Wind Power Applications Research Articles

Design of 66 kV dry-type step-up transformers for large capacity wind turbines

<p indent="0mm">The development of large-scale offshore wind power has become an inevitable trend in the current renewable energy development. Offshore wind power has moved from offshore to deep-sea, and the capacity of wind turbines has reached more than <sc>8 MW.</sc> The step-up transformer increases the output voltage of the wind turbine from <sc>0.69–1.4</sc> to <sc>35 kV</sc> and above, which is the key equipment of the wind power system. The deep-sea wind power is more than <sc>50 km</sc> away, and the voltage of the step-up transformer needs to be increased to <sc>66 kV</sc> and above. At present, the <sc>66 kV</sc> step-up transformer for offshore wind power generally adopts oil-immersed transformer technology, and <sc>66 kV</sc> step-up transformer with dry-type insulation is a blank product. Oil-immersed step-up transformers have the risk of oil leakage, which may cause fire or explosion accidents, while dry-type insulation step-up transformers have low fire risk, good explosion-proof performance, and new high reliability, and have significant technical advantages in offshore wind power applications. However, limited by the design method and manufacturing process technology, the traditional epoxy casting step-up transformer cannot solve the problem of excessive partial discharge under high voltage, which is caused by high-voltage winding interface defects, restricting the application of this technology in66 kV step-up transformers. This paper breaks through the technical limitations of traditional epoxy cast transformers, innovates from the insulation design mechanism, and proposes a new design method for a <sc>66 kV</sc>/10 MVA step-up transformer based on silicone rubber insulation. By analyzing the generation mechanism of the interface defect of the epoxy casting transformer’s high-voltage winding, a design method of high-voltage insulated shielding wires incorporating semiconducting shielding layers is proposed. The outer conductor of the wire is first wrapped with the semiconducting shielding layer, and then the insulating layer is wrapped. The semiconducting shielding layer and the insulating layer use same base materials. The semiconducting shielding layer can shield the conductor interface defects, the material of the semiconducting shielding layer is designed with the same base material of the insulating layer, so the two layers can be fully compatible, which can effectively suppress the interface defects. According to a certain winding form, the high-voltage insulated shielding wire is wound into a coil structure with a certain number of turns, then integrally cast silicone rubber insulation, forming the overall structure of the high-voltage winding. The high-voltage winding is designed with sheds structure, which increases the creepage distance along the surface, and realizes the high creepage insulation design with a compact height space. The <sc>66 kV</sc>/10 MVA step-up transformer structure is designed, taking into account factors such as insulation, electric field, magnetic field, heat dissipation, and structural strength, etc. The electric field, magnetic field and thermal field of the 66 kV/10 MVA step-up transformer under steady-state operating conditions were analyzed, the electric field distribution characteristics and maximum field strength parameters of the high-voltage winding were obtained, and the magnetic field distribution and thermal field distribution characteristics of the transformer were analyzed. The rationality of the step-up transformer design is verified by multiphysics analysis. The principle prototype of 66 kV transformers was developed, and AC withstand voltage and partial discharge tests were carried out. Under the test parameters of 55 kV/<sc>30 min,</sc> the partial discharge amount was less than 5 pC. The terminal-to-ground 120 kV/<sc>1 h</sc> withstand voltage test was carried out on the high-voltage winding, during the test, partial discharge amount is less than 5 pC, the performance is good, which verifies the feasibility of the design method.

Detailed Model of the Grid-Connected Cascaded Doubly Fed Induction Machine

The Cascaded (Brushless) Doubly-Fed Induction Machine (CDFIM) is a promising substitute for the commonly used Doubly-Fed Induction Machines (DFIM) for wind power application. The CDFIM offers reliable performance and low maintenance due to the absence of slip rings and graphite brushes. In this study, a detailed analytical model for the CDFIM is proposed in order to clearly show the controllable input (i.e., current from inverter side) and output (i.e., total output torque) relationship. The proposed model is expressed in the frequency (Laplace) domain. Field oriented (i.e., vector) control approach is adopted in order to achieve a precise dynamic model for the grid connected CDFIM. The steady-state and dynamic behavior of derived torque terms are presented and explained individually. Dynamic response of the total output torque is calculated, both analytically and numerically in a simulation and the results are shown to be consistent. Next, the torque-sharing and power-sharing concepts of the CDFIM are presented to further study the system behavior under different rotor velocities. Finally, to verify the proposed model, an experimental setup, using a cascaded DFIM was used, and the results are reported.

A comparative study of five numerical methods for the estimation of Weibull parameters for wind energy evaluation at Eastern Jerusalem, Palestine

Wind power provides a clean and feasible solution to generate electricity. The development of wind power applications requires a deep analysis of wind profiles and an accurate prediction of wind energy at a study site. This work explores the distribution of wind speed to estimate the two Weibull parameters (shape and scale) that are widely utilized for modeling and providing an accurate and efficient estimation of wind resource and power. These two parameters are calculated based on measured daily wind speed data from 2008 to 2018, collected in Jerusalem, Palestine. Three assessment criteria were used to assess the goodness of fit; they are Root Mean Square Error (RMSE), Mean Absolute Percentage Error (MAPE), and chi-square. The findings revealed that of the five estimation methods being considered in this study, both the Empirical Method (EM) and the Method of Moment (MoM) were the most accurate in determining the values of the Weibull shape and scale parameters to approximate wind speed distribution at the study site. Based on the goodness-of-fit tests, both methods provide lower values of the used assessment criteria. The statistical performance tests rejected the Energy Pattern Factor Method (EPFM) as an adequate method due to the higher values of chi-square and revealed that the Maximum Likelihood (MLM) and the Modified Maximum Likelihood (MMLM) methods ranked third and fourth, respectively.

Exploring Wind Speed for Energy Considerations in Eastern Jerusalem-Palestine Using Machine-Learning Algorithms

Wind energy is one of the fastest growing sources of energy worldwide. This is clear from the high volume of wind power applications that have been increased in recent years. However, the uncertain nature of wind speed induces several challenges towards the development of efficient applications that require a deep analysis of wind speed data and an accurate wind energy potential at a site. Therefore, wind speed forecasting plays a crucial rule in reducing this uncertainty and improving application efficiency. In this paper, we experimented with several forecasting models coming from both machine-learning and deep-learning paradigms to predict wind speed in a metrological wind station located in East Jerusalem, Palestine. The wind speed data were obtained, modelled, and forecasted using six machine-learning techniques, namely Multiple Linear Regression (MLR), lasso regression, ridge regression, Support Vector Regression (SVR), random forest, and deep Artificial Neural Network (ANN). Five variables were considered to develop the wind speed prediction models: timestamp, hourly wind speed, pressure, temperature, and direction. The performance of the models was evaluated using four statistical error measures: Root Mean Square Error (RMSE), Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and coefficient of determination (R2). The experimental results demonstrated that the random forest followed by the LSMT-RNN outperformed the other techniques in terms of wind speed prediction accuracy for the study site.

Performance improvement of stand-alone induction generator using distribution SSC for wind power application

Self-excited induction generators (SEIGs) are used in wind turbine system because of high reliability, rigidity, simple structure, and capability to work under severe badly operating conditions. This type of generator has a poor terminal voltage and frequency regulation during changing the connected loads due to the absence of constant excitation current. Therefore, it is essential to stabilize the generated voltage and frequency besides suppress the injected harmonic current components. In this work, the dynamic performance of SEIG with distribution static series compensator (DSSC) is analyzed. The DSSC based on neuro-fuzzy controlled (NFC) is applied to control both voltage and frequency to enhance the regulation of SEIG. The NFC is used to control the DSSC which leads to balance the requirement of the reactive and active power of stand-alone grid under load variation and attempts to obtain a constant terminal voltage. The model is simulated using MATLAB/Simulink. The NFC structure designed to regulate and control the output voltage of the SEIG driven by a wind turbine to feed a consumer in remote and rural places. Furthermore, the power system parameters calculated depending on the d-q theory. Modeling results explained that the suggested controller is consistent and tough related to the conventional types.

Design of Active Continuous Variable Transmission Control System with Planetary Gear

Planetary gearboxes have been employed in various applications due to their advantages of maintaining a high speed-reduction ratio, such as in wind power applications which have now become a prevailing green energy resource. A traditional power transmission machine of the wind turbine has a fixed gear-ratio mechanical gearbox for speed-increasing transmission. The purpose of this study is to propose an active continuous variable transmission (ACVT) control system with a planetary gear to apply to the wind turbine. The planetary gear holds three terminals, i.e., the ring gear, the planet carrier, and sun gear, and the motions of three terminals can be controlled purposely by the servomotors to achieve ACVT. The three different transmission types of the proposed ACVT can be operated. The dynamic characteristic of the planetary gear is expressed in block diagram form, and a pseudo derivative feedback feed-forward controller of the velocity control loop is designed for the required performance. The results can be used to verify the effect of the proposed ACVT with the planetary gear.

Energy production features of rooftop hybrid photovoltaic–wind system and matching analysis with building energy use

Rooftop photovoltaic (PV)–wind hybrid systems serve as a promising energy supply source to mitigate environmental concerns and satisfy high energy demands. Most of energy matching studies focused on the matching capability of photovoltaic generation with building load, and the application of wind power to complement PV was rarely considered. In the context, this study explored the production aspects of PV–wind turbine (WT) hybrid systems and their potential to meet building energy use demands in densely built urban areas. Both solar and wind resources in 18 cities in eastern China were classified into three energy output levels, and Hangzhou was selected as a representative city for analysis of the complementarity of the two resources. Based on the modeling of hybrid PV–wind system generation, a PV/WT production feature curve was generated by k-means clustering. The matching between renewable energy production and building energy use and the influences of different wind resources and building heights were analyzed for rooftop hybrid systems in two typical residential buildings. The results reveal that the wind and solar resources in Hangzhou are partly complementary in terms of time sequence and power output. For the multi-story and high-rise residential building considered, a rooftop hybrid PV–WT system was concluded to be beneficial in improving energy generation, reliability, and load matching performance in a limited space. The technical performance for the high-rise case was inferior to that for the multi-story case considered. In the case of residential buildings, the matching between on-site supply and load is influenced by the local wind resources and building height. The richer the urban wind resource, the greater the load cover ratio and the self-sufficiency of the installed rooftop hybrid system. However, the load matching performance declines with increasing building height. The proposed general method for analyzing rooftop hybrid PV–WT systems can enable widespread and efficient solar and wind energy utilization in densely populated and built urban areas.

ASSESSMENT OF THE PROSPECTS FOR THE USE OF WIND POWER IN THE TURKESTAN REGION

The article considers proposals on the prospects of wind power in various regions of the Turkestan region based on statistical data on wind speed. The average wind speed in the Turkestan region was determined by means of Internet programming, methods of analysis and evaluation of promising proposals. Based on the results of the examination, it was found that the wind speed in the Turkestan region is the most effective when using alternative energy sources, including wind energy. A physical comparative analysis of the amount of power that can be obtained from a wind power plant and electricity sources was also carried out. The results of the study can be used as a theoretical basis for the application of wind power in the Turkestan region and in the preparation of state programs. In the course of our research work, the Disa A300, Terex TW 600, Direct wind 900/52 wind turbines were considered, taking into account that the average annual wind speed ranges from 3-6 m/s. It was found that the average wind speed in May, June, July is 5-6 m/s. It was found that the amount of energy received from wind turbines during this period of time is higher than in other months. The introduction of wind power in the Turkestan region can become an incentive to improve the social situation of the population, reduce prices.

A new power system active rescheduling method considering the dispatchable plug-in electric vehicles and intermittent renewable energies

The significant penetration of renewable power generations (RGs) and the large-scale use of plug-in electric vehicles (PEVs) have brought tangible impacts in tackling the climate change challenge the mankind has been facing due to substantive green-house gas and pollutant emissions from fossil-fuel based thermal power generation plants. However, the uncertainty of RGs has also exerted significant challenges to the grid operation and control. Therefore, dynamic power system scheduling to accommodate the intermittent RGs and mass roll-out of PEVs has become extremely important. In this paper, a novel power system rescheduling strategy is proposed to tackle this problem. Considering the uncertainty of the wind energy, a set of indices according to different wind power application scenarios is proposed to initiate a rescheduling scheme for power generations. In addition, a social learning particle swarm optimization algorithm based on real-value and binary parallel is proposed to schedule the output of generator units and the charging and discharging of the PEV. The effectiveness of the proposed active rescheduling framework and solving algorithm has been verified by extensive experiments considering different number of generating units and scenarios, achieving up to over 5.3% cost reduction. The experimental results have also shown that through expropriate management of the charging and discharging of PEVs would be significantly alleviate the negative impact on the grid stability caused by the intermittent wind power generations.

Electromagnetic characteristic analysis of a REBCO magnet with a current bypass/distribution winding technique under an asynchronous rotating magnetic field

Generally, high-temperature superconducting rotating machines (HTSRMs) are considered synchronous machines. If the output of the HTSRM fluctuates based on frequent changes in the electrical or mechanical loads, there is the concern that an asynchronous rotating magnetic field (RMF) is applied from the stationary copper armature winding to the high-temperature superconducting (HTS) field winding in the rotary. This may act as a magnetic disturbance to the HTS field magnet, resulting in permanent damage. To enhance the reliability of HTS magnets in wind power and electric propulsion applications, winding methods with current bypass/distribution characteristics, such as no-insulation (NI) and metal-insulation (MI), have attracted scholarly attention because of their high thermal and electrical stabilities, resulting in their self-stabilizing and protective performances. To verify the feasibility of the NI and MI winding techniques for wind power generators, the basic characteristics under a time-varying magnetic field must be studied, contrary to HTS magnet applications under a time-static magnetic field. Therefore, the electromagnetic characteristics of rare-earth barium copper oxide (REBCO) magnets applied with NI and MI winding technologies were compared and analyzed in this study, considering the magnetically transient situations in which an asynchronous RMF is applied to REBCO magnets. In addition, we developed a characteristic evaluation device similar to a synchronous rotating machine to generate the unsynchronized RMF. Moreover, various basic tests were performed to target the small racetrack-type field windings. The critical current, n-value, terminal voltage, and center magnetic field are investigated under various values of the frequency and current amplitude of the three-phase armature winding, and their behaviors are discussed in detail based on the characteristic resistances of the two test magnets.

Comparative study of reformed neural network based short‐term wind power forecasting models

Short-term prediction of wind power plays a vital role in wind power application. In order to improve the accuracy of wind power forecasting, this paper investigates neural network combined forecasting models to forecast the wind power, the data of a real wind farm, the Pacific Wind Farm, is used. In view of the difficulty of predicting the large fluctuations of wind power, the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) algorithm is used to decompose the wind power time series which can reduce the complexity of the forecasting process, and then the intrinsic mode function (IMF) signal is predicted by the BP Neural Network, wavelet neural network (WNN) and long short-term memory (LSTM) neural network respectively, and the final result is obtained through wavelet reconstruction. By comparing with a single model, the combined prediction model has better prediction accuracy and stability, among them, the NMAE predicted by CEEMDAN-GA-BP in January was 4.167%, and the NRMSE was 6.590%. Reformed neural network based short-term wind power forecasting models proposed in here provides very useful information for operation and control of high renewable energy penetrated power systems.

A Review on Switched Reluctance Generators in Wind Power Applications: Fundamentals, Control and Future Trends

With the ever growing environmental concerns, renewable energy sources emerge as a promise of clean and abundant energy, enabling long-term sustainable development. In this context, wind power gained significant interest due to its relative low cost and availability. Switched reluctance generators (SRGs) are suitable candidates for wind energy conversion systems, as they present a simple structure, robustness, a wide range of speed and are capable of operating in harsh environments. The machine, however, poses challenges such as high torque ripple, acoustic noise production and highly nonlinear behavior. Nonetheless, with the use of adequate control strategies, high dynamic performance SRG-based wind energy conversion systems can be achieved. As a result, this article presents a state of the art review of SRGs in wind power applications. First, the fundamentals of the SRG are presented. Next, two categories of firing angle control are reviewed: optimization and closed-loop control. Then, voltage and power control strategies are discussed, being divided in model-independent and model-based approaches. After that, a review on grid-tied SRG-based wind energy conversion systems is carried out. The most common filter topologies as well as the employed control strategies are detailed. Lastly, an outline of the discussed topics is presented and future trends as well as suggestions for future investigation are listed.

Permanent Magnet Vernier Machines for Direct-Drive Offshore Wind Power: Benefits and Challenges

Permanent magnet Vernier (PM-V) machines, at low power levels (few kWs), have shown a great potential to improve the torque density of existing direct-drive PM machines without much compromising on efficiency or making the machine structure more complicated. An improved torque density is very desirable for offshore wind power applications where the size of the direct-drive machine is an increasing concern. However, the relatively poor power factors of the PM-V machines will increase the power converter rating and hence cost. The objective of this paper is to review the benefits and challenges of PM-V machines for direct-drive offshore wind power applications. The review has been presented considering the system-level (direct-drive generator + converter) performance comparison between the surface-mounted permanent magnet Vernier (SPM-V) machines and the conventional SPM machines. It includes the indepth discussion on the challenges facing the PM-V machines when they are scaled up for multi-MW offshore wind power application. Other PM-V topologies discussed in literature have also been reviewed to asses their suitability for offshore wind power application.

Grid Forming Stator Flux Control of Doubly-Fed Induction Generator

The doubly fed induction generator is widely used in wind power applications. For stand-alone operation of this machine, the control of the stator flux with fixed voltage and frequency has been proposed. This paper extends the stator flux control of the doubly fed induction machine by droop mechanisms, which vary the setpoint of flux magnitude and frequency depending on active and reactive power. This gives the doubly fed induction generator system unknown grid supporting and grid forming performance. The validation of the proposed control scheme has been conducted on a 10kVA testbed system. The closed-loop behavior of the system has been proven to enable grid-tied and islanded operation with the same control structure. The system response to load changes and islanding events show no disruptive transients in both conditions.

Improved dfig dftc by using a fractional-order super twisting algorithms in wind power application

Background: The direct flux and torque control are a robust, simple, and alternative approach control formulation that does not require decomposition into symmetrical components; the direct flux and torque control schemes have been proved to be preponderant for doubly-fed induction generators due to the simple implementation.&#x0D; Aim: This work presents the minimization of electromagnetic torque and rotor flux undulations of doubly-fed induction generators using fractional-order super twisting algorithms and modified space vector modulation techniques.&#x0D; Methods: The main role of direct flux and torque control is to regulate and control the electromagnetic torque and rotor flux of doubly-fed induction generators for wind turbine systems. The direct flux and torque control is a traditional control algorithm and robust technique. Fractional-order super twisting algorithms are a new and proposed nonlinear controller; characterized by a robust controller and a simpler algorithm, which gives a good harmonic distortion of current compared to other methods.&#x0D; Novelty: The A fractional-order super twisting algorithm is proposed. Proposed nonlinear controller construction is based on the traditional super twisting algorithm and fractional calculus to obtain a robust controller and reduces the electromagnetic torque and rotor flux undulations of doubly-fed induction generators. We use in our study a 1.5 MW doubly-fed induction generator integrated into a single-rotor wind turbine system to minimizes the electromagnetic torque, stator current, rotor flux undulations. As shown in the results figures using fractional-order super twisting algorithms ameliorate effectiveness especially minimizes the electromagnetic torque and rotor flux, and minimizes harmonic distortion of stator current (0.16 %) compared to the traditional control scheme.&#x0D; Results: As shown in the results figures using fractional-order super twisting algorithms ameliorate effectiveness especially minimizes the electromagnetic torque and rotor flux, and minimizes harmonic distortion of stator current (0.16 %) compared to the traditional control scheme.&#x0D; Conclusion: The direct flux and torque control are a robust, simple, and alternative approach control formulation that does not require decomposition into symmetrical components; the direct flux and torque control schemes have been proved to be preponderant for doubly-fed induction generators due to the simple implementation.

Fuzzy Logic Based Fault Current Prediction in Double Fed Induction Generator Based Wind Turbine System

Over the past few years, the wind turbine industry has expanded widely and is increasingly taking production into account. There are various reasons why wind energy in electricity networks can be accumulated. In the event of a wind production, it not only remains safe and sustainable, but has low operating costs. DFIG's numerous advantages in the production of power electronic converters and the growth of double feeding induction generators, and their benefits of low conversion capacities, high energy and flexible power control were extensively used in large-scale wind power applications. DFIG as a wind turbine linked to a grid which is subjected to various forms of faults in this innovation. Crowbar is used and is a kind of a safety mechanism for wind turbine generators. Fuzzy Logic is also used to safeguard DFIG for defects presented in this paper.

Dynamic Modeling and Control of BDFRG under Unbalanced Grid Conditions

The Brushless Doubly-Fed Reluctance Generator (BDFRG) is a potential alternative to the Doubly Fed Induction Generator (DFIG) in wind power applications owing to its reasonable cost, competitive performance, and high reliability. In comparison with the Brushless Doubly-Fed Induction Generator (BDFIG), the BDFRG is more efficient and easier to control owing to the cage-less rotor. One of the most preferable advantages of BDFRG over DFIG is the inherently better performance under unbalanced grid conditions. The study conducted in this paper showed that conventional vector control of the BDFRG results in excessive oscillations of the primary active/reactive power, electromagnetic torque, and primary/secondary currents in this case. In order to address such limitations, this paper presented a new control strategy for the unbalanced operation of BDFRG-based wind generation systems. A modified vector control scheme was proposed with the capability to control the positive and the negative sequences of the secondary currents independently, thus greatly reducing the adverse implications of the unbalanced supply. The controller performance has been validated by simulations using a 1.5 MW BDFRG dynamical model built upon the positive and negative sequence equations. The main benefits of the new control strategy are quantified in comparison with conventional PI current control design.

Global warming potential and energy dynamics of conservation tillage practices for different rabi crops in the Indo-Gangetic Plains

A field experiment was conducted during 2007–2019 under various rabi (winter) crops (viz., wheat, maize, barley and mustard) on a Vertisol in sub-tropical Indo-Gangetic Plains (IGP) with different tillage systems to assess energy indices, greenhouse gas (GHG) emission and carbon sustainability index in assured irrigated fields. The tillage systems were: no tillage sown by a zero till drill (NT), no tillage with retention of previous crop residues at 6 t ha−1 and sowing by a happy turbo seeder (HT), and conventional tillage (CT) where sowing was performed by a multi-crop zero till drill after twice harrowing + twice tilling + once rotavator operations. Significantly higher input energy was observed in wheat followed by maize, barley and mustard. Among tillage systems, CT plots consumed higher input energy that was about 20, 21 to 22, 25 to 26 and 20–22% higher than HT and NT in wheat, maize, barley and mustard, respectively. However, output energy and energy use efficiency were highest in HT. The total GHG emission (kg CO2 equivalent ha−1) was highest in wheat (2,351) followed by maize (2,274), barley (1,859) and mustard (1,652). Among tillage systems, CT produced about 31–34%, 33–34%, 37–40% and 28–30% higher GHG emission than HT and NT under wheat, maize, barley and mustard, respectively. The CT plots had lower carbon sustainability index and carbon efficiency than ZT and HT in all crops. In short, HT recorded significantly higher energy use efficiency and lower global warming potential (GWP) than CT in all crops. Thus, HT could be a promising agro-technique for production of rabi crops in the IGP. Among rabi crops, barley production was energy efficient and had less GWP. In rabi crop production, the highest energy sources was mineral fertilizer use (25–49%) and second highest source was irrigation water (14–44%). These can be substituted with use of the organic sources of fertilizers and application of solar and wind power in irrigation, respectively.

Sensorless adaptive control of brushless doubly-fed reluctance generators for wind power applications

A novel model reference adaptive system for the rotor position/speed estimation and sensorless operation of a brushless doubly fed reluctance generator with maximum power point tracking is presented. Its main advantage over the existing designs are the inherent robustness and stability afforded by the complete parameter independence of the reference model using only the measured currents of the converter-fed (secondary) winding. In addition, the respective stationary frame current components are estimated by the adaptive model using the voltage and current measurements of the grid-connected (primary) winding at line frequency, offering higher accuracy. The simulation and experimental results have demonstrated the excellent real and reactive power controller performance for typical operating characteristics of wind turbines.

Design of a Medium Voltage Generator with DC-Cascade for High Power Wind Energy Conversion Systems

This paper shows a new concept to generate medium voltage (MV) in wind power application to avoid an additional transformer. Therefore, the generator must be redesigned with additional constraints and a new topology for the power rectifier system by using multiple low voltage (LV) power rectifiers connected in series and parallel to increase the DC output voltage. The combination of parallel and series connection of rectifiers is further introduced as DC-cascade. With the resulting DC-cascade, medium output voltage is achieved with low voltage rectifiers and without a bulky transformer. This approach to form a DC-cascade reduces the effort required to achieve medium DC voltage with a simple rectifier system. In this context, a suitable DC-cascade control was presented and verified with a laboratory test setup. A gearless synchronous generator, which is highly segmented so that each segment can be connected to its own power rectifier, is investigated. Due to the mixed AC and DC voltage given by the DC-cascade structure, it becomes more demanding to the design of the generator insulation, which influences the copper fill factor and the design of the cooling system. A design strategy for the overall generator design is carried out considering the new boundary conditions.