Article Impact of Load Changes on Voltage Stability in Cargo Ship Electrical Systems

Study Case Impact of Load Changes on Voltage Stability in Cargo Ship Electrical Systems Michael Kurniawan (2018123456) University of Cincinnati, 2600 Clifton Ave, Cincinnati, OH 45221, United States michaelkurniawan2019@gmail.com Abstract Voltage stability reflects the ability of a ship's electrical system to maintain voltage values both under normal conditions and after a disturbance. In addition to disturbances, factors such as load addition and system configuration changes can also affect voltage stability. When the voltage on the receiving side drops below the normal limit, instability can occur that has the potential to cause voltage collapse, which if not handled can lead to a total or partial blackout. The process of electricity generation on ships carried out by generators is affected by changes in reactive power requirements at the load, where these reactive power fluctuations have a direct impact on the stability of the generator terminal output voltage so that proper regulation is needed to keep the generator stable. Transient stability in a power system is concerned with its ability to maintain synchronization and balance between generation power and loading, where under normal conditions all generators operate at synchronous speed. However, major disturbances such as the removal of generation, starting of motors with large power, or short circuits can cause changes in rotor speed that can potentially result in loss of synchronization in a ship's electrical system. Integration of the ship's electrical system using a ring distribution system has the advantage of flexibility in power delivery, because electricity supply can be carried out through two or more generators. Analysis of the system stability response to sudden disturbances is crucial to determine the right technical recommendations to improve the reliability of the ship's electrical system. Keywords: voltage stability, voltage collapse, blackout, reactive power, transient stability, generator synchronization, ring distribution system, ship electrical disturbance, rotor speed, power balance. MICHAEL KURNIAWAN 1 Study Case INTRODUCTION In shipboard power generation, voltage stability is a crucial aspect as it affects the reliability of the overall electrical system. Voltage instability can cause disruptions in power delivery, impacting the quality and performance of the ship's equipment, and in the worst case can even result in a load shedding mechanism. The process of electrical power generation by the generator is affected by changes in reactive power requirements at the load, where these reactive power fluctuations greatly affect the stability of the generator terminal output voltage. Therefore, the output voltage must be controlled so that the generator remains stable in compensating for reactive power requirements. Voltage stability reflects the ability of the system to maintain voltage values under normal conditions and during disturbances. In addition to disturbances, factors such as load addition and changes in system configuration also play a role in affecting the voltage stability of the power system. Voltage instability occurs when the voltage on the receiving side drops below its normal limit, which can lead to voltage collapse and lead to total or partial blackouts. Voltage stability analysis on shipboard electrical power distribution systems is very important, considering that these systems are critical elements in ship operations. For example, in a shipboard electrical power distribution system shown in Figure 1.1, there are four generators that each supply power to various electrical equipment on the ship. To analyze the generator loading system-which is often modeled as a single-line diagram-the Electrical Transient Analysis Program (ETAP) is used to simulate the dynamics of voltage stability and system response to load changes. Figure 1.1 Shipboard electrical power distribution system MICHAEL KURNIAWAN 2 Study Case LITERATURE REVIEW Ship electrical installations play an important role in optimizing ship operations, starting from the power generation unit in the form of a generator which is then channeled through the power distribution system. The design of this system must meet the electrical requirements of the ship, including the selection of an appropriate generator based on the calculation of power requirements and installation space conditions. Ship electrical systems are generally supplied by two or more generators, and can be supported by emergency generators or batteries. The generated electrical power is consolidated in the Main Switch Board (MSB), while the emergency system is connected to an emergency switchboard that will activate automatically in the event of a main power interruption. On large ships, power distribution typically uses two or three load center switchboards placed forward, aft, and if possible, amidships. Each switchboard receives power from the ship service switchboard via a feeder bus, which is more efficient compared to long lines directly to the rest of the ship. Each switchboard is housed in an appropriate room, which also serves as an electrical service and maintenance center. The electrical power delivered from the MSB is then distributed to the various main loads according to the ship's needs. Electrical loads on ships fall into three main groups. Lighting loads include the entire lighting system on board, including gangways, enclosed and open rooms, and power sockets for low-power equipment. These loads generally use a single-phase 220 V voltage with a frequency of 50 Hz. Power loads include equipment such as pumps (ballast, bilge, FW), lifting machinery (cranes, anchors), refrigeration systems, and air conditioners, which operate on three-phase 220 V/380 V voltage with a frequency of 50 Hz. Communication and navigation loads consist of navigation equipment with 220 V voltage and instruments based on 36 V DC or 24 V DC, which are powered by rectifiers and supported by batteries through UPS to maintain power stability. The main power source from the generator has a line voltage of 390 V or phase voltage of 225 V at a frequency of 50 Hz. To ensure power quality, the voltage drop in the transmission cables should not exceed 3% as per BKI rules, so that the voltage at the load terminals remains at 380 V (line voltage) or 220 V (phase voltage). Power distribution is carried out through feeders that deliver electricity from the switchboard to auxiliary equipment and heaters, either individually or in groups. These feeders are generally used for large main propulsion equipment and are located in the same room as the distribution switchboard, although they can also be used for large motors in other locations on the ship. This group of loads receives power supply through the distribution panel, which serves as the power supply center for the various ship systems, as shown in Figure 2.1. MICHAEL KURNIAWAN 3 Study Case Figure 2.1 Shipboard electrical power sharing system Alternating current power generation systems (AC generators) have become the gold standard in ship electrical installations. Compared to direct current (DC) systems, the use of AC systems provides a number of advantages, including: 1. More cost-effective in terms of cost, equipment weight, and space requirements. 2. Easier and less maintenance. 3. Higher level of equipment availability. 4. Better system reliability. Nowadays, DC distribution systems are rarely applied on new ships because AC systems are more economical, simpler, and lighter in terms of maintenance. In addition, single cable systems with Hull Return are also rarely used. Based on SOLAS 1960 regulations, preventive measures are required in accordance with applicable regulations. One of the shortcomings of the single cable system is the lack of indicators that show underload conditions when isolation is performed on the cable. In addition, Megger testing of the circuit can only be done after removing the lights or turning off the circuit breaker. A three-phase AC electrical distribution system with an isolated neutral is the most commonly used configuration. At medium voltage, 440 V systems are more often chosen over 380 V because of the cost savings associated with using smaller copper cables. However, 415 V systems are sometimes used for vessels with larger power requirements, which require networks with a 240 V neutral voltage as well as specific standards for the equipment used. In this case, the system will use a four-wire cable with an earthed neutral but no Hull Return. Meanwhile, the 380 V system is widely used in mainland Europe. In 3.3 kV systems, a threeMICHAEL KURNIAWAN 4 Study Case wire cable configuration is used with the neutral earthed through a resistor. However, in some cases, designers prefer systems with isolated neutrals, as applied to medium voltage systems. Generator The ship's generator serves as a provider of electrical energy for all equipment on board. The capacity of the generator is determined by the load factor, which varies depending on the type of ship and the shipping route. Fluctuating field factors, changing load conditions, as well as irregular usage periods affect the electrical power demand. Under some conditions, a large difference in power consumption leads to a decrease in generator efficiency and an increase in the cost of electricity production per kWh. Therefore, determining the generator capacity must consider the overall operation of the ship to remain efficient and optimized. Generators on ships are used to power a variety of equipment, such as motors in engine rooms and decks, lighting systems, communications, navigation, air conditioning, sanitation, kitchens, cold storage, alarms, and fire systems. The working principle of a generator is based on the movement of a rotor that cuts through a magnetic field to produce a difference in voltage and electric current. In designing a ship's electrical system, it is important to take into account the maximum and minimum power requirements within a certain period of time so that the electricity supply remains stable. Load analysis needs to be done to determine the amount of power required under various operational conditions, such as when the ship is maneuvering, sailing, docking, or leaning. This aims to ensure that the generator is able to meet the power requirements optimally according to the ship's conditions. Figure 2.2 Generator The calculation of backup power is very important to anticipate spikes in electrical loads in a short time, such as when operating large power motors. Based on BKI regulations, the ship's generator power output must be at least 15% higher than the power requirements listed in the power balance. In addition, future load growth must also be taken into account. Generator capacity is determined through the preparation of a power balance table, which records all electrical equipment on the ship and its capacity. With this table, power requirements under various operational conditions can be analyzed more accurately. According to BKI Vol. IV (Chapter I, D.I), all equipment required for normal service should be accounted for at full MICHAEL KURNIAWAN 5 Study Case power, the reserve load should be recorded, and the total incoming power should be calculated taking into account the time similarity factor. In addition, if there is a cooling installation, its power requirements must also be taken into account in sizing the ship's generators. Determining the maximum and minimum power requirements is essential for optimizing the generating system configuration and determining the generator run time. Electrical loads on ships can be grouped into four main categories, namely loads on the hull deck, hatch cooling equipment, electromotors that support the machinery system, as well as lighting, communication, navigation, and danger sign systems. This grouping of electrical loads is adjusted to the five operational conditions of the ship, namely preparation for sailing, sailing, berthing, loading and unloading, and maneuvering. The purpose of this grouping is to simplify the calculation of the load factor of each equipment, considering that not all devices operate continuously in every sailing condition. To obtain a more accurate load calculation, an electric load analysis is used, which is outlined in the calculation of electric power balance table. Ship Generator Workload (Load Factor) The load factor of shipboard equipment is the ratio of the time the equipment is in use to its total operational time, expressed as a percentage. Some infrequently used equipment, such as fire pumps, anchor windlass, capstans, and boat winches, are considered to have zero load because they only operate under certain conditions. Diversity Factor of Ship Generators Electrical equipment on ships has a usage pattern that is not always the same, so the loading can be categorized into two types: 1. Continuous Load - This load comes from equipment that operates continuously during the voyage, such as navigation lights and Controllable Pitch Propeller (CPP) pumps. 2. Intermittent Load - This load comes from equipment that is used periodically during the voyage, such as fuel transfer pumps and fresh water pumps. Generator Reactive Power The reactive power that can be generated by a generator depends on the prime mover capability and the MVA rating of the generator. This reactive power capacity is limited by three main factors, namely the field current limit, armature current limit, and end region heating limit. MICHAEL KURNIAWAN 6 Study Case Description: S = Complex power (VA) P = Active power (W) Q = Reactive power (VAR) Et = Generator terminal voltage (V) It = Generator terminal current (A) θ = Power factor angle Generator Control Voltage regulation on the generator is controlled by the Automatic Voltage Regulator (AVR), which is responsible for measuring the terminal voltage and comparing it to a desired reference value. If a voltage difference occurs, an error signal is used to adjust the exciter output, which then controls the field voltage on the main generator. When operating in steady state, the high-gain feedback control system ensures that the terminal voltage remains within normal limits, with a voltage deviation of about 0.5% from no-load to full-load conditions. In addition, the terminal voltage is also subject to changes due to reactive power fluctuations. If the voltage drops to 15%, the AVR will automatically increase excitation and balance the voltage in about 15 seconds. Figure 2.3 Voltage response of generator/AVR Power System Stability Power system stability refers to the ability of a system to return to a balanced operating condition after a disturbance. The system remains intact as long as the power grid remains functional without disconnection of generators or loads, unless disconnection is necessary to isolate the disturbed element to maintain the continuity of system operation. Power systems are constantly undergoing changes in load, generator output, and other operating parameters.These system disturbances are categorized into two main types: 1. Minor disturbances, which are gradual changes in load that the system can compensate for with automatic adjustments. MICHAEL KURNIAWAN 7 Study Case 2. Major disturbances, such as short-circuits on transmission lines that can cause instability if not immediately addressed. Power system stability can be classified into three main types: 1. Rotor angle stability: The ability of the system to maintain the balance of generator rotor angles after a disturbance. 2. Frequency stability: The ability of the system to maintain the operating frequency within normal limits despite load changes. 3. Voltage stability: The ability of the system to keep the voltage stable after a disturbance. Ring Distribution Network A ring distribution network is an electricity distribution system consisting of two or more feeder lines that are interconnected to form a closed circuit. This system offers economic benefits because in the event of a disturbance, the impact is limited to the disturbed channel, while the other channels can still deliver electricity from alternative sources, so that the continuity of electricity supply is maintained. However, if the load increases, the capacity of this system will be overburdened and its performance will decrease. However, if there is more than one power source in the system, power distribution becomes more efficient with more stable voltage regulation. There are two main types of ring distribution networks: 1. Open Loop: Equipped with normally-open switches, which remain open under normal conditions. 2. Close Loop: Utilizes normally-close switches, which remain closed under normal conditions. Transient Stability Under stable operating conditions, the power system must be able to maintain a balance between the mechanical power generated by the prime mover and the electrical power supplied to the load. In a stable state, the generator rotates at a synchronous speed. Power imbalances can result in changes in frequency and voltage, especially when large disturbances occur. If these disturbances are not addressed immediately, acceleration or deceleration of the generator rotor can lead to loss of system synchronization. Power system stability is divided into three main categories: 1. Steady state stability: The ability of the system to maintain synchronization after small disturbances, such as load fluctuations. 2. Transient stability: The ability of the system to remain stable after a major disturbance within one swing cycle, before the AVR starts working. MICHAEL KURNIAWAN 8 Study Case 3. Dynamic stability (dynamic): The ability of the system to reach a new equilibrium after a transient period with the help of AVRs and governors. An imbalance between the power generated by the generator and the load power can cause transient conditions, resulting in generator rotor swings. If the rotor angle difference is too large, synchronization will be disrupted. For example, if the generating power is in excess, most of the extra energy will be converted into kinetic energy, so the rotor angle accelerates. Even if the rotor speed increases, synchronization can still be maintained as long as the rotor angle difference is within the tolerance limit to the synchronization loop reference. Transient Condition Stability Analysis Transient stability analysis using the Electrical Transient Analysis Program aims to examine the limits of power system stability before, during, and after changes or disturbances to the system. In this simulation, the system is modeled dynamically, where the user can determine the disturbance scenario that occurs. The network equations and machine differential equations are solved interactively to evaluate the system and machine responses in the time domain. From the response results, users can: 1. Identify system transient conditions, 2. Perform stability analysis, 3. Determine optimal settings for protection equipment, 4. Implement system changes to improve stability. The dynamic performance of power systems plays an important role in their design and operation. Transient stability studies are used to analyze machine power angles, speed changes, system frequency, active and reactive power flows, and voltage levels at busbars. Some of the major factors that can cause system instability include: 1. Short circuit faults, 2. Disconnection of tie-connections in utility systems, 3. Starting of electric motors, 4. Removal of one of the generators from the system, 5. Sudden changes in load or generation. Since the stability of the power system is related to electromechanical phenomena, the role of synchronous machines is very important. When a disturbance occurs, the rotor angle will undergo oscillations that can cause fluctuations in the system power flow. If these oscillations are not properly controlled, they can lead to overall system instability. Therefore, power system stability is often analyzed based on the rotor angle stability of synchronous machines. MICHAEL KURNIAWAN 9 Study Case Various development strategies can be applied to improve power system stability, including: 1. Changing the system configuration, 2. Designing and selecting rotating equipment with better specifications, such as increasing the moment of inertia, reducing transient reactance, and improving voltage regulator performance, 3. Using a Power System Stabilizer (PSS), 4. Improve the performance of the protection system, 5. Implement a Load Shedding scheme to reduce the load automatically to maintain system stability. MICHAEL KURNIAWAN 10 Study Case RESEARCH METHOD The research methodology provides an overview of the procedures and stages taken in this research. In this section, the steps taken in the thesis work are explained systematically. The flow of these stages can be seen in the flowchart in Figure 3.1. Start Study Literature Data Collection Study Literature Circuit Modelling No Result Yes Data Analyst Conclusion End MICHAEL KURNIAWAN 11 Study Case Problem Formulation The initial stage in this research is problem formulation. At this stage, the problems that are the focus of the research are identified and formulated so that they can be analyzed further. Problem formulation also aims to determine the main reason for this research. In this study, the problem studied is about voltage stability in ship electrical systems. Literature Study After the problem is identified, the next step is to conduct a literature study. This stage aims to find and review references related to the problems studied, including solutions that can be applied. Literature studies are conducted by referring to various sources such as books, scientific articles, and journals that discuss voltage stability. Some of the references used in this study include: 1. Power System Analysis 2. Power System Stability and Control 3. Definition and Classification of Power System Stability 4. Articles and journals that discuss ship electrical systems (Marine Electrical Ship). 5. Articles and journals regarding the Electrical Transient Analysis Program (ETAP). Data Collection This stage includes the collection of data needed to support the analysis in the study. The data collected includes: 1. Ship data used as the object of research. Figure 3.2: General Arrangement of KM Ship. Mhar. MICHAEL KURNIAWAN 12 Study Case Here are the main data about the KM ship. Mhar and cargo equipment (Cargo Crane): Figure 3.3: Cargo Crane of KM Ship. Mhar Ship. 2. Specification of KM Ship Generator. Mhar Table 3.2.1: Specifications of generators used on KM ships. Mhar. MICHAEL KURNIAWAN 13 Study Case Table 3.2.2 Generator Specification Modeling and Simulation After the data is obtained, the next step is modeling the ship's electrical system using the Electrical Transient Analysis Program (ETAP). This modeling aims to design the system so that it can be simulated and analyzed further. Figure 3.5 SLD at software MICHAEL KURNIAWAN 14 Study Case In this modeling, there are several branch buses connected to the main bus, including: Figure 3.6 Bus Fuel System Figure 3.7 Bus Lo System Figure 3.8 GS System Bus MICHAEL KURNIAWAN 15 Study Case Figure 3.9 Main Deck Bus Figure 3.10 Poop Deck Bus Figure 3.11 ESB Bus After the modeling is complete, the system will be run in simulation to analyze the voltage stability and system response to various operational conditions. MICHAEL KURNIAWAN 16 Study Case RESULTS AND DISCUSSION General Description The Single Line Diagram of the General Cargo ship electrical system is modeled using ETAP 12.6 software, based on the IV design design data that has been calculated previously. Simulations are carried out to analyze system stability when experiencing major disturbances, such as generator outage, motor starting, and short circuit. General Cargo ship electrical systems generally implement an interconnection system to increase reliability when a disturbance occurs. The advantage of this system is its ability to channel power from several generators to the load, so that the electricity supply is maintained. In this research, the ship's electrical system is developed using a ring distribution system, with the aim of increasing system reliability when facing sudden major disturbances. General Cargo ships have main buses and branch buses connected to the interconnection system and ring system. The voltage generated is utilized to operate low voltage motors, lump loads, and various other electrical equipment. General Cargo Ship Case Study Planning System testing against disturbances aims to analyze the system's response to various possible disturbances. Therefore, a simulation is carried out by giving a direct disturbance to the ship's electrical system. Some types of disturbances analyzed in this study include: 1. Generator Outage When a vessel undergoes a change of state, for example from loading and unloading to sailing, it is possible that 1-2 generators will be removed from the system. In this condition, monitoring of the system transient response, including changes in frequency and voltage after the disturbance occurs, is carried out to ensure that the system continues to operate according to established standards. 2. Motor Starting In this scenario, the induction motor with the largest power in the system, namely the induction motor on the loading and unloading crane, will be started when the system is already running, which is 2 seconds after the operation starts. The system response to this condition, especially the voltage changes during the starting process, is analyzed to assess the stability of the system. 3. Short Circuit In this case, a three-phase short circuit is assumed to occur on one of the system buses. This fault can have a significant impact on the stability of the system as a whole. The analysis is carried out to assess the impact of the disturbance and how the circuit breaker (CB) responds in handling the disturbance. MICHAEL KURNIAWAN 17 Study Case The following is Table 4.1, which summarizes the case study that will be tested on the General Cargo ship electrical system during the Cargo Handling process. This table also includes information related to the equipment affected by the disturbance and the circuit breaker (CB) response in dealing with these conditions. Table 4.1 Case Study of System cargo Ship Handling No Case Study 1 Cargo Handling - 1 Gen.OFF Description Generator 3 disconnects from the system after 2 seconds of system operation 2 Cargo Handling - 2 Gen.OFF Generators 2 and 3 are removed from the system after 2&3 seconds. 3 Cargo Handling - 1Gen.OFF + Load shedding (LS1) Generator 3 is released from the system then proceed with the load shedding scheme 4 Cargo Handling - 1 Motor Start (MS1) 1 The Cargo Crane motor on the main deck bus is started at 3 seconds after the system starts. 5 Cargo Handling - 2 Motor Start 2 Cargo Crane motors on the main deck (MS1) bus are started simultaneously when 5 seconds after the system is running. Steps to Achieve System Stability 1. The stability of the electrical system is influenced by disturbances that occur, so it is necessary to analyze the response of frequency, voltage, and rotor angle at the bus and generator as a reference for system stability. Some steps taken to maintain system stability include: 2. Observing changes in frequency, voltage, and rotor angle due to large disturbances that appear suddenly. 3. Analyze whether the changes are still within permissible limits and ensure the system can return to a stable condition after the disturbance. 4. If the disturbance causes the system to become unstable, then load shedding is carried out as a preventive measure. MICHAEL KURNIAWAN 18 Study Case Transient Stability Simulation System stability response can be analyzed by modeling using ETAP software, which allows representation of disturbances that may occur in the field. With this modeling, system stability testing becomes more practical and systematic. Transient stability simulations on General Cargo ships are carried out with several scenarios, such as during the loading and unloading process, sailing, and ship maneuvers, with various types of disturbances, including generator disconnection, motor starting, and short circuit. The stability analysis results are obtained by comparing the system voltage response in each disturbance scenario. Transient Stability Simulation When Generator Outage In this simulation, tests are carried out on the impact of generator release from the electricity system with various scenarios as follows: 1. Scenario 1: One Generator Outage (1Gen.OFF, t = 2s) In this scenario, the system has been operating for 2 seconds before experiencing a disturbance in the form of the release of one generator (Generator 3). This disturbance causes the voltage on the main bus to decrease, with the biggest impact occurring on the bus directly connected to the generator. From the simulation results, there is a voltage transient, where other generators try to stabilize the system conditions. The largest voltage drop was recorded at 24.45% at the 6th second. This voltage drop occurs because the load remains the same, but the available power is reduced due to the loss of the generator. With a fixed amount of power, the current that must be supplied to the load increases, so the voltage drops significantly. Based on voltage standards, this condition is not safe for equipment, so load shedding and the use of voltage relays are required to keep the voltage within the allowed limits. MICHAEL KURNIAWAN 19 Study Case 2. Scenario 2: Removal of Two Generators (2Gen.OFF, t = 2s & 3s) In this scenario, Generator 2 and Generator 3 experienced a disturbance and left the system gradually, namely at seconds 2 and 3. Based on the simulation results: - At 2.8 seconds, the voltage dropped to 90.4%. - At 3 seconds, there was a more drastic voltage drop. - The largest drop reached 46.06% at the 8.2 second. According to voltage standards, this condition is high risk and can cause damage to most equipment components. Therefore, the system should not be operated under these voltage conditions. 3. Scenario 3: Removal of One Generator with Load Shedding (1Gen.OFF + LS1, t = 1s) MICHAEL KURNIAWAN 20 Study Case In this scenario, after Generator 3 was released at the 2nd second, load shedding (LS1) was performed to reduce the impact of the disturbance on the system. When compared to the first scenario, it can be seen that: The voltage did not decrease drastically, but dropped to 73.8%, and then increased again to 112.1% at the 11th second. Although the stability of the system improved with the Load Shedding method, the voltage is still not fully within safe limits. Therefore, it is necessary to conduct additional analysis so that the voltage does not experience excessive overvoltage or undervoltage. Simulation of Transient Stability When Starting Motor This simulation is carried out with the assumption that a three-phase induction motor (Cargo Crane) is operated after the system is running. This motor with large power has the potential to affect system stability, so it is necessary to analyze how it affects the voltage of the electrical system. 1. Scenario 1: Starting One Motor (t = 3s) In this scenario, the motor of Cargo Crane 1 starts operating after the system runs for 3 seconds. Based on the simulation results: - The voltage experienced transients due to the high starting current of the motor. - The current required during starting is usually 6-10 times the nominal current. - The lowest voltage was recorded at 4.6 seconds, which was 94.79%. - The highest voltage occurred at 8 seconds, which was 105.63%. - Since the voltage is still within safe limits, a motor with a power of 134 kW MICHAEL KURNIAWAN 21 Study Case can still be operated under these conditions without destabilizing the system. 2. Scenario 2: Starting Two Motors (t = 5s) In this scenario, the motors of Cargo Crane 1 and Cargo Crane 2 are started simultaneously after the system has been running for 5 seconds. From the simulation results: - There are larger voltage transients compared to the previous scenario. - The lowest voltage dropped to 18.3% at the 19th second. - The highest voltage was recorded at 104.12% at the 8th second. - After reaching steady state, the voltage was at 87.74% at the 22.01nd second. Based on voltage standards, this condition is unsafe because the voltage drop is too large. Therefore, two motors should not be switched on simultaneously, as it may cause the system to become unstable. CONCLUSION Based on the simulation results and analysis in this final project, some conclusions that can be drawn are as follows: 1. Disturbances due to the release of generators in scenarios 1Gen.OFF and 2Gen.OFF before the implementation of load shedding have the potential to destabilize the electrical system of the General Cargo ship. This disturbance causes the lowest voltage drop on Bus 1, which is 24.45% at the 6th second and 46.06% at the 8th.2 second. 2. The application of load shedding in the 1Gen.OFF scenario is needed to maintain the stability of the system to stay within the allowable limits, in accordance with the voltage standards set by BKI. 3. Starting a motor for one Cargo Crane with a power of 134 kW when three generators are operating is still allowed, because the voltage changes that occur are still within MICHAEL KURNIAWAN 22 Study Case the tolerance limits according to BKI standards. This process caused the lowest voltage drop of 99.75% at the 1.821th second. 4. Starting motors for two 2 × 134 kW Cargo Cranes directly when three generators are operating is not allowed, as it causes a significant voltage drop. This process resulted in the lowest voltage dropping to 18.3% at the 19th second, potentially destabilizing the system. 5. From the results of this analysis, it can be concluded that load management and the application of load shedding strategies are very important to maintain the stability of the General Cargo ship's electrical system, especially in the face of sudden load disturbances or surges. MICHAEL KURNIAWAN 23 Study Case REFERENCE MICHAEL KURNIAWAN 24 Study Case MICHAEL KURNIAWAN 25