted string is left as the only one connected, as shown in Figure 7 A, but is still successful, and therefore may be applicable in situations in which disconnecting strings is particularly laborious and the faulted string is unknown ahead of time.

[0155] The extended tracing path demonstrated in Figure 7B validates the flexibility’ and adaptability of the proposed method in localizing ground faults even in complex circuit setups. It shows that even when the exact faulted string is not known ahead of time, the trace signal can still guide the technician towards the fault location, ensuring successful and efficient fault identification and repair.

[0156] Figure 7C includes strings 722, 724, and 726. String 722 contains a ground fault. Figure 7C illustrates a generalized method that results in successful tracing of ground faults in parallel branched circuits. In this method, all strings 722, 724, and 726 are disconnected from the positive combiner bus, and the trace signal is connected on the negative combiner bus. This configuration significantly simplifies the tracing process, as it eliminates the needto identify, select, and disconnect specific strings on the positive side, which can be time- consuming.

[0157] In particular, as shown in Figure 7C, by disconnecting all strings 722, 724, and 726 on the positive side and connecting the trace signal to the negative combiner bus, the trace signal flows only on the faulted string 722 and leads directly to the point of the fault. The trace signal, represented by the dotted path, originates from the negative combiner bus and terminates at the point of the fault, indicating the location of the ground fault in the circuit.

[0158] This method offers significant efficiency in the fault localization process. By disconnecting all strings on the positive side, the technician doesn’t need to determine which strings to disconnect, thus saving time. In typical PV system designs, the positive side is relatively easier to disconnect because connections are typically hand-operated or ‘'fingersafe” devices, and the negative side is relatively more difficult to disconnect because connections are typically screwed or bolted and require tools. In some other PV systems designs, the negative-side connectors may be easier to disconnect than the positive side connectors. The described method is effective if strings are opened on only the positive side or if all strings are opened on only the negative side, so the user can disconnect whichever side is easier or otherwise preferable. Therefore, this method enables the relatively more difficult-to-manage connections to remain in place, reducing the time required and need for manipulation of connections with tools in the presence of high-voltage hazards.

[0159] In conclusion, Figure 7C establishes the advantages of a generalized workflow for tracing faults in parallel branched circuits. By disconnecting all strings on one side (the positive side in this example) and connecting the trace signal on the other bus terminal (in this case the negative terminal), the tracing process is significantly simplified and expedited, addressing the previously experienced limitation of time savings in systems with parallel circuits.

[0160] Figure 7D includes strings 732, 734, and 736. String 732 contains a ground fault. Figure 7D illustrates an alternative scenario in which all strings remain connected at both the negative combiner bus and the positive combiner bus. Even though this configuration may complicate the tracing process, the identification and localization of the ground fault is still feasible. Specifically, the trace signal is allowed to flow through all strings 732, 734, and 736, encompassing a broad path that spans the entire circuit.

[0161] Despite this extended propagation route, the trace signal will still display a detectable change in characteristics at the site of the ground fault. This change can include ashift in the polarity and / or amplitude of the trace signal, offering a clear indication of the ground fault’s location in the circuit. The technician can monitor these changes in the trace signal to locate the fault, even though the signal is flowing through all connected strings.

[0162] This configuration depicted in Figure 7D highlights the robustness and adaptability of the proposed method. While it may increase the complexity of the tracing process due to the extensive path, it demonstrates the method’s capability of localizing ground faults even in complex and interconnected circuit setups. It underscores the flexibility of the method to identify and locate ground faults under varying circuit conditions, further solidifying its practicality and effectiveness in a wide range of electrical circuit configurations.

[0163] For the scenario depicted in Figure 7D, a comparison of trace signals on different paths may be used to localize the ground fault. Specifically, Figure 7D illustrates a schematic representation of the trace signal propagating through parallel branches of the circuit, including both a directly faulted string (string 732) and the unfaulted branches (strings 734 and 736), which are only indirectly faulted only because they are connected to the same bus terminals as string 732.

[0164] As shown, a direct path of the trace signal travels through the directly faulted branch from the positive side of the directly faulted string 732 to the point of the fault to ground. As shown, an indirect path of the trace signal also travels in an indirect path through the unfaulted string 736 from the positive bus into the positive side of string 736. then along to the negative side of string 736, then along to the negative bus, then into the negative side of the directly faulted string 732, and then to the point of the fault to ground. This condition presents a challenge in identifying the location of the fault, as the trace signal exists on both sides of the fault and on multiple strings. To overcome this challenge, one approach to distinguishing these paths can be implemented, which involves analyzing the characteristics of the trace signal on each path.

[0165] Specifically, the direct path of the trace signal through the directly faulted string 732 has a lower total impedance than the indirect path through the unfaulted string. The direct path of the trace signal includes only two panels with impedance Z so the path has a total impedance of 2Z, while the indirect path includes an entire string of panels plus an additional panel in a path for a total impedance of 4Z. Because the indirect path has a higher impedance, the current amplitude of the signal on the indirect path will be low er than the current amplitude of the trace signal on the direct path. By designing the signal detector and associated analysis system to allow a clear comparison of the relative amplitude of the tracesignal, these two paths can be distinguished, and the fault can be located by following the signal path with the larger current amplitude. This can be achieved by performing measurements with the sensor at a fixed distance from the wires, so that the measured signal would then correspond to the scaled current amplitude of the trace signal.

[0166] Alternatively, the transmitter can inject a signal that would be modulated by the impedance of the fault path in such a way that the difference in impedance would produce a difference in modulation that can be detected and analyzed by the signal detector and associated analysis system. For example, two frequencies. Fl and F2, can be injected that would be modulated according to the impedance of the current path, and the ratio of I(F 1) to I(F2) would indicate the impedance of the trace signal path to differentiate the directly faulted branch and unfaulted branch. This modulation-based approach allows for a nuanced differentiation of the direct trace signal path and the indirect trace signal path, further enhancing the efficacy and accuracy of the proposed method.

[0167] Figure 7D also exemplifies a potential application of constructive and deconstructive interference to further optimize the fault identification and localization process. Particularly, the transmitter can be designed to generate specific current waveforms that would create constructive or deconstructive interference between the direct and indirect paths to the ground fault. This approach leverages the difference in the amplitude of the trace signal that may exist between the directly faulted branch and the indirectly faulted branch.

[0168] In the case of constructive interference, the transmitter can generate waveforms that would enhance the trace signal on the faulted branch. This can be achieved by synchronizing the phase of the waveforms, resulting in an increased amplitude of the trace signal at the location of the fault or an increased signal amplitude on only the directly faulted path. This increased signal strength would provide a clear indication of the fault’s location, aiding the technician in rapidly identifying and locating the ground fault.

[0169] Alternatively, in the case of deconstructive interference, the transmitter can generate waveforms that would suppress the trace signal on the unfaulted branch. This can be achieved by introducing a phase shift in the waveforms, resulting in a decreased amplitude of the trace signal along the unfaulted branch. This reduced signal strength would further differentiate the faulted branch from the unfaulted branch, making it easier for the technician to trace the faulted path and locate the ground fault.

[0170] Furthermore, a three-terminal configuration, as previously described, can further enable this interference-based approach. With this configuration, the transmitter can be connected to three points in the circuit, effectively creating two separate paths for the tracesignal. By applying the constructive or deconstructive interference principles, the trace signal on one path can be enhanced or suppressed relative to the other, providing a clear distinction between the faulted and unfaulted branches and facilitating swift and accurate fault localization.

[0171] Figure 8A illustrates an example interface and input protection circuit that can be positioned electrically between the signal generation circuit and either or both of the first terminal and the second terminal of the transmitter. The voltage divider circuit is configured to divide a voltage present at the first terminal and the second terminal of the transmitter when connected to the electrical circuit. This voltage divider circuit is specifically designed to safely operate under high-voltage conditions typical of solar fields, for example up to 1500V CAT III.

[0172] The LT spice simulation in Figure 8A also shows a potential design for protection circuitry to limit the voltage seen at the input to the transmitter device. A switch is controlled to switch a load in parallel between the two transmitter inputs R5. The switching frequency can be optimized for the desired frequency of the tracing signal. Resistors Rl, R15, and R5 function to limit the voltage seen at the switch and to limit the maximum current through the switch. The combination of Rl and R15 function as a voltage divider, dividing the input voltage by approximately R15 / R1. The summed resistance of Rl and R5 limit the maximum current that will be drawn through the switch. In certain embodiments, the values of Rl and R15 can be dynamically adjusted using a bank of switchable resistors or linear controlled resistive devices, such as IGBTs, to provide optimal voltage protection and current.

[0173] In some embodiments, the switching device can be an electrically isolated solid- state switch or a pair of FETs in a back-to-back configuration to isolate the rest of the system electronics from the switching device. This design enables the use in environments requiring a voltage rating of 1000V such as many commercial and industrial solar applications and 1500V for many utility-scale fields. The design also allows high voltage components to be contained and isolated at the front end of the device, accommodating for large component separation distances for creepage and clearance requirements, and allowing the rest of the device to be designed for much lower voltages, facilitating a smaller form factor. Additional options for the switching device include commercial off-the-shelf SiC FETs, such as those rated for 2000V or 3000V for example.

[0174] Figure 8B depicts an example circuit that allows coupling between the faulted circuit on input terminals A and B, and the transmitter electronics on the output terminals. The resistors Ri l l and R222 form a voltage divider network that reduces the DC voltage thatis present between IN_A and IN_B (e.g., which may be the connection to the PV array) to a smaller value between OUT A and OUT B (e.g., which connect to the transmitter electronics). This voltage divider circuit is specifically designed to safely operate under high- voltage conditions typical of solar fields, for example up to 1500V CAT III. If no other components were added, the resistors in the divider network would significantly limit the trace signal current amplitude that the transmitter could produce. Bypass capacitors Cl 11 are added so that DC voltage is affected by the divider network but the AC voltage and current associated with the trace signal can bypass the resistors in the divider network. This ensures that the transmitter electronics are protected from higher voltage without impeding the flow of the trace signal. This implementation of coupling thus provides an efficient and safe method of transmitting the trace signal, even in high voltage environments.

[0175] While the present subject matter has been described in detail with respect to various specific example embodiments thereof, each example is provided by way of explanation, not limitation of the disclosure. Those skilled in the art, upon attaining an understanding of the foregoing, can readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the subject disclosure does not preclude inclusion of such modifications, variations and / or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure cover such alterations, variations, and equivalents.

[0176] A system of one or more computers can be configured to perform particular operations or actions by virtue of having softw are, firmware, hardw are, or a combination of them installed on the system that in operation causes or cause the system to perform the actions. One or more computer programs can be configured to perform particular operations or actions by virtue of including instructions that, when executed by data processing apparatus, cause the apparatus to perform the actions.

[0177] One general aspect includes a transmitter for efficient localization of ground faults in a photovoltaic circuit may include one or more photovoltaic panels acting as an active voltage source. The transmitter also includes at least two connection terminals, the at least tw o connection terminals may include a first connection terminal configured to be electrically coupled to a first connection location of the photovoltaic circuit and a second connection terminal configured to electrically coupled to an electrical ground. The transmitter also includes at least one signal generation circuit may include a load that can be selectivelyconnected between the first connection terminal and the second connection terminal. The transmitter also includes a controller configured to: detect the active voltage source within the photovoltaic circuit; and, in response to detecting the active voltage source within the photovoltaic circuit, selectively connect the load between the first connection terminal and the second connection terminal to sink current from the active voltage source and produce a trace signal on the photovoltaic circuit that is detectable by a proximity -based signal detector. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0178] Example implementations may include any combination of one or more of the following features. The transmitter where the transmitter is configured to produce the trace signal having a frequency of at least 50 hz. The transmitter may be configured to produce the trace signal having a frequency of at least 1 khz. The photovoltaic circuit may include an ungrounded photovoltaic circuit. The transmitter may include an interface and protection circuit positioned electrically between the signal generation circuit and the first terminal of the transmitter that is electrically coupled to the first connection location, the interface and protection circuit configured to limit a voltage reaching the signal generation circuit or limit a current that can pass through the signal generation circuit. The transmitter may be operable in multiple operating modes associated with at least two different trace signals, where the transmitter is switchable between the multiple operating modes, and where the at least two different trace signals differ by at least one of amplitude, frequency, or phase. The transmitter can measure a voltage between connection terminals to determine if a fault is present within the photovoltaic circuit and communicates with the proximity-based signal detector to provide a continuous indication of whether fault is present. The transmitter further may include a third connection terminal configured to be electrically coupled to a second connection location of the photovoltaic circuit, and where the first connection location may include a negative terminal of the photovoltaic circuit and the second connection location may include a positive terminal of the photovoltaic circuit.

[0179] One general aspect includes a method for efficient localization of ground faults in an electrical circuit. The method includes electrically coupling a transmitter to a system ground and to a first connection location within the electrical circuit, where the electrical circuit may include one or more energized electrical circuit branches, the one or more energized electrical circuit branches may include one or more active voltage sources. The method also includes causing the transmitter to produce trace signal circulating as acurrent within a portion of the electrical circuit between the system ground and the first connection location. The method also includes tracing the trace signal through the electrical circuit with a proximity-based signal detector to identify a location at which one or more characteristics of the trace signal change, where the location at which one or more characteristics of the trace signal change is indicative of a location of a ground fault within the electrical circuit. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0180] Example implementations may include any combination of one or more of the following features. The method where the location at which one or more characteristics of the trace signal change may include a location at which a frequency, an amplitude, a phase, or a polarity of the trace signal changes. One or more voltage sources may include one or more direct current voltage sources. The electrical circuit may include an ungrounded electrical circuit. The electrical circuit may include a battery storage bank may include a plurality of batteries interconnected with one another. The electrical circuit may include a photovoltaic array may include a plurality of photovoltaic panels, and where the electrical circuit may include at least one photovoltaic string may include at least two of the plurality of photovoltaic panels connected in series. Causing the transmitter to produce the trace signal within the electrical circuit may include causing the trace signal to be present between one side of a string of photovoltaic panels and the ground fault; the method further may include disconnecting the string of photovoltaic panels from any other paralleled strings; and tracing the trace signal through the electrical circuit with the proximity-based signal detector to identify the location at which one or more characteristics of the trace signal change may include tracing the trace signal from the one side of the string of photovoltaic panels to the location at which one or more characteristics of the trace signal change. The electrical circuit may include a photovoltaic array may include a plurality of photovoltaic panels, where the plurality of photovoltaic panels are arranged into one or more groups of strings, and where each of the one or more groups of strings may include two or more strings of photovoltaic panels combined in parallel at a branch connection point. Causing the transmitter to transmit the trace signal into the electrical circuit may include causing the trace signal to be present between one side of the branch connection point of a first group of strings of the one or more groups of strings and the ground fault; the method further may include disconnecting from the one side of the branch connection point of the first group of strings all of the parallel strings in the first group of strings except a first string; and tracing the trace signal throughthe electrical circuit with the proximity-based signal detector to identify the location at which one or more characteristics of the trace signal change may include tracing the trace signal along the first string to the location at which one or more characteristics of the trace signal change. Causing the transmitter to produce the trace signal within the electrical circuit may include causing the trace signal to be present between one side of the branch connection point of a first group of strings of the one or more groups of strings and the ground fault; the method further may include disconnecting each of the parallel strings in the first group of strings from the other side of the branch connection point of the first group of strings; and tracing the trace signal through the electrical circuit with the proximity-based signal detector to identify the location at which one or more characteristics of the trace signal change may include tracing the trace signal from the one side of the first group of strings to the location at which one or more characteristics of the trace signal change. Causing the transmitter to transmit the trace signal into the electrical circuit may include causing the trace signal to be present betw een either of both sides of the branch connection point of a first group of strings of the one or more groups of strings and the ground fault; the method further may include leaving connected to the both sides of the branch connection point of the first group of strings more than one of the parallel strings in the first group of strings; and tracing the trace signal through the electrical circuit with the proximity-based signal detector to identify the location at which one or more characteristics of the trace signal change may include: collecting a plurality of measurements of the trace signal respectively from the multiple strings; and comparing the plurality of measurements to identify’ the location of the ground fault. The one or more groups of strings may include a plurality of groups of strings electrically connected at an inverter or recombiner to a common bus; causing the transmitter to transmit the trace signal into the electrical circuit may include causing the trace signal to be present between one side of the common bus and the ground fault; the method further may include disconnecting each of the plurality of groups of strings from the other side of the common bus; and tracing the trace signal through the electrical circuit with the proximity-based signal detector to identify the location at which one or more characteristics of the trace signal change may include analyzing which combined branch exhibits the largest trace signal to identify on w hich combined branch the ground fault is located. Implementations of the described techniques may include hardw are, a method or process, or computer softw are on a computer-accessible medium.

[0181] One general aspect includes a system for efficient localization of ground faults in an electrical circuit which may include one or more active voltage sources. The systemincludes a transmitter, which may include: at least two connection terminals, the at least two connection terminals may include a first connection terminal configured to be electrically coupled to a first connection location of the electrical circuit and a second connection terminal configured to electrically coupled to an electrical ground. The transmitter also includes at least one signal generation circuit may include a load that can be selectively connected between the first connection terminal and the second connection terminal. The transmitter also includes a controller configured to selectively connect the load between the first connection terminal and the second connection terminal to sink current from the active voltage source and produce a trace signal on the photovoltaic circuit. The system also includes a hand-held proximity-based signal detector configured to detect one or more characteristics of the trace signal at different locations of the electrical circuit to indicate a location of a ground fault within the electrical circuit. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices.

[0182] Example implementations may include any combination of one or more of the following features. The system where the proximity-based signal detector is operable in multiple operating modes, the multiple operating modes may include a proximity -based signal detection mode and a clamp-based signal detection mode. The proximity-based signal detector may include one or more magnetic field detectors, and where the one or more magnetic field detectors may include an induction coil, flux gate, or other magnetic sensor. The trace signal is produced as an alternating current signal with a frequency greater than Ikhz and detectable by a proximity -based magnetic field sensor. The signal detector utilizes one or more current clamps as an additional sensor device to detect the trace signal on a wire and to determine the one or more characteristics of the trace signal. The signal detector may be used for residual current detection to compare the trace signal flowing through the positive and negative sides of a first circuit branch and the amplitude of the trace signal flowing through the positive and negative sides at least one other circuit branch; and where a circuit branch with the largest difference in current between the positive and negative sides is identified as the faulted branch. Communication and control may be provided between the signal detector and transmitter, where the communication and control is performed wirelessly or via a coupling through the electrical circuit. The transmitter may produce the trace signal by injecting a voltage onto one or more of the terminals or by loading the electrical circuit and drawing current from the one or more active voltage sources within the circuit.Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

Claims

WHAT IS CLAIMED IS:

1. A transmitter for efficient localization of ground faults in a photovoltaic circuit comprising one or more photovoltaic panels acting as an active voltage source, the transmitter comprising: at least two connection terminals, the at least two connection terminals comprising a first connection terminal configured to be electrically coupled to a first connection location of the photovoltaic circuit and a second connection terminal configured to electrically coupled to an electrical ground; at least one signal generation circuit comprising a load that can be selectively connected between the first connection terminal and the second connection terminal; and a controller configured to: detect the active voltage source within the photovoltaic circuit; and in response to detecting the active voltage source within the photovoltaic circuit, selectively connect the load between the first connection terminal and the second connection terminal to sink current from the active voltage source and produce a trace signal on the photovoltaic circuit that is detectable by a proximity-based signal detector.

2. The transmitter of claim 1, wherein the transmitter is configured to produce the trace signal having a frequency of at least 50 Hz.

3. The transmitter of claim 1, wherein the transmitter is configured to produce the trace signal having a frequency of at least 1 kHz.

4. The transmitter of claim 1, wherein the photovoltaic circuit comprises an ungrounded photovoltaic circuit.

5. The transmitter of claim 1, further comprising an interface and protection circuit positioned electrically between the signal generation circuit and the first terminal of the transmitter that is electrically coupled to the first connection location, the interface andprotection circuit configured to limit a voltage reaching the signal generation circuit or limit a current that can pass through the signal generation circuit.

6. The transmiter of claim 1, wherein the transmiter is operable in multiple operating modes associated with at least two different trace signals, wherein the transmiter is switchable between the multiple operating modes, and wherein the at least two different trace signals differ by at least one of amplitude, frequency, or phase.

7. The transmiter of claim 1, wherein the transmiter measures a voltage between connection terminals to determine if a fault is present within the photovoltaic circuit and communicates with the proximity -based signal detector to provide a continuous indication of whether fault is present.

8. The transmiter of claim 1, wherein the transmitter further comprises a third connection terminal configured to be electrically coupled to a second connection location of the photovoltaic circuit, and wherein the first connection location comprises a negative terminal of the photovoltaic circuit and the second connection location comprises a positive terminal of the photovoltaic circuit.

9. A method for efficient localization of ground faults in an electrical circuit, the method comprising: electrically coupling a transmiter to a system ground and to a first connection location within the electrical circuit, wherein the electrical circuit comprises one or more energized electrical circuit branches, the one or more energized electrical circuit branches comprising one or more active voltage sources; causing the transmiter to produce trace signal circulating as a current within a portion of the electrical circuit between the system ground and the first connection location; tracing the trace signal through the electrical circuit with a proximity-based signal detector to identify a location at which one or more characteristics of the trace signal change, wherein the location at which one or more characteristics of the trace signal change is indicative of a location of a ground fault within the electrical circuit.

10. The method of claim 9, wherein the location at which one or more characteristics of the trace signal change comprises a location at which a frequency, an amplitude, a phase, or a polarity of the trace signal changes.

11. The method of claim 9, wherein one or more voltage sources comprise one or more direct current voltage sources.

12. The method of claim 9, wherein the electrical circuit comprises an ungrounded electrical circuit.

13. The method of claim 9, wherein the electrical circuit comprises a battery storage bank comprising a plurality of batteries interconnected with one another.

14. The method of claim 9, wherein the electrical circuit comprises a photovoltaic array comprising a plurality of photovoltaic panels, and wherein the electrical circuit comprises at least one photovoltaic string comprising at least two of the plurality of photovoltaic panels connected in series.

15. The method of claim 14, wherein: causing the transmitter to produce the trace signal within the electrical circuit comprises causing the trace signal to be present between one side of a string of photovoltaic panels and the ground fault; the method further comprises disconnecting the string of photovoltaic panels from any other paralleled strings; and tracing the trace signal through the electrical circuit with the proximity-based signal detector to identify the location at which one or more characteristics of the trace signal change comprises tracing the trace signal from the one side of the string of photovoltaic panels to the location at which one or more characteristics of the trace signal change.

16. The method of claim 9, wherein the electrical circuit comprises a photovoltaic array comprising a plurality of photovoltaic panels, wherein the plurality of photovoltaic panels are arranged into one or more groups of strings, and wherein each of the one or moregroups of strings comprises two or more strings of photovoltaic panels combined in parallel at a branch connection point.

17. The method of claim 16, wherein: causing the transmitter to transmit the trace signal into the electrical circuit comprises causing the trace signal to be present between one side of the branch connection point of a first group of strings of the one or more groups of strings and the ground fault; the method further comprises disconnecting from the one side of the branch connection point of the first group of strings all of the parallel strings in the first group of strings except a first string; and tracing the trace signal through the electrical circuit with the proximity -based signal detector to identify the location at which one or more characteristics of the trace signal change comprises tracing the trace signal along the first string to the location at which one or more characteristics of the trace signal change.

18. The method of claim 16, wherein: causing the transmitter to produce the trace signal within the electrical circuit comprises causing the trace signal to be present between one side of the branch connection point of a first group of strings of the one or more groups of strings and the ground fault; the method further comprises disconnecting each of the parallel strings in the first group of strings from the other side of the branch connection point of the first group of strings; and tracing the trace signal through the electrical circuit with the proximity -based signal detector to identify the location at which one or more characteristics of the trace signal change comprises tracing the trace signal from the one side of the first group of strings to the location at which one or more characteristics of the trace signal change.

19. The method of claim 16, wherein: causing the transmitter to transmit the trace signal into the electrical circuit comprises causing the trace signal to be present between either of both sides of the branch connection point of a first group of strings of the one or more groups of strings and the ground fault;the method further comprises leaving connected to the both sides of the branch connection point of the first group of strings more than one of the parallel strings in the first group of strings; and tracing the trace signal through the electrical circuit with the proximity -based signal detector to identify the location at which one or more characteristics of the trace signal change comprises: collecting a plurality of measurements of the trace signal respectively from the multiple strings; and comparing the plurality of measurements to identify the location of the ground fault.

20. The method of any of claims 16, wherein: the one or more groups of strings comprise a plurality of groups of strings electrically connected at an inverter or recombiner to a common bus; causing the transmitter to transmit the trace signal into the electrical circuit comprises causing the trace signal to be present between one side of the common bus and the ground fault; the method further comprises disconnecting each of the plurality of groups of strings from the other side of the common bus; and tracing the trace signal through the electrical circuit with the proximity -based signal detector to identify the location at which one or more characteristics of the trace signal change comprises analyzing which combined branch exhibits the largest trace signal to identify' on which combined branch the ground fault is located.

21. A system for efficient localization of ground faults in an electrical circuit comprising one or more active voltage sources, the system comprising: a transmitter, comprising: at least two connection terminals, the at least two connection terminals comprising a first connection terminal configured to be electrically coupled to a first connection location of the electrical circuit and a second connection terminal configured to electrically coupled to an electrical ground;at least one signal generation circuit comprising a load that can be selectively connected between the first connection terminal and the second connection terminal; and a controller configured to selectively connect the load between the first connection terminal and the second connection terminal to sink current from the active voltage source and produce a trace signal on the photovoltaic circuit; and a hand-held proximity-based signal detector configured to detect one or more characteristics of the trace signal at different locations of the electrical circuit to indicate a location of a ground fault within the electrical circuit.

22. The system of claim 21, wherein the proximity-based signal detector is operable in multiple operating modes, the multiple operating modes comprising a proximity -based signal detection mode and a clamp-based signal detection mode.

23. The system of claim 21, wherein the proximity -based signal detector comprises one or more magnetic field detectors, and wherein the one or more magnetic field detectors comprise an induction coil, flux gate, or other magnetic sensor.

24. The system of claim 21, wherein the trace signal is produced as an alternating current signal with a frequency greater than 1kHz and detectable by a proximity -based magnetic field sensor.

25. The system of claim 21. wherein the signal detector utilizes one or more current clamps as an additional sensor device to detect the trace signal on a wire and to determine the one or more characteristics of the trace signal.

26. The system of claim 21, wherein the signal detector is used for residual current detection to compare the trace signal flowing through the positive and negative sides of a first circuit branch and the amplitude of the trace signal flowing through the positive and negative sides at least one other circuit branch; and wherein a circuit branch with the largest difference in current between the positive and negative sides is identified as the faulted branch.

27. The system of claim 21, wherein communication and control is provided between the signal detector and transmitter, wherein the communication and control is performed wirelessly or via a coupling through the electrical circuit.

28. The system of claim 21, wherein the transmitter produces the trace signal by injecting a voltage onto one or more of the terminals or by loading the electrical circuit and drawing current from the one or more active voltage sources within the circuit.

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